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. - презентация

1 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 Russia 7th International Seminar on Flame Structure, July , 2011

2 Introduction SYNGAS, components: H 2 + 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.)

3 The scheme of power station with the integrated cycle of gasification. Introduction

4 The gas turbine Introduction P 0 - up to 40 atm, T 0 - up to 700 о С

5 Research Objectives Development of the reduced reaction mechanism for syngas oxidation at temperature Т 0 = K and pressure Р=10-30 bar Validation of the proposed reduced mechanism by comparing the simulated burning rate with experimental literature data

6 Characteristics of Unburnt Gases The fraction of CO in the fuel : а=[CO]/([CO]+[H 2 ])= and 0.75 The dilution ratio: D=[O 2 ]/([O 2 ]+[N 2 ])=0.209 (for fuel/air mixtures). Equivalence ratio was : f=([CO]+[H 2 ])/2[O 2 ], where [O 2 ], [N 2 ], [CO] and [H 2 ] - are concentration of oxygen, nitrogen, carbon monoxide and hydrogen respectively.

7 Background Literature experimental data

8 Mechanism for modeling H 2, CO oxidation. Background

9 Model Sun H., Yang S.I., Jomaas G., Law C.K. (Proceedings of the Combustion Institute 31, 2007) H 2 O 2 H 2 O H O OH HO 2 H 2 O 2 CO CO 2 HCO CH 2 O CH 2 OH AR N 2 HE 16 SPECIES and 48 REACTIONS

10 R1 H+O2=O+OHR2 O+H2=H+OH R3 O+H2=H+OHR4 H2+OH=H2O+H R9 H2+H2O=H+H+H2OR13 O+H+M=OH+M R14 H+OH+M=H2O+MR15 H+O2(+M)=HO2(+M) R19 H2+O2=HO2+HR21 HO2+H=OH+OH R22 HO2+O=O2+OHR23 HO2+OH=H2O+O2 R1 H+O2=O+OHR2 O+H2=H+OH R3 O+H2=H+OHR4 H2+OH=H2O+H R5 OH+OH=O+H2OR13 O+H+M=OH+M R14 H+OH+M=H2O+MR15 H+O2(+M)=HO2(+M) R19 H2+O2=HO2+H R21 HO2+H=OH+OH R23 HO2+OH=H2O+O2R24 HO2+OH=H2O+O2 R27 H2O2(+M)=OH+OH(+M)R36 CO+OH=CO2+H R37 CO+OH=CO2+HR38 CO+OH=CO2+H The sensitivity coefficients of burning velocity to the reactions rate constants for H 2 /CO/air flame, р=10, 20, 30 bar CO 5% CO 50% T 0 =300 K f=1 R1 H+O 2 =O+OH R15 H+O 2 (+M)=HO 2 (+M) R36+R37+R38 CO+OH=CO 2 +H

11 The sensitivity coefficients of burning velocity to the reactions rate constants for H 2 /CO/air flame, р= 20 bar =0.5, T 0 =300 and 700 K, =0.75 R1 H+O2=O+OH R3 O+H2=H+OH R4 H2+OH=H2O+H R14 H+OH+M=H2O+M R15 H+O2(+M)=HO2(+M) R19 H2+O2=HO2+H R21 HO2+H=OH+OH R36 CO+OH=CO2+H R37 CO+OH=CO2+H R38 CO+OH=CO2+H A rise of initial temperature does not influence on key reactions set

12 The sensitivity coefficients of burning velocity to the reactions rate constants for H 2 /CO/air flame, р= 20 bar =0.5, T 0 =300 and 700 K, =3.5 The most appreciable changes of sensitivity coefficients as T 0 rises from 300 to 700 K are observed in the rich flame for reactions R4 (in 8 times) and R15 (in 2 times). R4 H 2 +OH=H 2 O+H R15 H+O 2 (+M)=HO 2 (+M)

13 The sensitivity coefficients of burning velocity to the reactions rate constants for H 2 /CO/air flame, T 0 =300K, =0.5, р= 20 bar R39 HCO+M=H+CO+M R40 HCO+H=CO+H 2 R1 H+O 2 =O+OH R19 H 2 +O 2 =HO 2 +H R21 HO 2 +H=OH+OH The value of sensitivity coefficient to rate constants of the reactions depends on equivalence ratio.

14 The rate of production of H in H 2 /CO/air flame, T 0 =700K, =0.5, р= 20 atm. =0.3 =4.5 R4 H 2 +OH=H 2 O+H R3 H2O+H2=H+OH R37+R38 CO+OH=CO 2 +H R1 H+O 2 =O+OH R15 H+O 2 (+M)=HO 2 (+M) R4 H 2 +OH=H 2 O+H R3 H 2 O+H 2 =H+OH R1 H+O 2 =O+OH R15 H+O 2 (+M)=HO 2 (+M) R21 HO 2 +H=OH+OH

15 The rate of production of CO in H 2 /CO/air flame, T 0 =700K, =0.5, р= 20 atm. =0.3 =12 R36+R37+R38 CO+OH=CO 2 +H R39 HCO+M=H+CO+M R35 CO+HO 2 =CO 2 +OH R47 HCO+O 2 =CO+HO 2

16 Н 2 Н+OH H 2 O+H +O +OH 74% 25% CO 2 2 +H +O +OH 94% 5% Н 2 Н+OH H 2 O+H +O +OH 77% 23% CO 2 2 +H +O +OH 85% 6% +H HCO 9% Н 2 Н+OH H 2 O+H +O +OH 83% 17% CO 2 2 +H +O +OH 56% 5% +H HCO 39% =0.75 =2.0 =4.0 The main pathways for H 2 and CO consumption in H 2 /CO/air flame, р= 20 atm, T 0 =300K, =0.5

17 A reduced reaction mechanism for oxidation of H 2 /CO/O 2 Reartion A*A*nEa*Ea* S1.H+O 2 =O+OH6.73e S2.O+H 2 =H+OH5.06E S3.H 2 +OH=H 2 O+H1.168E S4.OH+OH=O+H 2 O3.348e S5.H+H+M=H 2 +M7.00E S6.H+OH+M=H 2 O+M2.212E S7.H+O 2 (+M)=HO 2 (+M)4.65E S8.H 2 +O 2 =HO 2 +H7.395E S9.HO 2 +H=OH+OH6.0E S10.HO 2 +OH=H 2 O+O 2 5E S11.CO+O+M=CO 2 +M3.0E S12.CO+OH=CO 2 +H1.8E S13.HCO+M=H+CO+M4.0E S14.HCO+H=CO+H E * – In: cm 3, mole, s, cal; rate constant expressed as k=A T n exp (-Ea/RT) 13 species (H 2, O 2, H 2 O, H, O, OH, HO 2, CO, CO 2, HCO, Ar, He and N 2 ) and 14 reactions

18 Flame speed of CO/H 2 /Air mixtures as function of equivalence ratio at P=10-30 atm, =0.05, 0.5, Thin lines: model of Sun H. et al., lines with symbols: reduced mechanism Testing of the reduced mechanism

19 Flame speed of CO/H 2 /O 2 /He mixtures as function of equivalence ratio Testing of the reduced mechanism Triangles: experimental data of Sun et al., dashed line: mechanism of Sun et al., circles: reduced mechanism P=20 bar P=10 bar

20 Testing of the reduced mechanism Flame speed of CO/H 2 /O 2 /He mixtures as function of equivalence ratio P=40 bar Triangles: experimental data of Sun et al., circles: reduced mechanism

21 Diamonds and triangles : experimental data of Natarajan et al, circles: reduced mechanism Testing of the reduced mechanism Flame speed of CO/H 2 /O 2 /He mixtures as function as function of at P=15 atm, T 0 =300K. ( =[CO]/([CO]+[H 2 ]) =0.6 =0.8

22 Lines: mechanism of Sun et al., symbols: reduced mechanism Testing of the reduced mechanism Temperature and concentration profiles in CO/H 2 /Air flame ( =0.5, Р=20 atm, T 0 =300K, =1)

23 Summary 1.Developed reduced reaction mechanism for syngas oxidation (14 steps, 13 species) satisfactorily predicts burning velocity at P=10-30 atm, T 0 = K, and Developed reduced reaction mechanism for syngas oxidation (14 steps, 13 species) satisfactorily predicts burning velocity at P=10-30 atm, T 0 = K, and = In H 2 / CO mixtures with с =0.05 the reaction from H 2 oxidation were shown to be key reactions; at =0.5 and higher the role of reaction CO+OH=CO2+H appreciably increases. 3.Pressure rise from 10 to 30 atm was not shown to influence the set of key reactions. 4.HCO-involving reactions were shown to play a noticeable role in sybgas oxidation only in rich mixtures or at high CO content in syngas.

24 Siemens Ltd. The research was performed under financial support of Siemens Ltd. under agreement #035-СT/2008 Thank you!

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26 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. Testing of the reduced mechanism

27 O 2 +3H 2 = 2H 2 O+2H(I)* 2H+M H 2 +M (II)* CO+H 2 O=CO 2 +H 2 (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 Проверка механизма горения сингаза на основе брутто-реакций Зависимость скорости реакций от температуры трех эффективных стадий для пламени СО/H 2 /Air (a=0.5, f=1.0, P=20 atm, T 0 =300K, D=0.209).

28 Аррениусовские параметры констант скоростей реакций для трех эффективных стадий в пламени СО/H2/Air (a=0.5, P=20 atm, T 0 =300K, D=0.209) f IIIIII AE a, cal/molA A Set# Set# Set# Set# Проверка механизма горения сингаза на основе брутто-реакций Скорость распространения пламени СО/H 2 /Air (a=0.5, P=20 atm, T 0 =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

29 Механизм реакций окисления H 2 /CO/O 2 * размерность констант скоростей см 3, моль, сек, кал, К, k = AT n exp(-E a /RT). NoРеакцияA*A*nEa*Ea* 1H + O 2 = O + OH O + H 2 = H + OH O + H 2 = H + OH H 2 + OH = H 2 O + H2.17E OH + OH = O + H 2 O3.35E H 2 + M = H + H + M2.23E H 2 + H 2 = H + H + H H 2 + N 2 = H + H + N H 2 + H 2 O = H + H + H 2 O O + O + M = O 2 + M O + O + AR = O 2 + AR O + O + HE = O 2 + HE O + H + M = OH + M H + OH + M = H 2 O + M H + O 2 (+M) = HO 2 (+M) k H + O 2 (+Ar) = HO 2 (+Ar) k H + O 2 (+He) = HO 2 (+He) k H + O 2 (+H 2 O) = HO 2 (+H 2 O) k H 2 + O 2 = HO 2 + H HO 2 + H = H 2 O + O HO 2 + H = OH + OH HO 2 + O = O 2 + OH HO 2 + OH = H 2 O + O 2 l HO 2 + OH = H 2 O + O NoРеакцияA*A*nEa*Ea* 25HO 2 + HO 2 = H 2 O 2 + O HO 2 + HO 2 = H 2 O 2 + O H 2 O 2 (+M) = OH + OH(+M) k H 2 O 2 + H = HO 2 + H H 2 O 2 + H = H 2 O + OH H 2 O 2 + O = OH + HO H 2 O 2 + OH = HO 2 + H 2 O H 2 O 2 + OH = HO 2 + H 2 O CO + O(+M) = CO 2 (+M) CO + O 2 = CO 2 + O CO + HO 2 = CO 2 + OH CO + OH = CO 2 + H l CO + OH = CO 2 + H CO + OH = CO 2 + H HCO + M = H + CO + M HCO + H = CO + H HCO + O = CO + OH HCO + O = CO 2 + H HCO + OH = CO + H 2 O HCO + HO 2 = CO 2 + OH + H HCO + HCO = H 2 + CO + CO HCO + HCO = CH 2 O + CO HCO + O 2 = CO + HO E HCO + O 2 = CO + HO Sun 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