Design And Research Of Bypass PIG For Long Distance Natural Gas Pipeline

Pipeline is the most safe and efficient transportation tool for petroleum and natural gas.However,due to corrosion,natural disasters and man-made damage other factors often lead to pipeline leakage,resulting in fire,explosion and other accidents.It is helpful to eliminate the hidden danger and reduce the accident rate of pipeline by detecting the long-distance pipeline periodically through sensors such as magnetic flux leakage sensors and ultrasonic sensors carried by PIG.The PIG utilizes the differential pressure formed by the fluid in the pipe at both ends of the PIG.This passive driving mode leads to PIG operation speed is difficult to control within the preset speed range,which reduces the reliability of the detection data and may causing damage to the pipe and the detector itself.In order to solve the problem that the speed of the PIG is difficult to control,a kind of bypass PIG which can control the speed is carried out in this paper.The main work includes the design of the overall scheme,design and research of speed control system and drive system of the bypass PIG and prototype trial and testing,embodied in the following aspects:(1)Through extensive access and retrieval of relevant documents at home and abroad,the application status of bypass PIG and the research status of its key components was deeply investigated,on this basis,according to the current pipeline inspection problems and the shortcomings of existing research on bypass PIG,puts forward the main research contents and the design and research route of the bypass PIG for long distance natural gas pipeline.(2)The structure,working principle and speed control mechanism of the variable speed pig are described,and the overall scheme design of the bypass PIG is completed.The bypass PIG overall size design and overall layout design.(3)The speed regulating performance of the bypass PIG is studied,and the design of speed regulating device is completed.Based on Fluent,the drag coefficient of the bypass PIG at different opening of the bypass valve was studied,and the fitting equation of the drag coefficient in flow field was established,on this basis,the structure design of the bypass valve of the bypass PIG is completed.(4)The mechanical properties of the bypass PIG were studied,and the structural design of the bypass PIG was completed.Firstly,the constitutive equation of the polyurethane material was established based on the mechanical properties of the polyurethane material.Secondly,the nonlinear finite element analysis software ABAQUS was used to simulate the mechanical behavior of the bypass PIG.The influence of structural parameters on the friction and contact pressure between the cup and the inner pipeline wall.Finally,the design method and flow of the bypass pig pipe are put forward,and completed the design of the bypass PIG's cup for DN800 long distance natural gas pipeline.(5)The prototype manufacture and test of the bypass PIG were carried out.Conbined with the speed control principle of bypass PIG,a method for improving the speed stability and reducing the power consumption of the bypass PIG is designed,and complete the control system hardware development.According to the overall design of the bypass PIG and the design of key components,completed the bypass PIG prototype trial and test,the test results show that the tested performance can meet the design requirements.