Factors affecting the extraction efficiency of an experimental, liquid-liquid, sieve-plate, pulse extractor

Abstract

It was the purpose of this investigation, using the ternary system acetone-toluene-water in the extraction of acetone from toluene using distilled water, to determine the operating characteristics of a pulse extraction column, and to determine the effects of solvent-to-feed ratio, feed concentration, and pulse amplitude on the overall mass transfer coefficient. The equipment used was operated at a temperature of 25±1 ºC, and consisted of a two-inch diameter glass column with eight sieve plates having 1/16-inch diameter holes on triangular centers, and a plate-free area of twenty-three per cent. The plate spacing used was eight inches. Pulsation of the liquids in the column was accomplished by means of a brass bellows actuated by a push rod driven by a motor-driven cam.

The determination of the column operating characteristics resulted in curves defining the operating flow rates at which the column could be operated without light- or heavy-phase flooding. The shape of the curves was a function of the feed and solvent flow rates, but was independent of the pulse amplitude.

Using flow rates taken from the column operating characteristic curves, a total or forty-five tests were made to determine the effect or pulse amplitude, feed concentration, and the solvent-to-feed ratio on the overall mass transfer coefficient. It was found that the overall mass transfer coefficient was the highest at a volumetric solvent-to-feed ratio of 0.50 for conditions of blowing, reached a minimum at a volumetric solvent-to-reed ratio of 1.00 at which there was no blowing or dumping, and increased slightly at a volumetric solvent-to-feed ratio or 1.50 at which dumping occurred. The overall mass transfer coefficient increased with increased feed concentration in a straight-line relationship. The overall mass transfer coefficient was also increased by an increase in the pulse amplitude.