Numerical and experimental study on a bypass pig motion in oil transmission pipeline: a case study
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ORIGINAL PAPER-PRODUCTION ENGINEERING
Numerical and experimental study on a bypass pig motion in oil transmission pipeline: a case study Asghar Talbizadeh1 · Mohammad Mehdi Keshtkar1 Received: 25 February 2020 / Accepted: 18 April 2020 © The Author(s) 2020
Abstract In the oil and gas industry, pipeline networks can be used to transport oil and petroleum products from production center to the consumption center. Regular cleaning and inspecting these pipelines is necessary due to the presence of oil deposits. Typically, pigging operation can be applied to clean and inspect of these pipelines. It is important that the velocity of a pig during its passage in the oil pipeline be controlled. Therefore, it is necessary to identify accurately the fluid flow around the pig in order to describe and evaluate the pigs’ motion. In this study, the computational fluid dynamics (CFD) approach has been applied to model fully turbulent flow around a sample of bypass pig and measure its dynamic velocity. This study tried not only to study the pig motion, but also to investigate the parameters affecting the bypass pig pressure drop and then the optimal state of these basic parameters in the design of a pig is determined. Finally, a numerical analysis of the pig motion is performed for a case study of a 20-ih pipeline to transport of gas oil between Rafsanjan, Yazd and Nain located in Iran and compared with the field test results. The results indicated that the fluid passing through the bypass, the weight and contact force had a significant effect on the pig’s speed, and when bypass diameter was larger, leading to the greater fluctuations. Keywords Transmission pipeline · Hydrodynamic optimization · Pig · Bypass · Computational fluid dynamics List of symbols D (m) Pipe diameter d (m) Diameter in the bypass hole of pig H (m) Disk height h(m) Disk height Kp (−) Pressure loss coefficient L (m) Length P (Pa) Pressure Pt (Pa) Total pressure t (m) Disk Thickness u (m/s) Velocity V (m/s) Average velocity y (m) Distance from the pipe wall Greek symbols 𝜇 (kg/ms) Dynamic viscosity 𝜈 (m2 ∕s) Kinematic viscosity 𝜌 (kg/m3 ) Density 𝜏 (Pa) Shear stress of wall
* Mohammad Mehdi Keshtkar [email protected] 1
Department of Mechanical Engineering, Kerman Branch, Islamic Azad University, Kerman, Iran
Introduction The speed control of the pig can be considered as one of the important problems for the pigging operation due to the limitation in speed and fluid flow inside the pipe. Lack of ability to control the speed of the pig can be caused both no cleaning, and in some more sensitive situations, collecting no information by means of the sensors installed on the pig. There are several methods of speed control of the pig and one of them is the use of bypass to control the pressure difference between the front and back of the pig. The estimation and control speed of pig and the time pig reaches the end of pipelines can greatly help the pipeline pigging success. Several researchers have studied the flow around the bypass pigs. Mc
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