Numerical investigation of the effect of the cylindrical height on separation performances of uniflow hydrocyclone

Cyclone performances can be improved by changing operational conditions and/or geometrical parameters. In this work, the influence of the cylindrical height on the flow field, pressure drop and separation performances within a uniflow hydrocyclone will be studied numerically using Computational Fluid Dynamics “CFD”. The simulation of the continuous phase is based on the Reynolds Averaged Navier-Stokes “RANS” approach, using the finite volume method. The turbulence model “Reynolds Stress Model: RSM” was used to numerically solve the adequate equations of a three-dimensional and turbulent flow in order to determine the flow field of the continuous phase. The interface between the liquid and the air core in hydrocyclones was modelled using the free surface model “Volume Of Fluid: VOF”. Based on the results of fluid flow, the stochastic Lagrangian model “Discrete Phase Model: DPM” was adopted in order to simulate particle trajectories and predict the separation efficiency. Comparison investigations showed that the cylindrical height has a significant effect, particularly on pressure drop and separation performances, as increasing the cylindrical length of a uniflow hydrocyclone improves the separation efficiency and pressure drop until a specific value is reached. Uniflow hydrocyclones with cylindrical height L/D=2.15 can be used for classification because their grade efficiency curve is “S” shaped, while the other studied cylindrical heights can be used for high separation because their grade efficiency curves showed a high efficiency even for small particles.