Hybrid SNCR/In Hybrid SNCR/In

-Duct S

Duct S

System

Dale Pfaff Dale Pfaff

FUEL TECH, INC. FUEL TECH, INC.

Batavia, IL Batavia, IL

Rich Abrams Rich Abrams

BABCOCK POWER ENVIRONMENTAL BABCOCK POWER ENVIRONMENTAL

Worcester, MA Worcester, MA

Environmental Controls Conference – Pittsburg

May 16 – 18, 2006
Agenda

 Hybrid Defined Hybrid Defined SNCR

• Traditional Traditional• Re-Designed Designed

 Compact SCR Design Compact SCR Design

• Tools

 Hybrid Goals Hybrid Goals Real Life Examples Real Life Examples Costs
Hybrid NO Hybrid NOx Control System Control System

“Cascade Cascade®”

STEAM TURBINE

AIR

PREHEATER(S)

ECONOMIZER

BYPASS

IN-DUCT SCR

BOILER

PRIMARY AIR

CATALYST

C

ECONOMIZER

LOW 

S

 Redesigned Redesigned SNCR 

System with SCR System with SCR (using urea) (using urea)

 Higher NO Higher NOx

Reduction and Reduction and Utilization than Utilization than SNCR

 NH3 slip consumed slip consumed

in SCR 

 Low SO2 to SO3

Conversion Rates Conversion Rates

 50 - 75% overall 75% overall 

NOx reduction reduction

 Low capital costs Low capital costs
Traditional Urea Based Traditional Urea Based 

Selective elective 

Catalytic atalytic 

Reduction (SNCR) of N

eduction (SNCR) of N

Primary 

Combustion

NOx

NOxOUT A

Urea 

Reagent

1,700 -

2,400 ° F

N

2/H

2O/CO2 (NH

3 Slip)

 Post Combustion Post Combustion Gas Phase React

Gas Phase React

 Furnace is the Re

Furnace is the Re

 Typical Combust

Typical Combust

 Process Paramet

Process Paramet

• Time• Temperature an

Temperature an

• Distribution Distribution 

 Widely Applicable Widely Applicable
Hybrid

1290 1470 1650 1830 2010 2190 

Low Temperatures• Slow Droplet Evaporation• Slow Kinetics• Low OH Concentration• Ammonia Slip

High Temp• Rapid Dro• Fast Kine• Increased • Urea Oxid

NOAm

“Right Side of the Slope Right Side of the Slope” Inj

Inj
Hybrid SNCR Injection Hybrid SNCR Injection
 CFD Modeli

CFD Modeli

 Cold Flow M

Cold Flow M

Expanded Duct Sectio

Expanded Duct Sectio

Hybrid In Hybrid In-Duct
Cold Flow Models and Flue Gas Mix

Cold Flow Models and Flue Gas Mix

• 1:40 scale flow model 1:40 scale flow model

BPI makes extensive use of flow modeling to guide BPI makes extensive use of flow modeling to guide designs and to ensure proper distribution designs and to ensure proper distribution

Delta Wing Mixe

Delta Wing Mixe
Typical Hybrid Process Go

Typical Hybrid Process G

 Multiple Levels of SNCR Injection 

Multiple Levels of SNCR Injection 

Load Following Capabilities Load Following Capabilities

 50 

- 75% Overall NOx Reduction, 

75% Overall NOx Reduction, 

ppm NH

3 Slip

 One Catalyst Layer at 1.3 m Dept

One Catalyst Layer at 1.3 m Dep

 SCR Inlet Temp = 650 SCR Inlet Temp = 650 

°F Norm / 

F Norm / 

Max

 No Ammonia Injection Grid No Ammonia Injection Grid Efficient Mixing to Achieve Unifor

Efficient Mixing to Achieve Unifor

Distribution Distribution

 SO

2 to SO

3 Conversion < 0.5 % Conversion < 0.5 %

 Fits within the Physical Space Lim

Fits within the Physical Space Lim
Commercial Compact S

and Hybrid (SNCR/SC

Examples
Example 1: Example 1: Compact In Compact In-Duct 

Duc

Exelon Handley Unit 3 Exelon Handley Unit 3

 Turbo Boiler Turbo Boiler – Gas 

Fired

 94% NOx Removal 94% NOx Removal 

SCR

 In-duct Reactor duct Reactor Delta Wing Mixing Delta Wing Mixing 

System

 Honeycomb Catalyst Honeycomb Catalyst
BPI - Handley Test Result

Handley Test Result

 Full load and low load NOx outlet Full load and low load NOx outlet 

concentrations achieved at 0.02 a

concentrations achieved at 0.02 a

0.01 lbs/Mmbtu respectively 0.01 lbs/Mmbtu respectively

 NOx removal efficiencies of >94% NOx removal efficiencies of >94%  Stack ammonia slip <3 ppm measu

Stack ammonia slip <3 ppm measu

 SCR system pressure loss as predic

SCR system pressure loss as predi

 NH3/NOx ratios < 6% RMS, per de

NH3/NOx ratios < 6% RMS, per de

 Optimization of unit in six operatin

Optimization of unit in six operatin
 T-fired CE furnace: 1990 BL of 0.

fired CE furnace: 1990 BL of 0.

lb/MMBTU lb/MMBTU

 Furnace and convective pass injec

Furnace and convective pass injec

Design Case: Design Case:

42% reduction, 0.45 #/ 42% reduction, 0.45 #/MMBtu, <5 ppm N

Operational Case: Operational Case:

35% reduction, 0.50 #/ 35% reduction, 0.50 #/MMBtu, <2 ppm N

Less than 10 % in convective pass Less than 10 % in convective pass

High Ammonia Slip Case High Ammonia Slip Case

54% reduction, 0.36 #/ 54% reduction, 0.36 #/MMBtu, ≈10 ppm NShort-term testing term testing

 Increased chemical in convective 

Increased chemical in convective 

Example 2: Fuel Tech Example 2: Fuel Tech 

Seward Station Seward Station - 147 MWg, Co
 Required Required NH3 Reduction Reduction from 2

from 

ppm to 2 ppm

 Rapid Flue Gas Mixing Rapid Flue Gas Mixing Minimum SO Minimum SO3 production production 

(Ammonium Salts) (Ammonium Salts)

 Minimum pressure drop Minimum pressure drop Withstand coal fired gas stream Withstand coal fired gas stream

SCR Expanded-duct Reactor D

 Maximum Reduction Achieved (>50%

Maximum Reduction Achieved (>50%

• System Tuned to 2, 10, or 20 System Tuned to 2, 10, or 20 ppm • Low-Load Operation at 2 Load Operation at 2 ppm Slip.

 Increased Chemical Utilization Increased Chemical Utilization Less than 2 Less than 2 ppm ammonia slip at SCR 

ammonia slip at SCR 

 Hybrid SNCR/SCR Operated for more 

Hybrid SNCR/SCR Operated for more 

years

Hybrid SNCR/SCR Perform

Hybrid SNCR/SCR Perform
Fuel

NOx Control 

System NSR

SNCR 

Reduction

SNCR 

Utilization

SCR 

Reduction

Re

Coal Standard SNCR 1.19 37.0% 31.1% - 3Coal Hybrid 0.79 41.1% 59.2% 16.3% 5Coal Hybrid 1.15 36.9% 45.7% 54.2% 7

Gas Hybrid 1.44 36.1% 38.6% 78.9% 8Gas Hybrid 1.56 39.0% 37.1% 83.6% 9

• Ammonia Slip at 10 Ammonia Slip at 10 ppm or less or less

Example 3; High Load (320MWe) 

Example 3; High Load (320MWe) 

Results Results
Example 4; AES Example 4; AES Greenidge Greenidge Appl

App

Hybrid System Hybrid System

 115 MW Coal Fired Unit, 2.9% S 115 MW Coal Fired Unit, 2.9% S 

Bituminous coal Bituminous coal

 Two levels of SNCR Two levels of SNCR In-duct reactor; single layer of ca

duct reactor; single layer of ca

 Short distance between economiz

Short distance between economiz

reactor reactor

 SNCR provides ~ 40% reduction SNCR provides ~ 40% reduction SCR provides balance SCR provides balance Overall system provides ~ 66% Overall system provides ~ 66% 

reduction reduction

All-In Capital Cost vs. NOx Red

 SCR $70 

- +$200?/KW +$200?/KW 

 SNCR $10 

- $30/KW 

 Hybrid $35 

- $80/KW 
 Hybrid combines redesigned SNCR with 

Hybrid combines redesigned SNCR with 

 Control Flexibility: Operating vs. Capita

Control Flexibility: Operating vs. Capita

Costs

 Hybrid can control slip and improve Hybrid can control slip and improve 

utilization utilization

 50% and 75% NOx Reduction with 50% and 75% NOx Reduction with 

significantly reduced SCR retrofit capita

significantly reduced SCR retrofit capit

 Each Unit Must Be Evaluated to Determ

Each Unit Must Be Evaluated to Determ

Feasibility for placement of an IN Feasibility for placement of an IN-DUCT 

DUC

COMPACT SCR. COMPACT SCR.

 2 Utility and 3 Industrial Hybrid Applica

2 Utility and 3 Industrial Hybrid Applica

Conclusions
Contacts: Contacts:

Mr. Dale Pfaff Mr. Dale Pfaff

Fuel Tech, Inc. Fuel Tech, Inc.

(630) 845 (630) 845

-4453

dpfaff@fueltechnv.com dpfaff@fueltechnv.com

Mr. Rich Abrams Mr. Rich Abrams

Babcock Power Environment

Babcock Power Environment

(508) 854 (508) 854

-1140

rabrams@babcockpower.com rabrams@babcockpower.com