Study On The Influence Of Inert Gases Suppressing On Explosion Of Oil-gas Mixture Gas In Humid Environment

As a critical lifeline,the energy transposition pipeline network plays an irreplaceable role for maintaining the operation of society.However,it is also lurking great risks due to a general phenomenon that space between underground drainage pipes and oil/gas pipelines relatively closing because of limited space or unreasonable layout design.At the same time,the complicated underground environment,metal corrosion and external forces may cause pipeline leak and gas diffusion.Therefore,the research on suppression of mixed gas explosion in pipelines has both theoretical value and social significance.This paper relies on the experimental platform set up by the National Natural Project"Explosion Mechanism and Prevention of Oil-Gas Mixtures Gas in Urban Drainage Culverts"(51474151)to study the suppression of inert gases on the explosion of oil-gas mixtures gas in humid environments.It obtains the explosion characteristics of oil-gas mixtures gas and the effects of N₂/CO₂ on the explosion of oil-gas mixtures gas in different humidity conditions by experiments and data analysis.In addition,the numerical simulation of Flacs software is verified effectiveness based on error analysis between explosive experiments and simulation data in the same operating conditions.Then,the Flacs is used to explore the suppression effect of N₂/CO₂ in different temperature and humidity conditions.The main conclusions are as follows:(1)Determine the upper and lower thresholds concentration and the concentration causing the most serious explosion of the methane-gasoline premixed gas by experiments.It is obtained that the premixed gas can explore within the range of mixed concentration of 5%?15%,otherwise explosion could not occur.Among the explosive reaction,the 10%methane+1.28%gasoline mixed gas,which with the higher methane concentration,reacts most violently.The explosion pressure spike can reach 0.2650 MPa,the flame velocity peak can reach 20.1743 m/s.And the 4%methane+3.84%gasoline mixed gas,which with higher gasoline concentration,reacts second violently,with explosion pressure spike reaching0.2483 MPa and flame velocity peak reaching 17.7019 m/s.(2)Determine the explosion characteristics of oil-gas mixture gas in different environmental humidity,through change the initial humidity in closed pipe to experiment.According to the result of experiments,the explosion pressure spike of the oil-gas mixture decreases slightly as the ambient humidity increases,as well as,the measured position moves backward.The positive impulse of the explosion increases then decreases,so it can be considered that it is not affected by the humidity regardless of the experimental error.The flame velocity peak gradually decreases,and its speed reduction rate increases.In addition,the 10%methane+1.28%gasoline experimental group effected by humidity more discernible than the 4%methane+3.84%gasoline experimental group.(3)Conduct comparative experiments in 40%and 100%humidity conditions with adding different concentrations of N₂ into the pipe.The results show that:in humid environment,the inhibitory effect of N₂on oil-gas mixture gas explosion mainly reflecting in reducing the completion of the reaction and the explosion impulse.While the suppression of explosion pressure and flame propagation speed effected by humidity.And the inhibitory effect of N₂ on the explosion intensity of the 4%methane+3.84%gasoline experimental group is more obvious than that of the 10%methane+1.28%gasoline experimental group in a humid environment.(4)Conduct comparative experiments in 40%and 100%humidity conditions with adding different concentrations of CO₂ into the pipe.The results show that:in a humid environment,the suppression effect of CO₂ on the explosion of oil-gas mixture gas significantly enhanced.For the same CO₂ concentration,the attenuation rate of the explosion strength of the oil-gas mixture gas in 100%relative humidity is significantly greater than that in 40%relative humidity.In the same humidity conditions,the suppression effect of CO₂ on the explosion intensity of the 4%methane+3.84%gasoline experimental group is more obvious than that of the 10%methane+1.28%gasoline experimental group.(5)Verify the Flacs numerical simulation can realistically reflect the explosion characteristics of oil-gas mixed gas in a humid environment and the effect of inert gas suppression on explosion in a humid environment by the error analysis between numerical simulation and experimental results.Furthermore,the effect of humidity on the suppression effect of inert gas in the condition of 30?is simulated.The results show that the effect of inert gas on the gas-air mixture gas is better under the condition of high ambient temperature and humidity.It can provide a certain reference for the actual explosion suppression work.