Simulation Study On Heating Mechanism Of Spontaneous Combustion Oxidation Of Coal In Dynamic Goaf

In the advancing process of the working face,we can predict the danger of coal spontaneous combustion and the location of high temperature in the goaf,and provide timely and effective prevention measures for the control of spontaneous combustion of coal in goaf.Based on the multi field coupling theory of coal spontaneous combustion in goaf,the simulation study of oxidation and heating about coal spontaneous combustion in the dynamic goaf under the advancing working face is carried out,which provides a basis for the prevention and control of spontaneous combustion of coal in the field.In order to descript the dynamic change of multi field distribution in goaf in the process of coal spontaneous combustion with the advance of working face,and promote the adaptability of goaf boundary moving step and the physical distribution changes,this paper presents an unsteady simulation method with a fixed coordinate system and variable physical field,analysising the dynamic effect of residual coal in goaf on seepage and oxidation environment.Based on the simulation method,the goaf flow parameters,the oxygen concentration field and temperature field distribution of Yima coal mine 13210 working face are workred out under different advancing distance and speed,and through the field test and the simulation results,the feasibility of the simulation method is verified.The results show that the dynamic evolution simulation method of coal spontaneous combustion in goaf better reflects the working face advancing double effect on goaf geometry and physical environment,achieving the dynamic geometry change of goaf and the physical distribution uniformity in the process coal spontaneous combustion,reflecting the correlation of the spontaneous combustion of coal field distribution change and size of goaf;the simulated results show that the physics field distribution of coal spontaneous combustion under the effect of goaf geometric boundary movement has the stage characteristics,with the increase of the advancing distance of working face,goaf flow field and oxygen concentration field distribution tends to be stable,while the temperature field appeared in the process of cooling obvious regularity of high temperature region forming tailing phenomenon.When the working face advancing distance is 240 m,and the speed were 2m/d,3m/d,4m/d and 5m/d,the oxygen concentration distribution,temperature distribution and oxygen consumption of coal spontaneous combustion in goaf was analyzed,with the increase of advance speed of working face: leakage airflow carrying oxygen into the deep goaf mining capacity increase;the highest temperature of oxidation heating gradually decreased;the position of high temperature zone move to the deep goaf and narrow width gradually gather to the the middle of the goaf;The degree of deviation between the high temperature area and the oxidation reaction position of coal remains increased,the containment procedure the spontaneous combustion process of coal increased..In the actual work of fire prevention and extinguishing,according to the different distance of working face,the coal spontaneous combustion prevention and control measures of goaf should be adjusted dynamically and governed in stages.Increasing the propulsion speed is favorable to the spontaneous combustion of coal;Oxygen zone and oxidation zone coal spontaneous combustion occurs at the same time,should still strengthen the deep hypoxic area of the goaf fire fighting and cooling work...