Study On The Leakage And Diffusion Law Of Gas Pipelines In Old Urban Area

At present,urban gas leakage and diffusion is a popular research hotspot in academic circles.Scholars have made fruitful studies on the diffusion law of household kitchen gas leakage,buried gas leakage and urban street gas leakage.However there are few studies on the law of gas leakage and diffusion in old residential areas and the influence of filling method of buried gas pipeline on the law of gas diffusion in soil environment.The shape and location of residential buildings in old residential areas will also have a great impact on the diffusion of gas.Gas pipelines in old residential areas are generally laid in a bad environment and are more prone to leakage hazards caused by third-party damage and corrosion and perforation.This paper takes an old residential area in Guiyang City as an example to study the influence of perennial wind speed,different gas pipeline operating pressure and different atmospheric wind speed on the gas leakage and diffusion law around the residential buildings in this residential area.The diffusion law of gas in soil environment is also studied according to the dependent variables such as filling mode,leakage aperture,superposition of multiple leakage holes and pipeline operating pressure of buried gas pipeline.In this paper,the numerical simulation method and FLUENT fluid computing software are used to simulate the leakage and diffusion of gas in air and buried gas pipeline.Through theoretical analysis,the main conclusions of gas diffusion in the air are as follows:(1)In the state of perennial wind speed,gas will spread out on the windward wall of slightly closed L-shaped residential buildings,thus causing certain security risks to residents and users in this area.In addition,in a relatively short time,gas will accumulate in large quantities and form explosive steam clouds in the cavity area surrounded by relatively closed U-shaped residential buildings and severely closed O-shaped residential buildings.The security of resident users in the area is threatened.(2)Controlling other variables,when only the pipeline operating pressure changes are considered,the pipeline operating pressure is proportional to the horizontal gas concentration distribution range in the area below the top of each residential building.(3)When other variables are controlled and only the change of wind speed is considered,the wind speed is proportional to the horizontal gas concentration distribution range in the area below the top of each residential building,and the more closed the shape of the residential building,the greater the influence of wind on the gas diffusion range.The conclusions of gas diffusion in soil environment are as follows:(4)The filling layers and filling sequence of different types of soil have a great influence on the diffusion of gas in the soil environment.With the increase of the filling layers of soil,the diffusion of gas in the positive direction of the Z-axis will be more significantly inhibited.However,the increase of soil layers will also lead to the increase of the diffusion rate and diffusion range of gas in other directions,especially in the horizontal direction.(5)The size of the leak aperture,the number of leak holes and the operating pressure of the buried gas pipeline are all proportional to the diffusion rate and range of gas in the soil environment.The influence of the leak aperture and the number of leak holes on the gas leakage and diffusion is significantly higher than other factors,so it is necessary to avoid the leakage of large holes and dense porous gas leakage accidents.This paper provides a certain reference for the gas company on the old residential gas leakage accident rescue and prevention plans,in addition,this paper has enriched the existing relevant research,has a certain theoretical and practical significance.