Systems - indianpowerstations.orgindianpowerstations.org/Presentations Made at IPS-2012/Day-2 at PMI... · we focus on your process Page 9 Coal Measurement Principle: ... controlled

we focus on your process

Page 1

Systems


Page 2

Our Target:

Boiler Combustion Optimization

with

Get a better view into

the combustion of your boiler !

Presentation


Page 3

Boiler Combustion Optimization

UBC

On-line measurement of the unburned carbon in the fly ash

Coal

On-line measurement of the coal mass flow between the mill and the burner

Air

On-line flow measurement of preheated excess air or flue gas

Presentation


Page 4

System Application for Boiler Optimization

Air

UBC

Coal

Steam generator

Burner S

econdary

air

Air preheater

FD-Fans

Excess Air

Electric

precipitator

Intermed. Fly-

ash bunker

Fly ash

Flue gas

Coal bunker

Coal

mill

Pu

lve

rize

d

fu

el

Pri

mary

air


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UBC


Page 6

UBC Measurement Principle: Unburned carbon content

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.

UBC = A + B f

A and B are the calibration

coefficients


Page 7

0

1

2

3

4

5

6

7

8

9

10

0 2 4 6 8 10

Block1 Sensor1

Block1 Sensor2

Block2 Sensor1

Block2 Sensor2

-0,60%

+0,60%

Unit 1 Sensor 1

Unit 1 Sensor 2

Unit 2 Sensor 1

Unit 2 Sensor 2

Single calibration at

different coal types

for several month

UBC Accuracy of the values


Page 8

Coal


Page 9

Coal Measurement Principle: Density

Microwave measurement:

2 sensors in one pipe are used to

measure the coal concentration

over the FULL cross sectional area

of the pipe

Easy installation:

The sensors are mounted through

easy drill and tap holes (14x1 mm)

Transmitter

Receiver

In case of roping:

cover full

cross section


Page 10

Velocity

W=S/T

Sensor 2

Coal Dust Pipe

Sensor 1 S=const.

Example

S=54 cm

T=26 ms w=20,8 m/s (average velocity of the particles !)

Signal Sensor 1

Signal Sensor 2

“Signature”

Y(t)=X(t-T) X(t)

Time T

correlation “Correlation”

T=-26 ms Optimum of

correlation

Coal Measurement Principle: Velocity


Page 11

Coal Absolute mass flows and velocities


Page 12

Coal psa Particle Size Analysis


Page 13

Example: Biomass PSA

Coal psa Particle size distribution


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AIR System Air


Page 15

Sensor 2

Air Duct or Pipe

Sensor 1 S=const.

Example

S=54 cm

T=26 ms w=20,8 m/s (average velocity of the air !)

Signal Sensor 1

Signal Sensor 2

“Signature”

Y(t)=X(t-T) X(t)

Time T

correlation “Correlation”

T=-26 ms Optimum of

correlation

Air Measurement Principle: Velocity


Page 16

Air Velocity trends and 4-20mA outputs


Page 17

13 golden rules for efficient combustion

I. Fuel preparation:

No 1. Fuel shall be consistent in size and quality

No 2. Fuel shall be fed to pulverizer by an accurate feeder (gravimetric feeder)

No 3. Pulverized fuel shall be 75% below 70 µm Coal psa

and less than 0.1% larger than 200 µm.


Page 18


II. Fuel conveying to the burners:

No 4. Primary air flow needs to be measured and Air

controlled to a tolerance of 3% of full scale value

No 5. Primary air to fuel ratio shall be accurately Coal

controlled when above the minimum

No 6. Fuel velocities shall always be higher than 23 m/sec Coal

No 7. Mill outlet temperature shall be consistent and

controlled temp to a tolerance of 5 K

No 8. The balance of coal velocities on all pipes shall be Coal

within a tolerance of 2 m/sec

No 9. The coal mass flow distribution shall be within Coal

a tolerance of 5 %


Page 19


III. Combustion:

No 10. Secondary air distribution controlled Air

to a tolerance of 5%

No 11. Overfire air distribution controlled Air


No 12. Swirl air settings controlled Air


No 13. Excess air level reduced to the point UBC

where UBC is below max taget value

(usually 5%)


Page 20

Checking the 13 Rules on a boiler

Boiler

Bunker Feed

Coal bunker

Four pulverizers

Burner Air

FD Fan

Burner pipes

Coal

PA

Primary Air

Secondary Air

16 Brenner Air

Coal

Coal psa


Page 21

This mill has no coarse particles in the Pf Test Data: PS Reuter West, Berlin

MECONTROL Coal Measurement with Feedersignal and Particlesize Distribution

0,0

5,0

10,0

15,0

20,0

25,0

06:00 08:24 10:48 13:12 15:36 18:00 20:24 22:48

Massfl

ow

[t/

h]

0

10

20

30

40

50

60

70

80

90

Part

icle

Fre

qu

en

cy [

%]

Sum Burner 1-4 [t/h] Feeder [t/h] > 200 µm [%] 90 - 200 µm [%] < 90 µm [%]

10.06.2007

Rule No 3: Particle size consistency


Page 22

MECONTROL Air

Primärluft Mühle 40

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

0:00 2:24 4:48 7:12 9:36 12:00 14:24 16:48 19:12 21:36 0:00

[Nm

³/h

]

0

50

100

150

200

250

300

350

400

450

500

[°C

]

PL M40- 1 PL M40- 2 M 40 dP Mühle 40 M 40 Temp. Mühle 40

27.07.2006 PROMECON we focus on your process

MECONTROL Air

Kohlenstaubgeschwindigkeit Mühle 40

0,0

5,0

10,0

15,0

20,0

25,0

30,0

35,0

40,0

00:00 02:24 04:48 07:12 09:36 12:00 14:24 16:48 19:12 21:36 00:00

[m/s

]

Brenner 41 Brenner 42

Brenner 43 Brenner 44

27.07.2006

BlnPA_D_IPC2 PROMECON we focus on your process

can check the PA flow into the mill as well as out of the mill

Graph shows PA flows into

the mill as well as Mill inlet

temperature

Graph shows the resulting

velocities out of the mill.

It can be checked if the

velocities into the mill are

appropriate for each load

point and coal type.

Rule No 4: Accurate PA flow control


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Pipe 42

0

500

1000

1500

2000

2500

3000

14:24:00 16:48:00 19:12:00 21:36:00 00:00:00 02:24:00 04:48:00 07:12:00 09:36:00

Velo

cit

y (

cm

/s),

Tem

pera

tur

-5000

0

5000

10000

15000

20000

Dic

hte Velocity

Density

Underperforming pulverizer

High standard deviation of concentrations and velocities

Variation of

velocity 1s:

1.53 m/s

(4.6 ft/sec)

Variation of

coal loading 1s:

123 g/m

Rule No 5: Accurate control of coal concentration


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Velocities

1000

1200

1400

1600

1800

2000

2200

09

:59

10

:19

10

:40

11

:00

11

:20

11

:40

12

:00

12

:20

12

:41

13

:01

13

:21

13

:41

14

:01

14

:21

14

:41

cm

/se

c

Pipe 1

Pipe 2

Pipe 3

Pipe 4

Velocities

Velocities

Low velocities cause pulsations in the coal flow

Results Coal

Vertical piping Horizontal piping

Rule No 6: Control of minimum coal velocities


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Drifting Mill outlet temperature at constant load

Rule No 7: Accurate control of mill outlet temperature


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Example Pipe Arrangement

Coal Valve

Adjustment of coal flow velocity

Rule No 8: Adjustment of coal velocities

Coal

Splitter Box

Pulverizer

Burner


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Here a large velocity spread has been corrected by a variable orifice

Rule No 8: Adjustment of coal velocities


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Same coal mass flow to every burner

Coal distribution before

the adjustment

Coal distribution after

the adjustment

Rule No 9: Adjustment of coal mass flows


Page 29

Typical Problems with delta P measurement

15% deviation

Rule No 10, 11 and 12: Adjustment of SA and OFA


Page 30

O2 set point reduction

Rule No 13: Adjustment of O2 set point with UBC value


Page 31

UBC Optimisation Results

2

3

4

5

6

7

8

Time

UB

C

[wt.

-%];

O

2 [

vo

l.-%

]

200

220

240

260

280

300

320

340

360

380

400

Seco

nd

ary

air

x 1

000 [

m³/

hr]

ST

P

O 2 right duct

UBC Basis: gash = 3.6 %

Secondary air Basis: n = 1.259

O 2 left duct

Trial run at “Wedel” power plant

Excess Air Reduction

Resulting efficiency increase:

0.42 %-pts !

= -0.08 %-pts

UBC: Cabs = -2 %-pts

Excess air: nabs= 7.6 %-pts

= 0.5 %-pts

Rule No 13: Adjustment of O2 set point with UBC value


Page 32

Example: Power station Stigsnaes, DONG Energy

Capacity 265 MWel

Erected in 1969 as oil fired unit

Later converted to coal

4 pulverizers with dynamic classifier

24 burners

Individually ducted secondary air


Page 33

Stigsnaes firing system

Coal

Splitter Box

Pulverizer

Burner


Page 34

NOx optimization


Page 35

Excess Air Reduction


Boiler / Mill optimization by UBC monitoring

General example calc.: Black coal utility plant

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%

O2-content of flue gas; UBC in fly ash

Incre

ase i

n e

ffic

ien

cy*

O2

UBC

at 7.2 % gA

at 3.6 % gA

UBC

*) Without power savings of fans


Page 36

Boiler efficiency increase

Documents

Systems - indianpowerstations.orgindianpowerstations.org/Presentations Made at IPS-2012/Day-2 at PMI... · we focus on your process Page 9 Coal Measurement Principle: ... controlled