CURRENT AND EMERGING MERCURY CURRENT AND EMERGING MERCURY AND MULTIPOLLUTANT CONTROL AND MULTIPOLLUTANT CONTROL TECHNOLOGIES TECHNOLOGIES ICAC Forum '03: ICAC Forum '03: Multi-Pollutant Emission Controls & Strategies Multi-Pollutant Emission Controls & Strategies October 14-15, 2003, Nashville, TN October 14-15, 2003, Nashville, TN Ravi Ravi K. K. Srivastava Srivastava , U.S. EPA, National Risk Management Research Laboratory, , U.S. EPA, National Risk Management Research Laboratory, Research Triangle Park, NC 27711 Research Triangle Park, NC 27711 James James Staudt Staudt , Andover Technology Partners, 112 Tucker Farm Rd., North Andover, MA , Andover Technology Partners, 112 Tucker Farm Rd., North Andover, MA 01845 01845 E. E. Stratos Tavoulareas Stratos Tavoulareas , Energy Technologies Enterprises Corp., 1112 , Energy Technologies Enterprises Corp., 1112 Towlston Towlston Rd., Rd., McLean, VA 22102 McLean, VA 22102 Wojciech Jozewicz Wojciech Jozewicz and and Michiel Doorn Michiel Doorn , ARCADIS , ARCADIS Geraghty Geraghty & Miller, Research Triangle & Miller, Research Triangle Park, NC 27709 Park, NC 27709
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CURRENT AND EMERGING MERCURY AND MULTIPOLLUTANT CONTROL ...€¦ · Wet FGD Modification 83 % of U.S.-installed FGD capacity Capable of removing SO2 in excess of 95 % Can remove oxidized
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CURRENT AND EMERGING MERCURYCURRENT AND EMERGING MERCURYAND MULTIPOLLUTANT CONTROLAND MULTIPOLLUTANT CONTROL
TECHNOLOGIESTECHNOLOGIESICAC Forum '03:ICAC Forum '03:
RaviRavi K. K. SrivastavaSrivastava, U.S. EPA, National Risk Management Research Laboratory,, U.S. EPA, National Risk Management Research Laboratory,Research Triangle Park, NC 27711Research Triangle Park, NC 27711James James StaudtStaudt, Andover Technology Partners, 112 Tucker Farm Rd., North Andover, MA, Andover Technology Partners, 112 Tucker Farm Rd., North Andover, MA0184501845E. E. Stratos TavoulareasStratos Tavoulareas, Energy Technologies Enterprises Corp., 1112 , Energy Technologies Enterprises Corp., 1112 TowlstonTowlston Rd., Rd.,McLean, VA 22102McLean, VA 22102Wojciech JozewiczWojciech Jozewicz and and Michiel DoornMichiel Doorn, ARCADIS , ARCADIS GeraghtyGeraghty & Miller, Research Triangle & Miller, Research TrianglePark, NC 27709Park, NC 27709
Natural sourcesNatural sources–– Volcanoes - annual tonnage not quantifiedVolcanoes - annual tonnage not quantified–– Forest fires - annual tonnage not quantifiedForest fires - annual tonnage not quantified
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Policy DriversPolicy DriversUtility MACTUtility MACT–– Maximum degree of emissions reduction achievable, taking in toMaximum degree of emissions reduction achievable, taking in to
consideration costconsideration cost–– At least as stringent as the best performing facilities for new sources;At least as stringent as the best performing facilities for new sources;
average of the top performing 12 percent for existing sourcesaverage of the top performing 12 percent for existing sources–– Emissions standard applicable to each sourceEmissions standard applicable to each source–– Section 112 does not allow trading between facilities to meet theSection 112 does not allow trading between facilities to meet the
standard; averaging among units at a given facility can be consideredstandard; averaging among units at a given facility can be considered
Clear SkiesClear Skies–– Emissions reductions from power plants: Emissions reductions from power plants: NOxNOx by 67 percent, SO2 by by 67 percent, SO2 by
73 percent, and mercury by 69 percent; to be phased-in between 2008-73 percent, and mercury by 69 percent; to be phased-in between 2008-2018; includes emissions cap and trade provisions2018; includes emissions cap and trade provisions
PM Transport Rule: regulatory approach that usesPM Transport Rule: regulatory approach that usesexisting CAA mechanisms to address transportedexisting CAA mechanisms to address transportedair pollutionair pollution–– Analyze sources of SO2 (for PMAnalyze sources of SO2 (for PM2.52.5) and ) and NOxNOx (for PM (for PM2.52.5 and and
ozone).ozone).–– Determine whether there is a significant contribution fromDetermine whether there is a significant contribution from
individual states.individual states.–– Controls effective 2009/2010 at the earliest.Controls effective 2009/2010 at the earliest.–– EPA develops an emissions budget for each state. States haveEPA develops an emissions budget for each state. States have
discretion in deciding which sources to control to meet the budget.discretion in deciding which sources to control to meet the budget.–– Plan to propose an optional cap-and-trade program similar to AcidPlan to propose an optional cap-and-trade program similar to Acid
Rain and Rain and NOxNOx SIP call. SIP call.
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>2500 °C
Hg°
APCDInletEntrained PM
CO2
H2O
SO2
NOx
HCl N2 Hg
Coal
Mercury Speciation:
300 °F
Hgo, Hg2+ compounds, particulate mercury Hg(p)
Mercury in Coal-fired BoilersMercury in Coal-fired Boilers
Temperature, °C
Thermochemical Equilibrium Calculations
Hg°
HgCl2HgO
0 300 600 900 1200
Mas
s Fr
actio
n
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Mercury SpeciationMercury Speciation
In general, speciation depends on:In general, speciation depends on:–– Coal properties (mercury, chlorine, and ash contents)Coal properties (mercury, chlorine, and ash contents)–– Time/temperature profileTime/temperature profile–– Flue gas composition and fly ash characteristicsFlue gas composition and fly ash characteristics
Mercury Capture in Existing EquipmentMercury Capture in Existing Equipment
Removal in PM ControlsRemoval in PM ControlsMercury can be adsorbed onto fly ash surfaces; HgMercury can be adsorbed onto fly ash surfaces; Hg2+2+ is ismore readily adsorbed than Hgmore readily adsorbed than Hg00
Mercury can be physically adsorbed at relatively lowerMercury can be physically adsorbed at relatively lowertemperatures (hot-side ESP vs. cold-side ESP)temperatures (hot-side ESP vs. cold-side ESP)
Capture in Wet ScrubbersCapture in Wet ScrubbersHgHg2+2+ capture depends on solubility of each compound; capture depends on solubility of each compound;HgHg00 is insoluble and cannot be captured is insoluble and cannot be capturedCapture enhanced by SCRCapture enhanced by SCR
•• Hg capture for differentHg capture for different coal-control technology coal-control technology combinations correlate combinations correlate with coal chlorine content with coal chlorine content
•• No data on UBC content No data on UBC content of fly ash of fly ash
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Chlorine vs. Mercury SpeciationChlorine vs. Mercury Speciation
ICR data for HgICR data for Hg00
at ESP & FF inletat ESP & FF inlet
HgHg00 oxidation appears oxidation appearsto be independent ofto be independent ofchlorine above 100chlorine above 100µµg/gg/g
Other important factorsOther important factors–– TemperatureTemperature–– Fly ash carbonFly ash carbon0%
20%
40%
60%
80%
100%
10 100 1,000 10,000Coal Chlorine, ppm dry
%H
g0 a
t PC
D In
let
Cold-side ESP & FFHot-side ESP
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Impact of Carbon In AshImpact of Carbon In Ash
0%10%20%
30%40%50%60%70%
80%90%
100%
0 100,000 200,000 300,000 400,000 500,000
C:Hg Ratio
Hg R
emov
al A
cros
s ES
P
DeVitoPlant APlant BPlant C
Cold-Side ESP, bituminous coal
Hot-side ESP, bituminous coal
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Speciation influences emissions controlSpeciation influences emissions control–– Ionic HgIonic Hg2+2+ is removed easily by wet scrubbers is removed easily by wet scrubbers–– Volatile elemental HgVolatile elemental Hg00 is difficult to capture is difficult to capture
SCR units are being used extensively to meetSCR units are being used extensively to meetcurrent current NOxNOx regulations regulationsSCR can convert elemental mercury in coalSCR can convert elemental mercury in coalcombustion flue gas into the ionic formcombustion flue gas into the ionic form–– field data in Europe and U.S. reflects increase infield data in Europe and U.S. reflects increase in
HgHg2+2+ across SCR reactor across SCR reactor
SCR and Mercury InteractionsSCR and Mercury Interactions
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SCR-Mercury R&DSCR-Mercury R&DTested 4 utility plants in the 2001 and 2 in 2002; retested 2 plants in 2002;Tested 4 utility plants in the 2001 and 2 in 2002; retested 2 plants in 2002;total of 8 data pointstotal of 8 data pointsOxidized mercury increase across SCR: bit. - up to 71%; Oxidized mercury increase across SCR: bit. - up to 71%; subbitsubbit. - 10% (one. - 10% (onedata point only)data point only)Removal in PM control and FGD (5 data points) - ~ 85% - 90%Removal in PM control and FGD (5 data points) - ~ 85% - 90%Results from repeated tests were consistent with previous data; impacts ofResults from repeated tests were consistent with previous data; impacts ofSCR catalyst aging not apparentSCR catalyst aging not apparentSCR systems with relatively lower catalyst volumes (space velocity greaterSCR systems with relatively lower catalyst volumes (space velocity greaterthan 3500 hr-1) also showed significant oxidation increasesthan 3500 hr-1) also showed significant oxidation increasesData gaps: PRB, blendsData gaps: PRB, blendsOngoing EPA bench- and pilot-scale research:Ongoing EPA bench- and pilot-scale research: HClHCl provides critical chlorine provides critical chlorinesource for Hgsource for Hg00 oxidation; oxidation; NOxNOx has a significant promotional effect; has a significant promotional effect; SOSOxx has haslittle effect under the conditions of this studylittle effect under the conditions of this study
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Some Retrofit Control OptionsSome Retrofit Control OptionsPlants with ESP or FF: Plants with ESP or FF: sorbentsorbent injection; injection; sorbentsorbentinjection + pulse jet FF (PJFF); circulating fluid bedinjection + pulse jet FF (PJFF); circulating fluid bedabsorber (CFBA) on bit.-fired for SOabsorber (CFBA) on bit.-fired for SO22 and mercury and mercurycapturecapture
Plants with dry FGD systems:Plants with dry FGD systems:–– Bit. coal - small amounts of carbon, if neededBit. coal - small amounts of carbon, if needed–– SubbitSubbit. coal - . coal - sorbentsorbent injection or injection or sorbentsorbent injection + pulse jet FF injection + pulse jet FF
(PJFF); ; (PJFF); ; sorbentsorbent injection + FF (upstream of SDA) if injection + FF (upstream of SDA) ifneutralization of chlorine is a concernneutralization of chlorine is a concern
Plants with wet FGD systems: SCR; oxidation catalysts,Plants with wet FGD systems: SCR; oxidation catalysts,reagents, and other systemsreagents, and other systems
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Carbon Injection ProjectsCarbon Injection ProjectsAlabama Power E.C. Gaston: unit 3, 270-MW, low-sulfur eastern bit. coals (0.14Alabama Power E.C. Gaston: unit 3, 270-MW, low-sulfur eastern bit. coals (0.14ppmppm Hg and 160 Hg and 160 ppmppm ClCl); hot-side ESP, COHPAC ); hot-side ESP, COHPAC baghousebaghouse; testing on one-half of; testing on one-half ofthe gas stream, nominally 135 MW; wet ash to pondthe gas stream, nominally 135 MW; wet ash to pond
WEPCO Pleasant Prairie: unit 2, 600-MW, PRB coal (0.11 WEPCO Pleasant Prairie: unit 2, 600-MW, PRB coal (0.11 ppmppm Hg and 8 Hg and 8 ppmppm ClCl););ESP (468 ftESP (468 ft22//kacfmkacfm), spray cooling, SO), spray cooling, SO3 3 conditioning; testing on one ESP chamberconditioning; testing on one ESP chamber(1/4 of the unit); fly ash sold for use in concrete(1/4 of the unit); fly ash sold for use in concrete
PG&E PG&E BraytonBrayton Point: unit 1, 245-MW, low-S bit. coal (0.03 Point: unit 1, 245-MW, low-S bit. coal (0.03 ppmppm Hg and 2000-4000 Hg and 2000-4000ppmppm ClCl); SO); SO3 3 conditioning system; 2 conditioning system; 2 ESPsESPs in series (550 ft in series (550 ft22//kacfmkacfm); PAC injection); PAC injectionbetween the between the ESPsESPs
PG&E Salem Harbor: 85-MW, low-S bit. coal (0.03-0.08 PG&E Salem Harbor: 85-MW, low-S bit. coal (0.03-0.08 ppmppm Hg and 206 Hg and 206 ppmppm ClCl););ESP (474 ftESP (474 ft22//kacfmkacfm); SNCR); SNCR
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Mercury Removal Trends with ACIMercury Removal Trends with ACI
High baseline removal due to highHigh baseline removal due to highlevels of LOI; minimal impact onlevels of LOI; minimal impact onreducing LOI from 30-35% to 15-20%reducing LOI from 30-35% to 15-20%at 300 at 300 ooFF
Temperature has greater effect thanTemperature has greater effect thanLOILOI
SNCR has no impact on Hg removalSNCR has no impact on Hg removal 0
10
20
30
40
50
60
70
80
90
100
270 290 310 330 350 370
17-19% LOI (45 lb/M Macf)20-24% LOI (55 lb/M Macf)25-29% LOI (68 lb/M Macf)>30% LOI30-35% LOI, C1, High Load21-27% LOI, C2, High LoadLS bitum coal
Hg
Rem
oval
(%)
Temperature (oF)
Source: ADA Environmental Solutions (2003)
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PG&E Salem HarborPG&E Salem Harbor(w/ PAC Injection)(w/ PAC Injection)
At lower temperatures,At lower temperatures,removal by PAC affected byremoval by PAC affected byhigh baseline removalhigh baseline removalAt higher temperatures, linearAt higher temperatures, linearbehavior (similar to that atbehavior (similar to that atBraytonBrayton Point Point
0
10
20
30
40
50
60
70
80
90
0 5 10 15 20 25
280-290 F298-306 F322-327 F343-347 F
Hg
Rem
oval
(%)
Injection Concentration (lb/106 acf)
Source: ADA Environmental Solutions (2003)
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Cost of Control with Carbon InjectionCost of Control with Carbon Injection((Low-sulfur Bituminous Coal)Low-sulfur Bituminous Coal)
Wet FGD ModificationWet FGD Modification83 % of U.S.-installed FGD capacity83 % of U.S.-installed FGD capacityCapable of removing SOCapable of removing SO22 in excess of in excess of95 %95 %Can remove oxidized HgCan remove oxidized HgThree routes for NO removal:Three routes for NO removal:–– gas phase oxidation to Ngas phase oxidation to N22OO55
–– oxidation to NOoxidation to NO22 and reduction to N and reduction to N2 2 in thein thescrubber via sulfate and bisulfate ionsscrubber via sulfate and bisulfate ions
–– other processes (Mitsubishi and other processes (Mitsubishi and LextranLextran))
Investigate SO2, Hg, Investigate SO2, Hg, NOx NOx removal andremoval andSO2 to SO3 conversionSO2 to SO3 conversion
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Development of Development of Multipollutant SorbentsMultipollutant Sorbents
SorbentSorbent Development Development–– Synthesis,Synthesis,
NO2 and SO2 capacity given as mg/g adsorbed in 1 hr at 80˚C;
Hg0 capacity given as µg/g adsorbed in 1 hr at 80˚C
•Types of Sorbents Being Studied–Sorbents synthesized using industrial by-products–Modified carbon-type sorbents–Surface modified Calcium Silicate Hydrate (C-S-H)–Multipollutant sorbents that also have adsorptive capacity for CO2