Effect of Plate Material on the Dispersed Phase Hold Up in Karr Reciprocating Columns
Karr reciprocating plate columns are used as liquid-liquid contactors and are known for their high volumetric efficiency and their usage has increased considerably in the last couple of decades. A few investigators have studied the wetting characteristics of the plate material in these columns but no systematic studies have been reported on the influence of plate materials on the dispersed phase hold up and the drop size in these columns. In this study a Kerosene-Phenol-aqueous system is used in a 50 mm Karr column with stainless steel, Nylon and Teflon plate material under both directions of mass transfer and dispersion.
It was found that the slip velocity was lower for the Teflon plates than the other plates for both directions of mass transfer for the aqueous dispersion. A similar influence was also seen on the sauter mean diameter. The dispersed phase hold up and drop size experimental data obtained has been compared with the existing prediction models and the accuracy of these models have been assessed. The promising models have been modified to apply for a range of plate materials and were used to calculate the mass transfer coefficient. It was found that the Teflon plates had a better mass transfer performance than the other plates and the performance of the Nylon plate was midway between the Teflon and stainless steel plate at 120 rpm for the aqueous dispersion. These findings are important in understanding plate ageing effects in the pharmaceutical industry.