The Accident Consequence Analysis And Leakage Numerical Simulation Of Urban Gas Pipeline Leakage And Diffusion

In recent years,natural gas,as an important clean energy,has been widely used in many fields such as power generation and heating,transportation,manufacturing,and daily life of residents.However,during the development of natural gas in China,the construction standards of natural gas pipeline entry corridors are still blank,and there is a lack of relevant actual monitoring data.This has brought great challenges to the operation of the city's underground comprehensive pipe corridors and the construction of the natural gas entering corridor projects under construction.Therefore,it is of great theoretical and engineering significance to analyze the leakage and diffusion of natural gas pipelines in the pipe corridor.This paper takes the natural gas pipeline in the corridor as the research object and uses the method of numerical simulation to analyze the law of natural gas leakage and diffusion and the consequences of the accident.First,according to the ventilation and explosion-proof requirements for the construction of natural gas pipelines into corridors,the six major risk factors for accidents were determined,and the implementation of various national standards in projects under construction was verified.On this basis,according to the actual engineering design data,the corresponding simplified physical model is separated.Aiming at the natural gas leakage accident in the confined space,the matching mathematical model and research method were selected,and the concentration distribution of natural gas was studied using Fluent numerical simulation software.The effects of leakage aperture,initial leakage velocity and cabin wind velocity on the leakage consequences are analyzed.The results show that the larger the leakage pore diameter and the higher the initial velocity at the leakage pore,the faster the diffusion velocity.When the large hole leaks,the concentration stratification of natural gas in the cabin is more obvious,and the intervals between layers with different concentrations are more even.When there is no ventilation,the leaked natural gas is symmetrically distributed in an umbrella shape with the orifice as the center;when there is ventilation,the natural gas is deflected and diffused in the downward wind direction.Increasing the frequency of ventilation can effectively dilute the natural gas.The higher the wind speed,the better the ventilation effect.Taking 1% of the natural gas volume fraction in the independent cabin as the alarm concentration,set the corresponding monitoring points according to the current national standards,and change the leakage pore diameter and leakage rate respectively,and compare the change of the alarm concentration range and the time interval of reaching the alarm concentration at special points.The results show that when the leakage time is 30 s,the leakage aperture increases from 5mm to 40 mm,the danger range increases from 5.5m to 18 m,and the alarm time is shortened from 13 s to 3.5s.The leakage speed was increased from 50 m / s to 150 m / s,the danger range was increased from 10 m to 22 m,and the alarm time was shortened from 18 s to 4.8s.The wind speed increased from 2m / s to3 m / s,and the danger range increased 18 m.Finally,the TNT equivalent method was used to calculate the consequences of the explosion,and the radius of property loss caused by the leakage aperture of 10 mm and the leakage velocity of 100 m / s was obtained.The schematic diagram of the shock wave was drawn using MATLAB software.In this article,through the study of the consequences of the accident of the natural gas pipeline leakage and diffusion process in the integrated pipeline corridor,we have a deeper understanding of the natural gas pipeline leakage accident in the independent cabin.The theoretical basis,and the consequences of the accident,are also clarified,which can also help in the preparation of emergency plans for gas leakage events in the pipe corridor.