Study On Characteristics Of Methane Explosion In Different Pipeline Structures And Inhibition Effect Of Water Mist

With the vigorous development of my country’s economy and the continuous improvement of scientific and technological level,new energy has been effectively developed and used.However,per capita energy consumption is still increasing day by day,and my country’s demand for coal energy still ranks first in energy.Gas explosion accidents occur frequently during coal mining,resulting in a large number of casualties and property losses.Therefore,the research on gas explosion prevention and control is still the focus of domestic and foreign scholars.In this paper,the influence of water mist in different pipeline structures on the propagation of gas explosions was studied.In a self-built transparent plexiglass pipeline,9.5%CH₄/Air premixed gas was used as the research object.The position and number of nozzles were analyzed,and their influence on the characteristic parameters such as explosion overpressure and flame propagation velocity during the explosion propagation process was analyzed,and the following conclusions were drawn based on the experimental phenomena:During the propagation of the explosion flame in the straight pipe,the chemical reaction zone moves along with it,and the change of the pressure difference before and after the reaction zone promotes the advance of the flame.The explosion shock wave ruptures the film at the lateral outlet of the pipeline,resulting in the outflow of the gas in the pipe and the deterioration of the quality.During the continuous backward propagation of the flame,the closer to the outlet,the lower the pressure,and the acceleration of the airflow comes from the conversion of part of the pressure energy into the kinetic energy of the forward flame,so that the reaction near the outlet is the most violent and the flame propagation speed is the largest.The effect of the position and number of water mist nozzles on the explosion is related to the state of flame propagation.When the flame spreads at a low speed,the water mist suppression effect is obvious,and the flame appears to stop or reverse transmission.This phenomenon is more obvious for a 3m tube than a 2m tube.When the flame spreads at high speed,spraying fine water mist in the area near the outlet end cannot effectively reduce the flame propagation speed,but aggravates the turbulence effect in the area,which accelerates the combustion reaction rate and makes the flame brighter.There are two effects of explosion flame propagation in the"return-shaped"pipeline,which are differential pressure driving and reaction propagation.The backward movement of the flame in the pipe in the horizontal direction is the dominant factor,and the backward movement in the vertical direction is the combined effect of the two.The water mist in the area near the ignition end can effectively suppress the overpressure and the flame propagation speed in the pipeline mainly because of its depressurization effect.When spraying water mist in the area near the outlet end,the closer the nozzle is to the explosion vent,the more significant the suppression effect is,because the spray pressure near the explosion vent replaces the external atmospheric pressure,effectively reducing the pressure difference between the upper and lower pipes and weakening the driving force of the flame.The effect of water mist on explosion propagation is the combined effect of the nozzle position and the number of nozzles.The average flame propagation velocity in the pipeline under the action of single water mist nozzle and double water mist nozzle near the ignition end is lower than that of pure explosion.28.59%and 38.27%.In the vicinity of the bifurcated pipe near the outlet end,the average flame propagation speed decreased by 13.77%when the double water mist sprinklers acted compared with the pure explosion,and the single sprinkler at the same position had a stronger flame suppression effect than the double sprinklers.There are 41 figures,10 tables,and 87 references in this paper.