Structure Optimization And Flow Field Analysis Of Jet Pig

In the petroleum and natural gas transportation industry,paraffin and other impurities condensed on the pipe wall often affect its transportation and efficiency as well as the safety of pipeline transportation.The commonly used pipeline cleaning method is pigging technology,and its main device is pig.In the process of pipeline cleaning,wax plug composed of paraffin and other impurities is often formed at the downstream end face of conventional pig,which blocks the pipeline and affects the efficiency of pigging and causes potential safety hazards.Jet pig is a kind of pig designed and manufactured to solve the problem of wax plug.It uses the high-speed fluid to break up the wax plug at the lower end of the pig and complete the pigging operation at the same time.Therefore,it is of great significance to optimize and study the structure of the jet pig to improve the jet pigging technology.First of all,this paper summarizes the causes of pipeline wax deposition,and expounds the working principle of jet pig.According to Newton's law,the mechanical analysis of the jet pig is carried out,and the relevant theoretical derivation is provided for the calculation of the jet velocity of the pig.Secondly,the working principle and mechanical analysis of disc perforating jet pig,baffled jet pig and composite jet pig are carried out to simplify the physical model,and the flow model is established and meshed by FLUENT software.Finally,using FLUENT software,the paper simulates and analyzes the distribution of velocity,turbulent kinetic energy and pressure of the flow field,draws the relevant lines and summarizes the rules,and changes the diameter,slope and inner surface curve of the baffles under the crude oil and product oil pipelines to the flow field at the outlet The velocity and turbulent kinetic energy are simulated and analyzed,and the relevant graphs and lines are drawn to summarize the rules.The influences of the internal surface changes of the baffles of the composite jet pig under the crude oil and product oil pipelines on the velocity,turbulent kinetic energy and pressure distribution of the outlet flow field are simulated and analyzed.The simulation results show that in the crude oil pipeline environment,the diameter of the baffle plate of the jet pig decreases linearly with the maximum velocity of the flow field,and increases linearly with the maximum turbulent kinetic energy of the flow field;the slope of the baffle plate decreases quadratic with the maximum velocity of the flow field,and increases quadratic with the maximum turbulent kinetic energy;the velocity of the jet pig with different internal surface curve baffle plate The change trend of turbulent kinetic energy in axial position is the same.In the simulation of the product oil pipeline,it is found that the flow velocity at the exit of the jet pig with the baffles of 28-36mm in diameter is basically the same,and the turbulent kinetic energy at the exit reaches the minimum value when the diameter of the baffles is 30mm;when the angle of the baffles is 170°,the maximum flow velocity at the exit is 9.085 m/s,when the angle of baffle is 170°,the minimum value of turbulent flow energy at the outlet is 7.475 m~2/s~2;the velocity and turbulent kinetic energy of the baffled jet pig with different inner surface curve have the same change trend in the axial position.The structure optimization analysis of three kinds of jet pigs shows that:a)for the disc perforation jet pig,in the crude oil pipeline,the optimal position of the perforation structure should be the ratio to the pipeline radius zero point eight eight In the oil product pipeline,the optimal perforation structure position should be selected as the ratio of perforation structure to pipeline radius zero point five five-zero point six five B)for baffled jet pig,in crude oil pipeline In the pipeline and the product oil pipeline,the type of baffle plate should be wittonzinsky function baffle plate;c)for the composite jet pig,the type of baffle plate should be wittonzinsky function baffle plate in the crude oil pipeline;in the product oil pipeline,when the pipe diameter is200-350mm,the third power function baffle plate should be selected,and the wittonzinsky function baffle plate should be selected under the other pipe diameter conditions.