Analysis of droplet coalescence and breakage characteristics in axis-in hydrocyclone with diversion-cone

Key words:  hydrocyclone  oil droplet  coalescence  breakage  turbulent kinetic energy  separation performance

Abstract:

The axis-in hydrocyclone is widely used for its pressure increasing flow channels which can realize good separation performances under the condition of low-pressure entrance. The CFD-PBM numerical simulation of oil droplets breakage and coalescence, and separation characteristics in the hydrocyclone was carried out. The influence of operation parameters on the breakage and coalescence was obtained. Meanwhile, the experiment study was carried out to validate the accuracy of the simulation results. The results show that at the place with greater turbulence kinetic energy, the radius of the oil droplet is smaller. With the increase of the entrance flow rate, the turbulent kinetic energy in the overflow and underflow is enhanced and the size of oil droplets decreases. Increasing the entrance flow rate not only increases the tangential velocity and separation efficiency, but also enhances the oil droplet breakage which can reduce the separation efficiency. For the axis-in hydrocyclone, when the entrance flow rate is 3.62 m³/h, the separation efficiency reaches the maximum value. Increasing the overflow split ratio can not only decrease the underflow oil concentration but also enhance the oil droplet breakage in the area of overflow which can result in the decrease of separation efficiency. When the overflow split ratio reaches 20％, the separation efficiency reaches the maximum value.