Separation Mechanism And Characteristics Study Of The Gas-injected Liquid-liquid Hydrocyclone

Gas-injected liquid-liquid hydrocyclone, a new kind of high efficient centrifugal separationequipment, developed based on the normal used liquid-liquid hydrocyclone. It has many virtues,such as small volume, large capacity, small cut size and high floatation speed. It has beenconcerned by many scholars and engineers.By mechanism analyzing, numerical simulation and engineering testing, the separationmechanism and flow field characteristics of the gas-injected liquid-liquid hydrocyclone werestudied.Numerical simulation was carried out by using hydrodynamic software FLUENT, based onReynolds average N-S equation. RNG k-ε model was taken as turbulent model, control volumemethod was considered, SIMPLE arithmetic method was applied. By modifying the correlationparameters in control equation, the interior flow field of the gas-injected liquid-liquidhydrocyclone was analyzed. By numerical calculating, the velocity distribution characteristics,pressure distribution characteristics, turbulent energy and its dissipation rate of the hydrocycloneflow field were obtained.Mixed model was adopted to treat with multiphase flow. The distribution rule and theseparating characteristics of oil-gas-water three-phase flow field were calculated. The oil phaseconcentration distribution and the radial velocity distribution of big cone segment shows that thebig difference in radial velocity between water phase and oil-gas compound body is the primaryreason for the fast, high efficient oil-water separation of gas-injected liquid-liquid hydrocyclone.For the sake of validating the numerical calculating result, the separation characteristics of thegas-injected liquid-liquid hydrocyclone were experimental studied, which includes laboratoryexperiments and oilfield locale examination. The examination result shows that under the sameconditions, the gas-injected liquid-liquid hydrocyclone could enhance oil-water separationefficiency by about 10%, compared to the normal used liquid-liquid hydrocyclone. When thegas was injected through inlets, the separation efficiency can reach about 95.7%, i.e., the oilconcentration of underflow can be reduced to 25.7mg/L, which is in accordance with thenumerical simulation result.This work provides theoretical base and experiences for further research of the separationmechanism, flow field characteristics and structural optimization design of the gas-injectedliquid-liquid hydrocyclones.