CUSEP—A New Mathematical Model of Pulsed Column Contactors Using the Purex Process

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Abstract
The mathematical basis for a computer code CUSEP (Clemson University Solvent Extraction Program) is described. The code simulates the temporal and steady-state concentration profiles in pulsed column contactors using the Purex process. Advantage is taken of the cellular structure of a pulsed column contactor caused by the presence of sieve plates and the turbulent flow to generate a set of equations that explicitly contain the instantaneous flow of the fluids caused by the pulse frequency and amplitude. The assumption is made that there are volumes in the contactors within which the time-averaged concentrations can be regarded as uniform. The size of these volumes is defined in terms of a parameter whose value is obtained by calibration against experimental data. Longitudinal diffusive remixing is shown to be negligible in comparison to convective remixing caused by the pulsing. Mass transfer between phases can occur at the equilibrium limit or can be allowed to deviate from it. The deviation is accounted for by a mass transfer area that is determined by the average size of droplets in the pulsed column and a mass transfer coefficient that is treated as a second input parameter. The code has been used to generate concentration profiles in several extraction (A-type) and stripping (E-type) contactors and in a partitioning (B-type) contactor. Agreement between calculated and available experimental concentration profiles is good.