Experimental Study On Deflagration Propagation Characteristics And Flame Retardant Technology Of Combustible Gas In A Confined Space

As a big country of coal production and consumption,more than 90% of coal mines in China adopt the way of shaft mining.Because of the narrow coal mine roadway,the flame spread rapidly in the roadway when the gas explosion occurs,which is a great threat to the life and equipment safety of miners and causes huge losses.So how to restrain the gas explosion and ensure the safety of miners’ life and property has become a key problem to be solved.Independent use of north China institute of science and technology of mesoscale explosion shock tube system under different injection pressure injection of inert gas(nitrogen and carbon dioxide)inhibition of premixed methane gas explosion has carried on the experimental study,the results show that with the method of injection of inert gas,whether the explosion suppression is closely related to the inert gas injection pressure,flame propagation speed increased with the increase of injection pressure showed a trend of decrease after the first increase,analysis that injection of inert gas diffusion in the pipeline,exacerbating the premixed methane gas turbulence,the entrainment of flame array,accelerated chemical reaction process.When the injection is at low pressure,the effect of inert gas on accelerating the turbulification of methane premixed gas in the diffusion process is stronger than that of inert gas on dilution and heat insulation,which is to accelerate the flame propagation.On the contrary,when the injection pressure is increased,the dilution and insulation effect of the inert gas gradually exceeds the intensified turbulence,which inhibits the explosion of the methane premixed gas.High-speed photography and laser schlieren technique of image,with the increasing of injection pressure,the shape of flame array variable is more and more strong,which in the spray 1.5 MPa when the inert gas lift,deformation of flame,the strongest is strongest on flame propagation speed increase,the injection 1.5 MPa when nitrogen flame highest peak 250 m/s,jet 1.5 MPa carbon dioxide when peak183 m/s.As to continue increasing the injection pressure,found that is impacted by the injection of inert gas flame front is divided,flame surface area is reduced greatly,explosion suppressed gradually,although when injection 2.5 MPa nitrogen flame front is divided,but the flame is still stay together,the flame propagation speed compared with the injection of 1.5 MPa when nitrogen decreased,but still higher than 9.5%methane premixed gases,and 2.5 MPa co2 injection,the flame propagation speed is accelerated,upstream of the pipe only at the start of the flame propagation speed downstream piping is decreased obviously,Analysis that injection of inert gas into the pipe under the influence of flame propagation direction is pushed to the downstream piping,and downstream of the premixed methane gas mixture,key play to the role of the explosion suppression,downstream of the pipeline from the schlieren images also confirmed that injection of inert gas under the influence of flame propagation direction,mainly to the downstream.However,when the 3.5MPa inert gas is injected,the flame is divided into several moving flame vortexes,which are wrapped by the diffused inert gas.The contact with the methane premixed gas is cut off,and the explosion suppression effect is significantly inhibited.At the same time,the detonation suppression effect of nitrogen and carbon dioxide is compared.The results show that under the same injection pressure,the detonation suppression effect of carbon dioxide is stronger than that of nitrogen.Under the condition of the injection of carbon dioxide,the flame propagation speed of growth and the matrix surface shape variables are less than the same nitrogen injection pressure,the main reason is that carbon dioxide in the dilution and isolation has better heat transfer effect,at the same time,carbon dioxide,as a kind of explosion products directly involved in the chain reaction in the process,the production of the free particle,so the explosion suppression effect than nitrogen.There are 44 figures,3 tables and 71 references in this paper.