An efficient numerical approach for transient simulation of multiphase flow behavior in centrifuges

S. Hammerich*, H Nirschl, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany

The mechanical solid-liquid separation is a common used process operation in industry, e.g. chemical, pharmaceutical, waste water treatment and food industry. Centrifuges can be utilized for a wide range of applications e.g. clarification, dewatering, classification. Tubular bowl centrifuges are designed for efficient separation or classification of fine solids due to realization of very high centrifugal acceleration. The separation process is determined by the flow conditions within the machine. The shape of the emerging sediment influences significantly the flow conditions during the separation process. This results in a time-dependent separation efficiency. But Centrifuges are dimensioned by a simplified analytical approach, so-called sigma theory. The complex transient and turbulent flow conditions and the emerging sediment are neglected. Due to this derivations occur between the theoretical and separation efficiency in operation. Therefore costly experiments in Terms of raw materials and time are currently required to optimize centrifuges.

A more efficient method compared to experiments is the application of numerical simulations. An efficient method to simulate the multiphase flow in solid bowl centrifuges taking into consideration the flow behavior of the sediment is being developed at the Institute for Mechanical Process Engineering and Mechanics at the Karlsruhe Institute for Technology. The multiphase is modelled as a mixed phase. To consider the flow behavior, the rheology behavior of suspension and sediment are differently modelled and locally and transient calculated within the centrifuge. The rheological behavior has a significant influence onto sediment distribution in a centrifuge. The influence was investigated by...

Session: L4 - Decanter and Tube Centrifuges
Day: 11 October 2016
Time: 14:45 - 16:00 h