Characteristics Of Coal Spontaneous Combustion Gas In Goaf Of Jiang Yuan Coal Mine And Its Influence On Gas Explosion

A large amount of heat is generated during the coal spontaneous combustion,causing the ambient temperature rises to form a dynamically changing temperature field;Coal spontaneous combustion will generate a large amount of flammable gas.They form the mixed gas with gas and air,and dynamic mixed gas flow field under the influence of air leakage and fire pressure;At the same time,the combustible gas will have a certain influence on the upper and lower limits of the gas explosion and the explosion characteristics.The above research is to provide theoretical basis and guiding significance for the prevention and control of gob area fires and gas explosions.This paper takes the special major gas explosion accident of Jiang Yuan Coal Mine in Jilin Province as the research background and analyzes the accident.The experimental system of coal spontaneous combustion in goaf is designed to study the variation of spatial temperature field of coal spontaneous combustion process in goaf,and the law of gas change in goaf.The effects of carbon monoxide on the explosion characteristics of methane at different concentrations and the effects of mixed gases generated in different stages of coal spontaneous combustion on the explosion characteristics of methane are studied by using a 20L spherical explosion device.The research results are as follows:?1?During the coal spontaneous combustion in goaf,the temperature of different measuring points is different,and The temperature in the central position of the space is higher than other measuring points,and the temperature change at the central position is taken as the change of coal temperature during the spontaneous combustion experiment;The spatial temperature field shows obvious dynamic change with the change of spontaneous combustion time:With the increase of spontaneous combustion time,the temperature field first moves longitudinally and then moves laterally.?2?The gases generated during the spontaneous combustion of coal in goaf are:CH₄,C₂H₄,C₂H₆,C₂H₂,C₃H₈,CO₂,etc.The highest concentration of combustible gas is CH₄,followed by CO.The most toxic and harmful combustible gas is CH₄,followed by CO.Different gas components are accompanied by different stages of spontaneous combustion of coal,and the gas content increases with the increase of spontaneous combustion time and temperature.?3?The lower explosion limit of methane is not affected by the gas flow state;however,the turbulent state will cause the increase of methane destructive power.Different concentrations of carbon monoxide have different effects on the lower limit and characteristics of methane explosion.When the concentration is lower than 0.04%,the methane explosion is suppressed,and the maximum pressure of the explosion is lowered,so that the lower explosion limit is increased;When the concentration is higher than 0.15%,the maximum pressure of methane explosion increases,and the lower explosion limit decreases.It is analyzed that CO activity is higher than that of methane,and oxygen reacts with CO first.The reaction of low concentration of CO and oxygen is not enough to explode or completely explode methane;The high heat released by the high concentration of CO reacts to increase methane activity and promote methane explosion.?4?The influence of the combustible gas generated by the initial,accelerated oxidation and combustion stages of coal spontaneous combustion on the explosion characteristics of methane is as follows:the maximum pressure of the explosion shows an increasing law,and the lower explosion limit is gradually reduced.It is believed that with the progress of coal spontaneous combustion stage,the composition and content of combustible gas are gradually increased,which promotes methane explosion and lowers the lower explosion limit.Coal spontaneous combustion in goaf increases the risk of gas explosion and even causes continuous gas explosion.The research results are of great significance for preventing the occurrence of coal spontaneous combustion in goaf and further revealing the mechanism of gas explosion and continuous explosion in goaf,and comprehensively and systematically preventing and controlling the occurrence of gas explosion accidents.