Study On Leakage And Diffusion Of Natural Gas Pipeline And Emergency Ventilation Of Tunnel

Tunnel is an important crossing mode of natural gas pipeline layed in mountainous western China.Leakage of natural gas pipeline in tunnel will form explosion conditions in closure/hemi-closure space,causing serious consequences such as loss of economic,environment,and life without being well handled.Therefore,study of emergency ventilation of tunnel natural gas pipeline is helpful for emergency maintenance efficiency,accident loss and safety production.This paper analyses and summarizes common types of natural gas pipeline crossing tunnel and causes of pipeline leakage,with deficiency of partial research in tunnel natural gas pipeline and investigation results of tunnel natural gas pipeline in mountain area.Rules of leakage and diffusion in different type of tunnel,emergency ventilation and emergency ventilation while leaking are discussed with FLUENT.Emergency response for leakage accident of tunnel natural gas pipeline is analyzed based on these rules.There are four main achievements of this paper:(1)Changing the orientation of leakage hole to find out its influence on natural gas leakage and diffusion in straightness tunnel.Study of draught fan’s location and air speed while ventilating in straightness tunnel can find relationships between change of volume fraction of natural gas in tunnel and ventilation time to make sure the best install location of draught fan and air speed.(2)Analyzing the change of volume fraction of natural gas in tunnel after emergency ventilation while leaking in straightness tunnel and get the distribution and volume fraction of gas when the environment of tunnel is stable.Relevant emergency ventilation method is set based on this part.(3)Studying leakage and diffusion rules in different portal and grade of slant tunnel,and change of volume fraction of natural gas under emergency ventilation can get relationship between volume fraction of natural gas in tunnel and ventilation time and distribution of gas when the environment of tunnel is stable.Relevant emergency rescue recommendations are raised in this part.(4)Studying rules of leakage/diffusion and emergency ventilation in different portal of transition area between straightness and incline and get change rule of natural gas in tunnel under different conditions.Relevant rescue recommendations and announcement are proposed based on that.