The Numerical Simulation of Spontaneous Combustion of Coalfield Outcrop and Its Application

One mathematical model of spontaneous combustion of coalfield outcrop was set up, reaction of coal with oxygen was simplified and volatile output during coal pyrolysis was deduced. The mathematical model was validated by one coal fire in Xinjiang of China. The results showed spontaneous combustion area spread along roof to outcrop and formed the temperature gradient from roof to floor because of aerotaxis of spontaneous combustion and directivity of seepage. The higher temperature zone located at the former and upper of combustion area. The highest temperature zone gathered within a small region near fire source, but the temperature gradient in rock was not obvious. Spontaneous combustion accelerated gas seepage in outcrop and higher seepage velocity conduced to spontaneous combustion. CO distributed at the downstream of fire source and centralized the zone neighboring fire source mainly. At last, the application of simulation results to locate the fire source for coal fire was discussed.