Experimental Study Of Gas Explosion And Its Suppression With Water Mist

China is one of the countries where the gas explosions frequently happened in coal mines. Gas explosion has been a serious threat to the health and sustainable development of coal mining industry. Although many investigations have been done at home and abroad and have made considerable achievements, gas explosion accidents still occur frequently. It's lack of effective methods and techniques in the suppression of gas explosion. It is of great significance to research and develop effective and environmentally friendly gas explosion suppression agent in coal mine gas explosion prevention.Water mist technology has been paid on increasingly attention for its environmentally friendly, consuming less water, quenching fire fast, to fight electrical fires or oil fires and other advantages. Many scholars at home and abroad have carried on this issue of experimental and numerical studies, also discussed and analyzed in theory, set up a variety of experimental devices. But they were more as a qualitative research, it has not obtained the quantitative relationship between physical characteristic of water mist and methane concentration.This article focuses on experimental study of the effect of the amount of water mist on gas explosion. The premixed methane-air explosion and its suppression with water mist experiments are carried out in a closed vertical pipe. The quantitative relationship between the amount of water mist and methane concentration are analyzed by collecting and analyzing pressure and fire information. The main work and conclusions are as follows:(1) Experimental apparatus used for experiments of gas explosion or suppressed with water mist and then collecting and analyzing pressure and flame signals are designed.(2) There are superimposed oscillations in the pressure rising process and "irregular" in the high-value of pressure zone in premixed methane-air explosion and suppressed with water mist experiments.(3) The explosion pressure, pressure increase rate and flame propagation velocity are greater when the methane concentration is closer to stoichiometric concentration. The flame propagation velocity achieves the maximum value at the distance of 0.425m from the bottom of the pipeline.(4) Carried out explosion suppression experiments with different water mist volume. Results show that the maximum explosion pressure, maximum pressure increase rate and maximum flame propagation velocity at 0.11g of the spray volume is bigger than that of the premixed methane-air explosion. With the increase of the amount of water mist, explosion pressure, pressure increase rate and propagation velocity is reduced.(5) Carried out explosion suppression experiments with different methane concentration. Results show that:When the spray volume reaches a certain value, each methane concentration of gas mixture will not be ignited when an explosion is completely suppressed. In these experiments about the gas mixture of 7.5% methane concentration, the gas mixture is not ignited when the water mist volume reaches 0.21g.