Law Study Of Goaf Gas Distribution Of Nitrogen Injection Of Thick Seam And Fully Mechanized Caving Mining In Pingshuo Mining Area

The spontaneous combustion of coal is one of the serious disaster in the coal mining, has become one of the main factors restricting the productive and efficient mine production safety and health development. Thick seam coal caving mining technology to promote high-yield and efficient operation of the protection of mine at the same time, the spontaneous combustion of coal fire prevention work is particularly important. Caving mining goaf roof off the large, leaving a large number of floating coal, coupled with Inoue air leakage, and thus the the goaf floating coal Leakage Flow in the oxygen oxidation reaction, resulting in the goafthe floating coal spontaneous combustion, a serious threat to mine safety in production.In this paper, Pingshuo mining Underground Mine spontaneous combustion thick seam caving goaf nitrogen injection parameters is based on empirical data, the lack of scientific and rational nitrogen injection parameters, parametric test of coal spontaneous combustion characteristics of different oxygen concentrations were obtained Pingshuomine four coal spontaneous combustion of the critical oxygen concentration, through theoretical analysis, experimental research and on-site determination goaf of fully mechanized caving face before and after the injection of nitrogen gas distribution law and the use of different nitrogen injection parameters given in the goaf Note nitrogen inerting goaf inerting effect, combined with CFD testing technology of effect, in order to optimize the goaf nitrogen injection against fire technical parameters of great significance in reducing the accident rate of Pingshuo mining spontaneous combustion fire, improve the management level of the mine Fire Prevention.Main contents and conclusions are as follows:1. To grasp the seam spontaneous combustion characteristics and indicators of early prediction, four seam coal sample temperature programmed oxidation test. The experimental results show that:the Pingshuo well work a mine four seam generate the critical temperature of the CO (refers to the coal samples detected temperature oxidation process of CO concentration in the rapidly changing point temperature) is80℃, C2H4in the temperature of120℃H2,appears a temperature of90℃, and its formation with increasing temperature was increased and then decreased again rising trend of C2H2temperature higher than220℃. Therefore, the Pingshuo well work a mine four seam indicators gas under the premise of using the CO, combination of C2H4and C2H2as indicators of comprehensive judgment on coal spontaneous combustion at different stages of its development trend forecasting.2. In order to master the critical oxygen concentration of seam spontaneous combustion, four seam of coal samples with different oxygen concentrations, temperature programmed oxidation test. The experimental results show that:As the concentration of oxygen in the environment of coal oxidation (18%,12%,10%,8%,5%), reduction of CO, C2H4in the generated initial temperature rendering "lag effect" is lagging behind10℃generation relative change of10%to80%. Four seam spontaneous combustion critical Pingshuo well work Mine four seam coal sample in the temperature-programmed linear regression relationship between the initial temperature and oxygen concentration indicator gases CO generated in the oxidation process under different oxygen concentrations.y=94.54272-3.21029x; to inferoxygen concentration of5%to provide a basis for optimizing the parameters of the goaf nitrogen injection.3. Pingshuo well work Mine14107fully mechanized caving face the laying of the beam pipe monitoring system, while taking advantage of self-developed mobile beam tube sampling system and ground gas analysis laboratory system, on-site monitoring of the goaf gas monitoring results show that not O2concentration (volume fraction) in the empty area of distribution boundaries correspond to the nitrogen injection under the conditions of mining location is:cooling belt>18%,<14m; oxidation with5%to18%,14～255m; suffocation with<5%,>255m.O2concentration (volume fraction) in the empty area of distribution boundaries correspond to the nitrogen injection under the conditions of mining location is:cooling belt≥18%,<14m; oxidation with5%to18%,14～162m; suffocation with<5%,>162m.On-site monitoring results show that the14107fully mechanized caving face before and after nitrogen injection goaf gas O2distribution law has changed, reflected in the range of "three zones" in the goaf cooling with no change in the oxidation zone of reduced nitrogen injection about93m, compared before and after nitrogen injection, suffocation with also will be ahead of93m.4. According to the result of the Pingshuo well work a mine by volume nitrogen injection, combined with relevant experience similar to mine at home and abroad, nitrogen injection flow the maximum principle,14107fully mechanized top coal face Fire Prevention Note nitrogen flow rate should be is notless than1460m3/h.5. Nitrogen injection location should not be within50m of the auxiliary transport Lane side face in the best position in the face after the80-100m range, the nitrogen injection port to the venue spacing is60m inerting goaf oxidation zone results. CFD simulation analysis and field, it is recommended that face low flow of nitrogen should try to maintain the continuity of injected nitrogen, to avoid intermittent nitrogen injection goaf oxidation zone to get better inerting effect.