Modeling of Hydrodynamics in a 25？mm ？ Pulsed Disk and Doughnut Column

The hydrodynamic parameters, namely, dispersed phase holdup and flooding throughput, have been investigated in 25？mm diameter pulsed disk and doughnut column (PDDC), in no mass transfer conditions. In this work, using existing correlations on plate pulsed columns, the dispersed phase holdup and the flooding throughput are empirically modelled well using the slip velocity concept. A good agreement is observed between experimental values and predicted values obtained from empirical correlation. The experimental data for dispersed phase holdup and flooding throughput has been modelled using the Van Delden model to describe the hydrodynamics characteristics of a PDDC and necessary adjustable parameters for drop size distribution and dispersed phase holdup are updated for 30% TBP-nitric acid system. The model parameters were estimated by minimizing the absolute error between experimental and theoretical values of flooding throughput and holdup data. It was found that the measured values and observed trends could be described accurately using this model after fitting holdup and flooding data. The error between the experimental and theoretical values of flooding throughput and holdup was found to be less than 10%. 1. Introduction Liquid-liquid extraction, a major unit operation in the chemical process industries, is also backbone of the aqueous route of nuclear fuel reprocessing. The irradiated fuel from the nuclear reactor contains a mixture of uranium and plutonium along with large number of fission products. For efficient reuse of uranium and plutonium, these are recovered from spent nuclear fuels by PUREX process. The pulsed column, equipped with perforated plate internals and having 23% free area, has traditionally been used in the PUREX process for almost the last six decades. Due to absence of moving parts, the pulsed columns have clear advantage over other mechanical contactors/extractors while processing corrosive or radioactive solutions. A new type of pulsed column with internals, comprising an assembly of alternate disk and doughnuts, has gained attention in recent times. However, the amount of literature available on these columns is severely limited and briefly reviewed as follows. Jahaya et al. [1] compared the performance of pulsed disc and doughnut column with pulsed sieve plate column of 75？mm diameter and 23% free area for toluene-acetone-water system. While comparing these two designs of extraction columns, they maintained the entire operating envelope identical, for both of the columns. They observed that although total throughput per unit