Suppression of Methane–Air Explosions Using Air Jet-Driven NaHCO₃ Powder and Porous Barriers

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.