气力提升系统气液两相流数值模拟分析

Numerical simulation of gas-liquid two-phase flow in gas lift system

污水处理、油田采油、液态金属冷却反应堆和磁流体动力转换器等领域采用气力提升系统有其显著优势.由于不同液体介质与气体介质密度对气力提升系统性能影响较大,因此本文基于Fluent仿真软件,采用欧拉模型、k-ω剪切应力输运湍流模型数值模拟了氮气-水、氮气-煤油、氮气-水银及空气-水、氩气-水、氮气-水下气力提升系统内气液两相流动行为,分析了系统稳定时提升立管内气相体积分数、提升液体流量、提升效率、提升管出口处液体径向速度的变化规律.研究结果表明:1)氮气-水、氮气-煤油、氮气-水银系统中,提升管内液体介质密度越大,提升管内气相体积分数越小、提升液体流量越大、提升效率越高;2)空气-水、氩气-水、氮气-水系统中,提升管内气体介质密度越大,提升管内气相体积分数越小、提升液体流量越大、提升效率峰值越小;3)提升管出口处提升液体径向速度随气体充入量的不断增加而整体波动升高,最终管轴中心附近液体速度较大,管壁附近液体速度较小.本文研究成果为污水处理、气举采油、液态重金属冷却核反应堆和磁流体动力转换器等应用领域的气力提升技术的优化提供科学的理论基础.

The gas-lift system has a lot of significant advantages in sewage treatment,deep well oil recovery,liquid metal cooled reactor and magnetohydrodynamic power converters.The densities of different liquid media and gas media have great influences on the performance of gas lift system.Therefore,based on Fluent simulation software,using Euler model and k-ω SST(shear stress transport)turbulence model,the gas-liquid two-phase flow behaviors in nitrogen-water,nitrogen-kerosene,nitrogen-mercury and air-water,argon-water,nitrogenwater of gas lift system are studied.The rules of gas volume fraction and liquid flow rate at lifting pipe,liquid radial velocity at lifting pipe outlet,promoting efficiency are analyzed.The results are shown as follows.1)In the nitrogen-water,nitrogen-kerosene and nitrogen-mercury system,the higher the density of liquid medium,the smaller the gas volume fraction in the lifting pipe is;the greater the flow rate of lifting liquid,the higher the promoting efficiency is.2)In the air-water,argon-water and nitrogen-water systems,the higher the density of gas medium,the smaller the gas volume fraction in the lifting pipe is;the larger the flow rate of lifting liquid,the smaller the peak value of promoting efficiency is.3)With the increase of gas flow rate,the liquid radial velocity at the lifting pipe outlet increases with overall fluctuation rising.Finally,the liquid velocity near the center of pipe axis is large,near the pipe wall is small.These research results provide the scientific theoretical basis for optimizing the gas lifting technology in applications such as sewage treatment,deep well oil recovery,liquid metal cooled reactor and magnetohydrodynamic power converters.