Research On Numerical Simulation Of Compound Hydrocyclone For Oil-water Separation

Most oil field in China has entered the middle and later period of exploitation at present, and the moisture content of many oil field is more than eighty percent. Due to the requirements of environment protection, a lot of produced liquid will be injected back to underground, so it needs high efficiency and energy saving oil-water separation technology. Because of good working performance, the hydrocyclone separation technology which is based on hydrocyclone separation principle, is widely used. However, the traditional hydrocyclone also has many shortcomings. Compound hydrocyclone which is in combination with the characteristics of static hydrocyclone and dynamic hydrocyclone, is a new kind of separation equipment, and it has broad application prospects.In this paper, internal strongly swirling flow inside compound hydrocyclone was researched through numerical simulation based on CFD. Geometric model was built by Gambit software, and Reynolds stress model combined with Mixture model was selected according to the anisotropic characteristics of internal flow field. The distribution situation of pressure field, velocity field and oil concentration field was obtained. The simulation results reveal the distribution rules of pressure, tangential velocity, axial velocity, radial velocity and oil volume fraction.This paper studied the influence of four operation parameters such as split ratio, oil concentration, flow and impeller speed on pressure loss and separation performance of compound hydrocyclone. The results show that smaller split ratio, larger flow and faster impeller speed will lead to increasing underflow pressure drop. Overflow pressure drop increases along with higher split ratio, oil concentration, flow and impeller speed. When split ratio and impeller speed increase, or flow decreases, simplified efficiency will increase accordingly. Through orthogonal test, the primary influencing factor of four operation parameters on underflow pressure drop is flow, followed by impeller speed, split ratio and oil concentration. The primary effect factor on overflow pressure drop is split ratio, followed by flow, oil concentration and impeller speed. The primary influencing factor on simplified efficiency is flow, followed by impeller speed, split ratio and oil concentration. According to orthogonal analysis, the operation parameter condition with maximum simplified efficiency could be obtained.The influence of some structure parameters of rotary impeller and overflow pipe on working performance was investigated in this paper. Through respectively changing impeller diameter, impeller length, leaves number and overflow pipe diameter, the change of underflow pressure drop, overflow pressure drop and so on were researched. It could provide a certain reference for future design and study.