Abstract
The inhibition of methane–air explosions by air-jet-driven NaHCO3 powders and porous barriers was investigated in this study. Flame images and overpressure data were recorded using high-speed cameras and pressure sensors. The inhibition mechanism of NaHCO3 powder was further investigated using the reaction mechanism of sodium-containing substances and methane combustion. The results showed that NaHCO3 powder driven by high-pressure gas jets reduces the average propagation speed of flame fronts and the rising rate of overpressure. The presence of porous barriers increases the turbulence intensity in the pipe and the travel time of the NaHCO3 particles. Thus, the contact time between the large particle powder and the flame increases, and the inhibiting effect on flame propagation gradually increases as the obstruction rate increases. NaHCO3 powder inhibits methane–air explosions through physical and chemical mechanisms. From a chemical perspective, sodium-containing radicals preferentially react with CO in the system to form CO2, reducing the production of H* and OH* radicals in the reaction system. The cycle of gaseous Na and NaOH also consumes H* and OH* radicals in the system, blocking the chain reaction.