The permeability of coal seam is an important parameter for the gas extraction and gas outburst control. However, most of the coal seams are low-permeability with outstanding characteristic in China. Therefore,it is a good technology to provide the theoretical basis for increasing the permeability of low-gas- permeability coal seam by shocking with high-pressure air. Based on the percolation theory of porous media and combining the gas pressure change after shocking the coal seam with high-pressure air, the solid-gas coupled mathematical model is presented for the flow in the coal seam. By applying the software, the numerical simulation is computed and analyzed for the gas pressure evolution owing to the multi-spot continuous shocking the coal seam by the high-pressure air under the different pressure values and strata pressure.
Based on the theory of coordinate inhibition three nitrogen-containing active structures of different aromatic in coal were established. Using quantum chemistry calculation method, the effect of hydrogen bonding on the formation of complexes that formed by three nitrogen-containing active structures of different aromatic and inhibitor were calculated in B3LYP/6-311G* levels. The results show that hydrogen bond can make H2O participation in forming complexes which formed by three nitrogen-containing active structures of different aromatic and metal ions. Hydrogen bonds play a molecular recognition and guiding role in the process of H2O involved in the formation of complexes. After H2O participating ligand through hydrogen bonds, the complexes formed Ca-O-H-O four-membered ring structure in the geometrical structures. It Shows that its stability are improved and not easy to contacts with O or reacting. It making coal spontaneous combustion can be well inhibition. After H2O participating ligand, aromatic change had little effect in stability of the complexes. It shows that different ranks of coal can get better inhibition effect after H2O participating ligand.
The permeability of coal is very important parameter on gas extraction, but it is difficult to get good effect by conventional method on low air permeability coal seam. Based on above reason, we put forward the research on technology for increasing the permeability of coal seam by impacting with high energy air, as for showing the effect we make experiment in Xin’an mine. The data display it increased to 155.96% of single hole maximum discharge, the average is 112.73%. The best result in study is the position of 2.5m far from experimental borehole, and the flow increased to 179.69%. All the data display that it can reach well result of increasing the permeability of coal seam by impacting with high energy air.
Coal mine gas disaster has the characteristic of destructive and complexity, in connection with the frequently of coal mine gas disaster, the paper studied on the propagation of gas explosion shock wave while pipe cross-sectional area changing from the experimental angle, designed the test system, the data of shock wave pressure when the pipe turning angle more or less than 90 degree was given, analyzed two situations: one was to analysis the influence of initial shock pressure effect on the attenuation coefficient under determination of pipeline turning angle; another was to analysis the influence of pipe turning angles effect on the attenuation coefficient under determination of initial shock wave overpressure, pointed out that the shock wave initial pressure and pipe turning angles were the two important factors which affect the shock wave overpressure attenuation coefficient. By comparison, the initial shock pressure had the larger influence. At last, the shock wave overpressure attenuation coefficient diversification formula was given when pipe turning angles was more or less than 90 degree.
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