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On Developing a Spectroscopic System for Fast Gas Temperature Measurements inCombustion Environments
Evseev, Vadim; Clausen, Sønnik
Published in:1st Joint Meeting of the Scandinavian-Nordic and French Sections of the Combustion Institute
Publication date:2009
Link back to DTU Orbit
Citation (APA):Evseev, V., & Clausen, S. (2009). On Developing a Spectroscopic System for Fast Gas TemperatureMeasurements in Combustion Environments. In 1st Joint Meeting of the Scandinavian-Nordic and FrenchSections of the Combustion Institute: [Programme and abstracts] The Combustion Institute.
Joint Meeting of the Scandinavian-Nordic and French Sections of the
C b ti I tit tCombustion InstituteComwell Borupgaard, Snekkersten (Copenhagen)
9–10 November 2009
On Developing a Spectroscopic System forSpectroscopic System for Fast Gas Temperature
iMeasurements in Combustion Environments
Vadim Evseev, PhD studentSønnik Clausen, senior scientist, PhDSønnik Clausen, senior scientist, PhD
DENMARK
Optical Diagnostics Group
Information on
gas temperatureEstimation of
fEconomical
inside combustion
gas temperaturegas composition
performance
Optimization
advances
Environment protection
Development of methods and equipment for on-line optical measurements of gas temperature and species
p
measurements of gas temperature and species concentrations
such as O2, NOx, SO2, CO, CO2, H2O and CxHy
in flames or hot gas flows inside boilers, exhaust pipes, engines, etc.using IR/UV emission/absorption spectrum measurements
Investigation of spectral properties of gases at high temperaturestemperatures
This allows to improve quality of spectrum modeling and thus to increase accuracy of on-line measurements
Calibration of temperature and infrared measuring
Risø DTU, Technical University of Denmark
equipment (accredited by DANAK)
9 November, 2009
On Developing a Spectroscopic System for Fast Gas Temperature Measurements in Combustion Environments
2
Outline
Fast gas temperature measurement
Existing techniques for gas temperature measurement
Development of a new technique for fast gas temperature measurementmeasurement
SchematicModelCalibrationCalibrationValidation
Application on an industrial boiler• Fast spectral measurements inside the boiler• Temperature calculation results
– Temperature variations with high temporal resolution
Further development of the systemMultichannel spectrometer2D T h
Risø DTU, Technical University of Denmark
2D Tomography
9 November, 2009
On Developing a Spectroscopic System for Fast Gas Temperature Measurements in Combustion Environments
3
Existing Techniques
High temporal resolution is necessary for combustion diagnostics• At least 1 kHz is needed in order to resolve temperature variations which occur e.g.
due to turbulent fluctuationsdue to turbulent fluctuationsContact
• Suction pyrometers: typical response time 15–60 s
Suction of gas
Radiation shield Thermocouple
Cooling Water
Cooling Water
Non-contact• FTIR: has been successfully applied for in situ non-contact gas analysis in industrial
combustors, typical temporal resolution 2 Hz
Radiation shield Thermocouple
C li W tCooling Water
Cooling Water
FTIRSpectrometer
CARS hi h t l d ti l l ti li t d t
Protection Tube
Optical Fibre Field Of View
Risø DTU, Technical University of Denmark
• CARS: very high temporal and spatial resolution, complicated setup
9 November, 2009
On Developing a Spectroscopic System for Fast Gas Temperature Measurements in Combustion Environments
4
A New System
IR CameraIR CameraGrating
SpectrometerGrating
SpectrometerOptical Fibre
Source
IR SpectrumIR Image
512
pixe
ls
Exposure 5
down to7 μs
ptime:
Risø DTU, Technical University of Denmark 9 November, 2009
On Developing a Spectroscopic System for Fast Gas Temperature Measurements in Combustion Environments
5
640 pixels
Wavelength Calibration
What is the correspondence between pixel numbers along the horizontal axis in the IR image and wavelengths?
40004000
CO and CO2 lines are used
3000
3500
3000
3500Working spectral region:
3800–5000 nm(2000–2600 cm-1)
els]
2000
2500
2000
2500
COResolving power: [D
igital
Lev
e
1000
1500
1000
1500
CO2
g p6 nm
(4 cm-1)
Inte
nsi
ty [
0
500
1000
0
500
1000 2
Wavelength [nm]
I
Risø DTU, Technical University of Denmark
3800 4000 4200 4400 4600 4800 50000
3800 4000 4200 4400 4600 4800 50000
9 November, 2009
On Developing a Spectroscopic System for Fast Gas Temperature Measurements in Combustion Environments
6
Wavelength [nm]
Mathematical Model
A static model of the spectral measurement:S (λ) – a received signal from a source [digital
( ) ( ) ( , ) ( )S R L T Bλ = λ λ + λ( ) ( ) ( , ) ( )S R L T Bλ = λ λ + λ
levels]L (λ,T) – unknown spectral radiance of the source [W / m2 sr m]R (λ) – a response (or instrument) functionB (λ) – constant background radiation
2 1S SR
−= 2 1S SR
−= Calibration of Intensities Scale (reference sources having known spectral radiance L are used)
S1 , S2 – received signals for a black body at temperatures T T
2 1( ) ( )BB BBRL T L T
=−2 1( ) ( )BB BBR
L T L T=
−
temperatures T1 , T2
LBB (T1), LBB (T2) – spectral radiance of the black body calculated from the Planck Law
( )2 1 2 1 1 2
2 1
BB BB BB BBS L L S L S LL
S S
− + −=
−( )2 1 2 1 1 2
2 1
BB BB BB BBS L L S L S LL
S S
− + −=
−
The unknown spectral radiance of the source is calculated using reference data
Risø DTU, Technical University of Denmark 9 November, 2009
On Developing a Spectroscopic System for Fast Gas Temperature Measurements in Combustion Environments
7
2 1S S2 1S S
Intensity Calibration
Variations (%) of the response function R for different pairs of reference source temperatures T1 , T2
7
x 10-7
7
x 10-7
3%Response Functions
for 18 pairs of T T
5
6
5
6
ance
]
for 18 pairs of T1 , T2from the region
30–920°C
3
4
3
4
pec
tral
Rad
ia
2
3
2
3
R[
DL
/Sp
0
1
0
1
Wavenumber [cm-1]
R
Risø DTU, Technical University of Denmark 9 November, 2009
On Developing a Spectroscopic System for Fast Gas Temperature Measurements in Combustion Environments
8
2000 2100 2200 2300 2400 2500 2600
2000 2100 2200 2300 2400 2500 2600 Wavenumber [cm 1]
Validation
Relative error δ (%) of reference source temperature measurement00
-10-10
0.6%
860°C:
-20-20
860 C
790°C
700°C
od
y
s w
ere
-30-30
δ[%
]
580°C
lack
bo
era
ture
s
-50
-40
-50
-40δ
Black body temperature measurements using
calibration data for the
Bte
mp
e
-60-60Wavenumber [cm-1]
calibration data for the T1 , T2 = 30°C , 920°C30°C 920°C
Risø DTU, Technical University of Denmark 9 November, 2009
On Developing a Spectroscopic System for Fast Gas Temperature Measurements in Combustion Environments
9
2000 2100 2200 2300 2400 2500 2600
2000 2100 2200 2300 2400 2500 2600
Industrial Boiler
A boiler of a biomass-coal power station
Thermal picture of the 40 MW flame
Risø DTU, Technical University of Denmark 9 November, 2009
On Developing a Spectroscopic System for Fast Gas Temperature Measurements in Combustion Environments
10
Spectra
Emission spectra for several insertion depths of the probeThe emission was from the gas, particles and walls Probe Positions:
1.81.8 Emission fromSolids 250cm
250cmTilt Up
CO2 Band
1.61.6
m2
srm
) ]
150 cm
250cmTilt Downto Straw
1
Exposure time:
1.2
1.4
1.2
1.4
e [
W /
(m
25 cm
250 cm1 ms
11
al R
ad
ian
ce
0.80.8
Wavenumber [cm-1]
Sp
ect
ra
Risø DTU, Technical University of Denmark
2000 2100 2200 2300 2400 2500 2600
2000 2100 2200 2300 2400 2500 2600
9 November, 2009
On Developing a Spectroscopic System for Fast Gas Temperature Measurements in Combustion Environments
11
Brightness Temperature
Brightness temperature is calculated from the Planck Law for each spectral point in each spectrum
1600
1700
1600
1700
Solids (Particles)
CO2 (Gases)
15001500 250cmTilt Up
[ °
C ]
1300
1400
1300
1400
150 cm
250cmTilt Downto Straw
mp
era
ture
12001200
Probe Positions:
25 cm
250 cm
Exposurehtn
ess
Tem
1000
1100
1000
1100
Wavenumber [cm-1]1 ms
Exposure time:
Bri
gh
Risø DTU, Technical University of Denmark 9 November, 2009
On Developing a Spectroscopic System for Fast Gas Temperature Measurements in Combustion Environments
12
2000 2100 2200 2300 2400 2500 2600
2000 2100 2200 2300 2400 2500 2600
Temperature Variations: Straw Region near Burner
Temperature is averaged throughout each band (CO2 and solids) in each spectrum taken at each time point and plotted versus time
16001600
Gases
1200
1400
1200
1400
Solids
]
1000
1200
1000
1200
ture
[
°C ]
800800
Tem
pera
t
600600
Time [ms]
Probe Position:
1 kHz
Temporal resolution: A point in the
straw region near burner
Risø DTU, Technical University of Denmark
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000
9 November, 2009
On Developing a Spectroscopic System for Fast Gas Temperature Measurements in Combustion Environments
13
Temperature Variations: Straw Region near Burner
Zoom In: 1kHz is enough to resolve temperature variations which occur due to turbulent fluctuations
1400
1500
1600
1400
1500
1600
Probe Position:
GasesA point in the straw region near burner
1200
1300
1400
1200
1300
1400
Solids
]
near burner
1000
1100
1000
1100
ture
[
°C ]
800
900
800
900
Tem
pera
t
Temporal resolution:
600
700
600
700
Time [ms]
1 kHz
Risø DTU, Technical University of Denmark
1900 1950 2000 2050 2100 2150 2200 2250
1900 1950 2000 2050 2100 2150 2200 2250
9 November, 2009
On Developing a Spectroscopic System for Fast Gas Temperature Measurements in Combustion Environments
14
Temperature Variations: Above the Straw Region
Here gas temperature is higher than that of particles. Most of heat is already released at this point, and hence gas is hotter than particles
1550
1600
1550
1600
Gases
1450
1500
1450
1500
]
1300
1350
1400
1300
1350
1400
Solids
ture
[
°C ]
1200
1250
1200
1250
Tem
pera
t
Temporal
1100
1150
1100
1150
Time [ms]
Probe Position:A point above straw region
1 kHz
Temporal resolution:
Risø DTU, Technical University of Denmark 9 November, 2009
On Developing a Spectroscopic System for Fast Gas Temperature Measurements in Combustion Environments
15
0 500 1000 1500 2000
0 500 1000 1500 2000
Temperature Variations: Above the Straw Region
Zoom In: Particles (solids) do not undergo as huge temperature variations as gases do
1550
1600
1550
1600
Gases
1450
1500
1450
1500
]
1300
1350
1400
1300
1350
1400
Solids
ture
[
°C ]
1200
1250
1300
1200
1250
1300
Tem
pera
t
1100
1150
1100
1150
Time [ms]
Probe Position:A point above straw region 1 kHz
Temporal resolution:
Risø DTU, Technical University of Denmark
1600 1650 1700 1750 1800
1600 1650 1700 1750 1800
9 November, 2009
On Developing a Spectroscopic System for Fast Gas Temperature Measurements in Combustion Environments
16
std of temperature values
How do temperature values deviate throughout each band in each spectrum?
8080Probe Position:
1 kHz
Temporal resolution: A point
above straw i
60
70
60
70 region
40
50
40
50
[ °C
]
20
30
20
30std
1010
GasesMean std: 13
Risø DTU, Technical University of Denmark 9 November, 2009
On Developing a Spectroscopic System for Fast Gas Temperature Measurements in Combustion Environments
17
0 500 1000 1500 20000
0 500 1000 1500 20000
SolidsTime [ms] Mean std: 0.8
Further development: Multichannel Spectrometer
Optical fibreSimultaneous spectral measurements
A multichannel assembly allows to perform spectral measurements simultaneously
IR Camera
Grating Spectro-
metermeasurements simultaneously from several positions
Slit
mxels
IR ImageIR Image
12 m
m
512
pix
0.55 mm640 pixels
Risø DTU, Technical University of Denmark 9 November, 2009
On Developing a Spectroscopic System for Fast Gas Temperature Measurements in Combustion Environments
18
640 pixels
Further development: 2D Tomography
e
On line 2D visualisation
Distribution in a section of o
n s
cale
centr
atio
TemperatureConcentration
e or
conc
an
nel
mete
r
per
ature
Mu
ltic
ha
pect
rom
2D Tomography of e.g. hot gas inside of an exhaust pipe shows distribution of temperature or concentrations in a pipe section
Tem
pM Sp
Risø DTU, Technical University of Denmark
of temperature or concentrations in a pipe section
9 November, 2009
On Developing a Spectroscopic System for Fast Gas Temperature Measurements in Combustion Environments
19
Conclusion
A system for fast gas temperature measurements for use on industrial scale has been developed
G ating spect omete + IR Came aGrating spectrometer + IR CameraMaximum possible temporal resolution 142 kHz
The system has been calibrated and validatedThe system has been calibrated and validated
It has been successfully applied on an industrial boilerSpectral measurements has been takenSpectral measurements has been taken
– at several points inside the boiler– with temporal resolution of 1 kHz
Temperature has been calculated for gases and solids– 1 kHz is high enough to resolve temperature fluctuations which occur
due to turbulenceReliability of results has been estimated
The system provides flexibility and is promising in further developmentsSimultaneous spectral measurements2D Tomography of combustion gases
Risø DTU, Technical University of Denmark
2D Tomography of combustion gases
9 November, 2009
On Developing a Spectroscopic System for Fast Gas Temperature Measurements in Combustion Environments
20