九道岭矿采空区注CO_2防灭火技术数值模拟研究

Study on numerical simulation of CO_2 injection fire prevention and extinguishing technique in goaf of Jiudaoling Mine

为抑制九道岭采空区自然发火危险,提出向采空区注CO_2的方法进行防火。为了探究合理的注CO_2的位置和流量,对九道岭矿的煤样进行封闭耗氧试验,得到煤样耗氧速度并确定窒熄带临界氧浓度。将封闭耗氧试验得到的煤样耗氧参数应用到采空区注CO_2数值模拟中,通过调节CO_2注入口的位置得到不同位置注CO_2时采空区氧浓度带宽度,随着注入位置逐渐深入采空区内部,自然氧化带宽度呈现先减小后增大的趋势,最终确定九道岭煤矿注CO_2最佳位置为距离工作面43 m的采空区进风侧内部。在该位置调节CO_2注入流量得到采空区内进风侧注CO_2的流量与自然氧化带宽度呈负指数关系,结合九道岭煤样自然发火期等参数最终确定最佳注入流量为158 m^3/h。在最佳注入位置和最佳注入流量的条件下注CO_2能够有效缩短采空区自然氧化带宽度,抑制九道岭采空区自燃危险。

In order to restrain the coal spontaneous combustion danger occurred in the goaf of Jiudaoling Mine,a carbon dioxide injection method of the goaf was applied to the fire extinguishing. In order to study the location and flow of the rational carbon dioxide injection,a sealed oxygen consumption experiment was conducted on the coal samples from Jiudaoling Mine. An oxygen consumption rate of the coal samples was obtained and the critical oxygen concentration in the suffocated zone was determined. The oxygen consumption coefficients of the coal sample obtained from the sealed oxygen consumption experiment were applied to the numerical simulation experiment of the carbon dioxide injection in the goaf. With the location adjustment of the carbon dioxide injection inlet,the width of the oxygen concentration zone in the goaf was obtained during the carbon dioxide injection with different location. With the injection location steadily entered in the internal part of the goaf,the width of the natural oxidation zone would firstly be reduced and then would be in an increased tendency. Finally,the optimum location of the carbon dioxide injection in Jiudaoling Mine was at the internal part of the air income side in the goaf with a distance of 43 m to the coal mining face. The location to adjust the carbon dioxide injection flow could have the results of a negative index between the carbon dioxide injection flow at the internal air income side of the goaf and the width of the natural oxidation zone. In combination with the spontaneous combustion period and other parameters of the coal samples from Jiudaoling Mine,the optimum injection flow was 158 m3/h finally determined. Under the conditions of the optimum location and the optimum injection flow,the carbon dioxide injection could effectively reduce the width of the natural oxidation zone in the goaf and could restrain the spontaneous combustion danger occurred in the goaf of Jiudaoling Mine.