Application of Combustion Optimization to Reduce Activated Carbon Requirements for MATS Compliance

Neil WidmerGE Energy

McIlvaine Hot Topic HourApril 18, 2013

2GE Energy

Electric Power 2010

Introduction

• Activated carbon injection system optimization

• Combustion optimization to enhance “native” Hg capture on fly ash

• Demonstrate over 70% mercury removal and reduce activated carbon injection

0

20

40

60

80

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0 2 4 6 8 10

Fly Ash LOI, %

Hg R

em

oval, %

Optimized

Non-Optimized

Pilot-scale data from Lissianski, et al.

3GE Energy

Electric Power 2010

Mercury Optimization Approach

Humidification

• Reduce Gas Temp.

• Improve ESP Perf.

• Increase Hg Capture

Sorbent Injection

• Injection System

• Injection Lances

•Multiple Sorbents

Air

Coal Mills

APH

Stack

ESP

Zonal Combustion Optimization• Combustion Sensors

• Adj. Riffle Boxes

4GE Energy

Electric Power 2010

Coal Fired Boiler Demonstration Site

• Boiler: 250 MW Opposed Wall Fired

• NOx Control: Low-NOX

Burners and Overfire Air

• PM Controls

– Electrostatic Precipitator (SCA ~ 249 ft2/kacfm;

– SO3 Conditioning System

Progress Energy Lee Station, Unit 3

Eastern Bituminous Coal• HHV ~ 12,450 Btu/lb• Sulfur ~ 0.82% wt.• Hg ~ 5.0 lb/TBtu

Eastern Bituminous Coal• HHV ~ 12,450 Btu/lb• Sulfur ~ 0.82% wt.• Hg ~ 5.0 lb/TBtu

Activated Carbon Injection (ACI) System

6GE Energy

Electric Power 2010

ESP Inlet Duct Characteristics

Photograph of duct work between air preheater (APH) exit and ESP inlet

Flue Gas fromAPH

Flue Gas to ESP

Velocity, fps

ACI Injection

H2O Injection

7GE Energy

Electric Power 2010

ACI Lance Design Optimization

Flue Gas Inlet

Outlet

ACI Lances

• CFD applied to optimize transport flow rate and lance design.

• Lance placement based upon existing ports.

8GE Energy

Electric Power 2010

Sorbent Injection System

• 250 ft3 day silo• 20 ton bulk trailer• Bulk bag unloader

Combustion Optimization

10GE Energy

Electric Power 2010

Zonal Combustion Tuning

Initial CO/O2 Profiles

Optimized CO/O2

Top

view

Combustion sensors provide spatial O2 and CO data to assist boiler tuning and operation

Boiler

Operations

11GE Energy

Electric Power 2010

Combustion Optimization

Coal flow balancing: coal flow deviation < 10%.

Air flow balancing: oxygen distribution balanced to within 15% (± 0.48% O2).

Burner tuning: achieved good stability and lowered NOX emissions.

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25

Deviation, %

A B C D E

Coal Mill

Baseline

Balanced

12GE Energy

Electric Power 2010

Impact of combustion optimization on stack mercury emissions & NOX

5.03

2.87

1.8

0

1

2

3

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5

6

Merc

ury

, lb/T

Btu

Coal Baseline Tuned

42%

63%

0.43

0.36

0.30

0.35

0.40

0.45

0.50

NOx, lb/M

MBtu

Baseline Tuned

16%

Activated Carbon Injection Performance

14GE Energy

Electric Power 2010

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0 5 10 15 20 25

Sorbent Injection, lb/MMACF

ACI Hg R

em

oval, %

Darco Hg, SO3 on

Darco Hg, SO3 off

Darco Hg-LH, SO3off

Sorbent Performance Characterization

15GE Energy

Electric Power 2010

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80

100

21-Aug 26-Aug 31-Aug 5-Sep 10-Sep 15-Sep

Tota

l Hg R

em

oval, %

Darco Hg 30-Day Performance TestOverall Mercury Reduction

Average sorbent injection rate:- without SO3 – 10 lb/MMACF - with SO3 – 15 lb/MMACF

16GE Energy

Electric Power 2010

Combustion optimization can reduce sorbent requirements

43

63

37

17

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Baseline Optimized

Tota

l Hg R

educt

ion, %

SorbentReduction

NativeReduction

17GE Energy

Electric Power 2010

Summary

• Combustion optimization improved “native” mercury capture

• Existing SO3 conditioning required twice the injection rate for the same mercury removal

• Long-term testing averaged 79% mercury removal

• Sorbent Injection impact on ESP performance were mitigated

• GE’s approach can reduce NOx and CO emissions, improve reliability and heat rate while providing mercury control