Research on synergistic effect of inert gas on methane explosion suppression performance of KHCO3 cold aerosol

Active powder spraying and explosion suppression device is one of the prevention and control equipment for methane explosion in coal mines. It can be actively sprayed at the initial stage of methane explosion after being filled with ultra-fine powder explosion suppressant, so that ultra-fine powder particles form cold aerosols and reduce the hazards of subsequent methane explosion. In order to further improve the explosion suppression performance of the active explosion suppression device, and to explore the explosion suppression law of cold aerosol explosion suppression agents, the methane explosion suppression characteristics of KHCO3 cold aerosol driven by inert gas was tested using a 5 L explosion tube system. The experimental results showed that N2 and CO2 significantly enhance the suppression performance of KHCO3 cold aerosol on 9.5% methane / air premixed gas explosion, which revealed lower max-pressure and longer time to max-pressure on methane explosion compared with the suppression by KHCO3 cold aerosol driven by air. Among them, 0.03 g/L KHCO3 cold aerosol reduced the max-pressure of methane explosion by 60.4%, but when the gas medium is filled with 15%～20% N2 or 5%～10% CO2, the same concentration of KHCO3 cold aerosol can completely suppress the explosion of methane. As the volume fraction of inert gas increased, the amount of KHCO3 cold aerosol was further reduced, thereby reducing the cost of active explosion suppression device. The experiment investigated the explosion of methane under the action of different concentrations of KHCO3 cold aerosols and different volume fractions of N2 and CO2, and obtained the optimal combination ratio of KHCO3 cold aerosols and inert gases, which can provide theoretical basis and technical parameters for the design of active explosion suppression system based on KHCO3 cold aerosol. In addition, the methane suppression mechanism of the KHCO3 cold aerosol system containing inert gas was discussed, and the reason for the synergistic effect of inert gas was analyzed.