Study On Prevention And Control Technology Of Spontaneous Combustion In Compound Goaf Of Near-distance Coal Seams Of Ximing Mine

In this thesis,the composite coal seam in the near-coal seam of Ximing Mine is taken as the research object.According to the characteristics of air leakage in the upper goaf of the roadway roof,the natural igniting characteristics of the residual coal in the composite coal seam in the near-distance coal seam are analyzed,and the air leakage measurement,laboratory experiment and beam are analyzed.Pipe monitoring,with the help of FLUENT simulation software,the distribution status and prevention and control technology of the spontaneous combustion danger zone in the goaf of the coal seam and the local air leakage area of the roof of the roadway are studied in the mining of the lower coal seam at a close distance,which is adopted for the composite goaf of the fully mechanized mining face.The nitrogen injection fire prevention measures provide a theoretical basis.Based on the basic theory of coal spontaneous combustion,combined with the characteristics of near-distance coal seam occurrence,the characteristics of natural combustion of residual coal in composite coal seam in near-distance coal seam are analyzed.The air leakage at the 49405 working face of Ximing Mine was measured by section element method.The air leakage in the goaf was 99.757m~3/min,and the air leakage in the upper connected goaf of the roadway roof was 24.480m~3/min.According to the theory of spontaneous combustion oxidization zone of coal in the goaf,the critical oxygen concentration of coal spontaneous combustion and the beam tube monitoring system,the spontaneous combustion oxidation zone of the coal in the goaf is divided.Based on the FLUENT numerical simulation software,based on the computational fluid dynamics mathematical model of the goaf,the numerical simulation analysis of the airflow field,oxygen concentration field and temperature field in the composite goaf of the 49405 working face of Ximing Mine was carried out,and the numerical simulation of the coal seam was carried out.The spontaneous combustion zone of the coal in the rear goaf and the spontaneous combustion zone of the coal in the measured goaf are basically consistent;at the same time,the measured air leakage and the numerical simulation of the air leakage are similar.The simulation software is used to predict the spontaneous combustion danger zone of the overlying goaf.For the spontaneous combustion danger zone of the composite goaf of Ximing Mine 49405 working face,the nitrogen injection fire prevention technology is used for analysis.For the 49405 working face goaf,the nitrogen injection pipeline is arranged on the working face inlet and the nitrogen injection release nozzle.The working face is 45m,and the reasonable nitrogen injection amount is 2000m~3/h~2500m~3/h.For the 49405 working face overlying goaf,while adopting measures such as cracking and sealing of the roof slab rock stratum,the method of using nitrogen injection to fill the goaf with drilling single hole is used to analyze the different nitrogen injection amount to the oxygen in the overlying goaf.The influence of temperature and spontaneous combustion danger zone is to determine the optimum nitrogen injection volume of single hole is 120m~3/h,and the reasonable nitrogen injection hole spacing is 36m.The thesis has 58 figures,5 tables,58 references.