回采情况下采空区煤自燃温度场理论与数值分析

摘要

In order to study the influence of coal spontaneous combustion parameters based on the coal spontaneous combustion theoretically, the coal spontaneous combustion mathematics model of goaf in the moving coordinate was established to master the coal spontaneous combustion process in goaf. Combined with the limit parameter calculation method of coal spontaneous combustion and the heat transfer theory, the analytical solution in one dimensional of mathematical model of spontaneous combustion was calculated. According to the results, the influence of different parameters on the coal spontaneous combustion of goaf was analyzed. The results show that increasing the mining speed can reduce the coal temperature effectively. The thicker the float coal and the faster the speed of wind, the more easily the coal will get burned. When the output heating of remnant coal is proportional to the temperature, the temperature of the goaf point to the working face is higher, and it presents index form increasing. When the heating power is constant, the temperature of the goaf point to the working face is higher, and it presents linear form increasing. The oxygen density decreases along the deep goaf field. And the output heat of remnant coal reduces when goes deeper, which is close to the actual situation. As the goaf area is a geometric space, its temperature field, oxygen concentration and velocity exist coupling effect. Thus it is necessary to study coal spontaneous combustion on condition of stopping, which is based on the technology of three-dimensional numerical simulation or two-dimensional numerical simulation.%为了从理论基础上研究煤自燃基础参数对煤自燃的影响,通过建立动坐标系下采空区煤自燃数学模型来掌握工作面回采时采空区煤自燃的过程.该模型结合煤自燃极限参数计算方法和热传导理论,计算简化后的自燃数学一维模型解析解,利用一维数值计算,分析不同参数对采空区煤自燃的影响.研究结果表明:增大回采速度,可以有效地减低煤温；浮煤越厚,漏风速度越大,煤越易自燃；当遗煤放热量与温度成正比时,距离工作面越远的点其温度越高,且呈指数形式增加；当发热量为常数时,采空区距离工作面越远的点其温度越高,且呈线性形式增加;考虑到沿采空区的深部方向,氧气浓度逐渐降低,遗煤放热量随着深度增加而逐渐减少,该数值结果与实际结果较接近;由于采空区是一个立体几何空间,采空区温度场与氧气浓度场、速度场存在耦合作用,因此,有必要基于三维或二维数值模拟技术继续深入研究回采情况下采空区煤自燃.