Mass Transfer Studies in Three-phase Fluidized Bed Using Response Surface Method

A. Sivalingam, N. M. Hariharan, T. Kannadasan, M. Thirumarimurugan and S. Gopalakrishnane

Abstract
Mass transfer characteristics of co-current three-phase fluidization were determined in terms of mass transfer coefficient and Sherwood number using Box-Behnken method. The experiment was carried out in a 5.4 cm I.D, 6 cm O.D and 160 cm high vertical Perspex column. Gypsum particles of diameter 0.0842 cm, 0.1676 cm and 0.2818 cm, water, and air were used as solid, liquid and gaseous phase respectively. Initially, the superficial liquid velocity was maintained constant and superficial gas velocities varied. After attaining steady state, at a particular gas velocity, the fluidized bed height and manometer readings were recorded for pressure drop estimation. The above-mentioned procedure was repeated for four different liquid velocities in a fluidized bed. The effect of individual phase holdup and mass transfer coefficient for various particle sizes with them specific liquid flow rates and gas flow rates were studied. It was observed that the mass transfer coefficient and Sherwood number increased with increase in superficial gas velocity and particle size in cocurrent three-phase fluidized bed. A quadratic model for bed porosity, gas holdup, Sherwood number and mass transfer coefficient were developed using response surface method (RSM).

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Keywords
Box-Behnken method, co-current three-phase fluidization, Sherwood number, mass transfer coefficient, response surface method