Hydrodynamics and Mass Transfer in a Lab‐Scale Stirred‐Pulsed Extraction Column

Abstract

An extraction column with energy input through simultaneous stirring and pulsation allows for efficient countercurrent extraction on lab-scale. While stirring generates small droplets with a narrow droplet size distribution, pulsation supports the axial transport of the dispersed phase, enabling countercurrent flow on this small scale. By studying the influence of several operating parameters, fundamental mechanics and characteristics of the column are revealed. Increasing the stirrer speed leads to smaller droplets and higher extraction performance as well as lower maximum throughput. The maximum throughput is increased by raising the pulsation intensity.

Overview of Innovative Technologies in Liquid‐Liquid Extraction Regarding Flexibility

“…To predict the hydrodynamic performance, empirical correlations for Sauter mean diameter and hold-up are presented in [60]. The empirical correlations from [61][62][63] were adapted by Grafschafter et al [60] with experiments performed with the system ShellSol T-water.…”

“…In [63], the influence of pulsation on the separation performance, droplet size distribution and flooring characteristics is shown. The standard test system n-butylacetate-acetone-water with an interfacial tension of 14 mN m -1 is utilized.…”

“…Flooding load of 15 m 3 m -2 h -1 can be reached [63]. Maximum throughput can be enhanced by raising the pulsation frequency and stroke length [63]. Through additional pulsation, flooding is prevented and stable countercurrent operation is possible in a miniaturized column.…”

“…Regarding capacity flexibility, due to two energy inputs, the stable narrow drop size distribution, shown in 63, leads to extended flooding capacity. Flooding load of 15 m 3 m −2 h −1 can be reached 63. Maximum throughput can be enhanced by raising the pulsation frequency and stroke length 63.…”

Equipment and Separation Units for Flow Chemistry Applications and Process Development

“…A detailed investigation of the influence of pulsation was carried out in a stirred‐pulsed column with DN15 . A relatively small pulsation stroke of 6 mm led to the highest column performance of approximately 25 theoretical stages per meter with the EFCE test system water (c)/acetone/ n ‐butyl acetate (d).…”