Simulation of the effects of different inert gas replacement schemes in sealed goaf
In response to the coal spontaneous combustion caused by external O2 entering the goaf through cracks under negative pressure during the gas extraction process in sealed goaf,a common solution is to inject inert gas to replace the extracted gas,it can balance the air pressure and prevent external air from entering the goaf,achieving the goal of preventing coal spontaneous combustion.The numerical simulation method was used to study the changes in the flow field of relevant physical parameters during the gas displacement process,and four schemes were proposed:free mixing displacement method,positive pressure displacement method,negative pressure displacement method,and positive-negative pressure displacement method.Using the maximum volume fraction of O2 less than 2%as the replacement standard,the replacement cost evaluation indicators of the four schemes were compared,including total consumption time,nitrogen consumption,ventilation fan operation time,and cumulative nitrogen injection time.Decision-making methods that can be used for gas replacement plan were identified,and suitable plans for sealed goaf under different geological conditions were provided.
sealed goafinerting replacementspontaneous combustion of coalair pressurenumerical simulation
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