Simulation of the hazard arising from the coupling of gas explosions and spontaneously combustible coal due to the gas drainage of a gob

摘要

The spontaneous combustion of residual coal and potentially subsequent gas explosions that occur during gas drainage of the gob were investigated. The 1262 fully-mechanized mining face of the Dingji Coal Mine (Huainan, China) was used as a research benchmark. The methane and oxygen distributions were simulated as well as the temperature field associated with different gas-drainage models. Using a steady-state simulation method for temperature cut-off, linear superimposition of various parameters was used to determine the hazardous zones arising from the coupling of gas and spontaneously combustible coal. The results show that when gas drainage is applied, the range of oxidation zone is different with different gas drainage modes. Among three different drainage modes, when applying the buried pipes and cross-measure boreholes mode, the methane concentration near the working face and in the upper corner of the return airway not only can be effectively reduced, but the size of the oxidation zone in the gob is the smallest. Based on the model of buried pipes, cross-measure boreholes and surface wells, the coupled gas-coal hazard zones were derived. The results show that the coupled hazard zone shifts to the deeper parts of the gob as a result of gas drainage, and the scope of the hazard zone is enlarged in the strike, dip, and vertical directions to different extents. The cooling effect is better when the nitrogen is injected into the deep part of the gob rather than the shallow part. Furthermore, nitrogen injected from double boreholes in the deep part appears to exert the largest cooling effect. (C) 2018 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.