Dynamic Simulation of Mechanical Fluid Separation in Solid Bowl Centrifuges

Abstract

Solid bowl centrifuges are used in a wide range of applications in the process industry. The aim is to separate the individual phases of a liquid/liquid, liquid/solid or liquid/liquid/solid system. The design of solid bowl centrifuges is based on the Σ-theory, which does not describe the separation process with a sufficiently high accuracy. This process results in numbers of experiments with high time and cost expenditure. In addition, Σ-theory only describes the stationary state and therefore do not allow the calculation of start-up processes and load changes. This chapter shows a new real-time capable numerical algorithm, which ensures a high computational efficiency and is therefore suitable for dynamic simulations of the process behavior of solid bowl centrifuges. The introduction deals with the state of the art and the existing problems concerning of the design of solid bowl centrifuges. Subsequently, material functions representing the separation properties in solid bowl centrifuges are expounded. The developed material functions are the basis for the dynamic simulation of the process behavior in solid bowl centrifuges described below. The residence time and flow conditions of the apparatus significantly influence the process behavior for semi-batch and continuous processes. The last two sections present the dynamic modeling of continuously operating decanter and semi-batch tubular centrifuges. Example simulations and comparisons to experiments validate the developed dynamic models and demonstrate the applicability for dynamic simulations.