Research On Blockage Detection Method For Natural Gas Pipeline Based On Pressure Wave

With the continuous development of China's social economy,the people's quality of life and standard of living are constantly improving.Nowadays,China's consumption of natural gas is increasing,natural gas has become an indispensable energy source in people's daily work and life.Pipeline transportation is one of the main modes of natural gas energy transportation,in order to achieve the strategic goal of healthy and sustainable development of the natural gas industry,China has begun to establish a natural gas supply and transmission network system that tends to be perfect.However,with the passage of time,some natural gas pipelines in China will enter the aging stage of frequent accidents.In addition,due to pipeline design defects,complex natural environment conditions,pipeline spanning many regions,various types of fluid media,pipe corrosion aging,human factors and other reasons,accidents such as blockage are likely to occur during the transportation of natural gas pipelines.Pipeline blockage is difficult to find in daily maintenance,it will not only affect the normal production,but also consume a lot of manpower and material resources in the later stage of the blockage removal work,which poses a huge threat to people's lives,property and living environment.In order to ensure the safety,economy and environmental protection of natural gas in the transportation process,to improve the service life of natural gas pipelines,we need to constantly strengthen the construction and maintenance of natural gas pipelines.Therefore,it is very necessary to conduct in-depth research on the detection methods of natural gas pipeline blockage and to explore an effective and practical detection method of pipeline blockage.The detection technology of natural gas pipeline blockage based on pressure wave method is studied in this paper.The physical model is established according to the type of natural gas pipeline blockage.Based on the relevant theories of pipeline hydrodynamics and thermodynamics,a complete mathematical model of unsteady flow in natural gas pipeline plugging is established.The principles and characteristics of various numerical methods are analyzed and summarized,and the characteristic line method is selected as the model solving method,and the boundary conditions suitable for pipeline blockage are put forward.The model verification program is designed by software MATLAB.Based on the analysis of pipeline transient flow process,the method of detecting and locating pipeline blockage based on pressure wave method is introduced.The formula for calculating the propagation velocity of pressure wave in pipeline medium is deduced,and the method for determining the detection characteristics of incomplete blockage is proposed.Wavelet transform is used to process pressure wave signal.The process of wavelet denoising is simulated.By comparing and optimizing the wavelet basis function,the method of judging whether the signal is singular at a certain point is put forward.The blockage location method combining pressure wave method and wavelet transform method is obtained.Through software MATLAB,numerical simulation is carried out for three situations: stable operation of natural gas pipeline,complete blockage and incomplete blockage.The simulation results show that the plugging transient flow model of natural gas pipeline established in this paper is correct.The relative error of location of blockage point is 1.76% in complete blockage and 0.95% in incomplete blockage.Consequently,the pressure wave method is feasible to detect the blockage of natural gas pipeline,and the accuracy is high,which meets the engineering requirements.