Effects of N₂/CO₂ on explosion characteristics of methane and air mixture

An experimental apparatus for the methane and air mixture explosion with N₂/CO₂ in a closed vessel was set up. A series of experiments have been performed to analyze the effects of N₂/CO₂ on explosion strength, limiting oxygen concentration, flammability limits and explosion suppression. Results show that explosion strength decreases with the volume fraction of N₂/CO₂ in the mixture. Limiting oxygen concentration decreases linearly with the volume fraction of N₂ in N₂/CO₂ mixture. The flammability limits change linearly with the volume fraction of N₂/CO₂ in the mixture. The higher the volume fraction of CO₂ in N₂/CO₂ mixture, the better the explosion suppression effect is. Based on experimental data, fitted equations and diagrams are made to predict methane flammability limits with N₂/CO₂ under different volume fraction ratio of N₂ and CO₂. The research results can be used as a reference for the inerting treatment design of methane explosion protection in process industries.