Study On The Law And Characteristics Of Gas Explosion Ignited By Electric Fire Source

With the increase of coal mining electrification, there are a lot of electric firesource in the coal mine, and the gas explosion accident caused by the electric fire isincreasing rapidly. Therefore, this thesis focuses on the mechanism and characteristicsof the coal mine gas explosion ignited by the electric fire, which can providesimportant theoretical and technical support for gas explosion accident prevention,investigation and rescue.Based on the theoretical analysis and experimental study, the influence of theelectric source ignition energy and gas concentration on the gas explosioncharacteristics has been studied.The variable ignition energy experimental platform has been constructedaccording to the capacitor discharge principle, and electric spark ignition energy hasbeen measured by using oscilloscope, the results shows that the actual ignition energyis far greater than the theoretical minimum ignition energy of gas explosion, which is0.28mJ. Then the effect of the charging voltage and electrode gap on spark energyhas been analyzed, the higher the charging voltage, the higher the ignition energy.And there is an optimum of the electrode gap, in which the ignition energy is thelowest, and the ignition energy increases with the increasing of the electrode gapwhen exceeding the optimum gap.At last, the gas explosion characteristics at different ignition energy and differentgas concentration have been studied experimentally in the gas explosion lab of NorthChina Institute of Science and Technology. The experimental results are as follows:(1) The flame velocity of gas explosion increases with the increase of distancebetween the test point and ignition point, and reaches the maximum near the exit. Theignition energy and flame speed are quadratic function relation as well as gasconcentration and flame speed, when the ratio of length to diameter of the pipe isconstant.(2) In the process of gas explosion, the pressure shock wave is in the front of theflame, and the propagation velocity is obviously higher than the flame speed. Theignition energy and gas explosion pressure peak are logarithmic function relationshipas well as ignition energy and explosion pressure peak rise rate. The larger theignition energy is, the stronger the explosion strength will be, and the shorter thereaction time, thus the larger the explosion peak pressure, the faster the peak explosion pressure rise rate. But with the increase of ignition energy, the amplitude ofthe pressure peak and the peak pressure rise is slowly and slowly.(3) The gas concentration and explosion pressure peak are quadratic functionrelation as well as gas concentration and explosion peak pressure rise rate. At aconcentration of9.5%, the explosion strength is the highest, explosion pressure peakand explosion peak pressure rise rate are the biggest.