Experimental Study On Explosion Mitigation Of Methane Containing Obstacles With Ultra-fine Water Mist

At present, the state obtains the coal resources mainly through coal mine underground mining, and gas explosion occurs frequently in the coal mining process, causing great casualties and economic loss. Obstacles such as machinery, equipment and structure almost exist in all explosive environment. Therefore, it has very important scientific significance and application value for studying the influence of obstacles on gas explosion in pipeline and the effect and mechanism for ultra-fine water mist mitigating such explosions.This paper summarized comprehensively the current research status about gas and coal-dust explosion and gas explosion mitigation technology through investigating extensive information and literature. Starting from the angle of the occurence and development of explosion in the tube, it described the form and mechanism for combustible gas explosion in pipeline, the characteristic parameters and flame transmission law. The experimental method and goal of explosion mitigation of methane containing obstacles with ultra-fine water mist were put forward on the base of introducing the ultra-fine water mist system. Considering every functional unit, the laboratorial gas explosive apparatus was improved and perfected to make it suitable for studying the influence of obstacles on methane explosion and explosion mitigation of methane with ultra-fine water mist.According to the obstacles existing inside the underground tunnels of the coal mine and the place where industrial methane was stored, four types of obstacles were considered and designed in the experiment. The effect of obstacles on the methane explosion was determined by measuring the change of the pressure and temperature parameters when different types of obstacles exist inside the explosion tube. The results show that the obstacles don't affect the variation trend of maximum pressure and maximum temperature following the methane concentrations, first, the both increase and then decrease with the increase of methane concentrations, and the maximum occurred at the best explosion concentration; The distance between the Obstacle and ignition electrode will affect the experimental result, if the distance is greater, the greater enhancement will occur; The more obstacles will produce stronger explosion ; type of explosion The reinforcement effect of Square ring was more obvious than the columned obstacles.The effect and mechanism of methane explosion containing obstacles mitigated by ultra-fine water mist was studied by exerting different volume quantity of ultra-fine water mist. It is found that methane explosion maximum pressure, pressure rising rate, the maximum temperature and temperature rising rate decreased as ultra-fine water mist was increased, with explosion mitigation efficiency raised greatly when the volume quantity come to a certain value. A High-speed camera was used to visualize the processes of methane explosion mitigation with ultra-fine water mist, and explosion delay time was analyzed through the video record. Ultra-fine water mist can be effect for its heat absorption and diluting oxygen followed by attenuating pressure wave intensity.