Air leakage velocity in intake goaf and distribution of air leakage in mining area are determined by Instantaneous and steady liberation of tracer gas SF6. Gas concentration and temperature in gob are measured and thr...Air leakage velocity in intake goaf and distribution of air leakage in mining area are determined by Instantaneous and steady liberation of tracer gas SF6. Gas concentration and temperature in gob are measured and three oxidation areas in goaf are determined. According to oxidation experiment of coal and in-site measurements, the gases of carbon monoxide and dioxide can be produced laraely by coal and oxygen combination at ambient temperature and the temperature of coai and rock In goaf con rise 10℃ due to heat produced by coai and oxygen combination.There is a great risk of spontaneous combustion in neighboring oId gob because of air leakage for pillar mining.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
Flow field in multilayer gob area, which formed in small hiden-depth, multi-coal layer groups, close distance, hard coal layer, and hard roof, possesses characteristics such as complex, changeable and unstable. Dynami...Flow field in multilayer gob area, which formed in small hiden-depth, multi-coal layer groups, close distance, hard coal layer, and hard roof, possesses characteristics such as complex, changeable and unstable. Dynamic balance theory of local flow field in multilayer gob area was built based on the realistic requirement that the serious threat on current mining coal layer by large-scale spontaneous combustion fire on close spontaneous combustion coal layer group of Datong Coal mining area at the ＇di-hard＇ conditions was caused by small coal pit mining. The kernel was in dynamic balance between flow field pressures of working face and local flow field in multilayer gob area was kept by transformation. Corresponding technology and set of devices were developed.展开更多
文摘Air leakage velocity in intake goaf and distribution of air leakage in mining area are determined by Instantaneous and steady liberation of tracer gas SF6. Gas concentration and temperature in gob are measured and three oxidation areas in goaf are determined. According to oxidation experiment of coal and in-site measurements, the gases of carbon monoxide and dioxide can be produced laraely by coal and oxygen combination at ambient temperature and the temperature of coai and rock In goaf con rise 10℃ due to heat produced by coai and oxygen combination.There is a great risk of spontaneous combustion in neighboring oId gob because of air leakage for pillar mining.
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 Key Projects of the National Natural Science Foundation of China （50834002）
文摘Flow field in multilayer gob area, which formed in small hiden-depth, multi-coal layer groups, close distance, hard coal layer, and hard roof, possesses characteristics such as complex, changeable and unstable. Dynamic balance theory of local flow field in multilayer gob area was built based on the realistic requirement that the serious threat on current mining coal layer by large-scale spontaneous combustion fire on close spontaneous combustion coal layer group of Datong Coal mining area at the ＇di-hard＇ conditions was caused by small coal pit mining. The kernel was in dynamic balance between flow field pressures of working face and local flow field in multilayer gob area was kept by transformation. Corresponding technology and set of devices were developed.
