Published Article

ABSTRACT One of the underlying challenges associated with multiphase transport is slugging. To grasp its fundamentals, a Computational Fluid Dynamics (CFD) analysis is employed to study the consequences of altering pipeline/riser systems’ superficial velocities on slugging. The analysis is carried out on six different combinations of air and water superficial velocities. Tested air superficial velocities ranges between 14 m/s and 4 m/s while keeping that of water constant at 2.5 m/s. Tetrahedral mesh of 0.017 cell size is employed in a 0.25m diameter pipeline riser system. The system design contains a 9m horizontally inclined flowline, connected to a 5-meter riser with the help of a 1.25m radius of curvature bend. A steady injection of equivalent volume fraction of water and air into the transient system with an initial bottom slug, induced by the inclination shows zero slugging at high velocities and substantial amount of slugs at lesser velocities. From the work, it was observed that with the absence of bubbles or any form of intermittency, in the flow line, the flow pattern along the line is stratified. It was also observed that varying the initial gas superficial velocity does not affect the incremental effect of gas phase volume fraction as flow heads towards the bend. Besides, it is obvious that the animation clips, 3 dimensional views, and volume fraction reports indicate higher liquid content along the bend during flow. Finally, it was observed that the tendency for slugging increases as the inlet superficial velocity of the gas is reduced. The slug length also increases as the superficial gas velocity is reduced. It was concluded that slugging tends to increase along the pipeline riser system as the slip ratio reduces and that increase in air velocity while keeping that of the liquid constant will prevent slugging in the pipeline riser system. One of the recommendations was that a detailed comparison between CFX result and field data should be made to check for the level of accuracy that CFX result can render. Keywords: Riser; Slugging; Simulation; Pipeline; CFD; Multiphase flow; Superficial Velocity; ANSYS CFX....