Selection on Gas Extraction Methods in Upper Corner of Spontaneous Combustion Coal Seam

According to the gas overrun problem of upper corner in working face “partial Y” to “U” type ventilation mode, the causes of gas overrun in upper corner after the transformation of the “U” type ventilation is analyzed, with ANSYS-FLUENT simulation software, the mathematical model of residual coal gas seepage in goaf is established, the gas concentration distribution in goaf and variation of “three zones” width by quantitative comparative study of two extraction methods of trend high suction lane extraction and the adjacent lane piping extraction. It is determined that the gas flow in the goaf can be effectively reduced and the width of the spontaneous combustion zone in goaf is controlled, and the practical application effect is also investigated. The results show that the trend high level suction roadway extraction method, the extracted pressure relief gas purity is more than 100 m³/min, the extracting rate is above 90%, the gas concentration of upper corner is below 0.8% without the signs of spontaneous combustion in goaf, which effectively reduces gas overrun problem at the upper corner and fire risk and provides technical support for safety production of working face.