Research On Effect Of Spontaneous Combustion "Three Zones" Of Coal In Goaf Under The Condition Of Nitrogen Injection

Coal spontaneous combustion in the natural world has been an objective existence phenomena. Mine’s fire with the poisonous and harmful gas will also may lead to exploding of mine gas, meanwhile, it poses a serious security threat for underground personnel and production equipment. Coal spontaneous combustion also lead to large amounts of waste of coal resources and make the environment deteriorated, thus to bring personnel casualties and the huge economic loss, especially in recent years, with the development of the comprehensive mechanical coal mining technology, it also make the strength of coal mining strengthened unceasingly, and the goaf scope has become more wider, the ventilation system has become more complicated, it has made the coal spontaneous combustion fire become one of the main disasters in coal mine production safety effect. According to the data analysis, from the national key coal mines and unified state allocation coal mines, the number of spontaneous combustion accounts for more than90%of the total number of the mine fire, and the number of occurrence of spontaneous combustion of residual coal in goaf fire accounts for60%of the total number of the mine fire, therefore, underground goaf is the main area of spontaneous combustion fire.This paper under the background of factors of more residual coal, residual coal liable to spontaneous combustion, more falling height and working face advancing slowly in goaf of fully mechanized caving face of Zheng Hang Mine1504working face, through taking fire prevention measures that injecting nitrogen into goaf to decrease oxidized zone width, and establish complete fire prevention system of nitrogen injection and beam tube detection. First of all, through select the coal samples for NO.14、15coal, using the thermal analysis experiment and temperature programmed oxidation experiment to obtain the laws that heat release and oxygen absorption changing with temperature under the conditions of NO.14、15coal of different moisture and different particle size, meanwhile, obtain gas generation rules of NO.14、15coal under the conditions of low temperature oxidation, and optimizing CO and C2H4as index gas for goaf coal spontaneous combustion.Secondly, combining with the experience of nitrogen injection in the past, adopting nitrogen injection type of buried pipe from upper corner, and through numerical simulation by fluent software, determining the best location of the nitrogen injection port, that is it should be installed in depth goaf20m, meanwhile, it also guide the establishment of nitrogen injection scene and beam tube detection system. Then, processing the data of different gases composition accurately before and after injecting nitrogen with the MATLAB software combined with numerical analysis, and inverting the scope of "three zones" with limited data before injecting nitrogen, and obtain the law for gas distribution in goaf directly with MATLAB three-dimensional imaging technology, and determining the width of "three zones" before and after injecting nitrogen, and dividing dangerous areas in goaf, at last, evaluating the effect of injecting nitrogen, meanwhile, feed backing and adjusting the parameters of nitrogen injection in time, and the fire prevention system by nitrogen injection has been improved.