Abstract: The chemical kinetics of laminar premixed flames of the coal gasification syngas varied significantly with the different volume fractions of methane. The laminar flame speeds and adiabatic flame temperatures of syngas/air mixtures with CH₄ addition (volume fraction 0-70%) in the fuels were numerically studied at 300 K using GRI 3.0-Mech. To investigate the chemical kinetics effect of CH₄ on laminar premixed flame, the sensitivities of mass burning rate of mixtures with various CH₄ addition ratios and the mole fractions of vital radicals were calculated. The numerical results show that laminar flame speed, adiabatic flame temperature and equivalence ration at the peak laminar flame speed are decreased nonlinearly with the increase of CH₄ volume fraction, that when the volume fraction of CH₄ in the fuels is not higher than 30%, the laminar flame speed decreases rapidly due to the significant reductions of H radicals for rich mixtures, and that with the further increase of CH₄ volume fraction in the mixtures, the major decline of laminar flame speed is suppressed due to the deficient of OH radicals and reduction of CH₃ radicals.

Key words: syngas, CH₄, laminar premixed flames, sensitivity analysis, chemical kinetics