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
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
Based on heterogeneous and porous medium seepage of air leakage-diffusion equation, as well as, gas and porous medium synthesis heat transferring equation, a spontaneous combustion non-steady numerical model of nitrog...Based on heterogeneous and porous medium seepage of air leakage-diffusion equation, as well as, gas and porous medium synthesis heat transferring equation, a spontaneous combustion non-steady numerical model of nitrogen injection goaf was established, which can be solved by upwind finite element numerical simulation method si- multaneously. Taking the working face for example; air leakage seepage, nitrogen flow and gas distribution can be described in visual display in nitrogen injection goaf and the oxygen （O2）, carbon monoxide （CO） concentration and temperature distribution, as well as, their change were described in theory during the coal left behind combustion in goaf, which above reveals the complex mechanics course （mechanism） of seepage, diffusion and oxidation heat releasing during coal spontaneous combustion and its restraining. During the calculation, the effect factors of gas springing out and working face advancing were considered fully, and the spontaneous combustion course under different amount of nitrogen injection was simulated. The conclusions were obtained that under nitrogen injection condition, the high spontaneous combustion temperature area lean to the inlet air, but the shape becomes narrower, with the amount of nitrogen rising, the spontaneous combustion period becomes longer till to it does not happen. Meanwhile the nitrogen injection accelerates gas springing out in goaf. The result that turns out in theory simulation fits to practical nitrogen injection.展开更多
According to the classification standard of spontaneous combustion ＂three zone＂ in gob and the analysis of aerodynamics and energy equation of relax loose coal body, the paper used the method of computer simulation ...According to the classification standard of spontaneous combustion ＂three zone＂ in gob and the analysis of aerodynamics and energy equation of relax loose coal body, the paper used the method of computer simulation analysis to get the air distribution. The paper also determined the three zone area of H2103 fully mechanized caving face in Beizao Mine.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
The CO gas in the upper comer along with the work of mining face in different coal-seam of Lingwu coal-field has deeply affected judgment for the degree of the coal spontaneous combustion and safety work. For this iss...The CO gas in the upper comer along with the work of mining face in different coal-seam of Lingwu coal-field has deeply affected judgment for the degree of the coal spontaneous combustion and safety work. For this issue, a new calculation and forecast model of the carbon monoxide concentration in the upper comer of mining face was deduced for analyzing and calculating the date from the lab and test-in-place, during this course using the knowledge of heat transfer, fluid dynamics, and mathematics. The model took into account the characteristics of the coal spontaneous combustion, coal mining conditions, and other correlate factors, so the CO concentration of the upper comer safe under the normal condition, and it is in danger when the coal reached spontaneous combustion, which can be calculated accurately with the model and compared with the measured concentration with a tolerance of less than 12%.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.
文摘Based on heterogeneous and porous medium seepage of air leakage-diffusion equation, as well as, gas and porous medium synthesis heat transferring equation, a spontaneous combustion non-steady numerical model of nitrogen injection goaf was established, which can be solved by upwind finite element numerical simulation method si- multaneously. Taking the working face for example; air leakage seepage, nitrogen flow and gas distribution can be described in visual display in nitrogen injection goaf and the oxygen （O2）, carbon monoxide （CO） concentration and temperature distribution, as well as, their change were described in theory during the coal left behind combustion in goaf, which above reveals the complex mechanics course （mechanism） of seepage, diffusion and oxidation heat releasing during coal spontaneous combustion and its restraining. During the calculation, the effect factors of gas springing out and working face advancing were considered fully, and the spontaneous combustion course under different amount of nitrogen injection was simulated. The conclusions were obtained that under nitrogen injection condition, the high spontaneous combustion temperature area lean to the inlet air, but the shape becomes narrower, with the amount of nitrogen rising, the spontaneous combustion period becomes longer till to it does not happen. Meanwhile the nitrogen injection accelerates gas springing out in goaf. The result that turns out in theory simulation fits to practical nitrogen injection.
基金Supported by the National Natural Science Foundation of China（50534080）
文摘According to the classification standard of spontaneous combustion ＂three zone＂ in gob and the analysis of aerodynamics and energy equation of relax loose coal body, the paper used the method of computer simulation analysis to get the air distribution. The paper also determined the three zone area of H2103 fully mechanized caving face in Beizao Mine.
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.
文摘The CO gas in the upper comer along with the work of mining face in different coal-seam of Lingwu coal-field has deeply affected judgment for the degree of the coal spontaneous combustion and safety work. For this issue, a new calculation and forecast model of the carbon monoxide concentration in the upper comer of mining face was deduced for analyzing and calculating the date from the lab and test-in-place, during this course using the knowledge of heat transfer, fluid dynamics, and mathematics. The model took into account the characteristics of the coal spontaneous combustion, coal mining conditions, and other correlate factors, so the CO concentration of the upper comer safe under the normal condition, and it is in danger when the coal reached spontaneous combustion, which can be calculated accurately with the model and compared with the measured concentration with a tolerance of less than 12%.
