NUMERICAL SIMULATION OF TEMPERATURE FIELD WITH SPONTANEOUS COMBUSTION IN OPEN REGION NITROGEN INJECTION GOAF

To study the complicated mechanical process of spontaneous combustion of remnant coal ingoafs under the conditions of open region nitrogen injection, based onseepage continuous equation, gas dispersion equation and integrated heattransfer equation, a non-steady numerical model of spontaneous combustion ofcoal in nitrogen injection goaf is established, and these equations aresolved by windward finite element method. The spontaneouscombustion process in goaf with different flux of nitrogen is computated,and the flow pattern of air leakage and the flow pattern ofnitrogen are expressed by graphs, together with the variation ofoxygen and carbon monoxide concentration and temperaturedistribution in goaf. Some influencing factors, such as gaseffusion and the advance of working front are taken into account duringcomputation. It is concluded that a high temperature zone usually appears atthe inlet air side in goaf spontaneous combustion under open region nitrogeninjection, but the shape turns to narrow. The spontaneous combustion periodwill become long with the increase of nitrogen injection quantity untilspontaneous combustion stops. Theoretical simulation result andpractical nitrogen injection conditions are in general agreement.