Hydrodynamics of pulsed columns: The effect of new parameters affecting the pressure drop
Résumé
In industrial solvent extraction units, minimizing the energy input of liquid–liquid contactors is essential. Knowledge of the pressure drop evolution with both geometry and operating conditions is therefore required in order to achieve optimal sizing of the column. In this paper, yet unexplored parameters possibly affecting pressure drop in pulsed columns are investigated, namely the packing mounting clearance and the pulsation features. Their effect on pressure drop is addressed based on an experimental study, otherwise complemented by CFD simulations. The three possible types of flow (permanent flow, oscillating flow, and their combinations) have been actually investigated and compared, for both a disk and doughnut column (DDC) and a perforated plate column (PPC). Our experiments categorically confirm that the pressure drop along the column depends only on the mean fluid velocity, and is independent of the flow-type. This was moreover evidenced regardless of the pulsing device used (mechanical or pneumatical). Additionally, the influence of the mounting clearance required for the assembly of packing elements in industrial columns has been investigated and quantified for the first time. Thanks to an original DDC set-up, we measured the effect of a controlled non-zero gap between the rings and the wall on the pressure drop, hence completing the list and the analysis of parameters influencing the energy consumption in a pulsed column.