Method Exploration Of Decelerating The Propagation And Quenching The Flame Of Methane Explosion In Duct

As a major hazard to mine safety,gas explosion is often accompanied by the burning of high temperature flame to the roadway equipment and the impact of high pressure shock wave on the roadway's memory,causing casualties,and huge losses of property and adverse social effects.How to control the gas explosion and solve the damage caused by gas explosions to people and equipment fundamentally is an important topic that is constantly being studied by experts and scholars from various countries.This paper explores how to achieve the deceleration and even extinguishing of the flame propagation process,so as to solve the hazard of gas explosion more effectively.In this paper,a small explosion platform is built on the basis of the existing conditions in the laboratory.The platform consists of seven systems,including piping systems,gas distribution systems,pressure and optoelectronic data acquisition systems,high-speed camera,ignition systems,inhibitor charging systems,and baffle systems.The system was designed according to the requirements of the working conditions during the experiment,and relevant data such as the flame propagation process and the pressure change process involved in the experiment were collected and recorded.In experiments which N₂ and R125 ?pentafluoroethane? were injected into a gas explosion in a straight pipeline,compared with the explosion process without injection of inhibitors,N₂ injected at a pressure of 0-0.1 MPa,propagation time was transmitted from Extending 352ms to 365ms,the maximum flame propagation speed also decreased from 8.40467 to 8.23345m/s,a decrease of 2.02%.After the N₂ injection pressure rose to 0.2-0.3MPa,the propagation time reached 395ms.At this time,the maximum flame propagation velocity in the tube decreased.To 7.6515 m/s,a decrease of 8.96%.However,when the pressure of R125 is increased to 0.3MPa,the flame propagation takes 432ms.At this time,the maximum flame propagation speed in the tube is6.981151m/s,a decrease of 16.93%.To a certain extent,the injection of N₂ and R125can decelerate the flame propagation of the gas explosion,and the R125 effect is slightly better than the N₂ effect.Through the study of the presence or absence of lateral pressure relief on the propagation of gas explosion,we found that the propagation speed of the explosion flame under the two conditions is not much different before the explosion flame reaches the lateral pressure relief port.The maximum flame propagation speed is reached before the lateral pressure vent.In the case of lateral pressure relief,after the flame passes through the lateral pressure relief port,the flame propagation speed decreases from the maximum value of 4.12651 m/s to 0.51064 m/s,a drop of 87.63%,and it remains low-speed propagation during the subsequent process.It makes the flame propagation with lateral pressure relief is 7.81 times as much as the flame propagation under the condition of no lateral pressure relief from the lateral pressure outlet to the left end of the pipe.In addition,the lateral pressure relief port setting can reduce the second overpressure peak value from 5.83kPa to 2.06kPa,a decrease of 64.33%without affecting the peak formation time.The third peak pressure is from 5.73kPa was reduced to 1.338kPa,a decrease of 76.65%.The effect of weakening the overpressure in the pipe was much better than the injection effect of N₂ and R125 in the straight pipe.That is,the lateral pressure relief can reduce the spread of gas explosion greatly.After adding a different angle baffle on the basis of the newly added lateral opening,compared with the 842 ms without flame propagation of the baffle,the flame propagation needs 773 ms at 60°baffle and 839 ms at 30°.After installation,the overall flame propagation in the pipe is accelerated.The greater the angle,the more obvious the accelerating effect of the baffle,but the boundary between the baffle and the pipe wall ?1.2m from the ignition source? is the boundary.Before this,the flame propagation speed is long board>Medium board>Small board,then changed to Small board>Medium board>Long board.More than this,the setting of the baffle and the straight pipe forms a concave-convex wall surface.Under the influence of the baffle,a fourth overpressure peak appears due to interference with the pressure change.The peak value increases with the baffle angle and the arrival time decreases..However,no matter how the baffle angle changes,the gas explosion still travels straight back along the pipeline.After the explosion,two nozzles are installed the lateral pressure relief port downstream to inject N₂,the flame propagation time of the gas explosion is 532ms when the N₂ injection pressure is 0-0.1 MPa.Compared to the 842 ms wit hout N₂ injection,the injection of a small amount of gas has accelerated the pro pagation of the rear blast in the pipeline.With the increasing of the injection pr essure of N₂,the full dilution speed of N₂ to the premixed gas of the whole sec tion is accelerated.Under the N₂ injection pressure of 0.1-0.2MPa,the flame pro pagation along the pipeline has been blocked and blocked by the right end of th e nozzle.Continue to increase the N₂ injection pressure to 0.2-0.3MPa,the effect of obstructing the propagation of the explosion flame is more obvious.Obvious flame cannot be observed from the side of the pressure relief vent,the gas exp losion along the pipeline is blocked,and the rear gas explosion is extinguished.However,under the condition of no side pressure relief,even if the N₂ injection pressure is 0.2-0.3MPa,the gas explosion flame will continue to spread rapidly along the pipeline,and it only takes 395ms to complete the propagation within t he pipe.Therefore,only after a significant slowdown in the propagation of gas e xplosion flames,a“cross section”can be formed within a sufficient period of ti me under proper injection pressure to extinguish the gas explosion.