Numerical Simulation Analysis Of Leakage And Diffusion Of Buried Low Pressure Natural Gas Pipeline

With the continuous development of industrial industry at home and abroad,air quality problems are increasingly obvious.In order to prevent the deterioration of air quality,natural gas has gradually become the main fuel in the 21 st century.At present,Beijing has built more than 20000 kilometers of urban gas high,medium and low pressure pipe network,which is close to the level of developed cities in the world.However,with the increase of buried natural gas pipeline construction and pipeline service life,gas pipeline safety has gradually become the focus of attention.Based on the investigation and statistics of gas pipeline leakage events in Beijing a area gas operation Institute in recent five years,it is found that the third-party external force damage and corrosion damage of gas pipeline are the main causes of gas pipeline leakage events.Combined with the case analysis of pipeline leakage events in this operation Institute,the severity level of gas leakage events is established.Based on the basic theory of leakage of buried gas pipeline and porous media theory,the leakage model of buried low-pressure natural gas pipeline is established as the leakage model of small holes in the pipeline according to the actual situation of the project.With the help of ANSYS fluent fluid dynamics simulation software,the leakage of natural gas is simulated and studied under the three influencing factors of different leakage holes,different soil moisture content and different buried depth of gas pipeline.After the leakage,the methane concentration distribution of the gas diffused into the atmosphere through the soil is analyzed,and the leakage and diffusion law of the buried natural gas is obtained.Finally,the leakage detection data of the buried natural gas is compared with the actual data for verification.Based on the simulation results of CFD software,it can be concluded that the diffusion of natural gas(methane)in soil air region can be divided into rapid growth stage,slight decline stage and stable stage.The leakage pore size,soil moisture content and buried depth of the pipeline will affect the diffusion speed of natural gas,providing a certain reference for the pipeline network operators.