Prediction model for spontaneous combustion hazard zone in downward ventilation gob of gently inclined coal seam

Abstract

To analyze the distribution characteristics of regions with potential spontaneous combustion hazards in the goaf under descending ventilation in gently inclined coal seams with different spontaneous combustion tendencies, a seepage model of the inclined goaf was established. Based on this model, CFD simulation was utilized to obtain the distribution characteristics of oxygen and temperature fields within the descending ventilation goaf under different fire source conditions (simulating the spontaneous combustion tendency of coal left in the goaf). Finally, the simulation results were validated by the data of O2 volume fraction in different areas of goaf observed at 81309 working face of Bade Coal Mine. The results show that with the increase of heat source intensity (spontaneous combustion tendency of coal left in goaf), the effect of fire air pressure in goaf is enhanced, and the difference of oxidation zone width between the inlet and return air sides in goaf is gradually reduced. The measured results show that the critical positions of the choking zone in the goaf corresponding to the inlet and return air side and the middle of the working face are 200, 290 and 175 m away from the working face, respectively, which are consistent with the simulation results when the fire source power is 65 W/m2, indicating that the established model is more accurate and can be used to study the spontaneous combustion distribution of the working face of inclined coal seam prone to spontaneous combustion.

Keywords

• spontaneous combustion tendency
• downward ventilation
• danger area of spontaneous combustion
• goaf seepage model
• numerical simulation