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 nternational Seminar on Flame Structure, July 11 -1
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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.
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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.)
The scheme of power station with the integrated cycle of gasification.
Introduction
The gas turbine
Introduction
P0 - up to 40 atm,
T0 - up to 700 оС
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.
BackgroundLiterature experimental data
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)
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.
* 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
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