Experimental Study On Auto-ignition During Discharge Of High-pressure Gas

Coal and gas outburst strength and mine pressure are increased continuously in process of Coal mining, with mining depth deepening continuously. and the mining face long and inbreak space high for fully-mechanized sublevel caving mining is adopted coal mining at present, when large area top inbreak, shock is likely to be produced to induce gas trigger spontaneous combustion phenomenon in the process of large high-concentration methane pouring out of mining face with high speed to result in methane gas disasters; Moreover, transporting (storing) pressure which is increased more and more in gas transported and stored procedure, spontaneous combustion phenomenon also can be triggered once the accidental leakage. However, relevant research results still have been rarely put forward at present. Therefore, the research of this field is carried out urgently to prevent serious accident bringing from natural gas (methane) leakage spontaneous combustion for providing technical guidance and theories basis.Based to engineering background in the paper, the experimental platform of auto-ignition during discharge of high-pressure gas was designed and built according to principle of similitude, rapidly discharging process of high-pressure gas was achieved by rupture disc, spontaneous combustion during discharge of high-pressure gas was simulated physical chemistry phenomenon of which high-pressure gas spreaded in pipe and from pipeline jet to atmosphere via rupture disc. Experimental system was composed of experimental device of self-igniting during discharge of high-pressure gas and data acquisition and measurement system.Combining method of theoretical analysis and experimental research was adopted in the paper. Firstly shock producing and developing process was analysed, the state parameter equation of gas before and after shock and shock overpressure change formula were deduced under given ideal condition on the basis of correlation theory of gas, pressure and temperature of medium jump after shock wave was obtained, and analysing correlations among overpressure of shock wave,speed of propagation and initial pressure, which provide theoretical basis for developing experiment of auto-ignition during discharge of high-pressure gas. Secondly, the auto-ignition phenomenon was studied experimentally, and the spread of nozzle jet flame was also studied when auto-ignition; Influence law of initial pressure and downstream piping length to auto-ignition was studied. Then experiment of auto-ignition during discharge of high-pressure gas on different conditions was carried out to comparatively analyse the propagating character of shock and generating process of gas auto-ignition.Results by experiment showed that the occurrence of self-ignition on abrupt discharge of high-pressure gas into the atmosphere on some discharge conditions of initial pressure and the downstream piping length; initial pressure is greater, the greater shock wave strength and the greater propagation speed the in pipe, so gas spontaneous combustion phenomenon is easier induced; and the occurrence possibility of self-ignition at high pressure with a short piping, furthermore, the pressure at which these ignitions occurred appeared to be decreasing with increasing the piping length. It explains gas auto-ignition phenomenon is more advantageous to occur with the pipe length increasing,...