Research On Method For Leakage Detection Of Flammable Gas Pipeline

Flammable gas,with its advantages of clean,high efficiency and convenient transportation,has been widely used in urban life and petrochemical production in recent years.Pipeline transportation is one of the most important way of gas transportation.However,due to natural disasters,pipeline aging and man-made damage,pipelines will inevitably leak in operation.It is of great significance to detect pipeline leakage in time and locate the leakage location for ensuring safe operation of pipeline and reducing economic losses.Based on acetylene pipeline transportation in Dalian Shipyard,this paper studies the detection method of flammable gas pipeline leakage based on negative pressure wave by combining theory with simulation.Based on this method,a design scheme for pipeline leak detection is provided for shipyard.Firstly,the basic principle of leak detection for flammable gas pipeline based on negative pressure wave is described.According to the propagation characteristics of negative pressure wave in pipeline,the location formula of leakage hole is deduced,and the factors that may affect leakage positioning accuracy are also analyzed.According to the knowledge of fluid mechanics,the mathematical model of gas flow in pipeline is established.According to the requirement of calculation accuracy and the characteristics of pipeline,two-dimensional model of pipeline leakage is established in ICEM CFD,and quadrilateral mesh is used for meshing.In FLUENT,the normal working condition and leakage of pipeline are simulated respectively.The variation of gas pressure and flow rate at both ends of the pipeline after gas pipeline leakage is obtained.Secondly,the leakage location method is studied in this paper.In order to simulate real industrial field signals,noise is added to the simulated pressure signals.The wavelet modulus maximum denoising method is used to denoise the noisy signal.The relationship between modulus maxima and singularity is used to solve the problem of time difference calculation(identification of sudden drop point of pressure signal)in leak location.The sudden drop point of denoising signal is identified to calculate the position of leakage point.In addition,the leakage holes at different locations in the pipeline are also simulated and the location errors are calculated.Finally,based on the above research,the leak detection scheme of acetylene pipeline is designed in Dalian Shipyard.The overall architecture of the system and the selection and distribution of sensors is included.