内含瓦斯抑制条件下极限平衡区顶煤自燃模拟

Numerical simulations of top coal spontaneous combustion in limit equilibrium zone under conditions of gas infuence

建立了瓦斯抑制条件下顶煤自燃数学模型,并给出了模型中各方程的边界条件、初始条件及各参数的确定方法,利用Fluent软件对给定条件下的极限平衡区顶煤自燃过程进行了模拟研究.模拟结果显示,靠近进风巷的顶煤升温较快;随着时间延长,高氧浓度区域逐渐向顶煤内部扩展;顶煤内瓦斯浓度梯度减小,最高瓦斯浓度降低.通过对模拟数据分析得出,顶煤升温过程为加速过程,内含瓦斯明显延长了顶煤的自然发火期;供风量对顶煤自然发火期影响不大,但对顶煤高温区中心点位置的影响较大;自然发火期与其耗氧速度存在负指数函数关系.

Models for spontaneous combustion in top coal under conditions of gas influence were established. The boundary and initial conditions were given and the methods of computation were discussed. Fluent was used to perform the numerical simulations. The results showed that the temperature increases most rapidly in coal located near the inlet airway. A zone of high oxygen concentration gradually expands into the interior of the top coal as time passes. The gas concentration gradient also had an effect on oxygen levels. The highest gas concentrations were lower in the interior of the coal. The temperature increase was an accelerated process, and gas conditions influenced the length of the spontaneous combustion period. Air volume had little affect on the period but the location of the high temperature zone was affected by the volume. A negative exponential function was found to describe the relationship between the spontaneous combustion period and the oxygen consumption rate.