Analysis And Research On Venting Process Of Natural Gas Pipeline

With the rapid development of China's natural gas industry,the volume of natural gas longdistance transmission pipelines is also increasing.As an important means to ensure the efficient and safe operation of pipelines,venting has been widely used in the field.In the event of an emergency or reconstruction,venting operations will be performed to varying degrees to prevent pipeline pressure from exceeding limits,ensure safety,and reduce the risk rate of accidents.However,the current on-site venting is basically a static venting model of an infinitely large container,ignoring the impact of friction caused by the venting process on the flow process,resulting in a static venting model that cannot accurately describe the dynamic change trend of various parameters during the venting process;meanwhile,the on-site venting only records Vent time,unable to grasp its specific venting process.Therefore,it is necessary to establish a dynamic model for natural gas pipeline venting and simulate the dynamic pipeline venting process in order to meet the requirements of the actual venting process and provide reliable technical guidance for the formulation and implementation of the venting operation plan.In view of the above problems,this paper has carried out research on the dynamic simulation technology of the venting process of natural gas pipelines,and has compiled a simulation calculation program for the venting process.Firstly,the two venting process models on site are analyzed,that is,the station venting model and the pipeline venting model.Then,the static and infinite station venting model is analyzed and simulated to determine the basic structural characteristics of the venting model.The flow process and principle provide theoretical support for the dynamic simulation of the venting process of natural gas pipelines.Secondly,make reasonable assumptions on the dynamic simulation model,determine the basic flow relationship,and calculate and compare the flow relationship with the program.A dynamic model of pipeline venting is proposed,which includes a nonlinear partial differential equations and initial boundary conditions..The characteristic equation method is used to solve the pipeline venting dynamic equation,and the Runge-Kutta numerical difference solution method is used to determine the initial distribution conditions of the venting flow,and the dynamic simulation coupling solution of the pipeline venting process is realized.Subsequently,the pipeline venting process simulation calculation program was written in Java.Compared with the literature data,the maximum relative error was 9.42%,and the maximum relative error was 9.58% compared with the software calculation result.The dynamic model of venting was verified.The calculation results can accurately describe the venting flow process of natural gas pipelines.Finally,the actual gas pipeline on the site is taken as an example to be compared with the calculation program again to verify the correctness of the program,and also to verify the correctness of its calculation results.Then,the factors that affect the venting time of the natural gas pipeline are analyzed in detail,and the four aspects of venting pipe diameter,main line pressure,venting pipeline length,and valve opening are studied,and the main factor affecting the venting time of the natural gas pipeline is finally vented Pipe diameter,main line pressure,and valve opening,and through comparison of planned venting methods,it is concluded that a three-stage venting method should be used for field venting,and the optimal valve adjustment times are optimized to guide the field venting.