Ladislav Steiner

Effect of mass transfer on drop size in a Karr column

Abstract This paper presents experimental data on drop size distribution and Sauter mean drop diameter in a 7.6 cm diameter reciprocating plate extraction column with and without mass transfer, using the liquid system toluene—acetone—water. The measured drop size distribution curves show that most of the break-up of the dispersed drops was achieved by the first few plates. The agitation rate was found to be the predominant factor in determining the mean drop diameter and the total interfacial mass transfer area. During mass transfer both the drop size distribution and the mean drop diameter were found to depend on the mass transfer direction. The measurements of the mean drop diameter in the absence of mass transfer were compared with published data and new correlations presented.

EFFECT OF MASS TRANSFER ON FLOODING AND HOLDUP IN A KARR COLUMN

This work considers flooding and dispersed phase holdup, with and without mass transfer, in a 7.6 cm diameter reciprocating plate extraction column using the liquid system toluene-acetone-water. The present flooding data in respect to the absence of mass transfer were well correlated by the hydrodynamic model based on the dispersion of drops by turbulent energy dissipation. During mass transfer the flooding characteristics were found to be dependent on the direction of mass transfer. Dispersed phase holdup data were obtained by two different measuring techniques. Local holdup was found to vary with column height, while the overall holdup depended on agitation speed, phase throughputs and mass transfer direction. The holdup data thus obtained are compared with data published for the case without mass transfer, and new correlations are presented.

PERFORMANCE OF JET PLATES IN PULSED LIQUID-LIQUID EXTRACTION COLUMNS.

Abstract Jet plates with elevated rims around their openings are assumed to improve the performance of pulsed extraction columns. A comparison with conventional plates was carried out in a pilot-plant size column with the system of water, toluene and acetone. Hold-up, drop size, backmixing and axial concentration profiles in both phases were measured simultaneously. Mass transfer coefficients were evaluated from measured data by minimising the deviations of measured concentration profiles from model prediction using standard and open-end stagewise backflow models. Equations from the literature for prediction of drop size, hold-up and backmixing coefficients were modified by recalculating the empirical coefficients from recent data to enable quantification of trends and replacement of missing values. The transfer coefficents correlated against actual velocity of the dispersed phase rised to a power between 0.6 and 1, the influences of pulsation velocity, drop size and actual velocity of the continuous phas...

MASS TRANSFER RATES IN LIQUID/LIQUID EXTRACTION WITH PARTIALLY MISCIBLE SOLVENTS

Abstract Models for simulating the performance of extraction columns have been extended to include partially miscible solvents. Simultaneously, a comprehensive experimental study was carried out in which the concentration profiles of all components and all relevant hydrodynamic parameters in a pilot plant were measured, using liquid systems recommended by the European Federation of Chemical Engineers. True mass transfer coefficients were determined from the experimental data using a computer-aided curve-fitting technique to allow for the influence of backmixing. The coefficients obtained in this way were similar to those calculated for single drops.