CFD Study of the Effect of Geometrical Shape of Separation Blades on the Rotor Performance of an Annular Centrifugal Extractor (ACE)

Annular centrifugal extractors have a great potential in the multiphase extraction of pharmaceutical, nuclear, and many other processes. Although the widespread use of this device, the design procedures are still unavailable because of the complexity of the fluid mechanics in the rotor region called the separation zone. From a structural point of view, this region has a complicated conception due to the different internals. This study presents a three-dimensional numerical simulation of the flow field inside the rotor region of an annular centrifugal extractor ACE. The industrial CFD code (Fluent) was used to model the highly swirling fluid flow in the settling zone with various geometries of separation blades (straight blades and curved blades). Numerical predictions and experimental results were compared in order to validate the proposed models. The velocity field with the k-ε model shows a good agreement with the experimental data available in the literature. The Volume of Fluid (VOF) method was employed to simulate the physics of the interface of air/water free surface. A comparison between the flow field and the performances of the ACE model design with vertical straight blades and with vertical curved blades was further investigated to study the effect of the geometric shape of the separation blades on the parameters of liquid holdup volume, the interface radius and the pressure drop. It was found that the geometry of the separating blades has a significant impact on the pressure drop, liquid hold-up volume and interface radius and general flow in the extractor-settling zone. The predicted pressure drop proved that the geometry of the ACE rotor with curved blades leads to a lower values of pressure drop.