Design of industrial crystallisers for a given product quality

The main challenge in the design of industrial crystallisers is to predict the influence of crystalliser geometry, scale, operating conditions and pro cess actuators on the process behaviour and product quality. The quality ch aracteristics, such as the crystal size distribution, inclusion content and morphology determine to a large extent the product performance and are the refore of importance. The quality of the product crystals is basically dete rmined by the rates at which crystals are born and attrited, grow or dissol ve and agglomerate in the different regions of the crystalliser. An analysi s technique is therefore introduced to describe the various crystallisation phenomena as a function of local process conditions such as supersaturatio n and energy dissipation. This technique is based upon: the derivation of pure kinetic parameters from an MSMPR experiment. setting up compartmental models for design alternatives in order to separat e kinetic and hydrodynamic phenomena. analysis of the process behaviour of the design alternatives by applying th e same kinetic model and parameters for each compartments. optimisation of the design alternatives with respect to product quality usi ng crystalliser geometry, operating conditions and the appropriate process actuators, like a fines removal system, as degrees of freedom. The advantage of this technique over conventional techniques is illustrated for an evaporative DTB crystalliser. (C) 1999 Elsevier Science B.V. All ri ghts reserved.