Method Exploration Of Preventing The Propagation Of Gas Explosion Along The Duct

CH₄explosion,as the main culprit of destroying mine safety,It often causes the high-pressure impact on the goods in the roadway and the high-temperature flame burning on the roadway equipment,which brings not only casualties,but also huge property loss and adverse social impact.How to better control the CH₄explosion is an important topic that experts and scholars in various countries continue to explore.This paper studies how to prevent the explosion flame without blocking the ventilation,so as to eliminate the gas explosion disaster more effectively.In this paper,on the existing conditions of the laboratory,an active explosion-prevention system was designed and used for this experiment.The system is mainly composed of five small parts:duct part,inflation part,ignition part,measurement part and fire extinguishing part.According to the requirements of experimental conditions,the system is designed to collect and record the pressure change process、flame propagation process and other relevant data involved in the experiment.After the explosion,the active prevention device is opened,and ABC powder is driven by nitrogen to spurt and form a suppression zone,forming a continuous suppression effect on the explosion flame and finally realizing the prevention.Through the study of the effect of ABC powder and nitrogen spurtion on the explosion prevention,it is found that:When the nitrogen pressure or ABC powder is gradually increased,the farthest distance of flame propagation will be shortened after exceeding the critical limit required for explosion prevention,and finally tend to the right nozzle.With the increase of nitrogen pressure,the critical amount of ABC powder needed to prevent the explosion is gradually reduced,and nitrogen has dual functions of suppressing and promoting explosion reaction.the peak value of overpressure caused by the rupture of PVC film is relatively stable,while the turbulence caused by he spurtion of nitrogen and ABC powder are much more complex.However,when the nozzle is close to the explosion source,it is necessary to increase the nitrogen spurtion pressure properly,so as to quickly form a suppression zone before the explosion flame reaches the nozzle.After studying the flame speed and the critical amount of ABC powder required for explosion prevention,it is found that:ABC powder mainly suppresses the explosion flame entering the suppression zone,and has little influence on the explosion flame propagating in the early stage.Without the upward vent,there is an approximate linear relationship between the flame propagation velocity（x）and the minimum ABC powder（y）required to prevent explosion.and the slope k is calculated to be between 1-2.After studying the relationship between the upward vent and the position of the nitrogen nozzle,it is found that the total propagation time of the explosion flame in the duct is extended from 185ms without upward venting to 259ms without N₂spurting,and the time is increased by 40%.The flame propagation speed is greatly reduced.upward venting will increase the membrane breaking pressure,resulting in the rise of the first pressure peak,and also reduce the time of the explosion maximum overpressure and delay pressure peak.When there is the upward vent,the explosion prevention effect of the nitrogen nozzle on the right is better than that of the nitrogen nozzle on the right.Therefore,after the reaction rate of the explosion flame is greatly weakened by the upward venting,the gas explosion propagation can be prevented without blocking the ventilation by reasonably setting the nozzles to spurt ABC powder and nitrogen to form the suppression zone.That is to say,the key to prevent the explosion flame is whether the suppression zone can be formed quickly before the flame reach,and continue to suppress the explosion flame until the flame reaction rate is 0.