Numerical Study on the Explosion Reaction Mechanism of Multicomponent Combustible Gas in Coal Mines

Combustible gases, such as CO, CH₄, and H₂, are produced during spontaneous coal combustion in goaf, which may cause an explosion under the stimulation of an external fire source. It is of great significance to study the influence of combustible gases, such as CO and H₂, on the characteristics of a gas explosion. In this study, CHEMKIN software (Version 17.0) and the GRI-Mech 3.0 reaction mechanism were used to study the influences of different concentration ratios between CO and H₂ on the ignition delay time, free radical concentration, and key reaction step of a gas explosion. The results show that the increase in the initial CH₄ and CO concentrations prolonged the ignition delay time, while the increase in the H₂ concentration shortened the time and accelerated the explosion reaction. The addition of H₂ promoted the generation of free radicals (H·, O·, ·OH) and accelerated the occurrence of the gas explosion. CO generated ·OH free radicals and dominated the methane consumption through the R119 and R156 reactions. As the concentrations of CO and H₂ increased, the R38 reaction gradually became the main driving factor of the gas explosion.