Experimental Characterisation and Modelling of Homogeneous Solid Suspension in an Industrial Stirred Tank

Abstract

In this work, we study the conditions needed to reach homogeneous distribution of aluminium salts particles in water inside a torispherical bottom shaped stirred tank of 70 L equipped with a Pfaudler RCI type impeller and three equispaced vertical baffles. The aim of the present study is to develop a CFD model describing the quality of particle distribution in industrial scale tanks. This model, validated with experimental data, is used afterwards to develop scale-up and scale-down correlations to predict the minimum impeller speed needed to reach homogeneous solid distribution Nhs. The commercial CFD software Fluent 14 is used to model the fluid flow and the solid particle distribution in the tank. Sliding Mesh approach is used to take the impeller motion into account. Assuming that the discrete solid phase has no influence on the continuous liquid phase behaviour, the fluid flow dynamics is simulated independently using the well-known -turbulence model. The liquid-solid mixture behaviour is then described by implementing the Eulerian Mixture model. Computed liquid velocity fields are validated by comparison with PIV measurements. Computed Nhs were found to be in good agreement with experimental measurements. Results from different scales allowed correlating Nhs values to the volumetric power consumption.

Improving the Homogenization of the Liquid-Solid Mixture Using a Tandem of Impellers in a Baffled Industrial Reactor

“…The numerical analysis, performed with the expert software Ansys ® Fluent, Release 16 employs the Eulerian multiphase model with a sliding mesh approach. The numerical data analysed and presented are similar to the results obtained and presented in other research papers [2][3][4][5][6][7][8][9][10].…”

“…Using CFD for modelling the complex flow inside industrial reactors proves to be an efficient, time saving and tractable method to analyze the performances of the stirring mechanism that is present in the reactor. Many researchers have used different types of expert CFD codes (Fluent, CFX) [2][3][4][5][6][7][8][9] for investigating the multiphase flow inside stirred reactors. A part of the previous research focused on identifying the appropriate turbulent model to be used [5,6].…”

CFD Simulation of Solid Suspension for a Liquid–Solid Industrial Stirred Reactor

“…The poor operation of the impeller, in both analyzed situations, is also underlined by the axial and radial distribution of the volume fraction distribution of the solid phase (Figure 5). mentioned by Calvo et al [4] and Hoseini et al [22], who obtained similar results. Figure 6 presents the velocity vector distribution of the liquid phase on two vertical planes, the upper two pictures, and on one the horizontal plane, the lower two pictures.…”

“…The investigation of the hydrodynamic performance of the impeller is based on the velocity vector distribution of the liquid phase in order to analyze the flow pattern as mentioned by Calvo et al [4] and Hoseini et al [22], who obtained similar results.…”