Research On Numerical Simulation Of Fully Mechanized Goaf In Fire Prevention And Extinguishing In Jiudaoling Coalmine

This article combines Liaoning Jiudaoling Coal Limited (Jiudaoling Mine)-825fully mechanized caving face goaf spontaneous combustion prevention practical problems and uses CFD numerical simulation technology for research. Goaf model is based on Jiudaoling Mine face actual size, it uses Gambit to build a3D model of fully mechanized caving face goaf with a tilt angle. Rock of caving goaf is non-uniform. Caving broken expansion coefficient and porosity distribution is based on "O"-ring distribution model. Viscous drag coefficient and the inertial resistance coefficient is calculated based on empirical formula which is determined by the nonlinear flow equations. Porous Media module is achieved by a custom function UDF, the gravity factor should be considered.Jiudaoling Mine actual mine fire prevention work is combined with numerical simulation. The nitrogen injection at room temperature40℃, the temperature20℃nitrogen injection, low temperature-20℃nitrogen injection, upstream wind, downstream wind, the case of central injection foam wall with nitrogen injection and without nitrogen injection, the case of injection foam wall at inlet hemi with nitrogen injection and without nitrogen injection, the case of low temperature-20℃downstream wind with nitrogen injection at the inlet hemi injection foam wall model10kinds use Fluent for numerical simulation.10different distributions under pressure isosurface line graph, the gas concentration profile are drawn. And through the contrast of normal and low temperature nitrogen injection, the contrast of upstream wind and downstream wind, the contrast of central foam wall and injection foam wall at inlet hemi with nitrogen injection and without nitrogen injection, the optimal solution for fire prevention is summed up.(1)Through at room temperature nitrogen injection and low temperature nitrogen injection simulation, it is that nitrogen injection near the bottom when goaf higher concentrations of nitrogen, oxygen concentration is greater than10%area of retraction about100m;(2) Through the result of contrast of upstream wind and downstream, it shows that using downstream wind ventilation can largely control efforts for goaf air leakage. It is less than the upstream wind reduced by about80m3/min. Downstream wind of spontaneous oxidation with oxygen concentrations is higher than16%of the region narrower than upstream wind60m. It is more favorable for the prevention of spontaneous combustion of coal.(3)The result is the contrast of normal or low temperature nitrogen injection and upstream wind (without injecting nitrogen). The amount of air leakage of nitrogen injection can reduce the leakage of about20m°by calculating, the low temperature nitrogen injection controlling leakage effect is more obvious than the high temperature nitrogen injection.(4) Central injection foam wall and inlet wind hemi injection foam wall comparing simulation with nitrogen injection and without nitrogen injection cases results fully explain foam wall with baffle effect. It can part to prevent air leakage. On this basis, further it can reduce nitrogen injection amount of air leakage. Oxygen layer of inlet wind hemi injection foam wall which is higher than10%oxygen concentration is about10times smaller than in the central area of the wall injection foam. So as to arrive, three models of low temperature nitrogen injection, downstream wind, foam wall inlet hemi are conducive to control the amount of air leakage in Jiudaoling Mine. It can reduce oxygen in goaf and shorten the legacy of coal spontaneous oxidation with oxygen layer width. Then through three conditions models of the establishment of low temperature nitrogen injection, downstream wind, foam wall of inlet hemi, the models are simulated by Fluent. Simulation results verify the correctness of inference.