Study On Variation Law Of Spontaneous Combustion "Three-zone"in Goaf Of Fully Mechanized Coal Face

In recent years, with the development of the coal mining technology, fully mechanized coal mining technology has been widely applied in our country. This technology improves the ability of coal mining greatly, however, it makes the falling space of goaf bigger, the falling of coal more, and air leak more serious. To some extent, all of these enhance the risk of float coal spontaneous combustion in the goaf. Moreover, owing to the complex goaf environment, it has become more difficult to divide the range of goaf spontaneous combustion "three-zones" by observation. Yet the rapid development of FLUENT opens a new way for this study.This paper makes the air flowing mathematical model in the goaf based on heterogeneity seepage continuous equation, component gas immiscible diffusion equation and the theory of porous media. By establishing the numerical model of Shaqu14205working face and solving the model numerically in the use of CFD software, the paper respectively simulation studies three special situations in the early, middle and late use of connection roadway, and it analyzes the goaf air speed and oxygen concentration distribution on the "U+L" ventilation system. Finally from the special to the general, the paper summarizes the goaf spontaneous combustion changing rule in any period use of connection roadway.In the goaf, the air speed and oxygen concentration distribution are important indices to influence the range of goaf spontaneous combustion "three-zones". By analyzing and summarizing the results of numerical simulation, it learns that the goaf air speed distribution. With the connection roadway moving towards to the goaf deep, the scope of goaf spontaneous combustion zone that influenced by the air speed increases gradually and shifts to the goaf deep. However, with the goaf deep air leakage increasing, the space of goaf spontaneous combustion that influenced by oxygen concentration distribution decreases. Combining with the air leakage and oxygen concentration and judging the danger zone of goaf left coal combustion, the danger zone has a trend of decreasing with the connection roadway moving to the goaf deep. To analyze and summarize these results, the paper puts forward some reasonable suggestions for preventing and controlling the goaf left coal combustion in the14205working face, and provides the corresponding theoretical guidance for the mine takes some related measures.