| Energy is the cornerstone of national economic development and social progress,and is closely related to the destiny of all mankind.With the gradual advancement of the State Council's Air Pollution Prevention and Control Action Plan,the “Thirteenth Five-Year Plan for Natural Gas Development”,“Opinions on Accelerating the Use of Natural Gas”and “Beijing's 13 th Five-Year Plan for Gas Development during the 13 th Five-Year Plan” "Construction Plan" and a series of plans and policies to promote the development of urban gas industry,the natural gas industry ushered in a development boom.With the vigorous development of today's society,natural gas has become one of the most widely used energy sources for life and industry.The transportation of natural gas is mainly pipeline transportation.Due to the wide application of natural gas,my country's urban areas are already full of natural gas pipelines.Once the natural gas pipeline leaks,due to the flammable,explosive,and toxic characteristics of natural gas,it will bring great security threats.Therefore,studying the leakage and diffusion process of natural gas pipelines has important practical significance for reducing accident hazards and formulating emergency rescue plans.This article is mainly based on the investigation and analysis of actual work,establishing the model of outdoor gas pipeline,and using CFD(Computational Fluid Dynamics)tools to carry out the numerical simulation of outdoor gas pipeline leakage.In-depth analysis and study of related factors affecting the leakage of outdoor overhead gas pipelines,and exploring the law of influence of each factor.Provide a new idea for similar related research work.The main research ideas are as follows: First,the steady-state and unsteady-state leakage models of natural gas pipeline leakage are briefly analyzed,and the jet theory and fluid mechanics equations are analyzed to determine the calculation method of natural gas leakage diffusion.Secondly,select the structural parameters,use SCDM software to establish a physical model of the area,and use ANSYS Meshing software to divide the mesh,considering the type of mesh,the quality of the mesh and the number of meshes.The setting of boundary conditions includes the inlet and outlet of the leaking hole model and the wall of the leaking gas pipe.In order to ensure the quality of the grid,the independence of the grid must be verified.The factors that affect the leakage and diffusion of gas pipelines are divided into three categories,namely,the size of the leakage aperture,the external wind speed,and the pressure in the pipeline.Using the controlled variable method,the different leakage aperture sizes(10mm×10mm,30mm×30mm,50mm×50mm),different external wind speeds(0m/s,2.5m/s,5m/s),and different pressures in the pipeline(0.15 MPa,0.25 MPa,0.35MPa)on the leakage law of gas pipelines.And carried out a comprehensive analysis from the obtained cloud chart.The following conclusions are drawn: when the pressure in the pipeline is kept constant,as the area of the leakage opening increases,the speed of natural gas injection is obviously attenuated,but its attenuation rate slows down.When the leakage area is 50mm×50mm,the height of gas diffusion is obviously higher than that of the leakage holes with areas of 10mm×10mm and 30mm×30mm,and the larger the area of the leakage hole,the higher the area with larger concentration distribution;as the wind speed increases As the pressure level of the gas pipeline increases,the leeward side will gradually form a vortex,and the gas concentration in the vortex area will be more and more obvious.The wind speed can indirectly increase the concentration of gas hazards,especially on the leeward side.The low pressure pipeline is high,which increases the hazard of gas leakage.Therefore,it is necessary to strengthen the inspection of gas pipelines with high pressure levels in the actual maintenance process to minimize the damage. |
PDF Full Text Request