采空区瓦斯抽采钻孔参数及注氮防灭火研究

钻孔抽采能够影响采空区内部风流的运动,从而导致采空区流场发生变化,增加工作面向采空区的漏风,同时钻孔周围呈现负压状态,漏风风流也不断向钻孔周围补充,采空区煤体在漏风集中区域呈现氧化升温状态,存在采空区遗煤自燃问题。针对上述问题,研究了钻孔抽采条件下采空区最优注氮防灭火方案。以白龙山煤矿10201工作面为背景,用数值模拟软件对工作面采空区进行仿真,分析了不同抽采参数下的采空区流场和温度场分布,依据合理钻孔参数确定了最优注氮条件。结果表明:抽采负压为30kPa时瓦斯抽采效果良好,氧化升温带增幅相对较低;钻孔间距为6m时抽采效果佳且工程量较小;进风侧注氮口与工作面距离为75m、注氮流量为1 500m^3/h时,可以很好地缩小氧化升温带宽度并节约成本。实际应用结果表明:综放工作面及上隅角瓦斯体积分数得到了有效控制,均低于1%;抽采管路及上隅角CO体积分数分别低于0.040%,0.032%,采空区煤体未发生自燃,采空区瓦斯抽采和注氮取得了良好的应用效果。

Research on gas drainage drilling parameters and nitrogen injection for fire prevention in goaf

Drilling and drainage can affect movement of air flow in goaf,thus leading to changes in goaf flow field,and increasing air leakage in goaf.At the same time,there is a state of negative pressure around the borehole,and the air leakage and air flow are constantly replenishing around the drilling.The coal body in goaf presents a state of oxidation and temperature rise in the area where the air leakage is concentrated,so there is a problem of spontaneous combustion of residual coal in goaf.For the above problem,the optimal nitrogen injection for fire prevention scheme in goaf under the condition of drilling drainage was studied.The 10201 working face of Bailongshan Coal Mine was used as the background for goaf simulation by numerical simulation software.The distribution of flow field and temperature field in goaf under different drainage parameters is analyzed,and the optimal nitrogen injection condition was determined according to the reasonable drilling parameters.The results show that the gas drainage effect is good when drainage pressure is 30 kPa,and the increase of the oxidation temperature rise zone is relatively low;the drainage effect is good and the engineering amount is low when drilling interval is 6 m;when the distance between working surface and intake side nitrogen injection port is 75 mand the nitrogen injection flow is 1 500 m^3/h,the width of oxidation temperature rise zone can be reduced and the cost can be saved.The actual application results show that the gas volume fractions of fully mechanized working face and the upper corner are effectively controlled,both of which are lower than 1%;the CO volume fraction of extraction pipe and upper corner is lower than 0.040% and 0.032% respectively,no spontaneous combustion occurred in the goaf,and gas drainage and nitrogen injection in the goaf achieved good application results.