(58w) Modeling Hydrocyclones Using Two Fluid Model (Eulerian-Eulerian) Approach

Hydrocyclones are vastly used in coal separation, petrochemical engineering, mineral processing and pulping. Tangential injection of the liquid into a cylindrical chamber causes the development of a vortex. The chamber has a restricted axial bottom outlet such that all of the liquid in the vortex cannot escape via this outlet. A portion of the liquid has to reverse its path and flow towards the axial top outlet. This reverse flow continues to rotate and an air core develops due to lower pressure at the axis of rotation. As a result the heavy components move circumferentially toward the wall of the vessel where they agglomerate and spin down the wall to the outlet at the bottom of the vessel. Light components move toward the axis of the hydrocyclone where they again move up toward the overflow outlet at the top of the vessel.

Numerical simulation is a powerful tool to understand the flow behavior, calculate the pressure drop, particle trajectories and collection efficiency of hydrocyclones. Also it can reduce the experimental costs required for testing and optimization. While extensive work has been done on performance, scale-up, and simulation of hydrocyclones the effect of used approach in the results is not yet clear and there are discrepancies between models according to mesh type, turbulence model and seeding rate.

In this work, the Two Fluid Model (TFM) approach will be compared with Lagrangian Particle Tracking (LPT) approach. In case of low feeding solids, the CFD-LPT approach results are accurate and computationally efficient. However, as the effect of inter-particle interactions as well as the reaction of particles on the fluid are ignored its application is limited. On the other hand, in TFM both the fluid and solid phases are treated as interpenetrating continuum media and therefore it can handle feeding solids at different concentrations. We used Reynolds Stress Model and compared various cases to show the advantages of TFM approach. In addition, we showed that an increase in the inlet pressure will increase the static pressure differential along the radius within the cyclone body hence more water split into overflow. At the end, we discuss the effect of particle density on efficiency of cyclone.