Simulation Study On The Influence Of High Ambient Temperature In Deep Goaf On Spontaneous Combustion Of Coal

As the coal mining depth gradually increases,the coal seam temperature and the surrounding rock temperature of the goaf increase.The higher coal rock temperature has an impact on the oxidation and heat release of the coal left in the goaf,increasing the risk of spontaneous combustion of the coal left behind and the temperature of oxidation rising.The process will be different from that of ordinary depth coal,and the oxygen concentration field and temperature field will be quite different.Therefore,research was carried out on the environmental high temperature problem brought by deep mining,and Mengcun Coal Mine,a high-temperature mine,was taken as the research object to simulate the oxidation and heating of left coal under the high temperature environment of deep mined area,and to study the effect of different coal rock temperatures on the spontaneous combustion process of left coalThe temperature in the mined-out area increases with the heat release from the oxidation of the leftover coal.This heating process is closely related to the time.Therefore,the unsteady state model of FLUENT is used to oxidize the warmed-up process of the leftover coal under the condition of dynamic advancement of the working face.Carry out the simulation.Since the local raw rock temperature of Mengcun coal mine reached 33?,and the rock temperature of coal mines in some areas of China has reached above 40?,the temperature rise process under the conditions of initial coal temperature of 23?,33? and 43? was studied.Analyze the influence of coal rock temperature on spontaneous combustion process of coal left in goaf.It is found that the high temperature points in the goaf are distributed in the range of 70 meters to 85 meters from the working surface in the direction of the strike.The temperature rising speed of the high temperature point undergoes the process of increasing first and then decreasing With the increase of the initial coal temperature,the temperature reached by the oxidation of leftover coal in the goaf gradually increased.At the same time,the higher the initial coal temperature,the greater the temperature increase.After 45 days of simulation,the initial coal temperature of 23? and 33? was simulated.The high temperature point temperature is 46.2?and 70.2? respectively.With the increase of the initial coal temperature,the location of the high temperature point in the mined-out area is gradually approaching the oxidation heating zone.The distance at the initial coal temperature of 33? is shortened by 6 meters compared to that at 23?,increasing the probability of coal spontaneous combustion.The higher initial coal temperature greatly shortens the time taken for the oxidation of the leftover coal.When the initial coal temperature is 33?,the temperature rises to 43? in 3.4 days,and then from 43?to 53? takes 6.4 days;When the initial coal temperature is 43?,the time it takes for the temperature to rise to 53? is 3.2 days.The heating time is 50%shorter than the 6.4 days when the initial coal temperature is 33?,which significantly accelerates the spontaneous combustion of the remaining coal.The research results provide a certain theoretical basis for the prevention and control of coal fire disaster at 401101 face of Mengcun Coal Mine.