Determination of Spontaneous Combustion Hazard Zone in Goaf based on Two-field Superposition Principle

In order to effectively solve the problem of spontaneous ignition in goaf of fully mechanized caving face,CFD technology was used to calculate the flow field in goaf.Taking the superposition field of oxygen volume fraction and velocity as the standard for the division of spontaneous combustion hazard zone,the relation between the spontaneous combustion hazard zone and the ventilation quantity of working face was analyzed,and the influence of nitrogen injection and gas extraction on spontaneous combustion hazard zone was also analyzed.The results show that the morphology of the oxidation zone has no change with the increase of air supply in the working face,but moves back as a whole,however,the area of spontaneous combustion hazard zone of "L" type increases,which increases the ignition risk.After nitrogen injection,the spontaneous combustion hazard zone is mainly located near the transportation lane of working face,which is a long and narrow area;gas extraction has great influence on spontaneous combustion hazard zone,the spontaneous combustion hazard zone increases obviously with the increase of extraction.