煤堆自燃的数值模拟及分析

Numerical simulation and analysis of the coal spontaneous combustion

为研究煤堆在自然堆积状态下的自燃影响因素,将不易现场观测的工程实际问题转化为计算机问题.建立了煤堆自然存放的二维模型以及煤堆自燃问题的能量方程和氧浓度方程相耦合的煤堆自燃发火的数学模型.采用多物理场耦合分析软件COMSOL进行解算.结果显示煤堆在第60天时发生自燃现象,到第100 d时煤堆已经完全自燃,并且氧浓度随着时间呈现三带分布.通过改变煤堆的高度和孔隙率后进行解算,显示出煤堆高度和孔隙率增加时,煤堆更加容易发生自燃现象.结果表明:煤堆自燃现象呈现明显的三带分布,并且孔隙率和煤堆高度与煤堆自燃现象的发生呈现正相关.

In order to study the influence factors of the spontaneous combustion of coal pile under the condition of natural accumulation, this paper transformed the real engineering issues which are not easy to be observed on site into problems can be simulated by computer, and established two dimensional model of natural storage of coal pile and the mathematical model of coal spontaneous combustion coupled with the energy equation and oxygen concentration equation. The multi-physical field coupling analysis software COMSOL was used to calculate the solution. The results show that the occurrence of spontaneous combustion occurred in 60th days; the coal stack has been completely spontaneous combustion by the 100th day; the oxygen concentration showed three bands distribution with time changing. By changing the height and porosity of coal pile, the calculation shows that with the coal stack height and porosity increase, the coal pile is more prone to spontaneous combustion phenomenon. The results of the analysis show that the phenomenon of spontaneous combustion of coal is three zone distribution, and the porosity and the height of coal pile and the occurrence of spontaneous combustion of coal is a positive correlation.