Analysis and Modeling of Liquid Holdup in Low Liquid Loading Two-Phase Flow Using Computational Fluid Dynamics and Experimental Data

Low liquid loading flow occurs very commonly in the transport of any kind of wet gas, such as in the oil and gas, the food, and the pharmaceutical industries. However, most studies that analyze this type of flow do not cover actual industry fluids and operating conditions. This study focused then on modeling this type of flow in medium-sized (6-in [DN 150] and 10-in [DN 250]) pipes, using computational fluid dynamics (CFD) simulations. When comparing with experimental data from the University of Tulsa, the differences observed between experimental and CFD data for the liquid holdup and the pressure drop seemed to fall within acceptable error, around 20%. Additionally, different pipe sections from a Colombian gas pipeline were simulated with a natural gas-condensate mixture to analyze the effect of pipe inclination and operation variables on liquid holdup, in real industry conditions. It was noticed that downward pipe inclinations favored smooth stratified flow and decreased liquid holdup in an almost linear fashion, while upward inclinations generated unsteady wavy flows, or even a possible annular flow, and increased liquid holdup and liquid entrainment into the gas phase.