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