高含水采出液T形管分离器的流场数值模拟

传统的油田集输工艺损耗能量大,运行成本高。鉴于此,基于Fluent数值模拟软件,采用RNG k-ε湍流模型和欧拉多相流模型对T形管分离器的流场特性以及油水分离过程展开研究。研究结果表明:油水两相速度分布规律基本相同,在主管中沿流动方向速度逐渐降低,分支管中速度最大,水相在主管顶部区域速度较小,在汇管中上述分布趋势更加明显;湍流在分支管和主管连接处、分支管和汇管连接处以及汇管上游较为剧烈,油水发生强烈掺混;入口流速对油水分离过程的影响较大,流速越大,流体的停留时间越短,分流扰动后恢复为分层流更加困难;流速越大,油水剪切作用增强,油滴更均匀分散在水中,混合层携带更多的油相,故操作中需要确定最佳流速;随着含油体积分数增大,混合层厚度增加,最终分离效率呈现先缓慢增加,后逐渐下降的趋势;分流比较低时,汇管主要流出底层水,分离效率较低;随着分流比增大,汇管的流量增大,油水间扰动增强,流体流经汇管携带了部分混合层流体,分离效果明显提升;但分流比继续增大,混合层全部流入汇管后,油层开始流入汇管,此时分离效率随着分流比的增大呈线性降低。基于研究结果,最优操作参数为:入口流速0.10~0.30 m/s,入口含油体积分数5%~9%,分流比0.5~0.7。研究结果为油水分离提供了新思路,可为探究高效分离效果的设备结构设计和优化提供参考。

Numerical Simulation of Flow Field in T-junction Separator of Produced Liquid with High Water Content

T-junction separator has the characteristics of simple structure,no moving parts,easy design and installation,less maintenance,low operating cost,low energy consumption and small footprint.It has a wide range of application prospects in the filed of oil-water pre-separation.Based on the Fluent numerical simulation software,the RNG k-εturbulence model and the Euler multiphase flow model are used to study the flow field characteristics of the T-junction separator and the oil-water separation process.The research results show that:the oil-water two-phase velocity distribution is basically the same.The velocity gradually decreases along the flow direction in the main pipe.The velocity is the highest in the branch pipe.The water phase velocity is smaller in the top area of the main pipe and even smaller in the manifold.The turbulence is violent at the junction of the branch pipe and the main pipe,the junction of the branch pipe and the manifold,and the upstream of the manifold,where oil and water are strongly mixed.The inlet flow rate has a greater impact on the oil-water separation process.Higher flow rate results in shorter residence time of the fluid,and make it more difficult to recover to stratified flow after split flow disturbance.In addition,greater flow rate leads to enhanced oil-water shearing effect,and the oil droplets are more uniformly dispersed,resulting in more oil phase carried in the mixed layer.So the optimal flow rate needs to be determined during operation.As the oil volume fraction increases,the thickness of the mixed layer increases.The separation efficiency depends on the relative value of the water phase flow ratio and the oil phase flow ratio in the manifold.The final separation efficiency shows a slow increase at first and then a gradual decrease.When the split ratio is low,the manifold mainly flows out of the bottom water,and the separation efficiency is low.As the split ratio increases,the flow of the manifold increases,and the disturbance between oil and water increases.The fluid flowing through the manifold carries part of the mixed layer fluid and separation effect is significantly improved.However,when the split ratio continues to increase,all the mixed layer may flow into the manifold,and the oil layer may begin to flow into the manifold.In this scenario,the separation efficiency decreases linearly with the increase of the split ratio.Based on the research results,the optimal operating parameters are:the inlet flow velocity is 0.10~0.30 m/s,the inlet oil volume fraction is 5%~9%,and the split ratio is 0.5~0.7.The study provides new ideas for oil-water separation.