Design And Research Of Speed Adjuster For Bypass PIG

Pipeline transportation is an important "lifeline" for national energy development and plays an important role in national economic and social development.With time passes by,the accident risk of pipelines becomes prominent,and leaks and explosions occur frequently.The regular inspection of pipelines by pigs with intelligent detection equipment helps to predict and control the risk of pipeline accidents in advance.However,the PIG is directly driven by the fluid in the pipeline,and its operating speed is difficult to control,which reduces the reliability of pipe cleaning and detection results.In order to control the pigging speed,a series of studies were conducted on the speed control device of the controllable speed pig.By comparing the performance parameters of the Bypass PIG at home and abroad,the bypass valve control speed pig was taken as the research object.The influence of the structural parameters of the bypass valve on its speed control performance was analyzed in detail,and a set of speed control device was designed and manufactured for the bypass valve.The specific research works are as follows:(1)After in-depth studies on the status of the Bypass PIG,the contents and technical route for the design of the speed control device of the Bypass PIG was proposed to solve problems in present researches.(2)Factors affecting the movement of the controllable speed pig were explained.The flow model of fluid in long-distance transportation pipes and the stress model for the movement of the Bypass PIG were established on the basis of some assumptions.The method of controlling the operating speed of pig by adjusting the pressure difference was proposed.The design conditions for the DN800 natural gas pipeline in Hangyong Line in Zhejiang were used for trial calculation of the maximum bypass area ratio of pigs.(3)The reverse analysis of commercial Bypass PIG was carried out.The fluid resistance coefficients of the Bypass PIG developed by ROSEN,Spetsneftegaz and TD Williamson were analyzed.The numerically calculated results were used to establish the relationship model among the relative opening degree,the fluid drag coefficient and the load torque of various speed governing devices.The bypass valve speed governing device was selected as the research object after taking into account the speed control ability,power consumption,and pigging efficiency of pigs.(4)Based on the flow resistance characteristics of the bypass valve.The main parameters of the bypass valve device of the Bypass PIG were designed.The maximum bypass area ratio of the bypass valve was determined by taking the frame size of the pig as the limiting condition.On this basis,the axial length,end face port and chamfering parameters of the discharge hole on the bypass valve,as well as the resistance coefficient characteristics of the motor compartment and the battery warehouse were studied.The bypass valve device was redesigned by adjusting the transmission strategy of natural gas.The hydraulic torque of the bypass valve was analyzed,and a bypass valve testing system with a diameter of 100 mm was established in the laboratory.The mutual verification of the test and simulation data of the bypass valve drag coefficient was realized.(5)Combining the results of theoretical research and experimental tests,the speed governing device of the Bypass PIG was designed.The finite element simulation analysis was performed on key components to verify the strength of the structural design.The speed control device was manufactured.