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7/27/2019 11-Presentation on Combustion Control by Online Coal Balancing
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The Principles Used InNew technologies combustion control
In Coal fired stations
7/27/2019 11-Presentation on Combustion Control by Online Coal Balancing
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Poor fuel/air control drives need to
operate at non-optimal excess air levels
Comfort
Zone
A/FA/F
Limited capability to controlcoal & air flow distribution toeach burner
Historical boiler capability
> Coal flow bias up to +/-30%
> Combustion air flow bias
up to +/- 20%Large burner-to-burner fuel-air ratio imbalance of up to
+/- 36%
7/27/2019 11-Presentation on Combustion Control by Online Coal Balancing
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Combustion optimization can help offset
problems due to low-NOx modifications
Main Fuel
Air
Overfire Air
Reburn Fuel
O2/CO
SensorsCombustionSensors
Fuel & AirControls
Optimization
Methodology
7/27/2019 11-Presentation on Combustion Control by Online Coal Balancing
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Baseline boiler emissions and
temperature characteristics
2,450
2,500
2,550
2,600
2,650
1.6 2.0 2.4 2.8 3.2
Oxygen, % wet
FEGT,deg.F Right
Avg.
Left
FEGT
0.00
0.10
0.20
0.30
0.40
1.6 2.0 2.4 2.8 3.2
Oxygen, % wet
NOx,lb/MMBtu
0.0
0.2
0.4
0.6
0.8
1.0
1.2
CO,lb/M
MBtu
NOx
CO
NOX & CO Emissions
7/27/2019 11-Presentation on Combustion Control by Online Coal Balancing
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Significant stratification in gas
temperatures and oxygen profile
7/27/2019 11-Presentation on Combustion Control by Online Coal Balancing
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Combustion sensors installed in furnace
and in backpassSensors Installed:
> In-situ CO sensors = 15
> Combustion sensor(LOI/FEGT) = 5
> Burner Profiler = 25
O2/CO Sensor Probe
7/27/2019 11-Presentation on Combustion Control by Online Coal Balancing
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0
20
40
60
80
100
120
140
160
180
200
220
240
260
Sensor results prior to boiler
optimization CO Sensor DataCombustion Sensors
0
1
2
3
4
5
6
7
8
9
RelativeLOI
1 2 3 4 5
Sensor
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Sensor response to changing oxygen
CO Sensors Econ. O2 Probes
2.86 3.71
1.53 2.26
3.57 3.10
2.17 N/A
2.30 3.29
1.01 2.05
3.55 3.00
1.85 N/A
1.57 2.54
0.50 1.43
3.06 2.55
1.77 N/A
1.15 2.08
0.36 1.46
2.69 2.23
1.48 N/A
Test #2
3.0% O2
0
40
80
120
160
200
240
280
320
360
400
440
Test #6
2.7% O2
Test #7
2.2% O2
Test #7
2.2% O2
7/27/2019 11-Presentation on Combustion Control by Online Coal Balancing
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Coal flow balancing and measurement
systems
Automated Coal Flow Dampers
Coal Flow Sensors
7/27/2019 11-Presentation on Combustion Control by Online Coal Balancing
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Balancing dampers can significantly
improve coal flow balance
0
5
10
15
20
25
30
35
CoalFlow
Balance,
%
(abs
olute)
A1A2A3A4
A5B1B2B3B4B5
C1C2C3C4C5
D1D2D3D4D5E1
E2E3E4E5
Coal Pipe
Baseline
Manually Balanced
Balancing limited
by low air velocities
Balancing limited
by low air velocities
7/27/2019 11-Presentation on Combustion Control by Online Coal Balancing
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Automatic balancing system is
successful attaining and maintaining fueldistribution
-25%
-20%
-15%
-10%-5%
0%
5%
10%
15%
Baseline Manual
Tune
Auto
Tune
B
urnerCoa
lFlow
Bias
Burner C1 Burner C2 Burner C3 Burner C4 Burner C5
Fuel Balancing PLC
7/27/2019 11-Presentation on Combustion Control by Online Coal Balancing
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Distributing burner air properly is a
critical step in combustion optimizationOnce fuel distribution is balanced, the initial
burner air settings can be set uniformly.The next step in optimizing combustion is to trim
air distribution.Burner air adjustments are made to move air toair-starved regions in the furnace and to improve
air and fuel mixing within regions.
7/27/2019 11-Presentation on Combustion Control by Online Coal Balancing
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Further Combustion optimization
through O2 / CO sensorsCO Profile after coal flow balancing only
0
60
120
180
240
300
360
420
480
540600
660
720
780
840
900
9601020
1080
1150
CO Sensor Levels (relative ppm)High CO
In Corner
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Adjust right-to-left air balance using upper rear wall
burners
Further Combustion optimization through
O2 / CO sensors
0
60
120
180
240
300
360
420
480
540
600
660
720
780
840
900
9601020
1080
1150
CO Sensor Levels (relative ppm)
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Adjust right-to-left air balance using lower rear wall
burners
Further Combustion optimization through
O2 / CO sensors
0
60
120
180
240
300
360
420
480
540
600
660
720
780
840
900
9601020
1080
1150
CO Sensor Levels (relative ppm)
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0
60
120
180
240
300
360
420
480
540
600
660
720
780
840
900
9601020
1080
1150
Adjust right-to-center air balance using upper rear wall
burners
Further Combustion optimization through
O2 / CO sensors
CO Sensor Levels (relative ppm)
7/27/2019 11-Presentation on Combustion Control by Online Coal Balancing
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Further Combustion optimization through
O2 / CO sensorsFinal result (next day)
0
60
120
180
240
300
360
420
480
540
600
660
720
780
840
900
9601020
1080
1150
0.000
0.001
0.002
0.003
0.004
0.005
-400 -200 0 200 400 600 800
Coal Flow Bias, %
ProbabilityDistr
ibutionFunction
Initial
Final
CO Sensor Levels (relative ppm)
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Summary
Sensors, fuel/air controls, and tuning methodology provideopportunity for continuous combustion optimization
Available technologies:
> Combustion Sensors> Automated coal flow balancing
> Tuning and Optimization
Combustion optimization can permit operation at reduced excess airand lead to:
> Reduced NOx
> Improved efficiency
> Reduced unplanned outages and load drops
> Recovered derate or increased output