CFD模型下采空区瓦斯抽采与注氮防灭火设计

CFD model based design of both gas drainage and nitrogen injection against fire in goaf

为寻求针对高瓦斯易自燃煤层的最佳注氮防灭火设计方案,以某矿综采面为原型,开发带有抽采孔的计算流体力学(CFD)模型。采用基于截断温度的稳态模拟方法,得出采场气体运移及分布的基本形态。在此基础上,分别模拟并分析不同抽采方式、抽采位置、抽采流量与注氮条件等因素对自燃危险区域分布的影响。结果表明:抽采方案的选择会直接影响采空区内部流场的形态,进而改变自燃危险区的分布。在相同注氮流量下,采空区深部注氮比浅部注氮能够达到更好的惰化效果,将自燃危险区域整体向前压缩。立体抽采时,应合理布置钻孔间距,以避免漏风通道相互贯通,配合采用注氮惰化缩减氧化自燃带范围,在实现瓦斯抽采最大化的同时防治遗煤自燃。

To find the optimum design scheme for fire prevention and extinction by nitrogen injection, a CFD model was developed based on the prototype of fully mechanized coal face in a certain coal mine in China. The numerical solution was obtained using a steady-state simulation method based on truncation temperature. On the basis, influences of extraction methods, extraction positions and the flow on the distribution of spontaneous combustion zone were analyzed. The results show that the selection of different gas drainage schemes directly affects the flow field in goaf, and then changes the distribution shape of spontaneous combustion danger zone. When a stereo gas extraction scheme was used, spacing between wells should be arranged properly for preventing air leakage channels communicating with each other which in combination with nitrogen injection can maximize the gas utilization and depress spontaneous combustion of remaining coal.