割煤截齿摩擦石英砂岩引燃(爆)煤壁短钻孔涌出瓦斯的危险性研究

Risk of igniting(exploding)gas from coal wall drill boreholes by coal cutting picks’friction against quartz sandstone

本文针对夹矸(石英砂岩)煤层的综采工作面,存在割煤截齿摩擦石英砂岩引燃(爆)浅孔抽放短钻孔涌出瓦斯的风险,以试验工作面为研究背景,通过Fluent数值模拟和MATLAB数据处理分析,研究了对采煤机滚筒后方浅孔抽放钻孔口周围瓦斯引燃危险区的分布规律,并在现场释放CO2模拟了钻孔瓦斯涌出的情况,测得的CO2体积分数分布与数值模拟结果基本一致。研究结果表明:当钻孔口处于采煤机滚筒后方不同位置时,其周围瓦斯引燃(爆)危险区的形状、大小及在钻孔口的分布方位都发生变化。随着钻孔瓦斯流量的增大,瓦斯引燃(爆)危险区的形状基本相同,面积增大,竖直长度随之线性增加;但在采煤机滚筒后方1 m这个最易引起爆炸的范围内,瓦斯引燃(爆)危险区的面积并不大,最大竖直长度为196 mm,如果在竖直方向将钻孔距石英砂岩的安全距离控制在392 mm以上,可以避免浅孔抽放短钻孔涌出瓦斯被引燃(爆)的风险。

In view of the fully mechanized mining face of the gangue(quartz sandstone)coal seam involving a risk of gas gushing out of the short boreholes ignited(exploded)by friction of coal cutting picks on quartz sandstone,with the experimental working face as research background,the distribution law of gas ignition(explosion)danger zone around the hole of shallow hole drainage drilling hole behind the shearer drum was studied through Fluent numerical simulation and MATLAB data processing analysis.CO2 was released to stimulate gas gushing from boreholes,and the measured concentration distribution of CO2 was found consistent with the simulation results.The results have shown that when the drill hole is located at different positions behind the shearer drum,the shape,size and distribution direction of the gas ignition(explosion)danger zone around it change accordingly;as the gas flow rate increases,the shape of gas ignition(explosion)danger zone remains basically the same,but its area increases,and its vertical length increases linearly;within the range of 1 m behind the shearer drum where explosion is most likely,the maximum vertical length of gas ignition(explosion)danger zone is 196mm,which can prevent the risk of gas gushing out of the short boreholes from being ignited.