| China is dominated by coal in energy supply and consumption in 21 st century, as the increase of mining scale, the quantity of gas emission in working face increased sharply, especially in large mining height face, and it will lead to gas over-limit in coal mine. There will be a serious threat for coal mine safety production. Gas emission of goaf is a major source of gas emission in working face, so studying the law of goaf gas is great significance for the coal mine gas control.This article general introduced the basic situation of Sihe coal mine, as well as4303 working face. Through separate source method to calculate the composition ratio of gas source in goaf and according to the 4303 working face actual situation of coal seam roof strata caving in sihe coal mine, the "three vertical zones" height range was simulated by using Flac3 D software. The law of goaf gas migration was obtained by Fluent software based on three dimensional model established by using Gambit.According to the analysis of gas concentration of air return way and moving upper corner, we know the gas concentration at moving upper corner is high, and the "three enter-two return" ventilation system cost property and laborious. Thus the high level borehole governance goaf gas was proposed in "two enter-one return" ventilation system.The required airflow of working face is obtained by calculation under the "two enter-one return" ventilation system, then using Fluent software to obtain goaf gas migration rules in the condition of high level borehole drainage with "two enter-one return" ventilation system. We concluded that the gas concentration was about 0.3percent in return air way and 0.5 percent in upper corner, and the gas in working face can reduced effectively. In the last, the optimal arrangement scheme of the high field drilling was proposed in theory.It will Provide the theoretical and technical support about Working face gas control for Sihe mine. |
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