CFD simulation and comparison of industrial crystallizers

Abstract

Simulation of flow patterns in eleven industrial crystallizers (standard Messo, Cerny direct contact, Swenson draft tube baffled, Swenson walker, Swenson evaporative, Oslo cooling, Oslo Krystal, APV Kestner, Batch Vacuum, stirred tank with disc turbine, and stirred tank with pitched blade impeller) have been carried out using computational fluid dynamics (CFD). Population balance modelling (PBM) is coupled with CFD to obtain better results. In all the cases, the crystallizer volume was 100 liter and the power consumption per unit volume was 1 kW/m 3 . The simulation results have been presented in terms of mean velocity components, turbulent kinetic energy and dissipation rate. On the basis of the flow patterns, these eleven crystallizers have been compared for crystal size distribution (CSD). It was found that Swenson Evaporative, Krystal and Batch Vacuum provide relatively low CSD.

Study on effect of process parameters and mixing on morphology of ammonium diuranate

“…Therefore, controlling supersaturation profile inside the crystallizer over the entire time of crystallization is expected to control the levels of nucleation, crystal growth, agglomeration and breakage, thereby controlling the morphology and crystal size distribution. It is known that the crystal growth is largely controlled by supersaturation level (it should be in metastable zone) [6] and diffusion of solute through solution [2]. Agglomeration of ammonium diuranate (ADU) like materials also depends on zeta potential barrier [7] and particle-particle interaction.…”

Crystallisation Route Map

“…The MPB equation of Eq. (30) can, thus, be written as follows: (31) The crystal shape evolution as shown in Fig. 22 demonstrates that the {100} and {110} faces will eventually disappear with the crystal expected to exhibit pure octahedral diamond-like morphology at steady state under the current simulation conditions, which has been observed in literature.…”

“…Each phase will have the corresponding conservation equations with a weighing factor to be its mass fraction. For further details, please refer to literature such as [31][32][33][34] and textbooks.…”

Application of the Lagrangian meshfree approach to modelling of batch crystallisation: Part I—Modelling of stirred tank hydrodynamics

“…Several reconstruction techniques were developed [5,6,7,8] however, no unified technique for reconstruction of a complete distribution from a finite number of moments is available in literature due to the fact that mathematically all the distribution moments up to infinity are required to achieve an accurate reconstruction [5]. To date, CFD models of stirred vessels were almost exclusively implemented in Eulerian reference frame using grid-based methods [9]. In majority of cases, CFD simulations use a two fluid model with an assumption of interpenetrating media, while recently this approach has been improved by modelling the solid phase using the Langrangian approach and the Newton's law of motion applied to individual particles [9].…”

“…To date, CFD models of stirred vessels were almost exclusively implemented in Eulerian reference frame using grid-based methods [9]. In majority of cases, CFD simulations use a two fluid model with an assumption of interpenetrating media, while recently this approach has been improved by modelling the solid phase using the Langrangian approach and the Newton's law of motion applied to individual particles [9]. However, there are some difficulties with the application of the grid based methods: convective transport should be simulated and can influence the integration time step and cause numerical problems [10], determination of free or moving boundaries and material interfaces is difficult [10,12], the computational requirements poorly scale with the size of the numerical system.…”