Slip and Characteristic Velocities in a Horizontal Pulsed‐Plate Extraction Column

Abstract

The slip velocity, the dispersed-phase hold-up, and the characteristic velocities of the phases in a horizontal pulsed extraction column were investigated under no-mass transfer conditions using four binary systems: kerosene-water, toluenewater, n-butyl acetate-water, and butanol-water. The effects of the pulsation intensity, the dispersed-and continuous-phase flow rates, and the interfacial tension on the dispersed-phase hold-up and slip velocity of the phases were investigated. Based on the obtained results, a semi-empirical correlation for estimating the slip velocity and the characteristic velocity was established, which proved to be in good agreement with the experimental findings.

Drop behaviour characteristics in different operating regimes in an L‐shaped pulsed sieve‐plate column

“…Therefore, it is found that Equations (3)(4)(5) can cover the experimental data accurately in the region from the upper end of the mixer-settler regime to the dispersion regime. On the other hand, they showed poor performance in most of the mixer-settler regime, especially at the lower end of the mixer-settler regime and then became more accurate along the way.…”

“…Also, g is the acceleration due to gravity, a is fractional free area of perforated plates, and the viscosity of the dispersed phase is m d . Moreover, Sreenivasulu et al [17] proposed the following correlation: Figure 8 shows the comparison of some of the experimental data of mean drop size in the vertical section of the column with those calculated by Equation (3) and Equation (4). Accordingly, it is found that available correlations in the literature give a satisfactory prediction of mean drop size in the dispersion regime with an AARE of < 15 %, while the predictive ability of these correlations is poor in the mixer-settler regime with an AARE of > 40 %.…”

“…Khajenoori et al [3] studied the effect of pulsation intensity and flow rates of the continuous and the dispersed phases on the mean drop size and drop size distribution in a horizontal pulsed sieveplate extraction column and in another study, they defined three operating regimes for the same column. [4] Rao et al [5] and Panahinia et al [6] investigated the non-ideal parameters in pulsed sieve-plate columns and revealed that axial dispersion reduces the mass transfer performance of the column. Lade et al [7] investigated the drop size, holdup in normal phase operation, and phase reversal operation in pulsed plate columns.…”

“…[8] On the other hand, regarding to propose a correlation for prediction of the transition between regimes, a large number of investigations have been made and various correlations for regime transition in extraction columns are proposed. [4,17,[25][26][27][28][29][30][31][32] Moreover, the applicability of computational fluid dynamics (CFD) and population balance equation (PBE) has been investigated for the simulation of drop behaviour in the column in various studies. [33,34] Among the various types of extraction columns, the L-shaped pulsed sieve-plate column is a novel type of extractor whose application for extraction, separation, and purification of rare earth elements has not been referred to in the literature.…”

“…In addition, it has been found that the mass transfer rate in vertical and horizontal structure of the columns is approximately comparable. [4] Therefore, it is believed that an L-shaped column would offer higher throughput compared to a horizontal column, while its required surface area is still low.…”