Analysis of Low Liquid Loading Two-Phase Flow Using CFD and Experimental Data

Abstract

Low liquid loading flow occurs very commonly in the transport of any kind of wet gas, where the changing pressure and temperature conditions along the pipeline cause the condensation of hydrocarbon gases and water. The presence of even a small amount of liquid load in the fluid has significant effects on the flow conditions, such as an important increase in the pressure drop and the formation of annular or stratified flow patterns. It can cause important flow assurance issues as well, such as pipe corrosion or unexpected wall stress on the pipeline. This makes the modelling and analysis of these types of flow particularly important to the Oil & Gas industry, in order to improve the design and operation of gas pipelines and downstream facilities. Because of that, this study focused on modelling this type of flow and analysing the effects of moderate or high pressures on the flow conditions, in medium diameter (6-in) pipes, using CFD simulation. A polyhedral mesh was used, and is fineness was determined with a mesh independence test. The physics models were tested against experimental data obtained at the University of Tulsa, focusing mainly on the turbulence and interface models. The selected turbulence model was the k – ? model, and the analysis on the interface models is still ongoing. The Interface Momentum Dispersion model, however, has promising results, though it requires a high computational cost. An inverse relation between the pressure and the liquid holdup was still able to be determined, since the higher gas density and viscosity cause a higher drag force on the liquid face, which reduces its holdup.