An experimental approach to the kinetics of the combustion ... 4_C/4... · Effect of gas...
Transcript of An experimental approach to the kinetics of the combustion ... 4_C/4... · Effect of gas...
An experimental approach to the kinetics of the combustion
in O2/CO2-atmospheres
Stephanie TappeHans Joachim Krautz
Chair of Power Plant TechnologyB d b U i it f T h l C ttb
1st Oxyfuel Combustion Conference Cottbus, 7th-11th September 20091
Brandenburg University of Technology CottbusGermany
Outline
1 Motivation
2 ALVA 20 and experimental set up2 ALVA 20 and experimental set up
3 Experimental results and discussion
4 Summary and outlooky
1st Oxyfuel Combustion Conference Cottbus, 7th-11th September 20092
Outline
1 Motivation2 ALVA 20 and experimental set up2 ALVA 20 and experimental set up
3 Experimental results and discussion
4 Summary and outlooky
1st Oxyfuel Combustion Conference Cottbus, 7th-11th September 20093
Motivation
Combustion procedure
• Preheating• DryingDrying• Devolatilization, ignition and combustion of volatile matters
(homogeneous gas reaction)• Ignition and combustion of charg
(heterogeneous gas-solid reaction)
Oxyfuel-atmosphere:Oxyfuel atmosphere:• Increased CO2 partial
pressure• Increased H2O partial
1st Oxyfuel Combustion Conference Cottbus, 7th-11th September 20094
Increased H2O partial pressure
C b ti f l til tt
Effects of increased CO2-concentrations
Combustion of volatile matters Heat capacity
heat transfer ignition
Combustion of char
Heat capacityflame temperature reaction rate
CO2-concentration CO2 concentrationdiffusion rateschemical reaction mechanisms
1st Oxyfuel Combustion Conference Cottbus, 7th-11th September 20095
Focus of work
Effect of increased CO2-concentrations in the burning behaviour
Applying ALVA 20• Registration of the whole combustion sequence• Close-to-reality-conditions - high heating rates
- fluid dynamics
Applying ALVA 20
y- particle interactions
1st Oxyfuel Combustion Conference Cottbus, 7th-11th September 20096
Outline
1 Motivation
2 ALVA 20 and experimental set up2 ALVA 20 and experimental set up3 Experimental results and discussion
4 Summary and outlooky
1st Oxyfuel Combustion Conference Cottbus, 7th-11th September 20097
20 kWth atmospheric laboratory test facility - ALVA 20
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Temperature range
Experimental set up
Temperature range 800 – 1000°C
Particle size 1.25 - 2.00 mm
FuelGer1, Ger2Pol, US-Bl
Gas compositionGas composition air, O2/CO2 with 5-50 vol.-% O2
1st Oxyfuel Combustion Conference Cottbus, 7th-11th September 200910
Data analysis
I j ti E d f
n vo
l.-%
) Injection of sample
End ofexperiment
trat
ion
(in
Char combustion
2-co
ncen
t
Combustion ofvolatile matters
0 10 20 30 40Ti (i )
O2
1st Oxyfuel Combustion Conference Cottbus, 7th-11th September 200911
Time (in s)
Outline
1 Motivation
2 ALVA 20 and experimental set up2 ALVA 20 and experimental set up
3 Experimental results and discussion4 Summary and outlooky
1st Oxyfuel Combustion Conference Cottbus, 7th-11th September 200912
Combustion sequences for different O2-concentrations60
%) 05/95 10/90 21/79 30/70 40/60 50/50
50
(in v
ol.-%
05/95 10/90 21/79 30/70 40/60 50/50
Ger1
30
40
ntra
tion
20
en c
once
n
0
10
Oxy
ge
1st Oxyfuel Combustion Conference Cottbus, 7th-11th September 200913
0 10 20 30 40 50Time (in s)
Combustion sequences for different gas compositions
Ger1
1000°C
800°C
Pol
1000°C
0 10 20 30 40 50
air air21/79 21/79
Pol
800°C
0 10 20 30 40 50Time (in s)
air air21/79 O2/CO2 21/79 O2/CO2
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0 10 20 30 40 50Time (in s)
Data interpretation – Approach I
25
20
25
n vo
l.-%
)
tv
10
15
trat
ion
(in
5
10
-con
cent
00 10 20 30 40 50
Time (in s)
O2
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Time (in s)
Effect of gas composition for Ger1 and Ger250
)
air 21/79 30/70 40/60 50/50 Ger1
30
40
on ti
me
(in
s)40
50
n s)
air 21/79 30/70 Ger210
20
Com
bust
io
20
30
stio
n tim
e (i
n
01050 1100 1150 1200 1250 1300 1350
Temperature (in K)
0
10Com
bu
1st Oxyfuel Combustion Conference Cottbus, 7th-11th September 200916
01050 1100 1150 1200 1250 1300 1350
Temperature (in K)
Effect of gas composition for Pol, US-Bl50
air 21/79 30/70 40/60 50/50 Pol
30
40
on ti
me
(in
s)
air 21/79 30/70 40/60 50/50 Pol
50 10
20
Com
bust
io
30
40
on ti
me
(in
s) 01050 1100 1150 1200 1250 1300 1350
Temperature (in K)
0
10
20
Com
bust
i
air 21/79 30/70 US-Bl
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01050 1100 1150 1200 1250 1300 1350
Temperature (in K)
Determination of keff,char 25 2
kX )1l (20
n vo
l.-%
)
0tkX eff )1ln(
10
15
trat
ion
(in
4
-2
ln (1
-X)
5
10
2-co
ncen
t
-6
-4 l
00 5 10 15 20 25 30
O2
-8
1st Oxyfuel Combustion Conference Cottbus, 7th-11th September 200918
0 5 10 15 20 25 30
time (in s)
Data interpretation –Approach II
20
25
vol.-
%)
15
atio
n (in
v
Char combustion
5
10
conc
entr
a
Combustion of
volatile
0
5
0 10 20 30 40 50
O2-
c volatile matters
1st Oxyfuel Combustion Conference Cottbus, 7th-11th September 200919
0 10 20 30 40 50Time (in s)
Data interpretation –Approach II
25
20
25
vol.%
)
fa fdfe
15
ratio
n (in
fb fc
5
10
2 con
cent
r
00 10 20 30 40 50
O2
1st Oxyfuel Combustion Conference Cottbus, 7th-11th September 200920
0 10 20 30 40 50Time (in s)
Outline
1 Motivation
2 ALVA 20 and experimental set up2 ALVA 20 and experimental set up
3 Experimental results and discussion
4 Summary and outlooky
1st Oxyfuel Combustion Conference Cottbus, 7th-11th September 200921
Summary and Outlook
T t• T tv
• c(O2) tv
• Combustion sequence changes:Trend: tv (air) > tv (O2/CO2) for c(O2)const but but f (T, fuel)
Next Steps:
• Considering specific surface area
• Determination of kinetics applying approach II (VM, char)
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Acknowledgement
The research work was financed by the DFG (Deutsche Forschungsgesellschaft).
It is sponsored at the title: „Charakterisierung des Abbrandverhaltens von Braunkohlen in O2/CO2-Atmosphären“ (Kr 1855/9-1).
1st Oxyfuel Combustion Conference Cottbus, 7th-11th September 200923
Thank you yfor your attention!
Contact: Stephanie Tappetappe@tu cottbus de
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Fuel composition
Proximate Analysis Ultimate Analysis
Moisture Ash Volatiles C-fix Heating value C H N S O value
Coal (wt.-%) (wt.-%) (wt.-%) (wt.-%) (MJ/kg) (wt.-%) (wt.-%) (wt.-%) (wt.-%) (wt.-%) Ger1 18.03 5.25 45.40 31.32 20.41 52.91 7.34 0.52 0.72 15.23 lig Ger2 8.81 13.32 50.94 26.93 23.29 56.40 12.53 0.48 3.30 5.16 Pol 7.00 6.92 29.89 56.19 27.83 70.65 6.96 1.13 0.41 6.93 US Bl 1 73 12 39 30 66 55 22 29 89 72 26 8 17 1 39 0 89 3 17bit US-Bl 1.73 12.39 30.66 55.22 29.89 72.26 8.17 1.39 0.89 3.17bit SA-Bl 8.48 15.33 22.12 54.06 24.34 65.16 3.45 1.55 0.47 14.04
1st Oxyfuel Combustion Conference Cottbus, 7th-11th September 200925
dn
Determination of keff,char
2
2Oeff
O nkdt
dnr
ktnO2)(
l
Reaction rate
)(
tkn eff
complO
O 2
2ln
tn )(
222)( OcomplOO nntn
complO
O
ntn
X,2
2)(
Conversion of O2
tkX eff )1ln(
1st Oxyfuel Combustion Conference Cottbus, 7th-11th September 200926
combustion process volatile matters Integration
Data interpretation –Approach II
combustion process volatile matters
char
Integration
Differentation
Combustion of volatile matters2
2)( OvolO nk
dtdn
tr t
d
t
tOOcomplO dttccVn
0
.
, )()0(222
dtdc
tr O2)( Char combustion
tkc
charO 2ln
1st Oxyfuel Combustion Conference Cottbus, 7th-11th September 200927
tkc char
O 0,2