Prediction of multiphase flow and separation efficiency of industrial centrifuges by means of numerical simulation

Centrifugal separation of particles in a suspension is one of the most common problems appearing in industry such as chemical processing, mining and mineral processing, solid-fuel industry, food processing, waste water treatment, pharmaceutical processes and biotechnology. The separation of the cream in the whole milk to obtain skimmed milk, the isolation of blood components, the purification of beverages, the removal of catalysts in multiphase reactors or the cleaning of waste water and industrial fluids such as lubricants or coolants, are some relevant examples where centrifugal separation is needed. Centrifuges are, together with sedimentation tanks and filters, one of the most commonly employed devices for mechanical solid-liquid separation. Sedimentation uses as its driving force a mass force based on the different densities of the phases. In sedimentation tanks this driving force is gravitational force while in centrifuges it is centrifugal force. Filters, instead, make use of differential pressure as a driving force. The choice of which technique should be applied for a specific separation task depends on the properties of the mixture, the purpose of the separation, whether the thickening of the solid phase or the clarification of the liquid, and the available time and space. The rapid development of the centrifugal technology nowadays allows high efficiencies separating very small particles, even in the nanometre range, from multiphase flows.