Selective Non-Catalytic Reduction: Overviewwpca.info/pdf/presentations/7) Overview of SNCRs.pdf ·...
Transcript of Selective Non-Catalytic Reduction: Overviewwpca.info/pdf/presentations/7) Overview of SNCRs.pdf ·...
Selective NonSelective Non--Catalytic Reduction: Catalytic Reduction: OverviewOverview
William H. Sun, Ph.D.William H. Sun, Ph.D.Fuel Tech, Inc.Fuel Tech, Inc.
WPCA/Duke NOx SeminarWPCA/Duke NOx SeminarHosted by Duke EnergyHosted by Duke Energy
Charlotte, NCCharlotte, NC
June 7, 2005June 7, 2005
- Gas phase reaction – Non-catalytic
- Reactions occur in 1600 – 2200 F -- Post Combustion
- Reaction products are typical combustion products -- CO2, H2O, N2
- No solid residue
- Easily Installed
- Easily combinable with other NOx control technologies
- Low Capital Cost
1600 –
2200 F
NOx
N2Injection Levels
CON2H4 + 2 NO + ½ O2 2 N2 + 2 H2O + CO2
Metering PumpsUrea
StorageTank
NOxOUT ProcessNOxOUT ProcessSelective NonSelective Non--CatalyticCatalytic
Reduction ProcessReduction Process
Urea SNCRUrea SNCR
CONCON22HH44 + 2 NO + ½ O+ 2 NO + ½ O22 2 N2 N22 + 2 H+ 2 H22O + COO + CO22
–– TycallyTycally applied under Oxidizing environmentapplied under Oxidizing environment–– Sensitive to temperature, CO, and residence timeSensitive to temperature, CO, and residence time–– Byproducts: NHByproducts: NH33 and COand CO–– Safe reagentSafe reagent
Reagent DistributionReagent Distribution–– Flue gas velocity, temperature, droplet trajectories, and reagenFlue gas velocity, temperature, droplet trajectories, and reagent t
dispersion modeled using CFDdispersion modeled using CFD–– Field measurements of temperature and flue gas speciesField measurements of temperature and flue gas species–– Multi level injectionMulti level injection–– Wall injectors and Wall injectors and MultinozzleMultinozzle lanceslances
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1200 1400 1600 1800 2000 2200Temperature (F)
NO
x R
educ
tion
(%)
0
50
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250
NH
3 Sl
ip (p
pm)
NOxNH3
NOx reduction and NH3 SlipNOx reduction and NH3 Slipchemical kinetic modelchemical kinetic model
0
50
100
150
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250
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1200 1400 1600 1800 2000 2200 2400Temperature (F)
NO
x (p
pm)
Increasing residence time
SNCR Temperature WindowSNCR Temperature Windowchemical kinetic modelchemical kinetic model
1300 1500 1700 1900 2100 2300Temperature (F)
050
100150
200250300
350400450500
NO
x (p
pm)
CO=1000 ppm
CO @ EQ. level
Increasing CO
CO lowers SNCR Temperature WindowCO lowers SNCR Temperature Windowchemical kinetic modelchemical kinetic model
-20
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1300 1500 1700 1900 2100 2300
Temperature (F)
NO
x R
educ
tion
(%)
50 ppm100 ppm200 ppm500 ppm
Effect of Baseline NOx on ReductionEffect of Baseline NOx on ReductionEquilibrium CO, NSR = 2, t =1 secEquilibrium CO, NSR = 2, t =1 sec
Byproduct: NHByproduct: NH3 3 SlipSlip
H2O + SO3 H2O + SO3 H2SO4H2SO4
NH3 + SO3 + H2ONH3 + SO3 + H2O NH4HSO4 (l)NH4HSO4 (l)
NH3 + NH4HSO4NH3 + NH4HSO4 (NH4)2SO4 (s)(NH4)2SO4 (s)
–– Formation temperature exists within the air heater Formation temperature exists within the air heater –– Formation temperature increases with SOFormation temperature increases with SO33 and NHand NH33 concentrationconcentration–– Higher temperature moves the deposition from cold to intermediatHigher temperature moves the deposition from cold to intermediate to hot e to hot
baskets of the air heater.baskets of the air heater.–– Ammonium salt deposition increases pressure drop across the air Ammonium salt deposition increases pressure drop across the air heater heater –– High fuel sulfur generates high SOHigh fuel sulfur generates high SO33 must maintain low NHmust maintain low NH33 slipslip
Formation Temperatures for Formation Temperatures for Ammonium SulfatesAmmonium Sulfates
AIR HEATER FOULING POTENTIALAIR HEATER FOULING POTENTIAL**
Deposition NumberDeposition Number
= [NH= [NH33][SO][SO33]{T]{Tff –– TTCECE}}
NHNH3 3 : Ammonia Slip in ppm: Ammonia Slip in ppmSOSO3 3 : Sulfur Trioxide in ppm: Sulfur Trioxide in ppmTTff : Formation Temperature of Ammonium Bisulfate in : Formation Temperature of Ammonium Bisulfate in °°CCTTCE CE : Metal Temperature at Air Heater Outlet in : Metal Temperature at Air Heater Outlet in °°CC
> 5000~7000 > 5000~7000 –– Fouling Potential ExistsFouling Potential Exists
* Based on EPA Report prepared by Radian Corporation, April, 1982
Effect of Fuel Sulfur and NH3 Slip on Fouling Potential Deposition Number=5000, 7000, 10000
Assumed Tce = 95 C, 100% Fuel Sulfur Conversion to SO2 & 1% SO2 to SO3 conversion
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0 0.5 1 1.5 2 2.5 3
Sulfur Content in Fuel (%)
NH
3 Sl
ip (p
pm)
Fouling Potential
No Fouling Potential
5000
10000
7000
Step 1: Define the Unit Geometry
Step 2: Block Out Obstructed Cells and Faces
Step 3: Define Mass and Heat Sources
Step 4: Solve for Flue Gas Temperatures & Velocities
Step 5: Generate Temperature Versus Residence Time Data for CKM
ComputerComputerModeling of FurnaceModeling of Furnace
BL Nox=0.47 lb/MMBtu, CO=250 ppm, NSR = 1.05
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1500 1600 1700 1800 1900 2000 2100 2200 2300 2400 2500
Chemical Release Temperature [deg F]
Fina
l NO
x (lb
/MM
Btu
)
0
40
80
120
160
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240
NH
3 Sl
ip (p
pm)
NOx = 0.14 ( 70% Reduction )
NOx = 0.20 ( 57% Reduction )
NOx = 0.30 ( 36% Reduction )
Chemical Kinetics ModelChemical Kinetics Model
LowLow--Temperature Limit SurfaceTemperature Limit Surface
NOx Reduction Contour: NOx Reduction Contour: Wall InjectorsWall Injectors
NOx Reduction Contour: NOx Reduction Contour: Wall Injectors and Wall Injectors and MNLsMNLs
Furnace & Furnace & Injection Injection Modeling Modeling @ 100% @ 100%
MCRMCR
Furnace & Furnace & Injection Injection Modeling Modeling
@ 75% MCR@ 75% MCR
Furnace & Furnace & Injection Injection Modeling Modeling
@ 50% MCR@ 50% MCR
SNCR Critical Process ParametersSNCR Critical Process Parameters
Residence TimeResidence TimeTemperatureTemperatureBaseline NOxBaseline NOxCO concentration in the injection regionCO concentration in the injection regionFuel Sulfur Fuel Sulfur Reagent distributionReagent distribution
NOxOUTNOxOUT®® SNCR PROCESS SCHEMATICSNCR PROCESS SCHEMATIC
Spill Protection
Reagent Fill From Truck
Stack Monitor
NOxOUT® A Storage Tank
Circulation Module in Enclosure
NOxOUT A Circulation LoopNOxOUT A Circulation Loop
Dilution Water Pressure Control and Injector Zone Metering Modules, Distribution Modules
Individual Injector Locations
Urea Reagent Storage (2 Urea Reagent Storage (2 ×× 25,000 gallon)25,000 gallon)
Urea Reagent Circulation ModuleUrea Reagent Circulation Module
Urea Reagent Metering ModuleUrea Reagent Metering Module
Independent Zone Metering ModuleIndependent Zone Metering Module
ThreeThree--position Distribution Moduleposition Distribution Module
Urea Injector with Automatic Retract MechanismUrea Injector with Automatic Retract Mechanism
Multiple Nozzle Lance Retract MechanismMultiple Nozzle Lance Retract Mechanism
NOxOUT Process ControlNOxOUT Process Control
A. A. FeedforwardFeedforward Control (LookControl (Look--up Tables)up Tables)–– Input Signals: Boiler Load and Input Signals: Boiler Load and FluegasFluegas TemperatureTemperature–– Controlling Parameters:Controlling Parameters:
»» injection zoneinjection zone»» chemical chemical flowrateflowrate»» atomizing air & dilution water pressuresatomizing air & dilution water pressures
B. Feedback Control (PID Controller)B. Feedback Control (PID Controller)–– Input Signal: NOx CEMInput Signal: NOx CEM–– Controlling Parameter: Chemical Controlling Parameter: Chemical FlowrateFlowrate to each to each
zonezone
UtililtyUtililty Boiler Experience SummaryBoiler Experience Summary
Unit Size: 50 ~ 620 Unit Size: 50 ~ 620 MWeMWeFuel Sulfur: 0.2% ~ 3.8%Fuel Sulfur: 0.2% ~ 3.8%Firing Type: TFiring Type: T--fired, Cyclone, Front Wall fired (wet fired, Cyclone, Front Wall fired (wet and dry bottom), front and rear wall fired, Cell firedand dry bottom), front and rear wall fired, Cell firedFuel: Coal (including PRB), Oil, GasFuel: Coal (including PRB), Oil, GasMajority were combined control technologies Majority were combined control technologies ––LNB/OFA + SNCRLNB/OFA + SNCR~50 Units~50 Units
Boiler TypesCirculating Fluidized BedBubbling Fluidized BedStoker, Grate FiredIncineratorsIndustrial
FuelsCoal – Bituminous and Sub-bituminousOil – #2 and #6Natural GasRefinery Gases (High CO)Municipal Solid WasteTire Derived FuelWoodSludge
NonNon--Utility ExperienceUtility Experience
Electric Utilities
Wood-fired IPPs / CoGen Plants
TDF Plants
Pulp & PaperGrate-firedSludge CombustorsRecovery BoilersWellons BoilersCyclones
Refinery Process Furnaces
CO Boilers
Petrochemical Industry
CoGeneration Package Boilers
Municipal Solid Waste
Process Units
Cement Kilns
General Industry ExperienceGeneral Industry Experience
United States
Czech Republic
France
England
Portugal
Germany
Italy
Poland
Spain
Sweden
Switzerland
Turkey
Korea
Taiwan
EXPERIENCE by EXPERIENCE by GEOGRAPHYGEOGRAPHY