Lagrangian simulations contribution to the knowledge of discs and doughnuts pulsed solvent extraction columns hydrodynamics

Abstract

This paper intends to evaluate in which way the Computational Fluid Dynamics (CFD), and more precisely Lagrangian simulations, can be used as a tool for getting information about the hydrodynamic behavior of the dispersed phase in extraction columns. As an example, the study is carried out on a particular contactor: the discs and doughnuts pulsed column. In a first part, details are given on the modeling and on the simulation hypothesis and principles. The second part is dedicated to the study of the dispersed phase transport via the plug flow with axial dispersion transport model parameters (mean residence time and axial dispersion coefficient) for several operating conditions (pulsation amplitude and frequency, droplet diameter). The comparison of simulation results with those for ‘single drop’ experiment shows that the simulations perfectly reproduce the trends concerning the influence of the operating parameters, although a gap still remains. The last part of this paper is devoted to the presentation of information that can be extracted from the simulations in order to contribute to a better understanding of the contactor operation: drop spreading in the compartments, slip velocity related to the mass transfer, and the turbulent kinetic energy seen by the drops related to the breakage.