Dispersed phase holdup in a pulsed disc and doughnut extraction column

Abstract

-Dispersed phase holdup has been measured in a 76 mm diameter pulsed disc and doughnut extraction column for three different liquid-liquid systems. The effects of operational variables such as pulsation intensity and dispersed and continuous phase flow rates on holdup have been investigated and found to be significant. The existence of three different operational regimes, namely mixer-settler, dispersion, and emulsion regimes, was observed when the energy input was changed. The results indicated that the characteristic velocity approach is applicable to this type of extraction column for analysis of holdup in the transition and emulsion regions. Empirical correlations are derived for prediction of the dispersed phase holdup in terms of the physical properties of the system and the operating variables in different operating regimes. Good agreement between prediction and experiments was found for all operating conditions investigated.

Prediction of dispersed phase holdup in pulsed disc and doughnut solvent extraction columns under different mass transfer conditions

“…It can be seen from Table 2 that the parameters in Equation 11 were different depending on the pulsing conditions and the extraction systems being studied. Table 2 Fitted parameters and AARE for predicting holdup using Equation 11 and Jahya experimental data [11] System Finally Torab-Mostaedi [13] proposed a correlation for prediction of holdup for a PDDC, based on nbutyl acetate-water, Toluene-water, and Kerosene-water system with stainless steel plates in the absence of mass transfer. For mixer settler regime and transition/emulsion regions, the correlation is as follows in Equation 13 and the fitted parameters and AARE are shown in Table 3.…”

“…PDDCs and at different operating conditions. For example, Figure 1 shows the comparison between the experimental PDDC holdup data from Jahya [11] and Torab [13] with the correlations developed by holdup data from Jahya [11] and Torab [13] Table 5. …”

“…Jahya [11] Torab [13] Milot [14] Symbol, units Jahya [11] Torab [13] Milot [14] Data source System Jahya [11] Alamine-H 2 SO 4 -Kerosene Jahya [11] Toluene-AcetoneMilot [14] TBP-HNO 3 -H 2 O Jahya [11] ,Torab [13] Kerosene-H 2 O, n-butyl acetate-H H 2 O Figure 2 Comparison between experimental correlation [5] (represented by Equation 14 not be fitted using single parameters and two sets of mass transfer conditions in Table 7. The AARE for holdup predicted individual parameters are less than 20%, and the AARE for holdup predicted using overall parameters % ( Figure 2).…”

“…Kumar and Hartland [4] (Equation 3) in a PDDC with different mass transfer directions. Experimental data was from Jahya [11] , Torab [13] and Milot [14] Although the Equation 14 has a smaller prediction error, it cannot predict the holdup for mass transfer from the continuous phase to the dispersed phase using one set of parameters. The unified holdup model [4] (Equation 3) did not provide any constants or references to the pulsed disc and doughnut column.…”

“…Fitted parameters and AARE for predicting holdup using Equation13 and Torab-Mostaedi[13] experimental data Using Equation 11 and 13, it can be seen that the holdup of PDDCs can be predicted well (AAREs in table 2 and 3 are relatively small). However, these two equations can only be used for predicting holdup using these specific columns, extraction systems and pulsing conditions.…”