PROMECON

USA

Boiler Combustion Optimization

Advanced

Instrumentation

for Improved

Plant Operation Presented to:

McIlvaine Webinar August 8, 2013

PROMECON

USA

Steam generator

Burners S

econdary

air

Air preheater

FD Fans

Combustion Air

Electrostatic

precipitator

Fly ash Silo

Fly ash

Flue gas

Coal bunker

Coal

mill

Pulverized

fuel

Pri

mary

air

MECONTROL

Coal

MECONTROL

Air/FG

MECONTROL UBC

“New” Instrumentation for Boiler Optimization

(Air Monitor Corporation)

PROMECON

USA Extended spatial filter method

Based on evaluation of the shadows of a

laser beam created by moving particles

Properties:

Measuring range 30µm to

6mm

Recording of particle velocity

and particle size

In-situ measurement on PF

pipes

Chord length measurement

optical path

single particle

laser source

Vp – direction of movement

PROMECON

USA Particle Size Analysis (PSA) 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

PROMECON

USA

Minimize energy losses from unburned carbon &

flue gas -- function of excess air levels

UBC

exhaust gas

Losses

Flue gas

UBC

Optimum

Efficiency Optimization Principle

Excess Air

PROMECON

USA

Key Functions

• SAMPLING

Instrument must collect a representative sample

• MEASUREMENT

Instrument must accurately measure the amount

of unburned carbon in the sample

PROMECON

USA

Sampling Approaches

• Extractive (remove ash from handling system to make

measurement)

Classical approach used for early instrument design

• In-situ (measurement made within ash handling system)

New approach – providing significantly better reliability

PROMECON APPROACH

PROMECON

USA

Sampling Location

Electric

precipitator

Fly ash

Flue gas

90% 9% 0.9%

Bulk ash

Sampler

(PROMECON)

Air Preheater

0.00015%

100%

Weak Correlation to Silos

Strong Correlation to Silos

Silos

Flue gas

Sampler

(Extractive)

Not representative Representative

PROMECON

USA

Extractive

Sampler

Flue Gas Duct

Nozzle

High CO/UBC rope

PROMECON

Sampler

Ash and gas not uniform Ash discharged in

dense quantities

Cross sectional coverage:

0.000005%

Cross sectional coverage: 2-8%

Fly ash concentration: 5g/m3

Fly ash concentration:

200,000 g/m3

Sampling of the Ash Flow

Ash Hopper

PROMECON

USA

Typical Fly Ash Loading Distribution

PROMECON

USA

Typical Fly Ash LOI Distribution

PROMECON

USA

Extractive Measurement PROMECON

In-Situ Measurement

320oF

Flue gas

duct

Ambient Temperature

Cyclone

separation/

classification

Transport

through

heated

pipes

Measure-

ment of Air/

Ash mixture

Static weighing of 5g sample

140oF

Sampling and measurement

in the hopper:

no extraction

no cyclone separation

no static weighing

no heating elements

ESP

Hopper

PROMECON

USA

Measurement Approaches

• Microwave – Basis: Response to microwave radiation

– Pros: Simple; Accurate; Infrequent calibration

Insensitive to fuel type or blend

Can be performed in-situ

Multiple sampling points w/ one instrument

– Cons: Higher initial cost (# sampling points?)

PROMECON

USA

Dielectric constant of fly ash is a function of

the carbon content. Measuring the shift of

frequency (microwave) in a resonator ( f)

enables the carbon content to be calculated.

UBC = A + B f

A and B are the

calibration coefficients

PROMECON UBC Measurement Principle

PROMECON

USA

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

Typical Measurement Data Accuracy

PROMECON UBC Instrument (%UBC)

La

bo

rato

ry M

ea

su

rem

en

t

(%U

BC

)

PROMECON

USA

Data from Reuter West power station, 11/12/2001

2

4

6

8

10

12

14

16

18

U

BC

[%

]

0 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

0

0,5

1

1.5

2

2.5

3

3.5

4

4.5

O2

[%]

UBC Fly ash (PROMECON UBC)

UBC Fly ash (Lab analysis)

O2 Boiler @ SCR outlet

Boiler/Mill Optimization w/ UBC Monitoring

PROMECON

USA

PROMECON

USA

Kanawha River UBC Data

0

1

2

3

4

5

0 1 2 3 4 5

Lab Kanawha River [%]

UB

C [

%]

Channel 0

Channel 1

Channel 2

Channel 3

Channel 4

Channel 5

Channel 6

Standard Deviation

of UBC Measurements

Channel 0: 0.17%

Channel 1: 0.15%

Channel 2: 0.28%

Channel 3: 0.15%

Channel 4: 0.10%

Channel 5: 0.16%

Channel 6: 0.25%

All Channels = 0.18%

PR

OM

EC

ON

UB

C [

%]

PROMECON

USA

Accurate measurement of a very key combustion parameter (UBC)

Optimization of mill/boiler performance

Improvement of NOx, CO, O2 and

UBC (quantity and consistency)

Operating cost savings by reduction of

primary losses and increased fly ash sales

Benefits to the Power Plant

PROMECON

USA

Boiler Combustion Optimization

Hot Gas Flow

Measurement

Air/Flue Gas

PROMECON

USA

How accurate is your air flow measurement?

-Venturi measurements usually control dampers to a fixed set point. Therefore the venturi measurement

indicates this set point during normal operation. Any deviations of inaccuracies therefore can not be observed

from the measurement value itself, because it indicates the desired value. The damper curves usually do not

allow the detection of deviations of the venturi measurement. But they often are not plausible(see picture)

-Since the O2 control loop usually corrects the deviations caused by a faulty air flow measurement,

the problem can not therefore be detected by a flue gas O2 monitor.

This problem causes loss in efficiency as well as unnecessary damper wear!!

0

5000

10000

15000

20000

25000

30000

35000

2:24 2:38 2:52 3:07 3:21 3:36 3:50 4:04 4:19 4:33 4:48

Sekund

ärlu

ft [N

m³]

0

10

20

30

40

50

60

70

80

90

100

Kla

ppe

nste

llung [%

]

7.1.02 8.1.02

venturi measurement!

air damper position!

venturi cleaning air!

same setpoint ?

same air flow?

PROMECON

USA

0

5000

10000

15000

20000

25000

30000

35000

2:24 2:38 2:52 3:07 3:21 3:36 3:50 4:04 4:19 4:33 4:48

Se

ku

nd

ärlu

ft [N

m³]

0

10

20

30

40

50

60

70

80

90

100

Kla

pp

en

ste

llu

ng

[%

]

Sekl. Vent.2 Br21 Sekl. MECONTROL Air.2 Br21 Klappe.2 Br21

7.1.02 8.1.02

MECONTROL Air No deviation between air flow

and damper position trending

MECONTROL Air/FG flow measurement

-no measurement drift, reduced damper control error and wear

-accurate air distribution to each burner

-unaffected by dust and dirt in the gas stream

-no pressure drop at the measurement location

PROMECON

USA

Sensor 2

Air Duct or Pipe

Sensor 1 S=const.

Example

S = 2 ft

T = 25 ms V = 80.0 ft/s (average velocity)

Signal Sensor 1

Signal Sensor 2

“Signature”

Y(t)=X(t-T)

T= 25 ms Optimum

correlation

X(t)

Time T

correlation “Correlation”

MECONTROL Air/FG

Measurement Principle

PROMECON

USA

Duct

Sensor 1

Sensor 2

Sensor box max. 4 Sensors/2 Channels

Sensor 3/4

4 x raw signals

Power Supply

24 VAC

Main Cabinet

MECONTROL Air/FG Overview

PROMECON

USA

PROMECON

USA

0

5000

10000

15000

20000

25000

30000

35000

6:00 7:12 8:24 9:36 10:48 12:00 13:12 14:24 15:36

Sekundärluft [N

m³]

0

10

20

30

40

50

60

70

80

90

100

Kla

ppenste

llung [%

]

Sekl. Vent.1 Br23 Sekl. Vent.2 Br23

Klappe.1 Br23 Klappe.2 Br23

2.1.02

How do these problems affect the damper control?

Damper control before cleaning of Venturi

Damper control after cleaning

A venturi measurement is highly non-repeatable when exposed to dust contamination in secondary

air ducts. This leads to a wrong stoicheometry as well as to increased wear of the damper actuators.

The problem does not become appearant on the venturi values themselves or the O2 values at the boiler

outlet, but mainly on the dynamic behaviour of the dampers themselves.

PROMECON

USA

Case Study: wall-fired boiler Despite constant O2 values, combustion conditions vary from day to day!

Venturi measurements indicated the same

air flow on both days.

However damper position showed large

variations. This result is not plausible as

the air ducts come off the same main duct

which showed the same static pressure

on both days.

1

2

3

4

Level 1

Level 2

Level 3

Level 4

Level 5

-8,0%

-6,0%

-4,0%

-2,0%

0,0%

2,0%

4,0%

6,0%

8,0%

10,0%

12,0%

14,0%

rel. Deviation

Burner

Deviation of air dampers on two consecutive

days (at same load)

Level 1 Level 2 Level 3 Level 4 Level 5

PROMECON

USA

PROMECON USA, Inc.

314 Collins Blvd.

Orrville, OH 44667

Ph: 330-683-9074

Fax: 330-683-9082

www.promecon.us

Contact Information