Research On Fire Prevention And Extinguishing Technology Of Liquid Carbon Dioxide In Yangchangwan Coal Mine

Mine fire is one of the five major natural disasters in coal mine,which not only causes a lot of loss of coal resources,but also seriously threatens the safety of coal mine production.Therefore,mine fire prevention and control is of great significance to the safe production of coal mines.In the end stage of Yangchangwan Coal Mine,CO gas appears in the goaf and there are various degrees of over-limit phenomenon.Once coal spontaneous combustion disaster occurs,it will cause serious harm.In this paper,the movement rule of carbon dioxide in goaf is comprehensively analyzed by theoretical analysis,numerical simulation and engineering application,and the technology of liquid CO₂ injection in goaf is designed to prevent and extinguish fire.Firstly,on the basis of previous studies on the caving characteristics of overlying strata in goaf,the distribution characteristics of porosity,viscous resistance coefficient and inertia resistance coefficient in goaf are analyzed in combination with the actual situation of goaf in II020205 working face of Yangchangwan Coal Mine,which provides an important basis for coding UDF of porosity,viscous resistance coefficient and inertia resistance coefficient.The air flow field and gas concentration field in the goaf are simulated,and the distribution law of oxygen concentration and CO₂ diffusion law in the goaf are obtained,and the optimum location of carbon dioxide injection drilling hole on the side of the air inlet roadway in the goaf is obtained.According to the range of CO₂ diffusion,the influence of CO₂ injection intensity on the inerting effect of goaf was quantitatively analyzed,and the optimum CO₂ injection intensity in goaf was obtained.The inerting mechanism of liquid CO₂ in goaf is analyzed,and two kinds of CO₂injection technology are studied.The problems of pipeline blockage and tube burst are solved during transportation of liquid CO₂.Finally,combined with the numerical simulation results and theoretical analysis,and according to the spontaneous combustion situation of II020205 working face in Changwan Coal Mine,the liquid CO₂ injection process was designed,and the location and injection intensity of the liquid CO₂ injection drilling holes in the side of the air entry roadway in goaf were determined.The actual effect of liquid carbon dioxide fire prevention and extinguishing technology in Yangchangwan Coal Mine was analyzed by monitoring the CO concentration in the working face and goaf.