Selective Non-Catalytic Reduction: Overviewwpca.info/pdf/presentations/7) Overview of SNCRs.pdf · Selective Non-Catalytic Reduction: Overview William H. Sun, Ph.D. Fuel Tech, Inc.

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

0

10

20

30

40

50

60

70

80

90

100

1200 1400 1600 1800 2000 2200Temperature (F)

NO

x R

educ

tion

(%)

0

50

100

150

200

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

200

250

300

350

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

0

20

40

60

80

100

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

0

5

10

15

20

25

30

35

40

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

0

0.1

0.2

0.3

0.4

0.5

0.6

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

200

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