Institute of Chemical Kinetics & Combustion, Novosibirsk 630090 Russia

1. Reducing of kinetic scheme for syngas oxidation at highpressure and elevated temperatureBolshova T.A., Shmakov A.G., Yakimov S.A., Knyazkov D.A., KorobeinichevO.P. Institute of Chemical Kinetics & Combustion, Novosibirsk 630090 Russia 7th International Seminar on Flame Structure, July 11 -15, 2011

2. 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.)

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

4. Introduction The gas turbine P0- up to 40 atm, T0- up to 700 оС

5. Research Objectives • Development of the reduced reaction mechanism for syngas oxidation at temperature Т0=300-700 Kand 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]+[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.

7. Background Literature experimental data

8. Background Mechanism for modeling H2, CO oxidation.

9. Model Sun H., Yang S.I., Jomaas G., Law C.K. (Proceedings of the Combustion Institute 31, 2007) H2 O2 H2O H O OH HO2 H2O2 CO CO2 HCO CH2O CH2OH AR N2 HE 16 SPECIES and 48 REACTIONS

10. 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+OH R15 H+O2(+M)=HO2(+M) R36+R37+R38 CO+OH=CO2+H 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+OH R3 O+H2=H+OH R4 H2+OH=H2O+H R5 OH+OH=O+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 R23 HO2+OH=H2O+O2 R24 HO2+OH=H2O+O2 R27 H2O2(+M)=OH+OH(+M) R36 CO+OH=CO2+H R37 CO+OH=CO2+H R38 CO+OH=CO2+H

11. 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+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 H2/CO/air flame, р= 20 bar =0.5, T0=300 and 700 K, =3.5 R15 H+O2(+M)=HO2(+M) R4 H2+OH=H2O+H 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).

13. The sensitivity coefficients of burning velocity to the reactions rate constants for H2/CO/air flame, T0=300K, =0.5, р= 20 bar R39 HCO+M=H+CO+M R40 HCO+H=CO+H2 R19 H2+O2=HO2+H R21 HO2+H=OH+OH R1 H+O2=O+OH The value of sensitivity coefficient to rate constants of the reactions depends on equivalence ratio .

14. The rate of production of H in H2/CO/air flame, T0=700K, =0.5,р= 20 atm. =4.5 =0.3 R4 H2+OH=H2O+H R3 H2O+H2=H+OH R37+R38CO+OH=CO2+H R4 H2+OH=H2O+H R3 H2O+H2=H+OH R1 H+O2=O+OH R15 H+O2(+M)=HO2(+M) R21 HO2+H=OH+OH R1 H+O2=O+OH R15 H+O2(+M)=HO2(+M)

15. The rate of production of CO in H2/CO/air flame, T0=700K, =0.5,р= 20 atm. =12 =0.3 R47 HCO+O2=CO+HO2 R36+R37+R38 CO+OH=CO2+H R39 HCO+M=H+CO+M R35 CO+HO2=CO2+OH

16. Н 2 CO +OH +OH +O +O 74 % 25 % 5 % 94 % CO Н +OH H O+H 2 2 CO +H 2 +O Н CO CO 2 2 +OH 6 % +OH +O +H 77 % 23 % 9 % 85 % Н +OH H O+H CO +H 2 HCO 2 +O Н CO CO 2 2 +OH 5 % +OH +O +H 8 3 % 17 % 56 % 39 % Н +OH H O+H CO +H 2 HCO 2 The main pathways for H2 and CO consumption in H2/CO/air flame, р= 20 atm, T0=300K, =0.5 =0.75 =2.0 =4.0

17. A reduced reaction mechanism for oxidation of H2/CO/O2 * – 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

18. Testing of the reduced mechanism Flame speed of CO/H2/Air mixtures as function of equivalence ratio at P=10-30 atm, =0.05, 0.5, 0.75. Thin lines: model of Sun H. et al., lines with symbols: reduced mechanism

19. Testing of the reduced mechanism Flame speed of CO/H2/O2/He mixtures as function of equivalence ratio P=10 bar P=20 bar Triangles: experimental data of Sun et al., dashed line: mechanism of Sun et al., circles: reduced mechanism

20. 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

21. Testing of the reduced mechanism Flame speed of CO/H2/O2/He mixtures as function as function of  at P=15 atm, T0=300K. (=[CO]/([CO]+[H2]) =0.8 =0.6 Diamonds and triangles: experimental data of Natarajan et al, circles: reduced mechanism

22. Testing of the reduced mechanism Temperature and concentration profiles in CO/H2/Air flame (=0.5, Р=20 atm, T0=300K, =1) Lines: mechanism of Sun et al., symbols: reduced mechanism

23. Summary • Developed reduced reaction mechanism for syngas oxidation (14 steps, 13 species) satisfactorily predicts burning velocity at P=10-30 atm, T0=300-700K, and =0.05 0.75. • In H2/CO mixtures with с =0.05 the reaction from H2 oxidation were shown to be key reactions; at =0.5 and higher the role of reaction CO+OH=CO2+H appreciably increases. • Pressure rise from 10 to 30 atm was not shown to influence the set of key reactions. • 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. The research was performed under financial support of Siemens Ltd. under agreement #035-СT/2008 Thank you!

26. Testing of the reduced mechanism 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.

27. Проверка механизма горения сингаза на основе брутто-реакций O2+3H2= 2H2O+2H (I)* 2H+MH2+M (II)* CO+H2O=CO2+H2 (III)* 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). * 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

28. 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 SunHetal, сокращенного механизма и трехстадийного механизма реакций на основе эфективных стадий с различными наборами кинетических параметров констант скоростей 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)

29. 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 Механизм реакций окисления H2/CO/O2 * размерность констант скоростей см3, моль, сек, кал, К , k = ATnexp(-Ea/RT).