CFD contribution to a design procedure for discs and doughnuts extraction columns

This paper deals with a Computational Fluid Dynamic contribution to a desig n procedure for discs and doughnuts extraction columns. The approach can be considered as a numerical alternative to experimental determinations of av erage hydrodynamic characteristics involved in the phenomenological and tra nsport models used in order to design these contactors. Simulations are car ried out by the ESTET calculation code coupled to the k - epsilon turbulent model, for steady-state regimes, and for pulsed flow regimes. In the case of the steady-state regime, correlations between turbulent characteristics of the steady flow and pressure drop in the column with geometrical paramet ers and dynamic condition are established. The numerical results are in ver y good agreement with the experimental ones available. In the case of the p ulsed flow regime, for which 24 different combinations of geometrical and p ulsation parameters have been examined, the results presented consist of th e averages over a pulsation cycle of hydrodynamic and mixing characteristic s correlated to the pulsation amplitude and frequency, the distance between disc and doughnut and the open free area of the internals. The numerical r esults are also in fairly good agreement with the experimental ones availab le.