On Developing a Spectroscopic System for Fast Gas ... · Evseev, Vadim; Clausen, Sønnik Published in: 1st Joint Meeting of the Scandinavian-Nordic and French Sections of the Combustion

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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.

https://orbit.dtu.dk/en/publications/62490b17-f241-4acb-b1aa-cab73c009665

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


2D Tomography

9 November, 2009


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


• CARS: very high temporal and spatial resolution, complicated setup

9 November, 2009


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


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


3800 4000 4200 4400 4600 4800 50000

3800 4000 4200 4400 4600 4800 50000

9 November, 2009


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



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



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



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



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


2000 2100 2200 2300 2400 2500 2600

2000 2100 2200 2300 2400 2500 2600

9 November, 2009


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



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


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


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


1900 1950 2000 2050 2100 2150 2200 2250

1900 1950 2000 2050 2100 2150 2200 2250

9 November, 2009


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




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



1600 1650 1700 1750 1800

1600 1650 1700 1750 1800

9 November, 2009


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



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



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


of temperature or concentrations in a pipe section

9 November, 2009


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


2D Tomography of combustion gases

9 November, 2009


20

Documents

On Developing a Spectroscopic System for Fast Gas ... · Evseev, Vadim; Clausen, Sønnik Published in: 1st Joint Meeting of the Scandinavian-Nordic and French Sections of the Combustion