Filtration Processes

Abstract

Solid/liquid separation by filtration is one of the unit processes of chemical engineering in the same way as distillation, crystallisation, heat transfer, etc. However there is a certain unpredictability about the process due to the inability of fully describing the properties of solid/liquid systems and of relating properties to the performance of equipment. For example in distillation the vapour/liquid equilibrium, together with the well known standard physical properties of the products concerned, can be sufficient for an adequate on-paper design of a plant with a throughput of several thousands of cubic meters per day. In filtration a knowledge of the properties of the liquid and the solid components, even down to the size distribution and physical chemistry of the particles, is not sufficient to allow reliable design without laboratory testing. Even in an established process small changes in physical conditions can not be easily taken into account. For example change in temperature may not just affect viscosity but also the flocculation of the particles and bring about large variations in performance of a piece of equipment.