11-Presentation on Combustion Control by Online Coal Balancing

7/27/2019 11-Presentation on Combustion Control by Online Coal Balancing

1/19

The Principles Used InNew technologies combustion control

In Coal fired stations


2/19

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%


3/19

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


4/19

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


5/19

Significant stratification in gas

temperatures and oxygen profile


6/19

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


7/19

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


8/19

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


9/19

Coal flow balancing and measurement

systems

Automated Coal Flow Dampers

Coal Flow Sensors


10/19

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


11/19

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


12/19

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.


13/19

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


14/19

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)


15/19

Adjust right-to-left air balance using lower rear wall

burners


O2 / CO sensors

0

60

120

180

240

300

360

420

480

540

600

660

720

780

840

900

9601020

1080

1150



16/19

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


O2 / CO sensors



17/19


18/19


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



19/19

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

11-Presentation on Combustion Control by Online Coal Balancing

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Transcript of 11-Presentation on Combustion Control by Online Coal Balancing