Dielectric Barrier Discharge (DBD) & Dielectric Barrier Discharge (DBD) & Progress in Large Progress in Large-Scale Ozone Generation Scale Ozone Generation d l l i l l i Progress in Large Progress in Large Scale Ozone Generation Scale Ozone Generation 3 rd rd Complex Plasma Summer Institute Complex Plasma Summer Institute Jose L Lopez PhD Jose L Lopez PhD Jose L. Lopez, PhD Jose L. Lopez, PhD Seton Hall University Seton Hall University Department of Physics Department of Physics South Orange, New Jersey (USA) South Orange, New Jersey (USA)
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Dielectric Barrier Discharge (DBD) amp Dielectric Barrier Discharge (DBD) amp Progress in LargeProgress in Large--Scale Ozone GenerationScale Ozone Generation
dd l l il l i
Progress in LargeProgress in Large Scale Ozone GenerationScale Ozone Generation
33rdrd Complex Plasma Summer InstituteComplex Plasma Summer Institute
Jose L Lopez PhDJose L Lopez PhDJose L Lopez PhDJose L Lopez PhD
Seton Hall UniversitySeton Hall UniversitySeto a U e s tySeto a U e s tyDepartment of PhysicsDepartment of Physics
South Orange New Jersey (USA)South Orange New Jersey (USA)
New Jersey New Jersey ndashndash Home of Seton HallHome of Seton Hall
New Jersey ndash The birth place of Plasma Science
Irving Langmuir (1881 ndash 1957) Nobel Laureate 1932Nobel Laureate 1932Birth of Plasma Science
The US Department of Energyrsquos Princeton Plasma Physics Laboratory (PPPL) is acollaborative national center for plasma and fusion science Its primary mission is tocollaborative national center for plasma and fusion science Its primary mission is todevelop the scientific understanding and the key innovations which will lead to anattractive fusion energy source Associated missions include conducting world-classresearch along the broad frontier of plasma science and technology and providing thehighest quality of scientific education
National Spherical Torus Experiment (NSTX)
Atmospheric Cold PlasmasErich Kunhardt amp Kurt Becker
An Atmospheric Pressure Plasma Generated with a
(Courtesy of K Becker)
Capillary-Plasma-Electrode Discharge
Two Types of plasmas
bull High‐temperature plasmas (Hot Plasmas)g p p ( )Tiasymp Te ge107 Keg fusion plasmas
T asymp T asymp T le 2 x 104 KTi asymp Te asymp Tg le 2 x 104 Keg arc plasma at normal pressure
bull Low‐temperature plasmas (Cold Plasmas)Ti asymp Tg asymp 300 KT ltlt T le 105 KTi ltlt Te le 105 Keg low‐pressure glow discharge
Plasmas are easier to be generated at low pressures
Low pressure plasmas (1 T f T )
at low pressures
are well understood
are used extensively nowadays
(1 mTorr ~ a few Torr)
are used extensively nowadays (eg in semiconductor industry for computer chips manufacturing)
However to generate low pressure plasmas
vacuum chambers + + = expensive vacuum pumps
pressure monitoring and pressure control devices
+ + =Generate Plasmas at Atmospheric PressureGenerate Plasmas at Atmospheric Pressure
What happens at air pressureWhat happens at air pressure
bull No vacuum is involvedDiffi l d ibull Difficult to generate and sustain
bull Run into some challenges such as glow toarc transition ndash Non controllable
Arc Discharge thermal plasma-Itrsquos hot and detrimental-Gas temperature can reach as high as 2x104 KGas temperature can reach as high as 2x10 K- Low voltage drop at cathode- High cathode current density
High Pressure Microplasmas
Stabilization of high-pressure plasmas ldquopd scalingrdquo ldquoprdquo uarr soplasmas pd scaling p uarr so ldquodrdquo darr to keep breakdown voltage low and minimize instabilities after breakdown -
MicroplasmasDimension a few millimeterDimension a few millimeter down to and below 100 m
Paschen Breakdown CurveH H i 60 100Human Hair 60 ndash 100 m
How do we solve this problemHow do we solve this problem
Transient (pulsed) plasmas In atmospheric plasmas for efficient gas heating atleast 100-1000 collisions are necessary Thus if the plasma duration is shorterleast 100 1000 collisions are necessary Thus if the plasma duration is shorterthan 10-6 ndash 10-5 s gas heating is limited Of course for practical purposes suchplasma has to be operated in a repetitive mode eg in trains of microsecondpulses with millisecond intervals
Micro-confinement Gas heating occurs in the plasma volume and the energy iscarried away by thermal diffusionconvection to the outside If the plasma has asmall volume and a relatively large surface gas heating is limited
Dielectric Barrier Discharges These plasmas are typically created betweenmetal plates which are covered by a thin layer of dielectric or highly resistivematerial The dielectric layer plays an important role in suppressing the currentthe cathodeanode layer is charged by incoming positive ionselectrons whichreduces the electric field and hinders charge transport towards the electrodeDBD also has a large surface-to-volume ratio which promotes diffusion lossesand maintains a low gas temperatureand maintains a low gas temperature
Advantages of Microplasmas Advantages of Microplasmas
bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures
Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y
hellip a new realm of plasma sciencehellip a new realm of plasma science
What can we do with microplasmasWhat can we do with microplasmas
Material Synthesis Plasma display Surface Treatment Lighting
H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)
Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges
Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)
Voltage Vpp 3ndash20 kV
Repetition frequency f 50 Hzndash30 kHz
Pressure p 1ndash3 bar
Gap distance g 02ndash5mm
Dielectric material thickness d 05ndash2mm
Relative dielectric permittivity r 5ndash10 (glass)
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Single and double DBD
Single dielectric Double dielectric
Role of the Dielectric (Insulator)
Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge
Serves two functions
1 Limits the amount of charge transportedby a single microplasma
2 Distributes the microplasmas over theentire electrode surface area
Equivalent Circuit of a Microdischarge
Microdischarge Activity and U-Q Lissajous Figure
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge
bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them
bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation
Time scale of the relevant processes of the DBD
HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)
Fundamental Operation of the DBDFundamental Operation of the DBD
Electron DensityTemporal Development (ns)
y
Outer Contour Linen = 1010 cm-3ne = 1010 cm 3
Inner Contour Linene = 1014 cm-3
Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)
E0=34 kVcm1010 cm-3
1010 cm-3 ne=1012 cm-3
1mm10 cm
ne=108 cm-3
An electron avalanche propagates towards the anode
Reverse propagationtowards the cathodepropagates towards the anode towards the cathode
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Cathode Layer Formation
E0=34 kVcm1010 cm-39 3 0
1mm
1010 cm-3
10 cmne=109 cm-31014
10131014
1013
10 cm1012
Just before the peak of the total current
Peak currentof the total current
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Local Field Collapse in Area Defined by Surface Discharge
ne=109cm-3 ne=1014 cm-3
Gap
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
C C-- - --- - - CG
CD
-- - - CG
CD
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
The US Department of Energyrsquos Princeton Plasma Physics Laboratory (PPPL) is acollaborative national center for plasma and fusion science Its primary mission is tocollaborative national center for plasma and fusion science Its primary mission is todevelop the scientific understanding and the key innovations which will lead to anattractive fusion energy source Associated missions include conducting world-classresearch along the broad frontier of plasma science and technology and providing thehighest quality of scientific education
National Spherical Torus Experiment (NSTX)
Atmospheric Cold PlasmasErich Kunhardt amp Kurt Becker
An Atmospheric Pressure Plasma Generated with a
(Courtesy of K Becker)
Capillary-Plasma-Electrode Discharge
Two Types of plasmas
bull High‐temperature plasmas (Hot Plasmas)g p p ( )Tiasymp Te ge107 Keg fusion plasmas
T asymp T asymp T le 2 x 104 KTi asymp Te asymp Tg le 2 x 104 Keg arc plasma at normal pressure
bull Low‐temperature plasmas (Cold Plasmas)Ti asymp Tg asymp 300 KT ltlt T le 105 KTi ltlt Te le 105 Keg low‐pressure glow discharge
Plasmas are easier to be generated at low pressures
Low pressure plasmas (1 T f T )
at low pressures
are well understood
are used extensively nowadays
(1 mTorr ~ a few Torr)
are used extensively nowadays (eg in semiconductor industry for computer chips manufacturing)
However to generate low pressure plasmas
vacuum chambers + + = expensive vacuum pumps
pressure monitoring and pressure control devices
+ + =Generate Plasmas at Atmospheric PressureGenerate Plasmas at Atmospheric Pressure
What happens at air pressureWhat happens at air pressure
bull No vacuum is involvedDiffi l d ibull Difficult to generate and sustain
bull Run into some challenges such as glow toarc transition ndash Non controllable
Arc Discharge thermal plasma-Itrsquos hot and detrimental-Gas temperature can reach as high as 2x104 KGas temperature can reach as high as 2x10 K- Low voltage drop at cathode- High cathode current density
High Pressure Microplasmas
Stabilization of high-pressure plasmas ldquopd scalingrdquo ldquoprdquo uarr soplasmas pd scaling p uarr so ldquodrdquo darr to keep breakdown voltage low and minimize instabilities after breakdown -
MicroplasmasDimension a few millimeterDimension a few millimeter down to and below 100 m
Paschen Breakdown CurveH H i 60 100Human Hair 60 ndash 100 m
How do we solve this problemHow do we solve this problem
Transient (pulsed) plasmas In atmospheric plasmas for efficient gas heating atleast 100-1000 collisions are necessary Thus if the plasma duration is shorterleast 100 1000 collisions are necessary Thus if the plasma duration is shorterthan 10-6 ndash 10-5 s gas heating is limited Of course for practical purposes suchplasma has to be operated in a repetitive mode eg in trains of microsecondpulses with millisecond intervals
Micro-confinement Gas heating occurs in the plasma volume and the energy iscarried away by thermal diffusionconvection to the outside If the plasma has asmall volume and a relatively large surface gas heating is limited
Dielectric Barrier Discharges These plasmas are typically created betweenmetal plates which are covered by a thin layer of dielectric or highly resistivematerial The dielectric layer plays an important role in suppressing the currentthe cathodeanode layer is charged by incoming positive ionselectrons whichreduces the electric field and hinders charge transport towards the electrodeDBD also has a large surface-to-volume ratio which promotes diffusion lossesand maintains a low gas temperatureand maintains a low gas temperature
Advantages of Microplasmas Advantages of Microplasmas
bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures
Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y
hellip a new realm of plasma sciencehellip a new realm of plasma science
What can we do with microplasmasWhat can we do with microplasmas
Material Synthesis Plasma display Surface Treatment Lighting
H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)
Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges
Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)
Voltage Vpp 3ndash20 kV
Repetition frequency f 50 Hzndash30 kHz
Pressure p 1ndash3 bar
Gap distance g 02ndash5mm
Dielectric material thickness d 05ndash2mm
Relative dielectric permittivity r 5ndash10 (glass)
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Single and double DBD
Single dielectric Double dielectric
Role of the Dielectric (Insulator)
Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge
Serves two functions
1 Limits the amount of charge transportedby a single microplasma
2 Distributes the microplasmas over theentire electrode surface area
Equivalent Circuit of a Microdischarge
Microdischarge Activity and U-Q Lissajous Figure
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge
bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them
bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation
Time scale of the relevant processes of the DBD
HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)
Fundamental Operation of the DBDFundamental Operation of the DBD
Electron DensityTemporal Development (ns)
y
Outer Contour Linen = 1010 cm-3ne = 1010 cm 3
Inner Contour Linene = 1014 cm-3
Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)
E0=34 kVcm1010 cm-3
1010 cm-3 ne=1012 cm-3
1mm10 cm
ne=108 cm-3
An electron avalanche propagates towards the anode
Reverse propagationtowards the cathodepropagates towards the anode towards the cathode
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Cathode Layer Formation
E0=34 kVcm1010 cm-39 3 0
1mm
1010 cm-3
10 cmne=109 cm-31014
10131014
1013
10 cm1012
Just before the peak of the total current
Peak currentof the total current
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Local Field Collapse in Area Defined by Surface Discharge
ne=109cm-3 ne=1014 cm-3
Gap
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
C C-- - --- - - CG
CD
-- - - CG
CD
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
The US Department of Energyrsquos Princeton Plasma Physics Laboratory (PPPL) is acollaborative national center for plasma and fusion science Its primary mission is tocollaborative national center for plasma and fusion science Its primary mission is todevelop the scientific understanding and the key innovations which will lead to anattractive fusion energy source Associated missions include conducting world-classresearch along the broad frontier of plasma science and technology and providing thehighest quality of scientific education
National Spherical Torus Experiment (NSTX)
Atmospheric Cold PlasmasErich Kunhardt amp Kurt Becker
An Atmospheric Pressure Plasma Generated with a
(Courtesy of K Becker)
Capillary-Plasma-Electrode Discharge
Two Types of plasmas
bull High‐temperature plasmas (Hot Plasmas)g p p ( )Tiasymp Te ge107 Keg fusion plasmas
T asymp T asymp T le 2 x 104 KTi asymp Te asymp Tg le 2 x 104 Keg arc plasma at normal pressure
bull Low‐temperature plasmas (Cold Plasmas)Ti asymp Tg asymp 300 KT ltlt T le 105 KTi ltlt Te le 105 Keg low‐pressure glow discharge
Plasmas are easier to be generated at low pressures
Low pressure plasmas (1 T f T )
at low pressures
are well understood
are used extensively nowadays
(1 mTorr ~ a few Torr)
are used extensively nowadays (eg in semiconductor industry for computer chips manufacturing)
However to generate low pressure plasmas
vacuum chambers + + = expensive vacuum pumps
pressure monitoring and pressure control devices
+ + =Generate Plasmas at Atmospheric PressureGenerate Plasmas at Atmospheric Pressure
What happens at air pressureWhat happens at air pressure
bull No vacuum is involvedDiffi l d ibull Difficult to generate and sustain
bull Run into some challenges such as glow toarc transition ndash Non controllable
Arc Discharge thermal plasma-Itrsquos hot and detrimental-Gas temperature can reach as high as 2x104 KGas temperature can reach as high as 2x10 K- Low voltage drop at cathode- High cathode current density
High Pressure Microplasmas
Stabilization of high-pressure plasmas ldquopd scalingrdquo ldquoprdquo uarr soplasmas pd scaling p uarr so ldquodrdquo darr to keep breakdown voltage low and minimize instabilities after breakdown -
MicroplasmasDimension a few millimeterDimension a few millimeter down to and below 100 m
Paschen Breakdown CurveH H i 60 100Human Hair 60 ndash 100 m
How do we solve this problemHow do we solve this problem
Transient (pulsed) plasmas In atmospheric plasmas for efficient gas heating atleast 100-1000 collisions are necessary Thus if the plasma duration is shorterleast 100 1000 collisions are necessary Thus if the plasma duration is shorterthan 10-6 ndash 10-5 s gas heating is limited Of course for practical purposes suchplasma has to be operated in a repetitive mode eg in trains of microsecondpulses with millisecond intervals
Micro-confinement Gas heating occurs in the plasma volume and the energy iscarried away by thermal diffusionconvection to the outside If the plasma has asmall volume and a relatively large surface gas heating is limited
Dielectric Barrier Discharges These plasmas are typically created betweenmetal plates which are covered by a thin layer of dielectric or highly resistivematerial The dielectric layer plays an important role in suppressing the currentthe cathodeanode layer is charged by incoming positive ionselectrons whichreduces the electric field and hinders charge transport towards the electrodeDBD also has a large surface-to-volume ratio which promotes diffusion lossesand maintains a low gas temperatureand maintains a low gas temperature
Advantages of Microplasmas Advantages of Microplasmas
bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures
Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y
hellip a new realm of plasma sciencehellip a new realm of plasma science
What can we do with microplasmasWhat can we do with microplasmas
Material Synthesis Plasma display Surface Treatment Lighting
H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)
Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges
Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)
Voltage Vpp 3ndash20 kV
Repetition frequency f 50 Hzndash30 kHz
Pressure p 1ndash3 bar
Gap distance g 02ndash5mm
Dielectric material thickness d 05ndash2mm
Relative dielectric permittivity r 5ndash10 (glass)
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Single and double DBD
Single dielectric Double dielectric
Role of the Dielectric (Insulator)
Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge
Serves two functions
1 Limits the amount of charge transportedby a single microplasma
2 Distributes the microplasmas over theentire electrode surface area
Equivalent Circuit of a Microdischarge
Microdischarge Activity and U-Q Lissajous Figure
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge
bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them
bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation
Time scale of the relevant processes of the DBD
HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)
Fundamental Operation of the DBDFundamental Operation of the DBD
Electron DensityTemporal Development (ns)
y
Outer Contour Linen = 1010 cm-3ne = 1010 cm 3
Inner Contour Linene = 1014 cm-3
Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)
E0=34 kVcm1010 cm-3
1010 cm-3 ne=1012 cm-3
1mm10 cm
ne=108 cm-3
An electron avalanche propagates towards the anode
Reverse propagationtowards the cathodepropagates towards the anode towards the cathode
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Cathode Layer Formation
E0=34 kVcm1010 cm-39 3 0
1mm
1010 cm-3
10 cmne=109 cm-31014
10131014
1013
10 cm1012
Just before the peak of the total current
Peak currentof the total current
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Local Field Collapse in Area Defined by Surface Discharge
ne=109cm-3 ne=1014 cm-3
Gap
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
C C-- - --- - - CG
CD
-- - - CG
CD
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
The US Department of Energyrsquos Princeton Plasma Physics Laboratory (PPPL) is acollaborative national center for plasma and fusion science Its primary mission is tocollaborative national center for plasma and fusion science Its primary mission is todevelop the scientific understanding and the key innovations which will lead to anattractive fusion energy source Associated missions include conducting world-classresearch along the broad frontier of plasma science and technology and providing thehighest quality of scientific education
National Spherical Torus Experiment (NSTX)
Atmospheric Cold PlasmasErich Kunhardt amp Kurt Becker
An Atmospheric Pressure Plasma Generated with a
(Courtesy of K Becker)
Capillary-Plasma-Electrode Discharge
Two Types of plasmas
bull High‐temperature plasmas (Hot Plasmas)g p p ( )Tiasymp Te ge107 Keg fusion plasmas
T asymp T asymp T le 2 x 104 KTi asymp Te asymp Tg le 2 x 104 Keg arc plasma at normal pressure
bull Low‐temperature plasmas (Cold Plasmas)Ti asymp Tg asymp 300 KT ltlt T le 105 KTi ltlt Te le 105 Keg low‐pressure glow discharge
Plasmas are easier to be generated at low pressures
Low pressure plasmas (1 T f T )
at low pressures
are well understood
are used extensively nowadays
(1 mTorr ~ a few Torr)
are used extensively nowadays (eg in semiconductor industry for computer chips manufacturing)
However to generate low pressure plasmas
vacuum chambers + + = expensive vacuum pumps
pressure monitoring and pressure control devices
+ + =Generate Plasmas at Atmospheric PressureGenerate Plasmas at Atmospheric Pressure
What happens at air pressureWhat happens at air pressure
bull No vacuum is involvedDiffi l d ibull Difficult to generate and sustain
bull Run into some challenges such as glow toarc transition ndash Non controllable
Arc Discharge thermal plasma-Itrsquos hot and detrimental-Gas temperature can reach as high as 2x104 KGas temperature can reach as high as 2x10 K- Low voltage drop at cathode- High cathode current density
High Pressure Microplasmas
Stabilization of high-pressure plasmas ldquopd scalingrdquo ldquoprdquo uarr soplasmas pd scaling p uarr so ldquodrdquo darr to keep breakdown voltage low and minimize instabilities after breakdown -
MicroplasmasDimension a few millimeterDimension a few millimeter down to and below 100 m
Paschen Breakdown CurveH H i 60 100Human Hair 60 ndash 100 m
How do we solve this problemHow do we solve this problem
Transient (pulsed) plasmas In atmospheric plasmas for efficient gas heating atleast 100-1000 collisions are necessary Thus if the plasma duration is shorterleast 100 1000 collisions are necessary Thus if the plasma duration is shorterthan 10-6 ndash 10-5 s gas heating is limited Of course for practical purposes suchplasma has to be operated in a repetitive mode eg in trains of microsecondpulses with millisecond intervals
Micro-confinement Gas heating occurs in the plasma volume and the energy iscarried away by thermal diffusionconvection to the outside If the plasma has asmall volume and a relatively large surface gas heating is limited
Dielectric Barrier Discharges These plasmas are typically created betweenmetal plates which are covered by a thin layer of dielectric or highly resistivematerial The dielectric layer plays an important role in suppressing the currentthe cathodeanode layer is charged by incoming positive ionselectrons whichreduces the electric field and hinders charge transport towards the electrodeDBD also has a large surface-to-volume ratio which promotes diffusion lossesand maintains a low gas temperatureand maintains a low gas temperature
Advantages of Microplasmas Advantages of Microplasmas
bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures
Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y
hellip a new realm of plasma sciencehellip a new realm of plasma science
What can we do with microplasmasWhat can we do with microplasmas
Material Synthesis Plasma display Surface Treatment Lighting
H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)
Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges
Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)
Voltage Vpp 3ndash20 kV
Repetition frequency f 50 Hzndash30 kHz
Pressure p 1ndash3 bar
Gap distance g 02ndash5mm
Dielectric material thickness d 05ndash2mm
Relative dielectric permittivity r 5ndash10 (glass)
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Single and double DBD
Single dielectric Double dielectric
Role of the Dielectric (Insulator)
Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge
Serves two functions
1 Limits the amount of charge transportedby a single microplasma
2 Distributes the microplasmas over theentire electrode surface area
Equivalent Circuit of a Microdischarge
Microdischarge Activity and U-Q Lissajous Figure
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge
bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them
bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation
Time scale of the relevant processes of the DBD
HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)
Fundamental Operation of the DBDFundamental Operation of the DBD
Electron DensityTemporal Development (ns)
y
Outer Contour Linen = 1010 cm-3ne = 1010 cm 3
Inner Contour Linene = 1014 cm-3
Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)
E0=34 kVcm1010 cm-3
1010 cm-3 ne=1012 cm-3
1mm10 cm
ne=108 cm-3
An electron avalanche propagates towards the anode
Reverse propagationtowards the cathodepropagates towards the anode towards the cathode
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Cathode Layer Formation
E0=34 kVcm1010 cm-39 3 0
1mm
1010 cm-3
10 cmne=109 cm-31014
10131014
1013
10 cm1012
Just before the peak of the total current
Peak currentof the total current
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Local Field Collapse in Area Defined by Surface Discharge
ne=109cm-3 ne=1014 cm-3
Gap
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
C C-- - --- - - CG
CD
-- - - CG
CD
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
The US Department of Energyrsquos Princeton Plasma Physics Laboratory (PPPL) is acollaborative national center for plasma and fusion science Its primary mission is tocollaborative national center for plasma and fusion science Its primary mission is todevelop the scientific understanding and the key innovations which will lead to anattractive fusion energy source Associated missions include conducting world-classresearch along the broad frontier of plasma science and technology and providing thehighest quality of scientific education
National Spherical Torus Experiment (NSTX)
Atmospheric Cold PlasmasErich Kunhardt amp Kurt Becker
An Atmospheric Pressure Plasma Generated with a
(Courtesy of K Becker)
Capillary-Plasma-Electrode Discharge
Two Types of plasmas
bull High‐temperature plasmas (Hot Plasmas)g p p ( )Tiasymp Te ge107 Keg fusion plasmas
T asymp T asymp T le 2 x 104 KTi asymp Te asymp Tg le 2 x 104 Keg arc plasma at normal pressure
bull Low‐temperature plasmas (Cold Plasmas)Ti asymp Tg asymp 300 KT ltlt T le 105 KTi ltlt Te le 105 Keg low‐pressure glow discharge
Plasmas are easier to be generated at low pressures
Low pressure plasmas (1 T f T )
at low pressures
are well understood
are used extensively nowadays
(1 mTorr ~ a few Torr)
are used extensively nowadays (eg in semiconductor industry for computer chips manufacturing)
However to generate low pressure plasmas
vacuum chambers + + = expensive vacuum pumps
pressure monitoring and pressure control devices
+ + =Generate Plasmas at Atmospheric PressureGenerate Plasmas at Atmospheric Pressure
What happens at air pressureWhat happens at air pressure
bull No vacuum is involvedDiffi l d ibull Difficult to generate and sustain
bull Run into some challenges such as glow toarc transition ndash Non controllable
Arc Discharge thermal plasma-Itrsquos hot and detrimental-Gas temperature can reach as high as 2x104 KGas temperature can reach as high as 2x10 K- Low voltage drop at cathode- High cathode current density
High Pressure Microplasmas
Stabilization of high-pressure plasmas ldquopd scalingrdquo ldquoprdquo uarr soplasmas pd scaling p uarr so ldquodrdquo darr to keep breakdown voltage low and minimize instabilities after breakdown -
MicroplasmasDimension a few millimeterDimension a few millimeter down to and below 100 m
Paschen Breakdown CurveH H i 60 100Human Hair 60 ndash 100 m
How do we solve this problemHow do we solve this problem
Transient (pulsed) plasmas In atmospheric plasmas for efficient gas heating atleast 100-1000 collisions are necessary Thus if the plasma duration is shorterleast 100 1000 collisions are necessary Thus if the plasma duration is shorterthan 10-6 ndash 10-5 s gas heating is limited Of course for practical purposes suchplasma has to be operated in a repetitive mode eg in trains of microsecondpulses with millisecond intervals
Micro-confinement Gas heating occurs in the plasma volume and the energy iscarried away by thermal diffusionconvection to the outside If the plasma has asmall volume and a relatively large surface gas heating is limited
Dielectric Barrier Discharges These plasmas are typically created betweenmetal plates which are covered by a thin layer of dielectric or highly resistivematerial The dielectric layer plays an important role in suppressing the currentthe cathodeanode layer is charged by incoming positive ionselectrons whichreduces the electric field and hinders charge transport towards the electrodeDBD also has a large surface-to-volume ratio which promotes diffusion lossesand maintains a low gas temperatureand maintains a low gas temperature
Advantages of Microplasmas Advantages of Microplasmas
bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures
Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y
hellip a new realm of plasma sciencehellip a new realm of plasma science
What can we do with microplasmasWhat can we do with microplasmas
Material Synthesis Plasma display Surface Treatment Lighting
H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)
Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges
Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)
Voltage Vpp 3ndash20 kV
Repetition frequency f 50 Hzndash30 kHz
Pressure p 1ndash3 bar
Gap distance g 02ndash5mm
Dielectric material thickness d 05ndash2mm
Relative dielectric permittivity r 5ndash10 (glass)
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Single and double DBD
Single dielectric Double dielectric
Role of the Dielectric (Insulator)
Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge
Serves two functions
1 Limits the amount of charge transportedby a single microplasma
2 Distributes the microplasmas over theentire electrode surface area
Equivalent Circuit of a Microdischarge
Microdischarge Activity and U-Q Lissajous Figure
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge
bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them
bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation
Time scale of the relevant processes of the DBD
HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)
Fundamental Operation of the DBDFundamental Operation of the DBD
Electron DensityTemporal Development (ns)
y
Outer Contour Linen = 1010 cm-3ne = 1010 cm 3
Inner Contour Linene = 1014 cm-3
Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)
E0=34 kVcm1010 cm-3
1010 cm-3 ne=1012 cm-3
1mm10 cm
ne=108 cm-3
An electron avalanche propagates towards the anode
Reverse propagationtowards the cathodepropagates towards the anode towards the cathode
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Cathode Layer Formation
E0=34 kVcm1010 cm-39 3 0
1mm
1010 cm-3
10 cmne=109 cm-31014
10131014
1013
10 cm1012
Just before the peak of the total current
Peak currentof the total current
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Local Field Collapse in Area Defined by Surface Discharge
ne=109cm-3 ne=1014 cm-3
Gap
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
C C-- - --- - - CG
CD
-- - - CG
CD
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
The US Department of Energyrsquos Princeton Plasma Physics Laboratory (PPPL) is acollaborative national center for plasma and fusion science Its primary mission is tocollaborative national center for plasma and fusion science Its primary mission is todevelop the scientific understanding and the key innovations which will lead to anattractive fusion energy source Associated missions include conducting world-classresearch along the broad frontier of plasma science and technology and providing thehighest quality of scientific education
National Spherical Torus Experiment (NSTX)
Atmospheric Cold PlasmasErich Kunhardt amp Kurt Becker
An Atmospheric Pressure Plasma Generated with a
(Courtesy of K Becker)
Capillary-Plasma-Electrode Discharge
Two Types of plasmas
bull High‐temperature plasmas (Hot Plasmas)g p p ( )Tiasymp Te ge107 Keg fusion plasmas
T asymp T asymp T le 2 x 104 KTi asymp Te asymp Tg le 2 x 104 Keg arc plasma at normal pressure
bull Low‐temperature plasmas (Cold Plasmas)Ti asymp Tg asymp 300 KT ltlt T le 105 KTi ltlt Te le 105 Keg low‐pressure glow discharge
Plasmas are easier to be generated at low pressures
Low pressure plasmas (1 T f T )
at low pressures
are well understood
are used extensively nowadays
(1 mTorr ~ a few Torr)
are used extensively nowadays (eg in semiconductor industry for computer chips manufacturing)
However to generate low pressure plasmas
vacuum chambers + + = expensive vacuum pumps
pressure monitoring and pressure control devices
+ + =Generate Plasmas at Atmospheric PressureGenerate Plasmas at Atmospheric Pressure
What happens at air pressureWhat happens at air pressure
bull No vacuum is involvedDiffi l d ibull Difficult to generate and sustain
bull Run into some challenges such as glow toarc transition ndash Non controllable
Arc Discharge thermal plasma-Itrsquos hot and detrimental-Gas temperature can reach as high as 2x104 KGas temperature can reach as high as 2x10 K- Low voltage drop at cathode- High cathode current density
High Pressure Microplasmas
Stabilization of high-pressure plasmas ldquopd scalingrdquo ldquoprdquo uarr soplasmas pd scaling p uarr so ldquodrdquo darr to keep breakdown voltage low and minimize instabilities after breakdown -
MicroplasmasDimension a few millimeterDimension a few millimeter down to and below 100 m
Paschen Breakdown CurveH H i 60 100Human Hair 60 ndash 100 m
How do we solve this problemHow do we solve this problem
Transient (pulsed) plasmas In atmospheric plasmas for efficient gas heating atleast 100-1000 collisions are necessary Thus if the plasma duration is shorterleast 100 1000 collisions are necessary Thus if the plasma duration is shorterthan 10-6 ndash 10-5 s gas heating is limited Of course for practical purposes suchplasma has to be operated in a repetitive mode eg in trains of microsecondpulses with millisecond intervals
Micro-confinement Gas heating occurs in the plasma volume and the energy iscarried away by thermal diffusionconvection to the outside If the plasma has asmall volume and a relatively large surface gas heating is limited
Dielectric Barrier Discharges These plasmas are typically created betweenmetal plates which are covered by a thin layer of dielectric or highly resistivematerial The dielectric layer plays an important role in suppressing the currentthe cathodeanode layer is charged by incoming positive ionselectrons whichreduces the electric field and hinders charge transport towards the electrodeDBD also has a large surface-to-volume ratio which promotes diffusion lossesand maintains a low gas temperatureand maintains a low gas temperature
Advantages of Microplasmas Advantages of Microplasmas
bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures
Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y
hellip a new realm of plasma sciencehellip a new realm of plasma science
What can we do with microplasmasWhat can we do with microplasmas
Material Synthesis Plasma display Surface Treatment Lighting
H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)
Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges
Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)
Voltage Vpp 3ndash20 kV
Repetition frequency f 50 Hzndash30 kHz
Pressure p 1ndash3 bar
Gap distance g 02ndash5mm
Dielectric material thickness d 05ndash2mm
Relative dielectric permittivity r 5ndash10 (glass)
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Single and double DBD
Single dielectric Double dielectric
Role of the Dielectric (Insulator)
Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge
Serves two functions
1 Limits the amount of charge transportedby a single microplasma
2 Distributes the microplasmas over theentire electrode surface area
Equivalent Circuit of a Microdischarge
Microdischarge Activity and U-Q Lissajous Figure
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge
bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them
bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation
Time scale of the relevant processes of the DBD
HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)
Fundamental Operation of the DBDFundamental Operation of the DBD
Electron DensityTemporal Development (ns)
y
Outer Contour Linen = 1010 cm-3ne = 1010 cm 3
Inner Contour Linene = 1014 cm-3
Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)
E0=34 kVcm1010 cm-3
1010 cm-3 ne=1012 cm-3
1mm10 cm
ne=108 cm-3
An electron avalanche propagates towards the anode
Reverse propagationtowards the cathodepropagates towards the anode towards the cathode
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Cathode Layer Formation
E0=34 kVcm1010 cm-39 3 0
1mm
1010 cm-3
10 cmne=109 cm-31014
10131014
1013
10 cm1012
Just before the peak of the total current
Peak currentof the total current
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Local Field Collapse in Area Defined by Surface Discharge
ne=109cm-3 ne=1014 cm-3
Gap
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
C C-- - --- - - CG
CD
-- - - CG
CD
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Plasmas are easier to be generated at low pressures
Low pressure plasmas (1 T f T )
at low pressures
are well understood
are used extensively nowadays
(1 mTorr ~ a few Torr)
are used extensively nowadays (eg in semiconductor industry for computer chips manufacturing)
However to generate low pressure plasmas
vacuum chambers + + = expensive vacuum pumps
pressure monitoring and pressure control devices
+ + =Generate Plasmas at Atmospheric PressureGenerate Plasmas at Atmospheric Pressure
What happens at air pressureWhat happens at air pressure
bull No vacuum is involvedDiffi l d ibull Difficult to generate and sustain
bull Run into some challenges such as glow toarc transition ndash Non controllable
Arc Discharge thermal plasma-Itrsquos hot and detrimental-Gas temperature can reach as high as 2x104 KGas temperature can reach as high as 2x10 K- Low voltage drop at cathode- High cathode current density
High Pressure Microplasmas
Stabilization of high-pressure plasmas ldquopd scalingrdquo ldquoprdquo uarr soplasmas pd scaling p uarr so ldquodrdquo darr to keep breakdown voltage low and minimize instabilities after breakdown -
MicroplasmasDimension a few millimeterDimension a few millimeter down to and below 100 m
Paschen Breakdown CurveH H i 60 100Human Hair 60 ndash 100 m
How do we solve this problemHow do we solve this problem
Transient (pulsed) plasmas In atmospheric plasmas for efficient gas heating atleast 100-1000 collisions are necessary Thus if the plasma duration is shorterleast 100 1000 collisions are necessary Thus if the plasma duration is shorterthan 10-6 ndash 10-5 s gas heating is limited Of course for practical purposes suchplasma has to be operated in a repetitive mode eg in trains of microsecondpulses with millisecond intervals
Micro-confinement Gas heating occurs in the plasma volume and the energy iscarried away by thermal diffusionconvection to the outside If the plasma has asmall volume and a relatively large surface gas heating is limited
Dielectric Barrier Discharges These plasmas are typically created betweenmetal plates which are covered by a thin layer of dielectric or highly resistivematerial The dielectric layer plays an important role in suppressing the currentthe cathodeanode layer is charged by incoming positive ionselectrons whichreduces the electric field and hinders charge transport towards the electrodeDBD also has a large surface-to-volume ratio which promotes diffusion lossesand maintains a low gas temperatureand maintains a low gas temperature
Advantages of Microplasmas Advantages of Microplasmas
bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures
Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y
hellip a new realm of plasma sciencehellip a new realm of plasma science
What can we do with microplasmasWhat can we do with microplasmas
Material Synthesis Plasma display Surface Treatment Lighting
H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)
Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges
Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)
Voltage Vpp 3ndash20 kV
Repetition frequency f 50 Hzndash30 kHz
Pressure p 1ndash3 bar
Gap distance g 02ndash5mm
Dielectric material thickness d 05ndash2mm
Relative dielectric permittivity r 5ndash10 (glass)
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Single and double DBD
Single dielectric Double dielectric
Role of the Dielectric (Insulator)
Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge
Serves two functions
1 Limits the amount of charge transportedby a single microplasma
2 Distributes the microplasmas over theentire electrode surface area
Equivalent Circuit of a Microdischarge
Microdischarge Activity and U-Q Lissajous Figure
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge
bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them
bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation
Time scale of the relevant processes of the DBD
HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)
Fundamental Operation of the DBDFundamental Operation of the DBD
Electron DensityTemporal Development (ns)
y
Outer Contour Linen = 1010 cm-3ne = 1010 cm 3
Inner Contour Linene = 1014 cm-3
Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)
E0=34 kVcm1010 cm-3
1010 cm-3 ne=1012 cm-3
1mm10 cm
ne=108 cm-3
An electron avalanche propagates towards the anode
Reverse propagationtowards the cathodepropagates towards the anode towards the cathode
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Cathode Layer Formation
E0=34 kVcm1010 cm-39 3 0
1mm
1010 cm-3
10 cmne=109 cm-31014
10131014
1013
10 cm1012
Just before the peak of the total current
Peak currentof the total current
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Local Field Collapse in Area Defined by Surface Discharge
ne=109cm-3 ne=1014 cm-3
Gap
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
C C-- - --- - - CG
CD
-- - - CG
CD
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Plasmas are easier to be generated at low pressures
Low pressure plasmas (1 T f T )
at low pressures
are well understood
are used extensively nowadays
(1 mTorr ~ a few Torr)
are used extensively nowadays (eg in semiconductor industry for computer chips manufacturing)
However to generate low pressure plasmas
vacuum chambers + + = expensive vacuum pumps
pressure monitoring and pressure control devices
+ + =Generate Plasmas at Atmospheric PressureGenerate Plasmas at Atmospheric Pressure
What happens at air pressureWhat happens at air pressure
bull No vacuum is involvedDiffi l d ibull Difficult to generate and sustain
bull Run into some challenges such as glow toarc transition ndash Non controllable
Arc Discharge thermal plasma-Itrsquos hot and detrimental-Gas temperature can reach as high as 2x104 KGas temperature can reach as high as 2x10 K- Low voltage drop at cathode- High cathode current density
High Pressure Microplasmas
Stabilization of high-pressure plasmas ldquopd scalingrdquo ldquoprdquo uarr soplasmas pd scaling p uarr so ldquodrdquo darr to keep breakdown voltage low and minimize instabilities after breakdown -
MicroplasmasDimension a few millimeterDimension a few millimeter down to and below 100 m
Paschen Breakdown CurveH H i 60 100Human Hair 60 ndash 100 m
How do we solve this problemHow do we solve this problem
Transient (pulsed) plasmas In atmospheric plasmas for efficient gas heating atleast 100-1000 collisions are necessary Thus if the plasma duration is shorterleast 100 1000 collisions are necessary Thus if the plasma duration is shorterthan 10-6 ndash 10-5 s gas heating is limited Of course for practical purposes suchplasma has to be operated in a repetitive mode eg in trains of microsecondpulses with millisecond intervals
Micro-confinement Gas heating occurs in the plasma volume and the energy iscarried away by thermal diffusionconvection to the outside If the plasma has asmall volume and a relatively large surface gas heating is limited
Dielectric Barrier Discharges These plasmas are typically created betweenmetal plates which are covered by a thin layer of dielectric or highly resistivematerial The dielectric layer plays an important role in suppressing the currentthe cathodeanode layer is charged by incoming positive ionselectrons whichreduces the electric field and hinders charge transport towards the electrodeDBD also has a large surface-to-volume ratio which promotes diffusion lossesand maintains a low gas temperatureand maintains a low gas temperature
Advantages of Microplasmas Advantages of Microplasmas
bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures
Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y
hellip a new realm of plasma sciencehellip a new realm of plasma science
What can we do with microplasmasWhat can we do with microplasmas
Material Synthesis Plasma display Surface Treatment Lighting
H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)
Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges
Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)
Voltage Vpp 3ndash20 kV
Repetition frequency f 50 Hzndash30 kHz
Pressure p 1ndash3 bar
Gap distance g 02ndash5mm
Dielectric material thickness d 05ndash2mm
Relative dielectric permittivity r 5ndash10 (glass)
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Single and double DBD
Single dielectric Double dielectric
Role of the Dielectric (Insulator)
Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge
Serves two functions
1 Limits the amount of charge transportedby a single microplasma
2 Distributes the microplasmas over theentire electrode surface area
Equivalent Circuit of a Microdischarge
Microdischarge Activity and U-Q Lissajous Figure
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge
bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them
bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation
Time scale of the relevant processes of the DBD
HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)
Fundamental Operation of the DBDFundamental Operation of the DBD
Electron DensityTemporal Development (ns)
y
Outer Contour Linen = 1010 cm-3ne = 1010 cm 3
Inner Contour Linene = 1014 cm-3
Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)
E0=34 kVcm1010 cm-3
1010 cm-3 ne=1012 cm-3
1mm10 cm
ne=108 cm-3
An electron avalanche propagates towards the anode
Reverse propagationtowards the cathodepropagates towards the anode towards the cathode
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Cathode Layer Formation
E0=34 kVcm1010 cm-39 3 0
1mm
1010 cm-3
10 cmne=109 cm-31014
10131014
1013
10 cm1012
Just before the peak of the total current
Peak currentof the total current
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Local Field Collapse in Area Defined by Surface Discharge
ne=109cm-3 ne=1014 cm-3
Gap
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
C C-- - --- - - CG
CD
-- - - CG
CD
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Plasmas are easier to be generated at low pressures
Low pressure plasmas (1 T f T )
at low pressures
are well understood
are used extensively nowadays
(1 mTorr ~ a few Torr)
are used extensively nowadays (eg in semiconductor industry for computer chips manufacturing)
However to generate low pressure plasmas
vacuum chambers + + = expensive vacuum pumps
pressure monitoring and pressure control devices
+ + =Generate Plasmas at Atmospheric PressureGenerate Plasmas at Atmospheric Pressure
What happens at air pressureWhat happens at air pressure
bull No vacuum is involvedDiffi l d ibull Difficult to generate and sustain
bull Run into some challenges such as glow toarc transition ndash Non controllable
Arc Discharge thermal plasma-Itrsquos hot and detrimental-Gas temperature can reach as high as 2x104 KGas temperature can reach as high as 2x10 K- Low voltage drop at cathode- High cathode current density
High Pressure Microplasmas
Stabilization of high-pressure plasmas ldquopd scalingrdquo ldquoprdquo uarr soplasmas pd scaling p uarr so ldquodrdquo darr to keep breakdown voltage low and minimize instabilities after breakdown -
MicroplasmasDimension a few millimeterDimension a few millimeter down to and below 100 m
Paschen Breakdown CurveH H i 60 100Human Hair 60 ndash 100 m
How do we solve this problemHow do we solve this problem
Transient (pulsed) plasmas In atmospheric plasmas for efficient gas heating atleast 100-1000 collisions are necessary Thus if the plasma duration is shorterleast 100 1000 collisions are necessary Thus if the plasma duration is shorterthan 10-6 ndash 10-5 s gas heating is limited Of course for practical purposes suchplasma has to be operated in a repetitive mode eg in trains of microsecondpulses with millisecond intervals
Micro-confinement Gas heating occurs in the plasma volume and the energy iscarried away by thermal diffusionconvection to the outside If the plasma has asmall volume and a relatively large surface gas heating is limited
Dielectric Barrier Discharges These plasmas are typically created betweenmetal plates which are covered by a thin layer of dielectric or highly resistivematerial The dielectric layer plays an important role in suppressing the currentthe cathodeanode layer is charged by incoming positive ionselectrons whichreduces the electric field and hinders charge transport towards the electrodeDBD also has a large surface-to-volume ratio which promotes diffusion lossesand maintains a low gas temperatureand maintains a low gas temperature
Advantages of Microplasmas Advantages of Microplasmas
bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures
Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y
hellip a new realm of plasma sciencehellip a new realm of plasma science
What can we do with microplasmasWhat can we do with microplasmas
Material Synthesis Plasma display Surface Treatment Lighting
H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)
Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges
Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)
Voltage Vpp 3ndash20 kV
Repetition frequency f 50 Hzndash30 kHz
Pressure p 1ndash3 bar
Gap distance g 02ndash5mm
Dielectric material thickness d 05ndash2mm
Relative dielectric permittivity r 5ndash10 (glass)
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Single and double DBD
Single dielectric Double dielectric
Role of the Dielectric (Insulator)
Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge
Serves two functions
1 Limits the amount of charge transportedby a single microplasma
2 Distributes the microplasmas over theentire electrode surface area
Equivalent Circuit of a Microdischarge
Microdischarge Activity and U-Q Lissajous Figure
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge
bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them
bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation
Time scale of the relevant processes of the DBD
HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)
Fundamental Operation of the DBDFundamental Operation of the DBD
Electron DensityTemporal Development (ns)
y
Outer Contour Linen = 1010 cm-3ne = 1010 cm 3
Inner Contour Linene = 1014 cm-3
Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)
E0=34 kVcm1010 cm-3
1010 cm-3 ne=1012 cm-3
1mm10 cm
ne=108 cm-3
An electron avalanche propagates towards the anode
Reverse propagationtowards the cathodepropagates towards the anode towards the cathode
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Cathode Layer Formation
E0=34 kVcm1010 cm-39 3 0
1mm
1010 cm-3
10 cmne=109 cm-31014
10131014
1013
10 cm1012
Just before the peak of the total current
Peak currentof the total current
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Local Field Collapse in Area Defined by Surface Discharge
ne=109cm-3 ne=1014 cm-3
Gap
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
C C-- - --- - - CG
CD
-- - - CG
CD
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Plasmas are easier to be generated at low pressures
Low pressure plasmas (1 T f T )
at low pressures
are well understood
are used extensively nowadays
(1 mTorr ~ a few Torr)
are used extensively nowadays (eg in semiconductor industry for computer chips manufacturing)
However to generate low pressure plasmas
vacuum chambers + + = expensive vacuum pumps
pressure monitoring and pressure control devices
+ + =Generate Plasmas at Atmospheric PressureGenerate Plasmas at Atmospheric Pressure
What happens at air pressureWhat happens at air pressure
bull No vacuum is involvedDiffi l d ibull Difficult to generate and sustain
bull Run into some challenges such as glow toarc transition ndash Non controllable
Arc Discharge thermal plasma-Itrsquos hot and detrimental-Gas temperature can reach as high as 2x104 KGas temperature can reach as high as 2x10 K- Low voltage drop at cathode- High cathode current density
High Pressure Microplasmas
Stabilization of high-pressure plasmas ldquopd scalingrdquo ldquoprdquo uarr soplasmas pd scaling p uarr so ldquodrdquo darr to keep breakdown voltage low and minimize instabilities after breakdown -
MicroplasmasDimension a few millimeterDimension a few millimeter down to and below 100 m
Paschen Breakdown CurveH H i 60 100Human Hair 60 ndash 100 m
How do we solve this problemHow do we solve this problem
Transient (pulsed) plasmas In atmospheric plasmas for efficient gas heating atleast 100-1000 collisions are necessary Thus if the plasma duration is shorterleast 100 1000 collisions are necessary Thus if the plasma duration is shorterthan 10-6 ndash 10-5 s gas heating is limited Of course for practical purposes suchplasma has to be operated in a repetitive mode eg in trains of microsecondpulses with millisecond intervals
Micro-confinement Gas heating occurs in the plasma volume and the energy iscarried away by thermal diffusionconvection to the outside If the plasma has asmall volume and a relatively large surface gas heating is limited
Dielectric Barrier Discharges These plasmas are typically created betweenmetal plates which are covered by a thin layer of dielectric or highly resistivematerial The dielectric layer plays an important role in suppressing the currentthe cathodeanode layer is charged by incoming positive ionselectrons whichreduces the electric field and hinders charge transport towards the electrodeDBD also has a large surface-to-volume ratio which promotes diffusion lossesand maintains a low gas temperatureand maintains a low gas temperature
Advantages of Microplasmas Advantages of Microplasmas
bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures
Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y
hellip a new realm of plasma sciencehellip a new realm of plasma science
What can we do with microplasmasWhat can we do with microplasmas
Material Synthesis Plasma display Surface Treatment Lighting
H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)
Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges
Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)
Voltage Vpp 3ndash20 kV
Repetition frequency f 50 Hzndash30 kHz
Pressure p 1ndash3 bar
Gap distance g 02ndash5mm
Dielectric material thickness d 05ndash2mm
Relative dielectric permittivity r 5ndash10 (glass)
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Single and double DBD
Single dielectric Double dielectric
Role of the Dielectric (Insulator)
Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge
Serves two functions
1 Limits the amount of charge transportedby a single microplasma
2 Distributes the microplasmas over theentire electrode surface area
Equivalent Circuit of a Microdischarge
Microdischarge Activity and U-Q Lissajous Figure
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge
bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them
bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation
Time scale of the relevant processes of the DBD
HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)
Fundamental Operation of the DBDFundamental Operation of the DBD
Electron DensityTemporal Development (ns)
y
Outer Contour Linen = 1010 cm-3ne = 1010 cm 3
Inner Contour Linene = 1014 cm-3
Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)
E0=34 kVcm1010 cm-3
1010 cm-3 ne=1012 cm-3
1mm10 cm
ne=108 cm-3
An electron avalanche propagates towards the anode
Reverse propagationtowards the cathodepropagates towards the anode towards the cathode
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Cathode Layer Formation
E0=34 kVcm1010 cm-39 3 0
1mm
1010 cm-3
10 cmne=109 cm-31014
10131014
1013
10 cm1012
Just before the peak of the total current
Peak currentof the total current
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Local Field Collapse in Area Defined by Surface Discharge
ne=109cm-3 ne=1014 cm-3
Gap
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
C C-- - --- - - CG
CD
-- - - CG
CD
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Plasmas are easier to be generated at low pressures
Low pressure plasmas (1 T f T )
at low pressures
are well understood
are used extensively nowadays
(1 mTorr ~ a few Torr)
are used extensively nowadays (eg in semiconductor industry for computer chips manufacturing)
However to generate low pressure plasmas
vacuum chambers + + = expensive vacuum pumps
pressure monitoring and pressure control devices
+ + =Generate Plasmas at Atmospheric PressureGenerate Plasmas at Atmospheric Pressure
What happens at air pressureWhat happens at air pressure
bull No vacuum is involvedDiffi l d ibull Difficult to generate and sustain
bull Run into some challenges such as glow toarc transition ndash Non controllable
Arc Discharge thermal plasma-Itrsquos hot and detrimental-Gas temperature can reach as high as 2x104 KGas temperature can reach as high as 2x10 K- Low voltage drop at cathode- High cathode current density
High Pressure Microplasmas
Stabilization of high-pressure plasmas ldquopd scalingrdquo ldquoprdquo uarr soplasmas pd scaling p uarr so ldquodrdquo darr to keep breakdown voltage low and minimize instabilities after breakdown -
MicroplasmasDimension a few millimeterDimension a few millimeter down to and below 100 m
Paschen Breakdown CurveH H i 60 100Human Hair 60 ndash 100 m
How do we solve this problemHow do we solve this problem
Transient (pulsed) plasmas In atmospheric plasmas for efficient gas heating atleast 100-1000 collisions are necessary Thus if the plasma duration is shorterleast 100 1000 collisions are necessary Thus if the plasma duration is shorterthan 10-6 ndash 10-5 s gas heating is limited Of course for practical purposes suchplasma has to be operated in a repetitive mode eg in trains of microsecondpulses with millisecond intervals
Micro-confinement Gas heating occurs in the plasma volume and the energy iscarried away by thermal diffusionconvection to the outside If the plasma has asmall volume and a relatively large surface gas heating is limited
Dielectric Barrier Discharges These plasmas are typically created betweenmetal plates which are covered by a thin layer of dielectric or highly resistivematerial The dielectric layer plays an important role in suppressing the currentthe cathodeanode layer is charged by incoming positive ionselectrons whichreduces the electric field and hinders charge transport towards the electrodeDBD also has a large surface-to-volume ratio which promotes diffusion lossesand maintains a low gas temperatureand maintains a low gas temperature
Advantages of Microplasmas Advantages of Microplasmas
bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures
Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y
hellip a new realm of plasma sciencehellip a new realm of plasma science
What can we do with microplasmasWhat can we do with microplasmas
Material Synthesis Plasma display Surface Treatment Lighting
H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)
Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges
Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)
Voltage Vpp 3ndash20 kV
Repetition frequency f 50 Hzndash30 kHz
Pressure p 1ndash3 bar
Gap distance g 02ndash5mm
Dielectric material thickness d 05ndash2mm
Relative dielectric permittivity r 5ndash10 (glass)
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Single and double DBD
Single dielectric Double dielectric
Role of the Dielectric (Insulator)
Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge
Serves two functions
1 Limits the amount of charge transportedby a single microplasma
2 Distributes the microplasmas over theentire electrode surface area
Equivalent Circuit of a Microdischarge
Microdischarge Activity and U-Q Lissajous Figure
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge
bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them
bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation
Time scale of the relevant processes of the DBD
HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)
Fundamental Operation of the DBDFundamental Operation of the DBD
Electron DensityTemporal Development (ns)
y
Outer Contour Linen = 1010 cm-3ne = 1010 cm 3
Inner Contour Linene = 1014 cm-3
Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)
E0=34 kVcm1010 cm-3
1010 cm-3 ne=1012 cm-3
1mm10 cm
ne=108 cm-3
An electron avalanche propagates towards the anode
Reverse propagationtowards the cathodepropagates towards the anode towards the cathode
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Cathode Layer Formation
E0=34 kVcm1010 cm-39 3 0
1mm
1010 cm-3
10 cmne=109 cm-31014
10131014
1013
10 cm1012
Just before the peak of the total current
Peak currentof the total current
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Local Field Collapse in Area Defined by Surface Discharge
ne=109cm-3 ne=1014 cm-3
Gap
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
C C-- - --- - - CG
CD
-- - - CG
CD
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Plasmas are easier to be generated at low pressures
Low pressure plasmas (1 T f T )
at low pressures
are well understood
are used extensively nowadays
(1 mTorr ~ a few Torr)
are used extensively nowadays (eg in semiconductor industry for computer chips manufacturing)
However to generate low pressure plasmas
vacuum chambers + + = expensive vacuum pumps
pressure monitoring and pressure control devices
+ + =Generate Plasmas at Atmospheric PressureGenerate Plasmas at Atmospheric Pressure
What happens at air pressureWhat happens at air pressure
bull No vacuum is involvedDiffi l d ibull Difficult to generate and sustain
bull Run into some challenges such as glow toarc transition ndash Non controllable
Arc Discharge thermal plasma-Itrsquos hot and detrimental-Gas temperature can reach as high as 2x104 KGas temperature can reach as high as 2x10 K- Low voltage drop at cathode- High cathode current density
High Pressure Microplasmas
Stabilization of high-pressure plasmas ldquopd scalingrdquo ldquoprdquo uarr soplasmas pd scaling p uarr so ldquodrdquo darr to keep breakdown voltage low and minimize instabilities after breakdown -
MicroplasmasDimension a few millimeterDimension a few millimeter down to and below 100 m
Paschen Breakdown CurveH H i 60 100Human Hair 60 ndash 100 m
How do we solve this problemHow do we solve this problem
Transient (pulsed) plasmas In atmospheric plasmas for efficient gas heating atleast 100-1000 collisions are necessary Thus if the plasma duration is shorterleast 100 1000 collisions are necessary Thus if the plasma duration is shorterthan 10-6 ndash 10-5 s gas heating is limited Of course for practical purposes suchplasma has to be operated in a repetitive mode eg in trains of microsecondpulses with millisecond intervals
Micro-confinement Gas heating occurs in the plasma volume and the energy iscarried away by thermal diffusionconvection to the outside If the plasma has asmall volume and a relatively large surface gas heating is limited
Dielectric Barrier Discharges These plasmas are typically created betweenmetal plates which are covered by a thin layer of dielectric or highly resistivematerial The dielectric layer plays an important role in suppressing the currentthe cathodeanode layer is charged by incoming positive ionselectrons whichreduces the electric field and hinders charge transport towards the electrodeDBD also has a large surface-to-volume ratio which promotes diffusion lossesand maintains a low gas temperatureand maintains a low gas temperature
Advantages of Microplasmas Advantages of Microplasmas
bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures
Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y
hellip a new realm of plasma sciencehellip a new realm of plasma science
What can we do with microplasmasWhat can we do with microplasmas
Material Synthesis Plasma display Surface Treatment Lighting
H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)
Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges
Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)
Voltage Vpp 3ndash20 kV
Repetition frequency f 50 Hzndash30 kHz
Pressure p 1ndash3 bar
Gap distance g 02ndash5mm
Dielectric material thickness d 05ndash2mm
Relative dielectric permittivity r 5ndash10 (glass)
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Single and double DBD
Single dielectric Double dielectric
Role of the Dielectric (Insulator)
Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge
Serves two functions
1 Limits the amount of charge transportedby a single microplasma
2 Distributes the microplasmas over theentire electrode surface area
Equivalent Circuit of a Microdischarge
Microdischarge Activity and U-Q Lissajous Figure
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge
bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them
bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation
Time scale of the relevant processes of the DBD
HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)
Fundamental Operation of the DBDFundamental Operation of the DBD
Electron DensityTemporal Development (ns)
y
Outer Contour Linen = 1010 cm-3ne = 1010 cm 3
Inner Contour Linene = 1014 cm-3
Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)
E0=34 kVcm1010 cm-3
1010 cm-3 ne=1012 cm-3
1mm10 cm
ne=108 cm-3
An electron avalanche propagates towards the anode
Reverse propagationtowards the cathodepropagates towards the anode towards the cathode
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Cathode Layer Formation
E0=34 kVcm1010 cm-39 3 0
1mm
1010 cm-3
10 cmne=109 cm-31014
10131014
1013
10 cm1012
Just before the peak of the total current
Peak currentof the total current
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Local Field Collapse in Area Defined by Surface Discharge
ne=109cm-3 ne=1014 cm-3
Gap
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
C C-- - --- - - CG
CD
-- - - CG
CD
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Plasmas are easier to be generated at low pressures
Low pressure plasmas (1 T f T )
at low pressures
are well understood
are used extensively nowadays
(1 mTorr ~ a few Torr)
are used extensively nowadays (eg in semiconductor industry for computer chips manufacturing)
However to generate low pressure plasmas
vacuum chambers + + = expensive vacuum pumps
pressure monitoring and pressure control devices
+ + =Generate Plasmas at Atmospheric PressureGenerate Plasmas at Atmospheric Pressure
What happens at air pressureWhat happens at air pressure
bull No vacuum is involvedDiffi l d ibull Difficult to generate and sustain
bull Run into some challenges such as glow toarc transition ndash Non controllable
Arc Discharge thermal plasma-Itrsquos hot and detrimental-Gas temperature can reach as high as 2x104 KGas temperature can reach as high as 2x10 K- Low voltage drop at cathode- High cathode current density
High Pressure Microplasmas
Stabilization of high-pressure plasmas ldquopd scalingrdquo ldquoprdquo uarr soplasmas pd scaling p uarr so ldquodrdquo darr to keep breakdown voltage low and minimize instabilities after breakdown -
MicroplasmasDimension a few millimeterDimension a few millimeter down to and below 100 m
Paschen Breakdown CurveH H i 60 100Human Hair 60 ndash 100 m
How do we solve this problemHow do we solve this problem
Transient (pulsed) plasmas In atmospheric plasmas for efficient gas heating atleast 100-1000 collisions are necessary Thus if the plasma duration is shorterleast 100 1000 collisions are necessary Thus if the plasma duration is shorterthan 10-6 ndash 10-5 s gas heating is limited Of course for practical purposes suchplasma has to be operated in a repetitive mode eg in trains of microsecondpulses with millisecond intervals
Micro-confinement Gas heating occurs in the plasma volume and the energy iscarried away by thermal diffusionconvection to the outside If the plasma has asmall volume and a relatively large surface gas heating is limited
Dielectric Barrier Discharges These plasmas are typically created betweenmetal plates which are covered by a thin layer of dielectric or highly resistivematerial The dielectric layer plays an important role in suppressing the currentthe cathodeanode layer is charged by incoming positive ionselectrons whichreduces the electric field and hinders charge transport towards the electrodeDBD also has a large surface-to-volume ratio which promotes diffusion lossesand maintains a low gas temperatureand maintains a low gas temperature
Advantages of Microplasmas Advantages of Microplasmas
bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures
Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y
hellip a new realm of plasma sciencehellip a new realm of plasma science
What can we do with microplasmasWhat can we do with microplasmas
Material Synthesis Plasma display Surface Treatment Lighting
H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)
Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges
Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)
Voltage Vpp 3ndash20 kV
Repetition frequency f 50 Hzndash30 kHz
Pressure p 1ndash3 bar
Gap distance g 02ndash5mm
Dielectric material thickness d 05ndash2mm
Relative dielectric permittivity r 5ndash10 (glass)
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Single and double DBD
Single dielectric Double dielectric
Role of the Dielectric (Insulator)
Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge
Serves two functions
1 Limits the amount of charge transportedby a single microplasma
2 Distributes the microplasmas over theentire electrode surface area
Equivalent Circuit of a Microdischarge
Microdischarge Activity and U-Q Lissajous Figure
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge
bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them
bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation
Time scale of the relevant processes of the DBD
HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)
Fundamental Operation of the DBDFundamental Operation of the DBD
Electron DensityTemporal Development (ns)
y
Outer Contour Linen = 1010 cm-3ne = 1010 cm 3
Inner Contour Linene = 1014 cm-3
Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)
E0=34 kVcm1010 cm-3
1010 cm-3 ne=1012 cm-3
1mm10 cm
ne=108 cm-3
An electron avalanche propagates towards the anode
Reverse propagationtowards the cathodepropagates towards the anode towards the cathode
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Cathode Layer Formation
E0=34 kVcm1010 cm-39 3 0
1mm
1010 cm-3
10 cmne=109 cm-31014
10131014
1013
10 cm1012
Just before the peak of the total current
Peak currentof the total current
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Local Field Collapse in Area Defined by Surface Discharge
ne=109cm-3 ne=1014 cm-3
Gap
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
C C-- - --- - - CG
CD
-- - - CG
CD
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
What happens at air pressureWhat happens at air pressure
bull No vacuum is involvedDiffi l d ibull Difficult to generate and sustain
bull Run into some challenges such as glow toarc transition ndash Non controllable
Arc Discharge thermal plasma-Itrsquos hot and detrimental-Gas temperature can reach as high as 2x104 KGas temperature can reach as high as 2x10 K- Low voltage drop at cathode- High cathode current density
High Pressure Microplasmas
Stabilization of high-pressure plasmas ldquopd scalingrdquo ldquoprdquo uarr soplasmas pd scaling p uarr so ldquodrdquo darr to keep breakdown voltage low and minimize instabilities after breakdown -
MicroplasmasDimension a few millimeterDimension a few millimeter down to and below 100 m
Paschen Breakdown CurveH H i 60 100Human Hair 60 ndash 100 m
How do we solve this problemHow do we solve this problem
Transient (pulsed) plasmas In atmospheric plasmas for efficient gas heating atleast 100-1000 collisions are necessary Thus if the plasma duration is shorterleast 100 1000 collisions are necessary Thus if the plasma duration is shorterthan 10-6 ndash 10-5 s gas heating is limited Of course for practical purposes suchplasma has to be operated in a repetitive mode eg in trains of microsecondpulses with millisecond intervals
Micro-confinement Gas heating occurs in the plasma volume and the energy iscarried away by thermal diffusionconvection to the outside If the plasma has asmall volume and a relatively large surface gas heating is limited
Dielectric Barrier Discharges These plasmas are typically created betweenmetal plates which are covered by a thin layer of dielectric or highly resistivematerial The dielectric layer plays an important role in suppressing the currentthe cathodeanode layer is charged by incoming positive ionselectrons whichreduces the electric field and hinders charge transport towards the electrodeDBD also has a large surface-to-volume ratio which promotes diffusion lossesand maintains a low gas temperatureand maintains a low gas temperature
Advantages of Microplasmas Advantages of Microplasmas
bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures
Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y
hellip a new realm of plasma sciencehellip a new realm of plasma science
What can we do with microplasmasWhat can we do with microplasmas
Material Synthesis Plasma display Surface Treatment Lighting
H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)
Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges
Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)
Voltage Vpp 3ndash20 kV
Repetition frequency f 50 Hzndash30 kHz
Pressure p 1ndash3 bar
Gap distance g 02ndash5mm
Dielectric material thickness d 05ndash2mm
Relative dielectric permittivity r 5ndash10 (glass)
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Single and double DBD
Single dielectric Double dielectric
Role of the Dielectric (Insulator)
Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge
Serves two functions
1 Limits the amount of charge transportedby a single microplasma
2 Distributes the microplasmas over theentire electrode surface area
Equivalent Circuit of a Microdischarge
Microdischarge Activity and U-Q Lissajous Figure
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge
bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them
bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation
Time scale of the relevant processes of the DBD
HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)
Fundamental Operation of the DBDFundamental Operation of the DBD
Electron DensityTemporal Development (ns)
y
Outer Contour Linen = 1010 cm-3ne = 1010 cm 3
Inner Contour Linene = 1014 cm-3
Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)
E0=34 kVcm1010 cm-3
1010 cm-3 ne=1012 cm-3
1mm10 cm
ne=108 cm-3
An electron avalanche propagates towards the anode
Reverse propagationtowards the cathodepropagates towards the anode towards the cathode
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Cathode Layer Formation
E0=34 kVcm1010 cm-39 3 0
1mm
1010 cm-3
10 cmne=109 cm-31014
10131014
1013
10 cm1012
Just before the peak of the total current
Peak currentof the total current
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Local Field Collapse in Area Defined by Surface Discharge
ne=109cm-3 ne=1014 cm-3
Gap
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
C C-- - --- - - CG
CD
-- - - CG
CD
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Stabilization of high-pressure plasmas ldquopd scalingrdquo ldquoprdquo uarr soplasmas pd scaling p uarr so ldquodrdquo darr to keep breakdown voltage low and minimize instabilities after breakdown -
MicroplasmasDimension a few millimeterDimension a few millimeter down to and below 100 m
Paschen Breakdown CurveH H i 60 100Human Hair 60 ndash 100 m
How do we solve this problemHow do we solve this problem
Transient (pulsed) plasmas In atmospheric plasmas for efficient gas heating atleast 100-1000 collisions are necessary Thus if the plasma duration is shorterleast 100 1000 collisions are necessary Thus if the plasma duration is shorterthan 10-6 ndash 10-5 s gas heating is limited Of course for practical purposes suchplasma has to be operated in a repetitive mode eg in trains of microsecondpulses with millisecond intervals
Micro-confinement Gas heating occurs in the plasma volume and the energy iscarried away by thermal diffusionconvection to the outside If the plasma has asmall volume and a relatively large surface gas heating is limited
Dielectric Barrier Discharges These plasmas are typically created betweenmetal plates which are covered by a thin layer of dielectric or highly resistivematerial The dielectric layer plays an important role in suppressing the currentthe cathodeanode layer is charged by incoming positive ionselectrons whichreduces the electric field and hinders charge transport towards the electrodeDBD also has a large surface-to-volume ratio which promotes diffusion lossesand maintains a low gas temperatureand maintains a low gas temperature
Advantages of Microplasmas Advantages of Microplasmas
bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures
Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y
hellip a new realm of plasma sciencehellip a new realm of plasma science
What can we do with microplasmasWhat can we do with microplasmas
Material Synthesis Plasma display Surface Treatment Lighting
H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)
Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges
Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)
Voltage Vpp 3ndash20 kV
Repetition frequency f 50 Hzndash30 kHz
Pressure p 1ndash3 bar
Gap distance g 02ndash5mm
Dielectric material thickness d 05ndash2mm
Relative dielectric permittivity r 5ndash10 (glass)
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Single and double DBD
Single dielectric Double dielectric
Role of the Dielectric (Insulator)
Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge
Serves two functions
1 Limits the amount of charge transportedby a single microplasma
2 Distributes the microplasmas over theentire electrode surface area
Equivalent Circuit of a Microdischarge
Microdischarge Activity and U-Q Lissajous Figure
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge
bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them
bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation
Time scale of the relevant processes of the DBD
HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)
Fundamental Operation of the DBDFundamental Operation of the DBD
Electron DensityTemporal Development (ns)
y
Outer Contour Linen = 1010 cm-3ne = 1010 cm 3
Inner Contour Linene = 1014 cm-3
Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)
E0=34 kVcm1010 cm-3
1010 cm-3 ne=1012 cm-3
1mm10 cm
ne=108 cm-3
An electron avalanche propagates towards the anode
Reverse propagationtowards the cathodepropagates towards the anode towards the cathode
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Cathode Layer Formation
E0=34 kVcm1010 cm-39 3 0
1mm
1010 cm-3
10 cmne=109 cm-31014
10131014
1013
10 cm1012
Just before the peak of the total current
Peak currentof the total current
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Local Field Collapse in Area Defined by Surface Discharge
ne=109cm-3 ne=1014 cm-3
Gap
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
C C-- - --- - - CG
CD
-- - - CG
CD
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
How do we solve this problemHow do we solve this problem
Transient (pulsed) plasmas In atmospheric plasmas for efficient gas heating atleast 100-1000 collisions are necessary Thus if the plasma duration is shorterleast 100 1000 collisions are necessary Thus if the plasma duration is shorterthan 10-6 ndash 10-5 s gas heating is limited Of course for practical purposes suchplasma has to be operated in a repetitive mode eg in trains of microsecondpulses with millisecond intervals
Micro-confinement Gas heating occurs in the plasma volume and the energy iscarried away by thermal diffusionconvection to the outside If the plasma has asmall volume and a relatively large surface gas heating is limited
Dielectric Barrier Discharges These plasmas are typically created betweenmetal plates which are covered by a thin layer of dielectric or highly resistivematerial The dielectric layer plays an important role in suppressing the currentthe cathodeanode layer is charged by incoming positive ionselectrons whichreduces the electric field and hinders charge transport towards the electrodeDBD also has a large surface-to-volume ratio which promotes diffusion lossesand maintains a low gas temperatureand maintains a low gas temperature
Advantages of Microplasmas Advantages of Microplasmas
bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures
Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y
hellip a new realm of plasma sciencehellip a new realm of plasma science
What can we do with microplasmasWhat can we do with microplasmas
Material Synthesis Plasma display Surface Treatment Lighting
H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)
Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges
Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)
Voltage Vpp 3ndash20 kV
Repetition frequency f 50 Hzndash30 kHz
Pressure p 1ndash3 bar
Gap distance g 02ndash5mm
Dielectric material thickness d 05ndash2mm
Relative dielectric permittivity r 5ndash10 (glass)
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Single and double DBD
Single dielectric Double dielectric
Role of the Dielectric (Insulator)
Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge
Serves two functions
1 Limits the amount of charge transportedby a single microplasma
2 Distributes the microplasmas over theentire electrode surface area
Equivalent Circuit of a Microdischarge
Microdischarge Activity and U-Q Lissajous Figure
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge
bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them
bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation
Time scale of the relevant processes of the DBD
HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)
Fundamental Operation of the DBDFundamental Operation of the DBD
Electron DensityTemporal Development (ns)
y
Outer Contour Linen = 1010 cm-3ne = 1010 cm 3
Inner Contour Linene = 1014 cm-3
Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)
E0=34 kVcm1010 cm-3
1010 cm-3 ne=1012 cm-3
1mm10 cm
ne=108 cm-3
An electron avalanche propagates towards the anode
Reverse propagationtowards the cathodepropagates towards the anode towards the cathode
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Cathode Layer Formation
E0=34 kVcm1010 cm-39 3 0
1mm
1010 cm-3
10 cmne=109 cm-31014
10131014
1013
10 cm1012
Just before the peak of the total current
Peak currentof the total current
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Local Field Collapse in Area Defined by Surface Discharge
ne=109cm-3 ne=1014 cm-3
Gap
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
C C-- - --- - - CG
CD
-- - - CG
CD
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Advantages of Microplasmas Advantages of Microplasmas
bull Low-cost of implementationpbull System flexibilitybull Atmospheric pressure operationbull High densities and high reaction ratesbull High densities and high reaction ratesbull Fast and efficient processesbull Easy to generate and sustain for a variety of gas mixtures
Gl lik d diffbull Glow-like and diffusebull Non-equilibrium (Te gt Tg) to thermalbull Unique chemistryq y
hellip a new realm of plasma sciencehellip a new realm of plasma science
What can we do with microplasmasWhat can we do with microplasmas
Material Synthesis Plasma display Surface Treatment Lighting
H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)
Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges
Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)
Voltage Vpp 3ndash20 kV
Repetition frequency f 50 Hzndash30 kHz
Pressure p 1ndash3 bar
Gap distance g 02ndash5mm
Dielectric material thickness d 05ndash2mm
Relative dielectric permittivity r 5ndash10 (glass)
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Single and double DBD
Single dielectric Double dielectric
Role of the Dielectric (Insulator)
Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge
Serves two functions
1 Limits the amount of charge transportedby a single microplasma
2 Distributes the microplasmas over theentire electrode surface area
Equivalent Circuit of a Microdischarge
Microdischarge Activity and U-Q Lissajous Figure
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge
bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them
bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation
Time scale of the relevant processes of the DBD
HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)
Fundamental Operation of the DBDFundamental Operation of the DBD
Electron DensityTemporal Development (ns)
y
Outer Contour Linen = 1010 cm-3ne = 1010 cm 3
Inner Contour Linene = 1014 cm-3
Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)
E0=34 kVcm1010 cm-3
1010 cm-3 ne=1012 cm-3
1mm10 cm
ne=108 cm-3
An electron avalanche propagates towards the anode
Reverse propagationtowards the cathodepropagates towards the anode towards the cathode
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Cathode Layer Formation
E0=34 kVcm1010 cm-39 3 0
1mm
1010 cm-3
10 cmne=109 cm-31014
10131014
1013
10 cm1012
Just before the peak of the total current
Peak currentof the total current
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Local Field Collapse in Area Defined by Surface Discharge
ne=109cm-3 ne=1014 cm-3
Gap
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
C C-- - --- - - CG
CD
-- - - CG
CD
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)
Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges
Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)
Voltage Vpp 3ndash20 kV
Repetition frequency f 50 Hzndash30 kHz
Pressure p 1ndash3 bar
Gap distance g 02ndash5mm
Dielectric material thickness d 05ndash2mm
Relative dielectric permittivity r 5ndash10 (glass)
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Single and double DBD
Single dielectric Double dielectric
Role of the Dielectric (Insulator)
Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge
Serves two functions
1 Limits the amount of charge transportedby a single microplasma
2 Distributes the microplasmas over theentire electrode surface area
Equivalent Circuit of a Microdischarge
Microdischarge Activity and U-Q Lissajous Figure
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge
bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them
bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation
Time scale of the relevant processes of the DBD
HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)
Fundamental Operation of the DBDFundamental Operation of the DBD
Electron DensityTemporal Development (ns)
y
Outer Contour Linen = 1010 cm-3ne = 1010 cm 3
Inner Contour Linene = 1014 cm-3
Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)
E0=34 kVcm1010 cm-3
1010 cm-3 ne=1012 cm-3
1mm10 cm
ne=108 cm-3
An electron avalanche propagates towards the anode
Reverse propagationtowards the cathodepropagates towards the anode towards the cathode
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Cathode Layer Formation
E0=34 kVcm1010 cm-39 3 0
1mm
1010 cm-3
10 cmne=109 cm-31014
10131014
1013
10 cm1012
Just before the peak of the total current
Peak currentof the total current
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Local Field Collapse in Area Defined by Surface Discharge
ne=109cm-3 ne=1014 cm-3
Gap
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
C C-- - --- - - CG
CD
-- - - CG
CD
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)
Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges
Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)
Voltage Vpp 3ndash20 kV
Repetition frequency f 50 Hzndash30 kHz
Pressure p 1ndash3 bar
Gap distance g 02ndash5mm
Dielectric material thickness d 05ndash2mm
Relative dielectric permittivity r 5ndash10 (glass)
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Single and double DBD
Single dielectric Double dielectric
Role of the Dielectric (Insulator)
Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge
Serves two functions
1 Limits the amount of charge transportedby a single microplasma
2 Distributes the microplasmas over theentire electrode surface area
Equivalent Circuit of a Microdischarge
Microdischarge Activity and U-Q Lissajous Figure
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge
bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them
bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation
Time scale of the relevant processes of the DBD
HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)
Fundamental Operation of the DBDFundamental Operation of the DBD
Electron DensityTemporal Development (ns)
y
Outer Contour Linen = 1010 cm-3ne = 1010 cm 3
Inner Contour Linene = 1014 cm-3
Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)
E0=34 kVcm1010 cm-3
1010 cm-3 ne=1012 cm-3
1mm10 cm
ne=108 cm-3
An electron avalanche propagates towards the anode
Reverse propagationtowards the cathodepropagates towards the anode towards the cathode
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Cathode Layer Formation
E0=34 kVcm1010 cm-39 3 0
1mm
1010 cm-3
10 cmne=109 cm-31014
10131014
1013
10 cm1012
Just before the peak of the total current
Peak currentof the total current
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Local Field Collapse in Area Defined by Surface Discharge
ne=109cm-3 ne=1014 cm-3
Gap
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
C C-- - --- - - CG
CD
-- - - CG
CD
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)
Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges
Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)
Voltage Vpp 3ndash20 kV
Repetition frequency f 50 Hzndash30 kHz
Pressure p 1ndash3 bar
Gap distance g 02ndash5mm
Dielectric material thickness d 05ndash2mm
Relative dielectric permittivity r 5ndash10 (glass)
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Single and double DBD
Single dielectric Double dielectric
Role of the Dielectric (Insulator)
Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge
Serves two functions
1 Limits the amount of charge transportedby a single microplasma
2 Distributes the microplasmas over theentire electrode surface area
Equivalent Circuit of a Microdischarge
Microdischarge Activity and U-Q Lissajous Figure
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge
bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them
bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation
Time scale of the relevant processes of the DBD
HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)
Fundamental Operation of the DBDFundamental Operation of the DBD
Electron DensityTemporal Development (ns)
y
Outer Contour Linen = 1010 cm-3ne = 1010 cm 3
Inner Contour Linene = 1014 cm-3
Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)
E0=34 kVcm1010 cm-3
1010 cm-3 ne=1012 cm-3
1mm10 cm
ne=108 cm-3
An electron avalanche propagates towards the anode
Reverse propagationtowards the cathodepropagates towards the anode towards the cathode
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Cathode Layer Formation
E0=34 kVcm1010 cm-39 3 0
1mm
1010 cm-3
10 cmne=109 cm-31014
10131014
1013
10 cm1012
Just before the peak of the total current
Peak currentof the total current
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Local Field Collapse in Area Defined by Surface Discharge
ne=109cm-3 ne=1014 cm-3
Gap
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
C C-- - --- - - CG
CD
-- - - CG
CD
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)
Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges
Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)
Voltage Vpp 3ndash20 kV
Repetition frequency f 50 Hzndash30 kHz
Pressure p 1ndash3 bar
Gap distance g 02ndash5mm
Dielectric material thickness d 05ndash2mm
Relative dielectric permittivity r 5ndash10 (glass)
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Single and double DBD
Single dielectric Double dielectric
Role of the Dielectric (Insulator)
Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge
Serves two functions
1 Limits the amount of charge transportedby a single microplasma
2 Distributes the microplasmas over theentire electrode surface area
Equivalent Circuit of a Microdischarge
Microdischarge Activity and U-Q Lissajous Figure
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge
bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them
bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation
Time scale of the relevant processes of the DBD
HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)
Fundamental Operation of the DBDFundamental Operation of the DBD
Electron DensityTemporal Development (ns)
y
Outer Contour Linen = 1010 cm-3ne = 1010 cm 3
Inner Contour Linene = 1014 cm-3
Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)
E0=34 kVcm1010 cm-3
1010 cm-3 ne=1012 cm-3
1mm10 cm
ne=108 cm-3
An electron avalanche propagates towards the anode
Reverse propagationtowards the cathodepropagates towards the anode towards the cathode
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Cathode Layer Formation
E0=34 kVcm1010 cm-39 3 0
1mm
1010 cm-3
10 cmne=109 cm-31014
10131014
1013
10 cm1012
Just before the peak of the total current
Peak currentof the total current
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Local Field Collapse in Area Defined by Surface Discharge
ne=109cm-3 ne=1014 cm-3
Gap
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
C C-- - --- - - CG
CD
-- - - CG
CD
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)
Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges
Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)
Voltage Vpp 3ndash20 kV
Repetition frequency f 50 Hzndash30 kHz
Pressure p 1ndash3 bar
Gap distance g 02ndash5mm
Dielectric material thickness d 05ndash2mm
Relative dielectric permittivity r 5ndash10 (glass)
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Single and double DBD
Single dielectric Double dielectric
Role of the Dielectric (Insulator)
Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge
Serves two functions
1 Limits the amount of charge transportedby a single microplasma
2 Distributes the microplasmas over theentire electrode surface area
Equivalent Circuit of a Microdischarge
Microdischarge Activity and U-Q Lissajous Figure
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge
bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them
bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation
Time scale of the relevant processes of the DBD
HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)
Fundamental Operation of the DBDFundamental Operation of the DBD
Electron DensityTemporal Development (ns)
y
Outer Contour Linen = 1010 cm-3ne = 1010 cm 3
Inner Contour Linene = 1014 cm-3
Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)
E0=34 kVcm1010 cm-3
1010 cm-3 ne=1012 cm-3
1mm10 cm
ne=108 cm-3
An electron avalanche propagates towards the anode
Reverse propagationtowards the cathodepropagates towards the anode towards the cathode
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Cathode Layer Formation
E0=34 kVcm1010 cm-39 3 0
1mm
1010 cm-3
10 cmne=109 cm-31014
10131014
1013
10 cm1012
Just before the peak of the total current
Peak currentof the total current
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Local Field Collapse in Area Defined by Surface Discharge
ne=109cm-3 ne=1014 cm-3
Gap
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
C C-- - --- - - CG
CD
-- - - CG
CD
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
H E Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications toHE Wagner R Brandenburg et al The barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 p417-436 (2003)
Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges
Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)
Voltage Vpp 3ndash20 kV
Repetition frequency f 50 Hzndash30 kHz
Pressure p 1ndash3 bar
Gap distance g 02ndash5mm
Dielectric material thickness d 05ndash2mm
Relative dielectric permittivity r 5ndash10 (glass)
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Single and double DBD
Single dielectric Double dielectric
Role of the Dielectric (Insulator)
Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge
Serves two functions
1 Limits the amount of charge transportedby a single microplasma
2 Distributes the microplasmas over theentire electrode surface area
Equivalent Circuit of a Microdischarge
Microdischarge Activity and U-Q Lissajous Figure
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge
bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them
bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation
Time scale of the relevant processes of the DBD
HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)
Fundamental Operation of the DBDFundamental Operation of the DBD
Electron DensityTemporal Development (ns)
y
Outer Contour Linen = 1010 cm-3ne = 1010 cm 3
Inner Contour Linene = 1014 cm-3
Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)
E0=34 kVcm1010 cm-3
1010 cm-3 ne=1012 cm-3
1mm10 cm
ne=108 cm-3
An electron avalanche propagates towards the anode
Reverse propagationtowards the cathodepropagates towards the anode towards the cathode
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Cathode Layer Formation
E0=34 kVcm1010 cm-39 3 0
1mm
1010 cm-3
10 cmne=109 cm-31014
10131014
1013
10 cm1012
Just before the peak of the total current
Peak currentof the total current
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Local Field Collapse in Area Defined by Surface Discharge
ne=109cm-3 ne=1014 cm-3
Gap
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
C C-- - --- - - CG
CD
-- - - CG
CD
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Typical operational conditions of barrier discharges Typical operational conditions of barrier discharges
Electric field strength E of first breakdown asymp150 Td (p = 1bar T=300 K)
Voltage Vpp 3ndash20 kV
Repetition frequency f 50 Hzndash30 kHz
Pressure p 1ndash3 bar
Gap distance g 02ndash5mm
Dielectric material thickness d 05ndash2mm
Relative dielectric permittivity r 5ndash10 (glass)
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Single and double DBD
Single dielectric Double dielectric
Role of the Dielectric (Insulator)
Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge
Serves two functions
1 Limits the amount of charge transportedby a single microplasma
2 Distributes the microplasmas over theentire electrode surface area
Equivalent Circuit of a Microdischarge
Microdischarge Activity and U-Q Lissajous Figure
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge
bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them
bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation
Time scale of the relevant processes of the DBD
HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)
Fundamental Operation of the DBDFundamental Operation of the DBD
Electron DensityTemporal Development (ns)
y
Outer Contour Linen = 1010 cm-3ne = 1010 cm 3
Inner Contour Linene = 1014 cm-3
Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)
E0=34 kVcm1010 cm-3
1010 cm-3 ne=1012 cm-3
1mm10 cm
ne=108 cm-3
An electron avalanche propagates towards the anode
Reverse propagationtowards the cathodepropagates towards the anode towards the cathode
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Cathode Layer Formation
E0=34 kVcm1010 cm-39 3 0
1mm
1010 cm-3
10 cmne=109 cm-31014
10131014
1013
10 cm1012
Just before the peak of the total current
Peak currentof the total current
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Local Field Collapse in Area Defined by Surface Discharge
ne=109cm-3 ne=1014 cm-3
Gap
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
C C-- - --- - - CG
CD
-- - - CG
CD
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge
Serves two functions
1 Limits the amount of charge transportedby a single microplasma
2 Distributes the microplasmas over theentire electrode surface area
Equivalent Circuit of a Microdischarge
Microdischarge Activity and U-Q Lissajous Figure
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge
bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them
bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation
Time scale of the relevant processes of the DBD
HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)
Fundamental Operation of the DBDFundamental Operation of the DBD
Electron DensityTemporal Development (ns)
y
Outer Contour Linen = 1010 cm-3ne = 1010 cm 3
Inner Contour Linene = 1014 cm-3
Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)
E0=34 kVcm1010 cm-3
1010 cm-3 ne=1012 cm-3
1mm10 cm
ne=108 cm-3
An electron avalanche propagates towards the anode
Reverse propagationtowards the cathodepropagates towards the anode towards the cathode
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Cathode Layer Formation
E0=34 kVcm1010 cm-39 3 0
1mm
1010 cm-3
10 cmne=109 cm-31014
10131014
1013
10 cm1012
Just before the peak of the total current
Peak currentof the total current
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Local Field Collapse in Area Defined by Surface Discharge
ne=109cm-3 ne=1014 cm-3
Gap
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
C C-- - --- - - CG
CD
-- - - CG
CD
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Th di l t i i th k f thThe dielectric is the key for the properfunctioning of the discharge
Serves two functions
1 Limits the amount of charge transportedby a single microplasma
2 Distributes the microplasmas over theentire electrode surface area
Equivalent Circuit of a Microdischarge
Microdischarge Activity and U-Q Lissajous Figure
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge
bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them
bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation
Time scale of the relevant processes of the DBD
HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)
Fundamental Operation of the DBDFundamental Operation of the DBD
Electron DensityTemporal Development (ns)
y
Outer Contour Linen = 1010 cm-3ne = 1010 cm 3
Inner Contour Linene = 1014 cm-3
Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)
E0=34 kVcm1010 cm-3
1010 cm-3 ne=1012 cm-3
1mm10 cm
ne=108 cm-3
An electron avalanche propagates towards the anode
Reverse propagationtowards the cathodepropagates towards the anode towards the cathode
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Cathode Layer Formation
E0=34 kVcm1010 cm-39 3 0
1mm
1010 cm-3
10 cmne=109 cm-31014
10131014
1013
10 cm1012
Just before the peak of the total current
Peak currentof the total current
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Local Field Collapse in Area Defined by Surface Discharge
ne=109cm-3 ne=1014 cm-3
Gap
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
C C-- - --- - - CG
CD
-- - - CG
CD
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge
bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them
bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation
Time scale of the relevant processes of the DBD
HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)
Fundamental Operation of the DBDFundamental Operation of the DBD
Electron DensityTemporal Development (ns)
y
Outer Contour Linen = 1010 cm-3ne = 1010 cm 3
Inner Contour Linene = 1014 cm-3
Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)
E0=34 kVcm1010 cm-3
1010 cm-3 ne=1012 cm-3
1mm10 cm
ne=108 cm-3
An electron avalanche propagates towards the anode
Reverse propagationtowards the cathodepropagates towards the anode towards the cathode
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Cathode Layer Formation
E0=34 kVcm1010 cm-39 3 0
1mm
1010 cm-3
10 cmne=109 cm-31014
10131014
1013
10 cm1012
Just before the peak of the total current
Peak currentof the total current
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Local Field Collapse in Area Defined by Surface Discharge
ne=109cm-3 ne=1014 cm-3
Gap
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
C C-- - --- - - CG
CD
-- - - CG
CD
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
B Eliasson and U Kogelschatz IEEE Transactions Plasma Science Vol 19 Issue 6 1063-1077 (1991)
Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge
bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them
bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation
Time scale of the relevant processes of the DBD
HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)
Fundamental Operation of the DBDFundamental Operation of the DBD
Electron DensityTemporal Development (ns)
y
Outer Contour Linen = 1010 cm-3ne = 1010 cm 3
Inner Contour Linene = 1014 cm-3
Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)
E0=34 kVcm1010 cm-3
1010 cm-3 ne=1012 cm-3
1mm10 cm
ne=108 cm-3
An electron avalanche propagates towards the anode
Reverse propagationtowards the cathodepropagates towards the anode towards the cathode
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Cathode Layer Formation
E0=34 kVcm1010 cm-39 3 0
1mm
1010 cm-3
10 cmne=109 cm-31014
10131014
1013
10 cm1012
Just before the peak of the total current
Peak currentof the total current
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Local Field Collapse in Area Defined by Surface Discharge
ne=109cm-3 ne=1014 cm-3
Gap
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
C C-- - --- - - CG
CD
-- - - CG
CD
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Fundamental Operation of the Dielectric Barrier DischargeFundamental Operation of the Dielectric Barrier Discharge
bull Many of relevant plasma processes that areof importance to achieving our goal occuron time scales that allow us to study themon time scales that allow us to study them
bull Optical emission spectroscopic studies willallow us to determine the temporal andspatial development of important plasmaspatial development of important plasmaspecies such as radicals (OH NO variousoxygen radicals) with high time resolution(less than 10 ns) and a spatial resolution onthe scale of mm in the plasma volumepfollowing pulsed plasma excitation
Time scale of the relevant processes of the DBD
HE Wagner R Brandenburg et al lsquoThe barrier discharge basic properties and applications tosurface treatmentrsquo Vacuum 71 417-436 (2003)
Fundamental Operation of the DBDFundamental Operation of the DBD
Electron DensityTemporal Development (ns)
y
Outer Contour Linen = 1010 cm-3ne = 1010 cm 3
Inner Contour Linene = 1014 cm-3
Streamer Propagation in 1 bar AirAA Kulikovsky IEEE Trans Plasma Sci 25 439-446 (1997)
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Starting Phase of a Microdischarge (1 bar 20 CO2 80 H2)
E0=34 kVcm1010 cm-3
1010 cm-3 ne=1012 cm-3
1mm10 cm
ne=108 cm-3
An electron avalanche propagates towards the anode
Reverse propagationtowards the cathodepropagates towards the anode towards the cathode
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Cathode Layer Formation
E0=34 kVcm1010 cm-39 3 0
1mm
1010 cm-3
10 cmne=109 cm-31014
10131014
1013
10 cm1012
Just before the peak of the total current
Peak currentof the total current
Numerical Results of Microdischarge Formationin Dielectric Barrier Discharges
Local Field Collapse in Area Defined by Surface Discharge
ne=109cm-3 ne=1014 cm-3
Gap
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
C C-- - --- - - CG
CD
-- - - CG
CD
Principals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD MicroplasmasPrincipals of DBD Microplasmas
Dielectric Barrier Discharge (DBD)Dielectric Barrier Discharge (DBD)Electric Field
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Los Angeles CA 10000 1986Fairfax VA ndash Corbalis 9000 2003MWD CA ndash Mills 9 000 2003
Ozonia Installations Ozone Plant Size [lbday] Start Up Date
MWD CA Mills 9000 2003Fairfax Co VA ndash Griffith 9000 2004MWD CA ndash Jensen 18750 2005Indianapolis IN ndash Belmont AWT 12000 2007I di li IN 12 000 2007Indianapolis IN ndash Southport AWT 12000 2007MWD CA ndash Diemer 13400 2008MWD CA ndash Weymouth 13400 2009
Ozonia North America - Potable Water SummaryTotal Number of Installations 90Total Installed Production gt 265000 lbsdayTotal Installed Production 265000 lbsday
Revision -B
Ozone Water TreatmentOzone Water Treatment
MWD Mills WTP - California
3 3 000 lbsda of o one3 3 000 lbsda of o one3 x 3000 lbsday of ozone3 x 3000 lbsday of ozone
Ozone Water TreatmentOzone Water TreatmentOzone Ozone -- How it worksHow it works
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
bullbull BOD COD and TOC reductionBOD COD and TOC reduction
Applications of Ozone
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Wastewater Treatmentbull Disinfection of Secondary and Tertiary Effluentsbull Color Reductionbull Color Reductionbull TOC Oxidation (Industrial)bull Oxidation of Odor Causing Compoundsbull Oxidation of Endocrine Disruptors (EDCrsquos) and p ( )
Pharmaceutically Active Compounds (PACrsquos)
Applications of Ozone
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
What are Endocrine Disruptors (EDCrsquos) and What are Endocrine Disruptors (EDCrsquos) and Ph ti ll A ti C d (PACrsquo )Ph ti ll A ti C d (PACrsquo )Pharmaceutically Active Compounds (PACrsquos)Pharmaceutically Active Compounds (PACrsquos)
bullbull EDCrsquosEDCrsquos andand PACrsquosPACrsquos areare NaturallyNaturally andand SyntheticSyntheticdd th tth t ff tff t thth b lb l llcompoundscompounds thatthat maymay affectaffect thethe balancebalance oror normalnormal
What can EDCrsquos and PACrsquos doWhat can EDCrsquos and PACrsquos do
bullbull Even in very small concentrations these compounds Even in very small concentrations these compounds y py pcan can disruptdisrupt normal bodily functionsnormal bodily functions
bullbull ManMan--made chemicals can trick the bodies endocrine made chemicals can trick the bodies endocrine system system
Applications of Ozone
Examples of Endocrine Disruptors1000rsquos of compounds that may be Investigated as EDCs ndash Some examples are
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Health and Beauty AidsHealth and Beauty Aidsbullbull Health and Beauty AidsHealth and Beauty Aidsbullbull SolventsSolventsbullbull PesticidesPesticidesbullbull SurfactantsSurfactantsbullbull PlasticsPlastics
F i idF i idbullbull FungicidesFungicides
Ozone Water TreatmentOzone Water Treatment
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Ozone Ozone -- Industrial ApplicationsIndustrial Applications-- Ultrapure Water for Pharmaceutical ApplicationsUltrapure Water for Pharmaceutical Applications
-- Wastewater disinfection color removalWastewater disinfection color removal
-- Soil and Groundwater Remediation Soil and Groundwater Remediation
-- Cooling Tower Water TreatmentCooling Tower Water Treatment
P l amp P Bl hiP l amp P Bl hi-- Pulp amp Paper BleachingPulp amp Paper Bleaching
High Purity OzonationHigh Purity Ozonation
Microchip manufacturingMicrochip manufacturing
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
What are the current issues in large-scale gozone generationg
Experimental Setup
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Front view of the two units after the redesign and reworking ofthe gas water and instruments connectionsthe gas water and instruments connections
Experimental Setup
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Top view of the twoexperimental unitsexperimental unitsSpectroscope (notshown) is to the left ofthe DBD The units weredifferent with respect todifferent with respect totheir electrodes onehad only the electrodecoated with thedielectric (ldquosingle-dielectric ( single-coatedrdquo) the other onehad the electrode andthe anode coated withthe dielectric (ldquodouble-the dielectric ( double-coatedrdquo)
Basics Generation of OzoneBasics Generation of Ozone
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
IR spectra of several methane variations The green curve envelopes all of the methane peaks at 1325 cm-1recorded at smaller methane admixtures Simultaneously the N2O5 peaks disappear as the methane peaks appear
N2O5 FormationN2O5 Formation2 52 5p=2 bara cwt=20degC q=35kWm2 f=1450Hz
45N2O5 AT95
30
35
40
N
2 B
lend
ing
N2O AT95N2O5 IGSN2O IGSN2O5 LGN2O LG
1 5
20
25
nt [p
pmV]
3
wt
05
10
15
NO
x co
nten
005 7 9 11 13 15 17
ozone conc [wt]
Amount of formed N2O5 and N2O as a function of ozone concentration at 3 wt of nitrogen admixture and fori l dvarious electrode arrangements
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Intensities in 3 wtN2+O2 plasmaIntensities in 3 wtN2+O2 plasma
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Plasma Chemistry in OzonizersPlasma Chemistry in Ozonizers
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
N
3
NO2
O2 O3
NO
N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
Primary electron-driven chemical reactions leading to the formation of N2O5 and N2O in a dry air plasma
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Plasma emission diagnostics role of N2Plasma emission diagnostics role of N2
Dry Air O2 N2
e - e -
O N2 N O2
O3 NO
O2 N O2
O3
O
N
ON
NO2
O2O3
N
NO N
NO2 O3
N2O
NO3 N
N2O4
NO2
NO2
N2O5
NO3
ONbullWith N2 present ndash less oxygen atoms are formed However the difference in intensity is
very small
Modeling of plasma chemistry incl the NxOy chemistry up to N2O5 for different Oxygen Nitrogen mixtures varying power deposition scenarios
and initial ozone background concentrations (up to 15) previously done
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
The role of N2 must be related to its by-products reacting on the surface of the electrodeThe role of N2 must be related to its by-products reacting on the surface of the electrode
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f O
The following facts which were verified on various oxygen-fed ozone generator vessels (utilizedwith and without pickling and passivation) were established
Ab 8 t f OAbove 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)
Above 8 wt of O3
1 Deterioration of the generator performance without N2 admixture even with pampp(removal of the pampp oxide layer during aggressive cleaning of surfaces is equivalent to thecase itho t pampp)case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of the
case without pampp)
2 The experiments performed by Pontiga et al in 2004 confirm the above conclusion The by-products seem to just conserve the properties of a surface it will deteriorate withoutthem A deterioration of the surface is due to oxidation which extends the thickness of thethem A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
them A deterioration of the surface is due to oxidation which extends the thickness of theoxide layer N2O5 is found to deposit as crystalline substance on surfaces which are slightlycooler than the N2O5-carrying gas An N2O5 layer seems to inhibit the advanced oxidation ofthe stainless steel surface
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
The Role of nitrogen (N2) in ozone generationThe Role of nitrogen (N2) in ozone generation
Three possibilities have to be considered for the oxygen-fedozone generator
Three possibilities have to be considered for the oxygen-fedozone generatorozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in
ozone generator
bull Excited N2 molecules lead to an increased O2 dissociation in2 2such case an increased efficiency is correlated to the N2admixture
2 2such case an increased efficiency is correlated to the N2admixture
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The by-products perform a chemicalphysical process on theelectrodes which turns out to be beneficial
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2
bull The UV emission from O2 dissociation that leads to photon orlight splitting of O3 is suppressed by N2g p g 3 pp y 2g p g 3 pp y 2
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Effect of methane on ozone efficiency and specific powerEffect of methane on ozone efficiency and specific power
Effect of Methane on Ozone Content in Outlet Gas and on Specific Power Pure O2
13 12
10
11
12
t 8
10
8
9
10
ne c
onte
nt w
t
6
8
ecifi
c po
wer
kW
hlb
5
6
7
Ozo
n
2
4 Spe
400E+00 20E+03 40E+03 60E+03 80E+03 10E+04 12E+04
Methane in feedgas ppm
0
Ozone content in the outlet gas Specif ic pow er of the ozone generatorg p p g
Effects of N2 and CH4Effects of N2 and CH4
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Pi t f h t lli N O t tPicture of an amorphous-crystalline N2O5 structurecaptured at the Orlando Skylake water plant in 2006
Plasma Chemistry with CH4 Impurities
OxygenO2 N2
e - e -
CHO N2
NO2
O NO
O2 N O2 O3
NOH
CH4e-
O3 NO
NO2
O2O3NO N
NO2 O
NO2
NO2
N2ONO3
N
O3
NO2
NO
HNO3
N2O4
N2O5
NO2
NO3
N2O5
Effect of methane on the electrode surfaces
a) b)
Inlet Outlet Outlet
) d)
I l t I l t
c) d)
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Electrode of the ozone generator afterseveral hours in CH8O2 and up to 2 wt of methane (a b c)
Inlet Inlet
three hours in CH8O2+traces of N2 and up to 1 wt of methane (d) Visible change of discharge character at about 13 length of electrode (a d)
Kinetics of CHx Conversion without N2
conversion by collisions
O2 + CHx 12wt O3 + CO2 +H2O
deposition vaporizationby sputtering
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
ibl b l 1000 CHreversible process below 1000ppm CH4
Effect of water on electrode surface with N2
Inlet
OutletOutlet
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Electrode of the ozone generator after several hours in H OO N
Inlet
Electrode of the ozone generator after several hours in H2OO2N2
Effect of water on electrode surface
Long term effect (800 hrs) of H2OO2N2
Kinetics of CHx Conversion with N2
conversion by collisionsHNO3 formation
O2 + N2 +CHx 12wtO2 + CO2 +H2O + HNO3
deposition vaporizationby sputtering
H2O + HNO3
by sputtering
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
irreversible process above a N2 threshold () ltlt 1000ppm N2
sticky deposit
p 2 ( ) pp 2 any CH4 concentration (60ppm)
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Plasma Chemistry with CH4 ImpuritiesPlasma Chemistry with CH4 Impurities4
bull Formation of NO and NO2 depends on O3 N2 and gas temperature Conclusion N2 admixture is the key factor
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
SummarySummaryyyThe mechanisms of formed NOx by-products follows the sameThe mechanisms of formed NOx by-products follows the sameprinciples as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentration
principles as the air fed ozone generators the amount of formed N2O5is found to depend on just three parametersozoneozone concentrationconcentrationozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)
ozoneozone concentrationconcentrationnitrogen admixturecooling water temperature ( = gas temperature)g p ( g p )
The conversion of methane to OH and H2O is found to depend on
g p ( g p )
The conversion of methane to OH and H2O is found to depend ondissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)
dissociation by electron impact ( microdischarge)energy distribution of electrons in the microdischarges (discharge gap)discharge gap)discharge gap)
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
high sedimentation on the structurehigh sedimentation on the structure
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
Degreacutemont Technologies ndash OzoniaIntelligent Gap SystemIntelligent Gap System
G Vezzuacute JL Lopez A Freilich and K Becker Optimizationof Large-Scale Ozone Generators IEEE Transactions onPlasma Science Vol 37 No 6 p 890-896 (2009)
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
ConclusionsConclusionsConclusionsConclusionsFundamentals of ozone synthesis in a DBD plasmay p
ndash Highly filamented DBD discharges are best-suitedfor the production of ozone concentrations in therange of 6 to 14 wtrange of 6 to 14 wt
ndash The preferred characteristic of the microdischargesare Townsend-like at reduced electric fields Enaround 190 Townsend
ndash Detrimental side-effects induced by by-productscan be avoided by a proper design of the electrodecan be avoided by a proper design of the electrodearrangement The phenomenon is related to thediffusion rates of formed by-product clusters
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
ConclusionsConclusionsConclusionsConclusionsBenefits from DBD microplasma tailoring
ndash Reduced power consumption of up to 10 improvement
ndash Increased ozone concentrations of up to 14 now achievable
ndash Improved neutralization and conditioning of detrimental by-products
ndash Reduced system capital and operational cost
New technologies to improve ozone p
generatorg
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
HV Pulsed Power SwitchingHV Pulsed Power Switching
Microchannel Generation of Ozone
Channel ArrayChannel Array
Microchannel
330 microm 230 microm
Some Cap-DBD Devices Operating in Air
Increase of 60 of
Spacing 225 μmof 60 of plasma
No space
Cap‐DBD ozone generation
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics
bull Ozone concentration is evaluated via Eco S d l UV 100 O A l (0 01Sensors model UV-100 Ozone Analyzer (001 ndash 900 ppm wiht an accuracy of plusmn2)
bull Three reactors 6 tubings 6rdquo with spacings of 0 μm 225 μm and 500 μm running at 3 kV μ μ μ g
SpacingOzone Concentration
3 kV rms 4 kV rms3 kV rms 4 kV rms
0 μm 660 ppm
225 μm 550 ppm
For a device of such small scale these ozone levels are promising
500 μm 380 ppm
J Mahoney W Zhu VS Johnson KH Becker and JL Lopez Electrical and optical emissionmeasurements of a capillary dielectric barrier discharge European Physics Journal D Vol 60 441-447(2010)
QuestionsQuestions
Thank YouFor more informationProf Jose L Lopez PhD
Thank YouFor more informationDepartment of Physics