Prediction of Concentration Profiles in an L‐Shaped Pulsed Extraction Column

Abstract

The L-shaped extraction pulsed plate column is believed to be able to perform under operating conditions between those of the vertical and the horizontal pulsed plate columns. It has an extraction efficiency similar to the vertical pulsed plate column. Here, the mass transfer performance of this novel column type was investigated and the application of three different models, i.e., the plug flow, the axial dispersion, and the back flow models, was evaluated to predict the solute concentration profile along the column length. The water-acetone-n-butyl acetate and the water-acetone-toluene systems were used. The influence of the operational parameters on the height of the mass transfer unit and the back flow coefficients was evaluated using the back flow model. New correlations were proposed to predict the height of the mass transfer unit along with the back flow coefficients in each phase, which were in satisfactory agreement with the experimental data.

Use of axial dispersion and plug flow models for determination of axial mixing and mass transfer coefficient in an l‐shaped pulsed packed extraction column

“…Moreover, a comparison between the values of the continuous and dispersed phase axial mixing coefficients shows that the continuous phase axial mixing coefficient is significantly higher than the dispersed coefficient. This is in accordance with the results obtained by many researchers . Also, the effect of the flow rates of both phases on the axial mixing coefficient is illustrated in Figure b and c for toluene and the flow rates of each of the phases only affect the axial mixing coefficient of the same phase.…”

“…Another important point is that the incremental trend of mass transfer coefficient is seen in both the horizontal and vertical sections, which means that both sections of the column are effective. Based on the results reported by Rafiei et al, for an L‐shaped pulse sieve plate column, increasing the pulsation intensity does not have a significant effect on the mass transfer coefficient in the vertical section because the flow regime is changed from the mixer‐settler to the dispersion. Therefore, in addition to the benefits mentioned for an L‐shaped extraction column, this item, which increases the mass transfer coefficient by increasing the pulsation intensity, is also an advantage of the L‐shaped pulsed packed column over the L‐shaped pulsed sieve plate column.…”

“…As was previously mentioned, there are numerous correlations for predicting in a pulsed extraction column and they are listed in Table S1. However, according to a review by Rafiei et al, the correlations proposed for a vertical or horizontal extraction column cannot be employed for an L‐shaped extraction column because of the differences in the behaviour of the hydrodynamic parameters as well as the effects of the two sections of the column on each other. On the other hand, according to a review by Yadav and Patwardhan, the correlation that is proposed for one system is not recommended for the other columns with different sizes or other chemical systems.…”

“…However, the production capacity in a horizontal pulsed column is lower than that in a vertical column in the same conditions and it requires more time to reach a steady state as well . Regarding the third category, the horizontal‐vertical pulsed column is a new extraction column that was recently introduced by Akhgar et al and Amani et al The main characteristics of this type in comparison to the horizontal and vertical type are as follows: The capacity of a horizontal‐vertical pulsed column is more than the horizontal and less than the vertical. …”

“…Akhgar et al and Amani et al have studied regime transition and characteristic velocity along with the two‐phase pressure drop and flooding characteristics in an L‐shaped extraction column. In addition, Rafiei et al have investigated the mass transfer performance of an L‐shaped pulsed sieve plate column. Considering the numerous industrial applications of extraction columns indoors and the complex behaviour of the usual parameters in an L‐shaped extraction column, further investigations, especially regarding the packed column, is required in order to compare the mass transfer performance, order of magnitude of axial mixing, throughput, flooding, and other important characteristics.…”