| Gas explosion is one of the major disasters in China's coal mine accidents.Prevention and control of gas explosion is the key to the safe production of coal mines.However,due to the complex environment under the mine,especially in the mine fire area,there are C2H4,CO,H2,C2H6 and other combustible gases,they are the risk of combustion and explosion.Therefore,a single study of gas explosion and explosion suppression has been unable to meet the production needs,the main target should be a multi-combustible gas explosion.Because CH4 is the main component of mine fire area,it mainly comes from the release of free gas in coal and rock and the product of coal spontaneous combustion,C2H4 is a sign that coal accelerates spontaneous combustion,so this paper selects CH4 and C2H4,using combustible gas explosion limit measuring device and multi-function spherical gas/dust explosion experiment to study the effects of different volume fraction of C2H4(0%,0.4%,0.8%,1.2%,1.6%,2.0%)on CH4 explosion at room temperature under normal pressure,using transient spectroscopy system to explore the spectral characteristics of the intermediate products in the explosive reaction process of the binary flammable mixture,using Gaussian quantum chemical software to carry out the micro-thermodynamics and kinetic analysis of the reaction,and reveal the mechanism of CH4/C2H4 mixed combustible system.The results show that:(1)After adding C2H4,the upper and lower limit of CH4 explosion decreased,and the lower limit decreased obviously,the explosion limit width and explosion risk increased,the critical oxygen concentration decreased,and the change trend was more obvious with the increase of C2H4 volume fraction.(2)Under an inert gas N2 atmosphere,the explosion lower limit of C2H4/CH4 system is gradually increased,the upper limit is decreased gradually,finally explosion limits overlap for a bit,the explosion lower limit of C2H4/CH4 system is gradually increased,the upper limit is decreased gradually,and finally explosion limits overlap for a bit,in addition,increasing the volume fraction of C2H4 in the mixed system,the N2 addition amount needed for the explosion coincidence point increases,the coincidence of the explosion limit decreases,and the the range of the explosion triangle becomes larger.(3)The addition of C2H4 promotes the explosion of 7%volume fraction CH4,on one hand,the maximum explosion pressure,the rise rate of maximum explosion pressure are increased,the time to reach the maximum explosion pressure is shortened,on the other hand,the spectral intensity of explosion intermediate products ·H,·OH and CH2O are enhanced;In contrast with the volume fraction of 7%CH4,the addition of C2H4 weakens the explosion of 11%volume fraction CH4,the maximum explosion pressure,the rise rate of maximum explosion pressure are decreased,the time to reach the maximum explosion pressure is prolonged,the spectral intensity of explosion intermediate products ·H,·OH and CH2O are weakened;For 9.5%volume fraction CH4,C2H4 would cause the maximum explosion pressure,the maximum explosion pressure rise rate increased firstly and then decreased,the time to reach the maximum explosion pressure shortened firstly and then prolonged,the spectral intensity of ·H,·OH and CH2O increased firstly and then decreased,that is to say,the addition of C2H4 below 1.2%volume fraction promoted the explosion of CH4,and the addition of C2H4 above the volume fraction of 1.2%weakened the explosion of CH4.(4)The microstructural response of the free radicals in the C2H4/CH4 mixed system was analyzed by the microscopic thermodynamics of Gaussian reaction,and the order of the reaction of the mixed system was summarized;The addition of C2H4,on the one hand,provides energy for the CH4 blast reaction,on the other hand,the presence of C2H4 promotes the generation of CH4 explosion critical free radicals·H,·O,·H and·HCO,so that the CH4 explosion chain reaction continues,from a micro perspective to explain the macro characteristics. |
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