Unburned Carbon Versus CO2 Emission

8/8/2019 Unburned Carbon Versus CO2 Emission

1/23

we focus on your process

Unburned Carbon

In the fly ash

UBC versus COUBC versus CO22 EmissionEmission


2/23


Coal bin

Mill

Precipitator

Air preheaterBurner

Air fan

Intermediate

storage tank

Pulverizedfuel

-

Air

Flue gas

Fly ash

Secondarya

ir

Primary

air

CoalUBC

AirSteam Generator

Heat Input:Coal

Losses:Flue gas heat lossGaseous LOI (CO)Unburned CarbonRadiationAsh Heat Loss


3/23


4/23


Sources of Improvement

CO

Carbon

in ashFlue gas heat

loss improvement(0.43 % absolute)

Otherimprovements(0.13 % absolute)

Goals of good combustion practice:

Reduction of excess air 5 [%-points]

Reduction of fly ash carbon content 1 [%-points]

Reduction of CO 80 [ppmdv]


5/23


Total boiler losses6 % (absolute)

reduction in flue gas heat loss

reduction in solid LOI (carbon in ash)

reduction in gaseous LOI (CO)

total fuel heat

savings = 0.57 %

Savings in CO2

emissions: 26 493 shtn/a CO2

emission credit

Assumed market price within intern. CO2 emission trading system:

5 $ per ton 132 000 $ per year

0.43%

0.04%

0.10%

reduced CO2 emission

Fuel savings: 10,000 shtn/yr at 30 US$ per shtn:300 000 US$ per year


6/23


Coal bin

Mill

Precipitator

Air preheaterBurner

Air fan

Intermediate

storage tankPulverizedfuel

-

Air

Flue gas

Fly ash

Secondarya

ir

Primaryair

CoalUBC

AirSteam Generator

Heat Input:Coal mass flow & CV

Losses:Flue gas temperature & O2COUnburned Carbon in Fly AshCoal analysis (Ash Content)Ash Temperature


7/23


MECONTROL

UBC Sensor

Screw MeasuringChamber

DriveShaft


8/23


Dielectric constant of fly ash is a function of the carboncontent. Measuring the shift of frequency in aresonator ( f) the carbon content can be calculated.

MECONTROL UBC Measurement Principle

UBC = A + B f

A and B are thecalibration coefficients



9/23


Measurement Data of MECONTROL UBC

Wedel

0

100

200

300

400

500

600

700

800

900

1000

18.07.2001

00:00

20.07.2001

00:00

22.07.2001

00:00

24.07.2001

00:00

26.07.2001

00:00

28.07.2001

00:00

Rest-C[0,0

1%

]

0

100

200

300

400

500

600

700

800

900

1000

Kanal 2

Kanal 3

Temperatur Kanal 2

Temperatur Kanal 3



10/23


Trial run at BEWAG "Reuter West" power plant

170

165

160

155

150

145

140

135

130

125

06:00 07:00 08:00 09:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00

Time

SecondaryAirx1000(in

verte

d)[m/h

]STP

1

2

3

4

5

6

7

8

9

10

UBC[%]

Secondary Air (MECONTROL Air)UBC ETG 17 (MECONTROL UBC)

UBC ETG 18 (MECONTROL UBC)

Remark: Listed values of secondary airamount are only for one burner plane.

1 % O2

Result of SA Reduction Trial Run


11/23


Result of SA Reduction Trial Run


Boiler Optimization Program

0

2

4

6

8

10

12

14

16

18

7:00 7:30 8:00 8:30 9:00 9:30 10:00 10:30 11:00 11:30 12:00 12:30 13:00 13:30 14:00 14:30 15:00 15:30 16:00 16:30 17:00

Time

UBC[%];

CO

x10

[mg/m]STP

0

0,5

1

1.5

2

2.5

3

3.5

4

4.5

O2

[%]

UBC Fly ash (MECONTROL UBC)

UBC Fly ash (Lab analysis)

CO Stack

O2 Boiler / DeNOx outlet

Trial run at BEWAG "Reuter West" power plant


12/23


Parameters for Efficiency Improvement



UBC

at 7.2 % A

General calculation example with parameter variationBasis: 5 % UBC in fly ash; 4.3 % O2 in flue gas

0.00%

0.05%

0.10%

0.15%

0.20%

0.25%

0.30%

0.35%

0.40%

0.45%

0% 1% 2% 3% 4% 5% 6%

UBC in fly ash

Increasei n

efficien

cy

*

*) Without power savings of fans

at 3.6 % A

UBC

O2

Excess air reduction

most efficient !

O2-content of flue gas; UBC in fly ash


13/23


Parameters for Efficiency Improvement

UBC

at 7.2 % ash in fuel

Efficiency Calculation Example with Parameter VariationBasisline: 5 % UBC in fly ash; 4.3 % O2 in flue gas

0.00%

0.05%

0.10%

0.15%

0.20%

0.25%

0.30%

0.35%

0.40%

0.45%

0% 1% 2% 3% 4% 5% 6%

UBC in fly ash

Increaseinfueleffi c

iency

*

*) Without power savings of fans

at 3.6 % ash in fuel UBC

O2

Excess air reduction

most efficient !

O2-content of flue gas; UBC in fly ash


14/23

we focus on your processwe focus on your process

Boiler / Mill Optimization by UBC Monitoring

Excess air: nabs = 7.6 %-pts

= 0.5 %-pts

2

3

4

5

6

7

8

Time

U

BC

[wt.-%];

O2

[v

ol.-%]

200

220

240

260

280

300

320

340

360

380

400

Sec

onda

ryairx1000[m/h

r]STP

O2 right duct

UBC Basis: ash = 3.6%

Secondary airBasis: n = 1.259

O2 left duct

Trial run at Wedel power plant

UBC: Cabs = -2 %-pts

= -0.08 %-pts

Resulting efficiency increase:0.42 %-pts !

Excess Air Reduction


15/23


Boiler / Mill Optimization by UBC Monitoring

Datteln

0

2

4

6

8

10

12

14

16

18

20

09.08.00:00

11.08.00:00

13.08.00:00

15.08.00:00

17.08.00:00

19.08.00:00

21.08.00:00

23.08.00:00

25.08.00:00

27.08.00:00

29.0800:00

Rest-C[%]

Kanal 0 geglttet

Mittelwert Kanal 0

Coal type change


16/23


Parameter Test at an E.ON Power Plant



2

2,5

3

3,5

4

4,5

5

10:00 11:12 12:24 13:36 14:48 16:00 17:12

O2

[Vol.-%]

240

245

250

255

260

265

270

275

280

Airflowrate

[kg/s

]

O2 downstream Eco

Sum SA-flow rate

SA2 TASA1+PA

PA

SA1

SA2

TL

TA

6 Burners x 4 levels


17/23


Parameter Test at an E.ON Power Plant


1

1.5

2

2.5

3

3.5

4

4.5

5

10:00 11:12 12:24 13:36 14:48 16:00 17:12

O2

[Vol.-%]

2

3

4

5

6

7

8

9

10

UBC[%

]

O2 Eco UBC Channel 0 UBC Channel 1 UBC Lab

SA2 TASA1+PA

= -0.18 %

UB

C=

+1.5

%

= +0.51 %

O2

=

-0.8%

total = +0.33 % efficiency increase !


18/23

we focus on your processwe focus on your processPower Station Farge, Power Utility E-on

2

2,5

3

3,5

4

4,5

5

10:00 11:12 12:24 13:36 14:48 16:00 17:12

O2

[Vol.-%

]

500

520

540

560

580

600

620

NOx[mg

/m]

O2 boiler out NOx before Kat.

SA2 TASA1+CA


19/23



1,50

1,75

2,00

2,25

2,50

2,75

3,00

3,25

3,50

3,75

4,00

4,25

1,50 1,75 2,00 2,25 2,50 2,75 3,00 3,25 3,50 3,75 4,00 4,25

UBC in the fly ash with secondary air control [%]

UBC

inth

eflyash

withou

tSAcontr

ol[%]

Coal type change during test phase

worse

better

stack fan failure

Results with O2 leveling

UBC reduction at an E.ON boiler (for constant O2 in flue gas)

Results of Boiler Optimization


20/23



750 MW units Germa

Amonia saving

15%

Fuel Saving

36%CO2 sales

27%

Ash

benefication

22%

savings potential


21/23


savings potential


750 MW units USA

NOx credits

55%

Fuel Savings

22%

CO2 sales

17%

Ash

benefication ?

6%


22/23


savings potential


$0,000

$50,000

$100,000

$150,000

$200,000

$250,000

$300,000

$350,000

$400,000

$450,000

$500,000

Nox credits /Amonia Fuel Savings CO2 sales Ash benefication ?

Savings pa 750 MW unit

USGermany


23/23


Determine the O2/ UBC, O2/ CO and

O2/ NOx impact due to different air admission

(Secondary air, Tertiary air, Overfire air, etc.)

Change overall O2-level on the back pass with

favorable excess air supply

Run boiler with optimized O2-settings

Action Items for UBC Control


Documents

Unburned Carbon Versus CO2 Emission