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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
100
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.
0
5
10
15
20
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
4
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
0
20
40
60
80
100
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
0
20
40
60
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
0
20
40
60
80
100
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
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