煤田露头自燃的渗流-热动力耦合模型及应用

Seepage-thermal dynamical coupling model for spontaneous combustion of coalfield outcrop and its application

分析了煤田露头介质内气体渗流及露头自燃热动力系统特征,建立了煤田露头自燃渗流--热动力耦合模型,推导了煤自燃过程中挥发分计算式.对新疆某煤田自燃火区进行了数值模拟.结果表明:开采引发煤田露头自燃时,燃烧中心集中在顶板附近,燃烧沿顶板向露头方向蔓延较快;高温区域靠近顶板,燃烧区域以外岩石内温度梯度变化不明显;自燃生成气体主要集中于露头自燃点下风侧方向,上风侧方向只有很小范围内有自燃气体存在;高温区域分布与自燃气体渗流方位位置一致;自燃加速了气体在煤岩介质内的渗流,有助于自燃的发展.根据模拟结果对煤田火区治理时火源探测、治理及监测等相关措施进行了具体分析.

The characters of gas seepage in coalfield outcrop and the thermal dynamical system of outcrop spontaneous combustion were analyzed. A model coupling seepage with thermal dynamics for spontaneous combustion of coalfield outcrop was set up. The calculation equation of volatile output during coal spontaneous combustion was deduced. One coal fire in Xinjiang Uygur Autonomous Region of China was selected as the simulated object by the seepage-thermal dynamic model. It is shown that when spontaneous combustion of coal outcrop results from the mining, the combustion center centralizes near the roof and spreads to the outcrop direction quickly. The high-temperature region locates below the roof and the temperature gradient out of the combustion area is not obvious. Gases produced by coal spontaneous combustion mainly flow in the downstream of the spontaneous combustion area and the combusted gases only exists a small region on the upstream of the combustion area. The higher temperature distribution accords with the seepage scope of spontaneous combustion gases. Whereas, coal spontaneous combustion accelerates gas seepage in the coal and rock medium and is helpful to development of spontaneous combustion. At last, based on the simulated results, some measures on the coalfield fire location, fire control and fire monitor were analyzed.