Piotr Synowiec

How to improve the crystal size distribution (CSD) in crystallizers with the inner suspension circulation

An analysis of limited crystal growth in the crystallizer with inner suspension circulation has been studied. The new exhaustively theoretical analysis of crystal attrition sources, pumping effect and power input requirements, as well as the experimental investigations in concentrated suspensions have been done, respectively. In the light of collected theoretical and experimental evidence, in the Draft Tube Magma (DTM) crystallizers there are no significant possibilities for improvement of crystal size. The new constructional modification of DTM crystallizer was proposed for achieving better crystal quality. The new apparatus, with two coaxial draft tubes and partially hydraulic magma classification, makes possible to increase the mean crystal size up to 33%. The product efficiency from unit volume in this case is comparable with a DTM vessel. Moreover, the favorable conditions of crystal growth in a new crystallizer enable one to extend the residence time to 8 h, and because of that, to produce the crystals of the average size up to 1000 μm.

Two-phase CFD simulation of the monodyspersed suspension hydraulic behaviour in the tank apparatus from a circulatory pipe

Two-phase CFD simulation of the monodyspersed suspension hydraulic behaviour in the tank apparatus from a circulatory pipe The hydrodynamics in fluidized-bed crystallizers is studied by CFD method. The simulations were performed by a commercial packet of computational fluid dynamics Fluent 6.x. For the one-phase modelling (15), a standard k-ε model was applied. In the case of the two-phase flows the Eulerian multi-phase model with a standard k-ε method, aided by the k-ε dispersed model for viscosity, has been used respectively. The collected data put a new light on the suspension flow behaviour in the annular zone of the fluidised bed crystallizer. From the presented here CFD simulations, it clearly issues that the real hydraulic conditions in the fluidised bed crystallizers are far from the ideal ones.

Multiphase CFD modeling - scale-up of Fluidized-Bed Crystallizer

Abstract The main goal of this study was to obtain a closer look to scale up problem of the Fluidized-Bed crystallizer operation, in particular for solids concentration larger than 10 vol.%. To achieve that a multi-phase CFD code was used. Such an approach to this problem has not been investigated until now. Data collected using CFD technique, impossible to obtain in any other way, especially for an industrial apparatus, provides the information about the suspension flow behaviour in such crystallizers.