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Reducing of kinetic scheme for syngas oxidation at high pressure and elevated temperature Bolshova T.A. , Shmakov A.G., Yakimov S.A., Knyazkov D.A., Korobeinichev O.P. Institute of Chemical Kinetics & Combustion, Novosibirsk 630090 Russia. - PowerPoint PPT Presentation
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Reducing of kinetic scheme for syngas oxidation at high pressure
and elevated temperature Bolshova T.A., Shmakov A.G., Yakimov S.A.,
Knyazkov D.A., Korobeinichev O.P.
Institute of Chemical Kinetics & Combustion, Novosibirsk 630090 Russia
7th International Seminar on Flame Structure, July 11 -15, 2011
Introduction• SYNGAS, components: H2 + CO • Production technology:
– Gasification of fossil fuels (mineral and brown coal)
– Processing of natural gas and natural hydrocarbons (catalytic and thermal methods)
– Gasification of combustible wastes• Spheres of application:
– Power engineering – Chemical engineering
• Problems: – Fire safety– Toxicity– Development of high-tech devices for
power chemical engineering (turbines, reactors, etc.)
Research ObjectivesResearch Objectives
•Development of the reduced reaction mechanism for syngas oxidation at temperature Т0=300-700 K and pressure Р=10-30 bar
•Validation of the proposed reduced mechanism by comparing the simulated burning rate with experimental literature data
Characteristics of Unburnt Gases•The fraction of CO in the fuel :
а=[CO]/([CO]+[H2])=0.05 0.5 and 0.75
•The dilution ratio:D=[O2]/([O2]+[N2])=0.209
(for fuel/air mixtures).
•Equivalence ratio was :f=([CO]+[H2])/2[O2],
where [O2], [N2], [CO] and [H2] - are concentration of oxygen, nitrogen, carbon monoxide and hydrogen respectively.
Mechanism for modeling H2, CO oxidation.
Authors Reactions Т0, K P, atm Initial data Dixon-Lewis and Williams (1977)
19 298 1(N2) H2/CO/O2 0.01/66/33-2/66/33
Konnov (2000) 40 298 1(N2) CO/H2 (95/5)/ air 20% (CO+H2)/ air 14% (CO+H2) / air CO/H2/ air (=1)
Davis et al (2005) 30 298 1 (N2) 1, 15 (He)
H2/air (φ=1 и 3)
H2/O2/He (φ=1-2.25) H2/CO/air (φ=1-.89)
Saxena and Williams (2006)
30 298 1 (N2) 10-20 ((He)
H2/O2/( N2, Ar, He) D=0.214; H2/O2/He D= 0.08
Li et al. (2007) 31 298 1 (N2) CO/H2=95/5 (=0.5-6)
CO/H2=50/50 (=0.5-4.5) H2/CO/N2 (28/25/47) (=0.7-1.4)
Sun et al. (2007) 48 298 1-2 (N2) 5-40 (He)
H2/CO/air (=0.5-5) H2/CO/O2/He (=0.7-3.5)
Background
Model Sun H., Yang S.I., Jomaas G., Law C.K. (Proceedings of
the Combustion Institute 31, 2007)
H2 O2 H2OH O OH HO2 H2O2
CO CO2 HCOCH2O CH2OH
AR N2 HE
16 SPECIES and 48 REACTIONS
R1 H+O2=O+OH R2 O+H2=H+OH R3 O+H2=H+OH R4 H2+OH=H2O+H R9 H2+H2O=H+H+H2O R13 O+H+M=OH+M R14 H+OH+M=H2O+M R15 H+O2(+M)=HO2(+M) R19 H2+O2=HO2+H R21 HO2+H=OH+OH R22 HO2+O=O2+OH R23 HO2+OH=H2O+O2
R1 H+O2=O+OH R2 O+H2=H+OHR3 O+H2=H+OH R4 H2+OH=H2O+HR5 OH+OH=O+H2O R13 O+H+M=OH+MR14 H+OH+M=H2O+M R15 H+O2(+M)=HO2(+M)R19 H2+O2=HO2+H R21 HO2+H=OH+OHR23 HO2+OH=H2O+O2 R24 HO2+OH=H2O+O2R27 H2O2(+M)=OH+OH(+M) R36 CO+OH=CO2+HR37 CO+OH=CO2+H R38 CO+OH=CO2+H
-0,4 -0,2 0 0,2 0,4
R1
R2
R3
R4
R9
R13
R14
R15
R19
R21
R22
R23
30 atm
20 atm
10 atm
-0,4 -0,2 0 0,2 0,4
R1R2R3R4R5
R13R14R15R19R21R23R24R27R36R37R38
30 atm
20 atm
10 atm
The sensitivity coefficients of burning velocity to the reactions rate constants for H2/CO/air flame, р=10, 20, 30 bar
CO 5% CO 50%T0=300 K
f=1
R1 H+O2=O+OHR15 H+O2(+M)=HO2(+M)
R36+R37+R38 CO+OH=CO2+H
The sensitivity coefficients of burning velocity to the reactions rate constants for H2/CO/air flame, р= 20 bar
=0.5, T0=300 and 700 K, =0.75
R1 H+O2=O+OHR3 O+H2=H+OHR4 H2+OH=H2O+HR14 H+OH+M=H2O+MR15 H+O2(+M)=HO2(+M)R19 H2+O2=HO2+H R21 HO2+H=OH+OHR36 CO+OH=CO2+HR37 CO+OH=CO2+HR38 CO+OH=CO2+H
A rise of initial temperature does not influence on key reactions set
The sensitivity coefficients of burning velocity to the reactions rate constants for H2/CO/air flame, р= 20 bar
=0.5, T0=300 and 700 K, =3.5
The most appreciable changes of sensitivity coefficients as T0 rises from 300 to 700
K are observed in the rich flame for reactions R4 (in 8 times) and R15 (in 2 times).
R4 H2+OH=H2O+H
R15 H+O2(+M)=HO2(+M)
The sensitivity coefficients of burning velocity to the reactions rate constants for H2/CO/air flame, T0=300K, =0.5, р= 20 bar
-0,3 -0,1 0,1 0,3 0,5 0,7 0,9
R1
R2
R3
R4
R5
R6
R7
R13
R14
R15
R19
R21
R22
R23
R24
R27
R33
R36
R37
R38
R39
R40
f=3,5
f=1
f=0,75
R39 HCO+M=H+CO+MR40 HCO+H=CO+H2
R1 H+O2=O+OH
R19 H2+O2=HO2+H R21 HO2+H=OH+OH
The value of sensitivity coefficient to rate constants of the reactions depends on equivalence ratio .
-0,06
-0,04
-0,02
0,00
0,02
0,04
0,06
700 1200
temperature, K
rate
of
pro
du
cti
on
of
H,m
ole
/cm
3-s
ec
R1 H+O2=O+OH
R3 O+H2=H+OH
R4 H2+OH=H2O+H
R15 H+O2(+M)=HO2(+M)
R21 HO2+H=OH+OH
R37 CO+OH=CO2+H
R38 CO+OH=CO2+H
-0,80
-0,40
0,00
0,40
0,80
1,20
1,60
2,00
2,40
700 900 1100 1300 1500 1700
temperature, K
rate
of
pro
du
ctio
n o
f H
,mo
le/c
m3-
se
c
R1 H+O2=O+OH
R3 O+H2=H+OH
R4 H2+OH=H2O+H
R15 H+O2(+M)=HO2(+M)
R21 HO2+H=OH+OH
The rate of production of H in H2/CO/air flame, T0=700K, =0.5, р= 20 atm.
=0.3 =4.5
R4 H2+OH=H2O+HR3 H2O+H2=H+OHR37+R38 CO+OH=CO2+H
R1 H+O2=O+OHR15 H+O2(+M)=HO2(+M)
R4 H2+OH=H2O+HR3 H2O+H2=H+OH
R1 H+O2=O+OHR15 H+O2(+M)=HO2(+M)R21 HO2+H=OH+OH
-0,023
-0,020
-0,017
-0,014
-0,011
-0,008
-0,005
-0,002
700 1000 1300 1600
temperature, K
rate
of
pro
du
ctio
n o
f C
O,m
ole
/cm
3-se
c
R33 CO+O+M=CO2+M
R36 CO+OH=CO2+H
R37 CO+OH=CO2+H
R38 CO+OH=CO2+H
-0,0015
-0,0012
-0,0009
-0,0006
-0,0003
0,0000
0,0003
0,0006
0,0009
700 1000 1300
temperature, K
rate
of
pro
du
ctio
n o
f C
O,m
ole
/cm
3-se
c
R33 CO+O+M=CO2+M
R35 CO+HO2=CO2+OH
R37 CO+OH=CO2+H
R38 CO+OH=CO2+H
R39 HCO+M=H+CO+M
R40 HCO+H=CO+H2
R47 HCO+O2=CO+HO2
R48 HCO+O2=CO+HO2
The rate of production of CO in H2/CO/air flame, T0=700K, =0.5, р= 20 atm.
=0.3 =12
R36+R37+R38 CO+OH=CO2+H
R39 HCO+M=H+CO+MR35 CO+HO2=CO2+OH
R47 HCO+O2=CO+HO2
Н2
Н+OH
H2O+H
+O
+OH
74% 25%
CO
CO2 CO2+H
+O
+OH
94% 5%
Н2
Н+OH
H2O+H
+O
+OH
77% 23%
CO
CO2
CO2+H
+O
+OH
85%
6% +H
HCO
9%
Н2
Н+OH
H2O+H
+O
+OH
83% 17%
CO
CO2
CO2+H
+O
+OH
56%
5% +H
HCO
39%
=0.75
=2.0
=4.0
The main pathways for H2 and CO consumption in H2/CO/air flame, р= 20 atm, T0=300K, =0.5
A reduced reaction mechanism for oxidation of H2/CO/O2
№ Reartion A* n Ea*
S1. H+O2=O+OH 6.73e+15 -0.5 16670
S2. O+H2=H+OH 5.06E+4 2.67 6290
S3. H2+OH=H2O+H 1.168E+08 1.52 3457.4
S4. OH+OH=O+H2O 3.348e+04 2.42 -1927
S5. H+H+M=H2+M 7.00E+17 -1.0 0.0
S6. H+OH+M=H2O+M 2.212E+22 -2.0 0.0
S7. H+O2(+M)=HO2(+M) 4.65E+12 0.44 0.0
S8. H2+O2=HO2+H 7.395E+05 2.433 53502
S9. HO2+H=OH+OH 6.0E+13 0.0 295
S10. HO2+OH=H2O+O2 5E+13 0.0 1105.8
S11. CO+O+M=CO2+M 3.0E+14 0.0 3000
S12. CO+OH=CO2+H 1.8E+5 1.9 -1160
S13. HCO+M=H+CO+M 4.0E+13 0.0 15540
S14. HCO+H=CO+H2 1.11E+14 0.0 0.0* – In: cm3, mole, s, cal; rate constant expressed as k=A Tn exp (-Ea/RT)
13 species (H2, O2, H2O, H, O, OH, HO2, CO, CO2, HCO, Ar, He and N2) and 14 reactions
Flame speed of CO/H2/Air mixtures as function of equivalence ratio at P=10-30 atm,
=0.05, 0.5, 0.75.
5% CO+ 95% H2
Equivalence ratio
0 1 2 3 4 5 6 7
Bur
n ve
loci
ty, c
m/s
0
50
100
150
200
250
10 atm, full mech20 atm, full mech30 atm, full mech10 atm, short mech (var 9)20 atm, short mech (var 9)30 atm, short mech (var 9)
50% CO+ 50% H2
Equivalence ratio
0 1 2 3 4 5 6 7
Bur
n ve
loci
ty, c
m/s
0
20
40
60
80
100
120
140
75% CO+ 25% H2
Equivalence ratio
0 1 2 3 4 5 6 7
Bur
n ve
loci
ty, c
m/s
0
20
40
60
80
100
T0=300 K
10 atm, full mech20 atm, full mech30 atm, full mech10 atm, short mech (var 9)20 atm, short mech (var 9)30 atm, short mech (var 9)
10 atm, full mech20 atm, full mech30 atm, full mech10 atm, short mech (var 9)20 atm, short mech (var 9)30 atm, short mech (var 9)
5%CO+95%H2
Equivalence ratio
0 2 4 6 8 10 12
Fla
me
spee
d, c
m/s
0
100
200
300
400
500
600
50%CO+50%H2
Equivalence ratio
0 2 4 6 8 10 12
Fla
me
spee
d, c
m/s
0
50
100
150
200
250
300
350
75%CO+25%H2
Equivalence ratio0 2 4 6 8 10 12
Fla
me
spee
d, c
m/s
0
50
100
150
200
250
T0=500 K
10 atm, full mech20 atm, full mech30 atm, full mech10 atm, short mech (var 9)20 atm, short mech (var 9)30 atm, short mech (var 9)
10 atm, full mech20 atm, full mech30 atm, full mech10 atm, short mech (var 9)20 atm, short mech (var 9)30 atm, short mech (var 9)
10 atm, full mech20 atm, full mech30 atm, full mech10 atm, short mech (var 9)20 atm, short mech (var 9)30 atm, short mech (var 9)
5%CO+95%H2
Equivalence ratio
0 2 4 6 8 10 12 14 16 18
Flam
e sp
eed,
cm
/s
0
200
400
600
800
1000
1200
T0=700 K
50%CO+50%H2
Equivalence ratio
0 5 10 15 20
Flam
e sp
eed,
cm
/s
0
100
200
300
400
500
600
700
75%CO+25%H2
Equivalence ratio
0 2 4 6 8 10 12 14 16 18
Flam
e sp
eed,
cm
/s
0
100
200
300
400
500
10 atm, full mech20 atm, full mech30 atm, full mech10 atm, short mech (var 9)20 atm, short mech (var 9)30 atm, short mech (var 9)
10 atm, full mech20 atm, full mech30 atm, full mech10 atm, short mech (var 9)20 atm, short mech (var 9)30 atm, short mech (var 9)
10 atm, full mech20 atm, full mech30 atm, full mech10 atm, short mech (var 9)20 atm, short mech (var 9)30 atm, short mech (var 9)
Thin lines: model of Sun H. et al., lines with symbols: reduced mechanism
Testing of the reduced mechanism
Flame speed of CO/H2/O2/He mixtures as function of equivalence ratio
0 1 2 3 4 5 6
Fla
me
sp
ee
d,
cm/s
0
50
100
150
200
Full mech, (Sun H. et al, 2007)Exp. data (Sun H. et al, 2007)Short mech., Var 9
CO/H2/O2/He
CO/H2=50/50 T0=300 K, P=10 atm, D=0.125CO/H2/O2/He
CO/H2=75/25 T0=300 K, P=20 atm, D=0.125
0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 4,5
Flam
e sp
eed,
cm
/s0
20
40
60
80
100
120
Exp. data (Sun H. et al, 2007)Short mech., Var 9
Testing of the reduced mechanism
Triangles: experimental data of Sun et al., dashed line: mechanism of Sun et al., circles: reduced mechanism
P=20 barP=10 bar
CO/H2/O2/HeCO/H2=95/5 T0=300 K, P=40 atm, D=0.125
1,0 1,5 2,0 2,5 3,0
Fla
me
spee
d, c
m/s
0
10
20
30
40
50
Experimental data (Sun H. et al, 2007)Short mech, var 9
Testing of the reduced mechanism
Flame speed of CO/H2/O2/He mixtures as function of equivalence ratio
P=40 bar
Triangles: experimental data of Sun et al., circles: reduced mechanism
Diamonds and triangles : experimental data of Natarajan et al, circles: reduced mechanism
0,0 0,2 0,4 0,6 0,8 1,0
Fla
me s
pee
d, c
m/s
10
25
40
55
70
Short mech, 14 reactions
Experimental data
P=15 bar, T0=300 K, =0.8, O2:He=1:9
0,0 0,2 0,4 0,6 0,8 1,0F
lam
e sp
eed
, cm
/s25
50
75
100
125
150
Short mech, var 9
Experimental data
P=15 bar, T0=600 K, =0.6, O2:He=1:9
Testing of the reduced mechanismFlame speed of CO/H2/O2/He mixtures as function as function of
at P=15 atm, T0=300K. ( =[CO]/([CO]+[H2])
=0.6=0.8
Lines: mechanism of Sun et al., symbols: reduced mechanism
mm
0,50 0,55 0,60 0,65 0,70 0,75
Mol
e fr
actio
n
0,00
0,05
0,10
0,15
0,20
Tem
pera
ture
, K0
500
1000
1500
2000
2500
H2COO2TÍ 2ÎCO2H2 short mechO2 short mechH2O short mechCO short mechCO2 short mechT short mech
CO+H2/AirP=20 atm, f=1, a=0.5, T0=300K
T
H2CO2
H2O
CO
O2
mm
0,50 0,55 0,60 0,65 0,70 0,75M
ole
frac
tion
0,000
0,002
0,004
0,006
0,008
0,010
HOHOHCO (x100)HO2Î Í short mechÍ short mechÎ short mechHO2 short mechHCO (x100) short mech
OH
H
O
Testing of the reduced mechanismTemperature and concentration profiles in CO/H2/Air flame (=0.5,
Р=20 atm, T0=300K, =1)
Summary1.1.Developed reduced reaction mechanism Developed reduced reaction mechanism
for syngas oxidation (14 steps, 13 species) for syngas oxidation (14 steps, 13 species) satisfactorily predicts burning velocity at satisfactorily predicts burning velocity at P=10-P=10-330 0 atm,atm, T T00=300-=300-7700K, 00K, and and =0.05 0.05 0.0.775.5.
2.2.In HIn H22//CO CO mixtures with mixtures with с с =0.05 =0.05 the the reaction from Hreaction from H22 oxidation were shown to be oxidation were shown to be key reactions; at key reactions; at =0.5 and higher the role of =0.5 and higher the role of reaction CO+OH=CO2+H appreciably reaction CO+OH=CO2+H appreciably increases.increases.
3.3.Pressure rise from 10 to 30 atm was not Pressure rise from 10 to 30 atm was not shown to influence the set of key reactionsshown to influence the set of key reactions..
4.4.HCO-involving reactions were shown to HCO-involving reactions were shown to play a noticeable role in sybgas oxidation only play a noticeable role in sybgas oxidation only in rich mixtures or at high CO content in in rich mixtures or at high CO content in syngas.syngas.
The research was performed under financial support of Siemens Ltd.Siemens Ltd. under
agreement #035-СT/2008
Thank you!
Flammability concentration limits for CO/H2/Air mixtures as functions of initial temperature (=0.5, p=1 bar) calculated using mechanism [1] - circles, reduced mechanism (var. #9) - triangles and literature data [Wierzba I., 2005] - squares.
Temperature, K
300 400 500 600 700 800
lim
0,0
0,1
0,2
0,3
0,4
6,0
8,0
10,0
12,0
14,0
Testing of the reduced mechanism
O2+3H2= 2H2O+2H (I)*2H+MH2+M (II)*CO+H2O=CO2+H2 (III)*
* Wang W., Rogg, B., and Williams F.A. in Reduced Kinetic Mechanism for Application in Combustion Systems (Peters, N., Rogg, B., Eds.), Springer-Verlag, Berlin, p.48, 1993, pp.44-57
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
300 500 700 900 1100 1300 1500 1700 1900 2100 2300
T, K
Rea
ctio
n r
ate,
mo
le/(
cm3*
s) W II
W I
W III
Проверка механизма горения сингаза на основе брутто-реакций
Зависимость скорости реакций от температуры трех эффективных стадий для пламени СО/H2/Air (a=0.5, f=1.0, P=20 atm, T0=300K, D=0.209).
Аррениусовские параметры констант скоростей реакций для трех эффективных стадий в пламени СО/H2/Air (a=0.5, P=20 atm, T0=300K, D=0.209)
f
I II III
A Ea, cal/mol A Ea, cal/mol A Ea, cal/mol
Set#1 1 1.01030 56500 9.31013 -21280 2.01014 36560
Set#2 2 1.201026 41830 3.71013 -18900 1.941015 31900
Set#3 3 1.551025 40370 3.221012 -26600 1.871013 34600
Set#4 3.5 1.61025 42723 8.791010 -36500 4.331013 39000
50% CO+ 50% H2
0 1 2 3 4 5
Fla
me
sp
ee
d, cm
/s
0
20
40
60
80
100
120
140
20 atm, full mech20 atm, short mech (var 9)
set #4set #1set #2set #3
T0
=300 K, P=20 bar
Проверка механизма горения сингаза на основе брутто-реакций
Скорость распространения пламени СО/H2/Air (a=0.5, P=20 atm, T0=300K, D=0.209) от f, рассчитанная с использованием детального механизма реакций Sun H et al,
сокращенного механизма и трехстадийного механизма реакций на основе эфективных стадий с различными наборами кинетических параметров констант скоростей
Механизм реакций окисления H2/CO/O2
* размерность констант скоростей см3, моль, сек, кал, К , k = ATnexp(-Ea/RT).
No Реакция A* n Ea*
1 H + O2 = O + OH 6.731015 -0.50 16670
2 O + H2 = H + OH 3.821012 0 7948
3 O + H2 = H + OH 8.791014 0 19170
4 H2 + OH = H2O + H 2.17E + 08 1.52 3457.4
5 OH + OH = O + H2O 3.35E + 04 2.42 -1927
6 H2 + M = H + H + M 2.23E + 14 0 96070
7 H2 + H2 = H + H + H2 9.031014 0 96070
8 H2 + N2 = H + H + N2 4.581019 -1.4 104400
9 H2 + H2O = H + H + H2O 8.431019 -1.1 104400
10 O + O + M = O2 + M 6.161015 -0.5 0
11 O + O + AR = O2 + AR 1.891013 0 -1788
12 O + O + HE = O2 + HE 1.891013 0 -1788
13 O + H + M = OH + M 4.711018 -1.0 0
14 H + OH + M = H2O + M 2.211022 -2.0 0
15 H + O2(+M) = HO2(+M) k∞ 4.651012 0.4 0
16 H + O2(+Ar) = HO2(+Ar) k∞ 4.651012 0.4 0
17 H + O2(+He) = HO2(+He) k∞ 4.651012 0.4 0
18 H + O2(+H2O) = HO2(+H2O) k∞ 4.651012 0.4 0
19 H2 + O2 = HO2 + H 7.40105 2.43 53502
20 HO2 + H = H2O + O 1.441012 0 0
21 HO2 + H = OH + OH 6.001013 0 295
22 HO2 + O = O2 + OH 1.631013 0 -445.1
23 HO2 + OH = H2O + O2 l.00 1013 0 0
24 HO2 + OH = H2O + O2 5.801013 0 3974
No Реакция A* n Ea*
25 HO2 + HO2 = H2O2 + O2 4.201014 0 11982
26 HO2 + HO2 = H2O2 + O2 1.301011 0 -1629.3
27 H2O2(+M) = OH + OH(+M) k∞ 3.001014 0 48480
28 H2O2 + H = HO2 + H2 1.691012 0 3755.4
29 H2O2 + H = H2O + OH 1.021013 0 3576.6
30 H2O2 + O = OH + HO2 8.431011 0 3970
31 H2O2 + OH = HO2 + H2O 1.701018 0 29410
32 H2O2 + OH = HO2 + H2O 2.001012 0 427.2
33 CO + O(+M) = CO2(+M) 3.001014 0 3000
34 CO + O2 = CO2 + O 2.531012 0 47700
35 CO + HO2 = CO2 + OH 1.15105 2.278 17545
36 CO + OH = CO2 + H l.00 1013 0 15995.4
37 CO + OH = CO2 + H 9.001011 0 4570.1
38 CO + OH = CO2 + H 1.011011 0 59.6
39 HCO + M = H + CO + M 4.001013 0 15540
40 HCO + H = CO + H2 1.111014 0 0
41 HCO + O = CO + OH 3.001013 0 0
42 HCO + O = CO2 + H 3.001013 0 0
43 HCO + OH = CO + H2O 1.021014 0 0
44 HCO + HO2 = CO2 + OH + H 3.001013 0 0
45 HCO + HCO = H2 + CO + CO 3.011012 0 0
46 HCO + HCO = CH2O + CO 2.701013 0 0
47 HCO + O2 = CO + HO2 5.90E109 0.932 737
48 HCO + O2 = CO + HO2 1.55104 2.38 -1526Sun H., Yang S.I., Jomaas G., Law C.K., High-pressure laminar flame speeds and kinetic modeling of carbon monoxide/hydrogen combustion Proceedings of the Combustion Institute 31 (2007) 439–446