co-firing optimization with continuous coal flow … optimization with continuous coal flow...

© EUtech Scientific Engineering GmbH Dennewartstrasse 25-27, 52068 Aachen, Germany www.eutech-scientific.de Phone:+49/241/963-2380 Fax:+49/241/963-2389

Co-Firing Optimization with Continuous Coal Flow Measurement

Dr.-Ing. Francesco Turoni

POWER-GEN Europe Köln June 13th, 2012


Introduction

Combustion optimization

EUcoalflow System

Applications and results

Summary

Contents


Introduction


Introduction

650 MW coal fired boiler with SCR (biomass co-firing)

High und local CO concentrations

Unbalanced coal flow distribution (coal flow hanks)

Coal flow not directly monitored and controlled

System information and ‘status quo’

High excess oxygen levels

Trade off between emissions and efficiency


Reduce process variability and shift operating point closer to the limits

Individual adjustment of air and fuel flow at burner level

Identify and utilize the intricate interplay of combustion parameters

Air/fuel ratio and performance Strategy

Introduction

l

hth

NOx

COLoI

l = 1.0 l

hth

NOx

COLoI

l = 1.0

lgeslopt

Air/fuel ratio (l) - optimised combustion settings

Air/fuel ratio (l) - regular combustion settings

System optimization

Adaptation to load changes


Why is coal and air flow control so important?

Controllable O&M variable Dh th

Coal fineness 0.1 - 0.3%

Primary air-flow 0.1 - 0.2%

Fuel line balance 0.1 - 0.3%

Particulate-air ratio 0.1 - 0.3%

Carbon-in-ash (LoI) 0.1 - 0.3%

Excess oxygen 0.1 - 0.3%

Total* 0.6 – 1.7%

* These benefits do not add up synergistically. Typically, an overall improvement in net efficiency will be around 0.3 – 1.0%



Measure

If you can´t measure, you can´t control.

Basic Idea

EUcoalflow sensors

EUcontrol Coalflow

Coal flow & primary air



Measure


Control If you can´t control, you can´t optimize.

Basic Idea

EUcoalflow sensors

Orificing valve

EUcontrol Coalflow




Measure


Control If you can´t control, you can´t optimize.

Optimize

If you don´t optimize, you waste money.

Basic Idea

Sec. air damper

Burner

EUcoalflow sensors

Orificing valve

EUcontrol Coalflow


Wind box



EUcoalflow Sensor

Coal mass flow 2 – 3 Sensors per pipe

Orificing valve Basic adjustment Pipe-to-pipe balancing Manual or motor driven

SA-Damper Control

Automatic adjustment of SA AFR at prescribed level

Basic Idea

Sec. air damper

Burner

EUcoalflow sensors

Orificing valve

EUcontrol Coalflow


Wind box


Mill upgradation

Coal dampers after classifier

Online coal flow measurement in each pipe

Adjust coal flows to acceptable reference limits (manual) Use excess O2 as global control variable

Optimize (emissions, heat rate, LoI, slagging, ...)

Applied actions and strategy



EUcoalflow system


Sensor type Microwave

Operating temp. < 200 °C

Flow density < 1000 g/m³

Sensor diameter 20 mm

Power supply 110/240 V AC

Sensor set-up 2 to 5 per pipe

Sensor

System specification

Data acquisition

Online determination of - Coal mass flow - Pipe-to-pipe distribution

Sensor & system calibration

Statistic functions

Features

System set-up

Sensor Control Unit


Mobile ECF System

Easy and quick set-up

- Quick release connector

- Purge air adapter

Comfortable control through ECF Software

Stand-alone operation and data acquisition (without PC)

Interface to DCS

Features

EUcoalflow system

Design


Installation and set-up

EUcoalflow system


EUcoalflow specification

Measurement principle

P0 = Power of reflected microwave

Caption

P(t

) Pow

er

t1 t2 t3 t (Time)

Mass flow:

m = f (P0,t) Microwave field Coal pipe

Particle Reflecting microwave

EUcoalflow sensor

P0

t1 t2 t3 t (Time)

|P(t

)/dt|

a

P(t)= a*t P(t)= -a*t +P1

t1/2 t2/2 t3/2

t1/2 t2/2 t3/2

P(t)= 2a*t

P0

P(t)= -2a*t +P1 P(t

) Pow

er

|P

(t)/

dt|

t (Time)

t (Time)

2a


Applications and results


Tests during load change

- High correlation with belt weigher data

- Online monitoring of inline balance in each burner pipe

High resolution signals

System results

High sensitivity

Conclusion


High fluctuation in the mass flow signal causes

fluctuating excess oxygen

(DCS signal) at constant load set point

High correlation of excess oxygen signal with fuel flow (biomass)

Direct visualisation of feeding and milling malfunctions

Control of secondary air flow

Immediate results Signal analysis

Conclusion

0

4

8

12

16

20

30

40

50

60

70

80

12

:00

12

:05

12

:10

12

:15

12

:20

12

:25

O2

Co

nce

ntr

atio

n [

%]

EUco

alfl

ow

mas

s fl

ow

[%

]

Time [hh:mm]

O2 Concentration EUcoalflow

System results


Tests with three mill settings

- Stable and reproducible signal

- Direct monitoring of load changes in each burner pipe

- Good correlation between EUcoalflow mass flow signal and mill load Linear fit can be used for signal calibration

y = 1,073.4x + 310.3

700

750

800

850

900

950

1000

1050

1100

40%

45%

50%

55%

60%

65%

70%

EUcoalflow raw signal Linear fit for calibration

0

200

400

600

800

1000

1200

1400

1600

0

100

200

300

400

500

600

700

800

11:3

0

11:4

0

11:5

0

12:0

0

12:1

0

12:2

0

12:3

0

12:4

0

12:5

0

13:0

0

13:1

0

13:2

0

13:3

0

13:4

0

13:5

0

14:0

0

14:1

0

14:2

0

14:3

0

Mean Burner 1 Mean Burner 2 Mean Burner 3 Mean Mill

System Results

Strong linearity Signal correlation

Load 45%

Load 55%

Load 65%

Conclusion Mill load

EU

coalflo

w

mean t

ota

l si

gnal

EU

coalflo

w s

ignal fo

r burn

er

1-3


Independent assessment of system upgradation

True system optimization

- Online monitoring and tuning of inline balance in each burner pipe

Efficiency improvement without emission worsening

System results

Application with co-firing

Conclusion

Clean combustion

-100% -75% -50% -25% 0% 25%

Increased efficiency

-45% -15% 10% 40%

before optimization after optimization


Active measurement and balancing of coal flow in all pipes

Real-time control of air-fuel ratios at burner levels

On-line monitor and supervision of mill operation

Improved combustion efficiency and emissions

- Improved efficiency (0.3 to 1%)

- Less NOx and CO emissions (-5 to -15 %)

- Less LOI

Less slagging and less cleaning demand

Positive effects on availability and maintenance

- Less down time

- Less boiler wall corrosion

Continuous profit through online measurement

Benefits


For more information, please visit us at booth 7A3

Thank you for your attention!

co-firing optimization with continuous coal flow … optimization with continuous coal flow...

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