Investigation On Droplet Entrainment Mechanism Of Low Liquid Loading Gasliquid Two-phase Flow In Wet Gas Pipelines

Entrainment fraction is one of the key parameters in gas-liquid two-phase Flow, It has a great impact on wellbore and flowline design, separator design and other aspects. When the gas velocity is sufficiently high, and due to the shearing action of the high gas flow rate, droplet entrainment occurs in the gas-liquid interface. The velocity of entrained liquid droplets is generally close to the flow velocity of the gas in the pipeline, this rate is much higher than the velocity of liquid portion at the bottom of the tube. The gas phase density changes after droplets are entrained, even if the amount of entrained droplets is tiny, it is greatly affect the pipeline pressure drop and liquid holdup. So it is very important to research the droplet entrainment mechanism of low liquid loading gas-liquid two-phase flow conditions. It will make the holdup and pressure drop prediction model perform much better Through improve the entrainment fraction calculation model, If it was applied to the actual project, the pipeline transportation efficiency will be further improved.This paper studies the droplets entrained formation mechanism of low liquid loading gasliquid two-phase flow in wet gas pipelines. Some of the existing models for entrainment fraction calculation were analyzed. A solving program is developed in Visual Basic 6.0 platform based on the calculation model of entrainment fraction in this paper. According to the comparative analysis of various calculation model and experimental data collected, a calculation model—Oliemans et al. modified model which is best suited for the low liquid loading gas-liquid two-phase flow conditions was selected. At the same time, a recommendation of calculation models for different gas and liquid superficial velocity was made. Then the chosen model was improved, and formed a improved entrainment fraction correlation. In addition to this,an evaluation was made between former models and the improved model. The result shows that improved model perform better than other models. At last, the effects of pipeline diameter, interfacial tension, gas liquid viscosity and other parameters on entrainment fraction are analyzed.