Mixing Study in an Unbaffled Stirred Precipitator Using LES Modelling

Abstract

This paper describes the CFD modelling of a reactor operating in the nuclear industry using LES approach. The reactor consists of an unbaffled stirred tank reactor in which plutonium precipitation reactions are carried out. The flow generated in such a precipitator is complex and there is very little information available in the literature about unbaffled reactors stirred with magnetic rod. That is why a hydrodynamic modelling has been developed using computational fluid dynamics (CFD) in order to get accurate description of mixing phenomena inside the precipitator and therefore to be able to predict the solid particle properties. Due to the strong turbulence anisotropy, the turbulence transport simulation is achieved by a large eddy simulation (LES) approach which gives unsteady solutions. The numerical simulations are performed in 3D using the Trio U code developed at the Commissariat a l'Énergie Atomique. The predictive performances of the modelling are analysed through a mixing phenomena study. Both experimental and numerical studies are performed. This work shows how hydrodynamics inside the reactor can have a noticeable effect on the precipitate properties and how LES modelling is a very effective tool for the process control.

Status and outlook for lithium-ion battery cathode material synthesis and the application of mechanistic modeling

“…CFD-PBM coupled mechanistic models have been developed to predict the effect of process parameters on product crystal properties in pharmaceutical [152], minerals [153], and nuclear industry [154,155]. Review by Bałdyga elaborates application of CFD-PBM models to 'design' product particles [152].…”

“…The model can be further used for scale-up investigations including how the mean size, size distribution, nucleation rate changes with scale up (specific power input, tank volume). The CFD-PBM models have been used to predict size evolution of uranium oxalate crystals during precipitation reaction in the nuclear industry [154,155]. Simulation of the flow field allowed accurate description of mixing and effect of hydrodynamics on the precipitate properties.…”

An integrated CFD methodology for tracking fluid interfaces and solid distributions in a vortexing stirred tank

“…Bertrand et al studied the plutonium precipitation reaction in a vortexing unbaffled stirred tank reactor. [ 20 ] In their experimental results, it was observed that the mean size of crystal size distribution varied significantly depending on the injection position of reagents. When injected into the free vortex, the reagents mixed uniformly and enhanced the crystal growth process, resulting in larger crystals.…”