On detailed analysis basis of spontaneous coal combustion for the three zones in mine goaf,we use O2 and CO concentrations to divide the three zones of the coal combustion.Through our experiment,we selected a typical ...On detailed analysis basis of spontaneous coal combustion for the three zones in mine goaf,we use O2 and CO concentrations to divide the three zones of the coal combustion.Through our experiment,we selected a typical working face and focused on the changes in gas concentrations.In order to overcome establishment limitations of actual layout location and underground conditions in a mine goaf,we based our observations on the three zones,combined them with numerical simulation,described the distribution and the changes in O2 and CO concentrations during the coal spontaneous combustion in the goaf,which provided us with an understanding of the distribution of coal spontaneous combustion in the three zones in the form of maps.Essentially,our study summarizes the changes of O2and CO concentrations in the entire goaf and shows them to be in agreement with our observations at the scene.The study shows that it is feasible to divide the three zones,given our comprehensive targets of O2,CO and our numerical simulation.This method avoids the limitation of dividing the three zones with a single target and the likely errors of observations at the scene.In addition,the method offers a basis for optimizing measures of fre-fghting with important and practical effects.展开更多
The adjustment of the gas drainage rate has an immediate impact on air leakage in gob,thus resulting in the change of self-heating of coal.While regulating the gas drainage parameters,the risk of spontaneous combustio...The adjustment of the gas drainage rate has an immediate impact on air leakage in gob,thus resulting in the change of self-heating of coal.While regulating the gas drainage parameters,the risk of spontaneous combustion of coal should be considered.The risk assessment of gas control and spontaneous combustion of coal under gas drainage in a tunnel was investigated at different gas drainage rates.The distributions of the air volume along the working face,the gas management effects and the width of the oxidation zone were subjected to risk analysis.As the simulation results showed,with increasing gas drainage rate,although the safety of gas dilution by ventilation was assured,the intensifying air leakage caused the oxidation zone to move into the deeper gob and led to an increase in the width of the oxidation zone.A risk assessment method was proposed to determine a suitable gas drainage rate for the upper tunnel.The correctness of the risk assessment and the validity of the numerical modelling were confirmed by the field measurements.展开更多
Based on the non-linear air leakage seepage equation for an anisotropic porous medium, on the seepage diffusion equation of multicomponent gas and on the seepage synthetic heat transfer equation of a porous medium, th...Based on the non-linear air leakage seepage equation for an anisotropic porous medium, on the seepage diffusion equation of multicomponent gas and on the seepage synthetic heat transfer equation of a porous medium, the numerical model for field flow problems of irregular patterns of a goaf with multiple points of leaking air is established and simultaneously solved by the upwind mode finite element method (G3 computer program). According to the complexity of irregular patterns of a goaf with multiple points of leaking air, the flow pattern in a large area of such a goaf and the variation in gases of methane, oxygen and CO and in temperature are theoretically described. In the calculation, the goaf is regarded as a caving anisotropic medium and the coupling effect of methane effusion on spontaneous combustion is considered. The simulation results agree well with practical experience. In addition, the spontaneous combustion process is also simulated, indicating that 1) the spontaneous combustion often takes place near the area where fresh air leaks in and 2) the fire sources can be classified into static and dynamic zones. Therefore, in practical fire preventing and extinguishing, we should clearly distinguish the upstream air leaking points from the downstream ones in order to take proper measures for leakage stopping.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 50974055 and 50906023)the Education Department of Hennan Province (No. 13A440333)
文摘On detailed analysis basis of spontaneous coal combustion for the three zones in mine goaf,we use O2 and CO concentrations to divide the three zones of the coal combustion.Through our experiment,we selected a typical working face and focused on the changes in gas concentrations.In order to overcome establishment limitations of actual layout location and underground conditions in a mine goaf,we based our observations on the three zones,combined them with numerical simulation,described the distribution and the changes in O2 and CO concentrations during the coal spontaneous combustion in the goaf,which provided us with an understanding of the distribution of coal spontaneous combustion in the three zones in the form of maps.Essentially,our study summarizes the changes of O2and CO concentrations in the entire goaf and shows them to be in agreement with our observations at the scene.The study shows that it is feasible to divide the three zones,given our comprehensive targets of O2,CO and our numerical simulation.This method avoids the limitation of dividing the three zones with a single target and the likely errors of observations at the scene.In addition,the method offers a basis for optimizing measures of fre-fghting with important and practical effects.
基金financially sponsored by the National Natural Science Foundation of China (Nos. 51774114 and 51404090)
文摘The adjustment of the gas drainage rate has an immediate impact on air leakage in gob,thus resulting in the change of self-heating of coal.While regulating the gas drainage parameters,the risk of spontaneous combustion of coal should be considered.The risk assessment of gas control and spontaneous combustion of coal under gas drainage in a tunnel was investigated at different gas drainage rates.The distributions of the air volume along the working face,the gas management effects and the width of the oxidation zone were subjected to risk analysis.As the simulation results showed,with increasing gas drainage rate,although the safety of gas dilution by ventilation was assured,the intensifying air leakage caused the oxidation zone to move into the deeper gob and led to an increase in the width of the oxidation zone.A risk assessment method was proposed to determine a suitable gas drainage rate for the upper tunnel.The correctness of the risk assessment and the validity of the numerical modelling were confirmed by the field measurements.
基金supported by the National Natural Science Foundation of China (No.50574038)the Scientific Research Foundation of Liaoning Technical University (No.2004-241).
文摘Based on the non-linear air leakage seepage equation for an anisotropic porous medium, on the seepage diffusion equation of multicomponent gas and on the seepage synthetic heat transfer equation of a porous medium, the numerical model for field flow problems of irregular patterns of a goaf with multiple points of leaking air is established and simultaneously solved by the upwind mode finite element method (G3 computer program). According to the complexity of irregular patterns of a goaf with multiple points of leaking air, the flow pattern in a large area of such a goaf and the variation in gases of methane, oxygen and CO and in temperature are theoretically described. In the calculation, the goaf is regarded as a caving anisotropic medium and the coupling effect of methane effusion on spontaneous combustion is considered. The simulation results agree well with practical experience. In addition, the spontaneous combustion process is also simulated, indicating that 1) the spontaneous combustion often takes place near the area where fresh air leaks in and 2) the fire sources can be classified into static and dynamic zones. Therefore, in practical fire preventing and extinguishing, we should clearly distinguish the upstream air leaking points from the downstream ones in order to take proper measures for leakage stopping.
