Titelmasterformat durch Klicken bearbeiten Untertitelmaster bearbeiten Datum ESP Performance Enhancements by SO 3 - Conditioning T. Riethmann, Evonik Energy Services GmbH H. Rhein, Evonik Energy Services GmbH O. Blauenstein, Pentol GmbH VGB Flue Gas Cleaning 2011, Helsinki 25 th May 2011
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TEV11-06 ESP performance enhancements by SO3-conditioning · Titelmasterformat durch Klicken bearbeiten Untertitelmaster bearbeiten Datum. ESP Performance Enhancements by SO. 3 -
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ESP Performance Enhancements by SO3 - Conditioning
T. Riethmann, Evonik Energy Services GmbHH. Rhein, Evonik Energy Services GmbHO. Blauenstein, Pentol GmbH
VGB Flue Gas Cleaning 2011, Helsinki25th May 2011
25/05/11 | ESP-Performance Enhancements Page | 2
OverviewLatest Installations History at STEAGChallenges in Dust Removal
ESP BasicsResistivity and Back Corona Effects
Enhanced ESP PerformanceCFD-Modeling for ESP OptimizationThe Step Beyond: Coal/Dust Characteristics & Operational OptimizationInstallation of Five New SO3 Conditioning Units in STEAG PlantsPerformance with Low Sulfur Coal
Summary
Content
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Project Background: Installation of Five SO3 – Conditioning Units at Steag
Decision of 2008 −
five new Pentol units:
Lünen 6 and 7 25 and 45 kgS /h 150 / 350 MWel
Herne IV 80 kgS /h 500 MWel + district heatingWest 1/2 each 45 kgS /h 2 x 350 MWel
Present Experience at Steag in Herne III since 2004
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History: First SO3 Unit at Herne III
1966 Commissioning Unit III
1986 Coal switch to 100 % low volatile German Coal, Re-Equipping:Ball-Mills, Low NOx -Burners
Rapping mechanismDischarge electrode withnegative high tension (20 - 80 kV)
Process Steps
1. Electron emission• Corona discharge
2. Charging of dust particle• Diffusion charging for particles < 0,5 µm• Field charging for particles > 0,5 µm
3. Transport of charged particles• Coulomb force• Stokes law
4. Dust Agglomeration on collecting electrode• Adhesion forces• Voltage
5. Dust Removal from Collecting electrode• Mechanical rapping• Shearing forces
Source: Rothemühle
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Back Corona Effects
U/I-CharacteristicsNormal Operation
0
100200
300
400
500600
700
800
0 20 40 60 80
S e c onda r y Vol t a ge [ k V]
U/I-Characteristics Beginning Back Corona
0
100
200
300
400
500
600
700
800
0 10 20 30 40 50 60 70 80
Secondar y V ol t age [ kV ]
U/I-Characteristics Severe Back Corona
0
100
200
300
400
500
600
700
800
0 10 20 30 40 50 60 70 80
Secondary Voltage [kV]
Seco
ndar
y Cu
rrent
[mA]
UO
pera
tion
d U1
d U2
UO
pera
tion
d U1
d U2
0.5 x duct gap
UO
pera
tion
d U1
d U2
Source: Rothemühle
•Through back corona ash particles are going back into the flue gas forming small craters in the ash layer•Extension of dust emission downstream ESP is caused by this effect•Back corona is avoided by modern ESP control systems
0.5 x duct gap 0.5 x duct gap
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Enhanced ESP Performance: Utilized Ways
Enhanced Process and ESP Control
Mechanical shape of the filter and rapping interval optimization
SO3 – Conditioning
Smoothing velocity and strand avoidance – achieved by CFD optimization
Reduction of Air Heater Slip
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Prior to modifications
Ductwork and guiding arrangements
Guide vane level in duct section between air heater and ESP
Perforated guide vanes and dividing wall for distribution to two ESP trains
Gas distributing wall made of "X-Richtblech" flow-directing plates
CFD Modelling for ESP Optimization
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Computational model
FLUENT model of the present ESP
Air heater outlet
"X-Richtblech" flow-directing plates
Hopper
Hopper partitioning walls
Collecting electrodes
Knee-high plates in aisles
Guide vane levels
"X-Richtblech" flow-directing plates
Dividing wall
CFD Modelling for ESP Optimization
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Guide vanes with extensions arranged on various levels
Inflow grate
Pressure drop at ESP outlet
Gas distributing walls made of " X-Richtblech"
Different hopper partitioning wall arrangement options
Edge areas of gas distributing walls
CFD Modelling for ESP OptimizationComputational model
FLUENT model variations
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Velocity pattern Prior to modificationvelocities in m/s
CFD Modelling for ESP Optimization
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Velocity pattern Optimized casevelocities in m/s
CFD Modelling for ESP Optimization
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Velocity pattern Optimized Case Detail: Sloping plates in first hopper velocities in m/s
CFD Modelling for ESP Optimization
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Hopper interiorgrate of sloping plates in the first hopper row
standard partitioning wall in the second hopper row
Extension of guide vanes and inlet flow grateextension of two guide vanes
Gas distributing wallspartial replacement of plates to implement the determined pressure drop coefficients
Outlet pressure dropInstallation of an outlet wall with vertically staggered pressure drop coefficients
Modifications
CFD Modelling for ESP Optimisation
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Fuel Qualities
GER Walsum GER Niederb. NOR Svalbard COL Cerrejon ZA Kleinkopje Sewage Sludge Animal MealCoal Analysis