Vivekananda Sinha

Pulsed disc and doughnut columns (PDDC) have become an integral part of the nuclear fuel reprocessing and hydrometallurgical industries for quite some time. In this study, five unified correlations have been proposed for the prediction of slip velocity, characteristic velocity, flooding throughput and flooding slip velocity over a wide range of operating parameters, column dimensions and chemical systems in a PDDC. Before formulation of the correlations, a detailed cross validation of the existing correlations with the reported and the present experimental results have been performed. Then the empirical equations have been formulated by correlating the reported results by various researchers along with the present experimental data. The total number of data points used for predicting the slip velocity, characteristic velocity, flooding throughput and flooding slip velocity is 584, 129,185 and 128, respectively. For slip velocity and slip velocity at flood point, two new correlations have been proposed. For characteristic velocity and flooding throughput, the reported and the present data points have been refitted using existing correlations. Good accuracy has been achieved between the predicted and experimental results.

A parametric study of the dispersed phase holdup, specific power consumption (P) and axial drop size distribution (ADSD) in a pulsed disc and doughnut column have been carried out with 30% Tri-Butyl Phosphate- 0.01 M nitric acid system. ‘P’ and holdup decreases with increasing percentage duty cycle and increases exponentially with increased pulsation. Whereas ‘P’ remains almost independent of total superficial velocity and phase flow ratio. At the top of the extraction section, the most uniform DSD have been observed. Subsequently, Unified empirical correlations have been developed over much wider range for predicting the holdup and Sauter mean diameter.