| The pigging operation of natural gas pipeline can clear the water,sediment and other impurities on the inner wall of the pipeline,which can effectively improve the production efficiency of natural gas gathering and transportation system,and ensure the smooth operation of natural gas pipeline transportation.However,there is a high false alarm rate in the way of manual monitoring and tracking,which is not suitable for all natural gas pipelines.How to realize the accurate location of the pipe cleaning device based on the coupled vibration characteristics of pipe soil in the process of pigging is an urgent problem to be solved in practical engineering.therefore,in order to solve the problem,the pigging pig-pipe soil coupling model for analysis of the model using the finite element software is established,the propagation law of defining the factors affecting pipeline vibration and vibration in soil,to detect the vibration signal using optical fiber to pigging and provide a theoretical basis for accurate positioning.The main work of this paper is as follows:(1)Analysis of rubber cup pig,purifier and other different types of pig,and were on the structure of various types of pig,materials,the scope of the study were studied,select the rubber cup pig,which is widely used as the research object to study the characteristics of the pig-pipe-soil model dynamic response in the pigging process;(2)According to the characteristics of the force of the pig and the characteristics of the forced vibration of the buried pipeline,the vibration equation of four degree of freedom in the working state of the pipe cleaner is established by using Darren Bell's principle,and the Euler beam element is used to describe the response characteristics of the pipeline.The coupling system model of the pig pipe-pipe-soil was established by the displacement relationship between the bowl and the pipe;(3)The coupling model is solved by the transient dynamical solver of ABAQUS finite element software,and the vibration of the pipeline under different operating speed and friction coefficient is analyzed.The results show that when the running speed is 0.8 m/s,the pipeline amplitude reaches the peak of 27 ?m.And the pipeline amplitude increases with the increase in the coefficient of friction between the pig and the pipe;(4)The decay rate of the amplitude in the vertical direction is minimum(66.1%)when the distance of the 1000mm is transmitted,but the attenuation rate of vibration velocity and acceleration is basically the same.In the calculation results of different soil elastic modulus,The vibration velocity of the soil with elastic modulus of lOMPa is 200mm,which is higher than that of other soil,and the maximum velocity can reach 70 ?m/s.In the elastic modulus of 50 MPa soil,the maximum vibration velocity of was 27 ?m/s,the results show that the elastic modulus of soil has great influence on the vibration velocity;(5)The frequency spectrum of the vibration signal is analyzed.The results show that the vibration frequency of the vibration signal is concentrated near the 5Hz with the increase of distance.On the basis of this,the 16 layer wavelet soft threshold de-noising method is used to get the vibration signal which is clear and easy to detect.According to the calculation results and the relevant specifications,it is suggested that the effect of laying optical fiber on the 500mm distance above the pipeline is better.According to the response characteristics of the pipe pipe soil coupling system and the law of vibration propagation in the soil,the vibration signal is identified by the optical fiber.The technical scheme of the tracking and positioning of the pigging,including spectrum analysis,wavelet denoising and fiber placement is proposed. |
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