A Model to Predict Liquid Holdup and Pressure Gradient of Near-Horizontal Wet-Gas Pipelines

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractA mechanistic two-fluid model with new closure relationships is proposed to predict liquid holdup and pressure gradient of stratified flow. The proposed closure relationships include correlations of wetted wall fraction, liquid-wall friction factor, and interfacial friction factor.An iterative calculation procedure is implemented to solve for liquid holdup and pressure gradient for a given set of operation conditions, pipe geometry, and fluid properties.Two sets of facilities, a small-scale with 51-mm ID and a large-scale facility with 150-mm ID test sections, were used to tune the model. Superficial gas and liquid velocities were varied from from 5 to 25 m/s, and 0.00025 to 0.03 m/s, respectively in the small-scale facility while they were varied from 7.5 to 21 m/s, and 0.005 to 0.05 m/s, respectively in the large-scale facility. The pipe inclination angle varied from -2˚ to 2˚. The liquid holdup was ranged between 0.003 and 0.12 emphasizing the low-liquid loading two-phase flow.The tuned model performance was then benchmarked against the high-pressure (up to 90 bar) SINTEF stratified flow data. The model predictions agreed well with measured values of liquid holdup and pressure gradient. The comparison between the present model and OLGA performance was also presented.