Unburned Carbon Versus CO2 EmissionUnburned Carbon Versus CO2 Emission

we focus on your process

Unburned Carbon In the fly ash

UBC versus COUBC versus CO22 Emission Emission


Coal bin

Mill

Precipitator

Air preheaterBurner

Air fan

Intermediate

storage tank

Pul

veriz

ed f

uel

-

Air

Flue gas

Fly ash

Sec

onda

ry a

ir

Prim

ary

air

Coal

UBC

AirSteam Generator

Heat Input: •CoalLosses: •Flue gas heat loss•Gaseous LOI (CO)•Unburned Carbon•Radiation•Ash Heat Loss


Combustion Heat Loss

Boiler radiationheat loss

Unburned carbonin ash

Sensible ashheat loss

Power Station Basis Data (example):

Mean continuous load (Basis: steam production) 100 %

Full-load (100% MCR) operating hours per year 6 000 [hrs]

Coal mass flow (100% load) 300 [shtn/h]

Excess air ratio (100% load) 1.25 –

Gross heat input (calculated for 100 % load) 7 109 [BTU/hr · 106]

Gross electric power output (100% load) 750 [MWel]

Net power efficiency 36 [%]

5.5%1.11%

CO

Flue gas heat loss Otherlosses


Sources of Improvement

CO

Carbonin ash

Flue gas heat loss improvement(0.43 % absolute)

Other improvements(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]


Total boiler losses6 % (absolute)

reduction in flue gas heat loss

reduction in solid LOI (carbon in ash)

reduction in gaseous LOI (CO)

total fuel heatsavings = 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


Coal bin

Mill

Precipitator

Air preheaterBurner

Air fan

Intermediate

storage tank

Pul

veriz

ed f

uel

-

Air

Flue gas

Fly ash

Sec

onda

ry a

ir

Prim

ary

air

Coal

UBC

AirSteam Generator

Heat Input: •Coal mass flow & CVLosses: •Flue gas temperature & O2

•CO•Unburned Carbon in Fly AshCoal analysis (Ash Content)•Ash Temperature


MECONTROL UBC Sensor

Screw Measuring Chamber

DriveShaft


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

MECONTROL UBC Measurement Principle

UBC = A + B f

A and B are the calibration coefficients



Measurement Data of MECONTROL UBC

Wedel

0

100

200

300

400

500

600

700

800

900

1000

18.07.200100:00

20.07.200100:00

22.07.200100:00

24.07.200100:00

26.07.200100:00

28.07.200100:00

Re

st-

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



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

Sec

on

dar

y A

ir x

100

0 (i

nve

rted

) [m

³/h

] S

TP

1

2

3

4

5

6

7

8

9

10

UB

C [

%]

Secondary Air (MECONTROL Air)

UBC ETG 17 (MECONTROL UBC)

UBC ETG 18 (MECONTROL UBC)

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

1 % O2

Result of SA Reduction Trial Run


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

UB

C [

%];

CO

x10

[m

g/m

³] S

TP

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 StackO2 Boiler / DeNOx outlet

Trial run at BEWAG "Reuter West" power plant


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

Incr

ease

in e

ffic

ien

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

we focus on your process we 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

UB

C

[wt.

-%];

O2 [

vol.

-%]

200

220

240

260

280

300

320

340

360

380

400

Sec

on

dar

y ai

r x

1000

[m

³/h

r] S

TP

O2 right duct

UBC Basis: ash = 3.6 %

Secondary air Basis: 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


Boiler / Mill Optimization by UBC Monitoring

Datteln

02468

101214161820

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

29.08.00:00

Re

st-

C [

%]

Kanal 0 geglättet

Mittelwert Kanal 0

Coal type change

we focus on your process we focus on your process Power 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

O 2

[V

ol.

-%]

500

520

540

560

580

600

620

NO

x [m

g/m

³]

O2 boiler out NOx before Kat.

SA2 TA SA1+CA



750 MW units Germany

Amonia savings15%

Fuel Savings36%CO2 sales

27%

Ash benefication ?

22%

savings potential


savings potential


750 MW units USA

NOx credits55%

Fuel Savings22%

CO2 sales17%

Ash benefication ?

6%


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

US

Germany


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 EmissionUnburned Carbon Versus CO2 Emission