Dispersed‐Phase Holdup and Characteristic Velocity in an Agitated‐Pulsed Solvent Extraction Column

Tan, Boren; Li, Longxiang; Lan, Minle; Wang, Yong; Qi, Tao

doi:10.1002/ceat.202000534

Cited by 11 publications

(19 citation statements)

References 38 publications

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“…Figure is a schematic representation of the experimental apparatus and the key dimensions of the extraction column. The hydraulic parameters of the column have been detailed in our previous work . The six-blade impellers positioned in the middle of each compartment are mounted on a shaft, which is driven by an electric motor (M, Figure ) via a variable-speed gearbox located on the top of the column.…”

Section: Methodsmentioning

confidence: 99%

“…Agitated–pulsed column (APC) has exhibited high mass transfer performance, which is attractive for formidable separation processes such as rare earth extraction, chiral separation, etc. − The hydrodynamic performance and continuous-phase axial dispersion coefficient have been measured and investigated. ,, According to the results of our previous work, high agitation speed causes the reduction of the Sauter mean diameter of droplets from 3 mm to about 0.9 mm or even smaller, which leads to a larger drag force coefficient and potentially increases the axial dispersion in the dispersed phase. , …”

Section: Introductionmentioning

confidence: 99%

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Study on Dispersed-Phase Axial Dispersion in an Agitated–Pulsed Solvent Extraction Column with a Step Tracer Injection Technique

Tan

Zhang

Wang

et al. 2021

Ind. Eng. Chem. Res.

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In this work, the residence time distribution (RTD) of the dispersed phase (aqueous phase) and continuous phase (organic phase) in an agitated–pulsed extraction column (APC) was measured online with a step tracer injection technique and the axial dispersion was subsequently calculated via RTD analysis. It was found that both the agitation speed and the pulsation intensity had noticeable effects on the axial dispersion of the dispersed phase, which escalates with the increase in the agitation speed and this is especially authentic at high pulsation intensity. The dispersed-phase axial dispersion coefficient also becomes higher with the increase in the dispersed-phase velocity. Compared with the dispersed-phase axial dispersion in the APC, the continuous-phase axial dispersion is 2–3 times higher. Empirical equations have been proposed to correlate the dispersed- and continuous-phase axial dispersion coefficients for variation of both agitation and pulsation conditions in APC. This study could be valuable for assessing the dispersed-phase axial dispersion in liquid–liquid extraction columns.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Study on Dispersed-Phase Axial Dispersion in an Agitated–Pulsed Solvent Extraction Column with a Step Tracer Injection Technique

Tan

Zhang

Wang

et al. 2021

Ind. Eng. Chem. Res.

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“…Such empirical correlations have been reported, 1,42,43 but there are limited studies on droplet movement in APCs. Thus,

V_{i}

has been calculated in this study from

V_{x} / x_{d, i}

, and a correlation of

x_{d}

which includes the drop size as a predictor variable has been developed based on our previous study 14 and the study by Kumar and Hartland 44

x_{d} goodbreak= 50.0 goodbreak\times \exp ((), 43.7 \frac{|Af - Afm|}{\sqrt{g d_{c}}} goodbreak+ 4.68 \frac{N^{2} d_{r}}{g}) goodbreak\times {[V_{x} {((), \frac{ρ_{y}}{italicgγ})}^{\frac{1}{4}}]}^{0.623} \exp ([], 5.91 V_{y} {(\frac{ρ_{y}}{gγ})}^{\frac{1}{4}}) {[d_{32} {((), \frac{ρ_{y} g}{γ})}^{\frac{1}{2}}]}^{- 0.217} goodbreak\times {(\frac{∆ ρ}{ρ_{y}})}^{- 0.838} {(\frac{μ_{x}}{μ_{w}})}^{0.0079} {[h_{c} {((), \frac{ρ_{y} g}{γ})}^{\frac{1}{2}}]}^{- 1.87}

To solve Equation (

15

), matrices A and B are defined as

A_{kj} goodbreak= ({, \begin{matrix} \frac{{d_{j}}^{2}}{2} \frac{a ((),, d_{c}, d_{k})}{{d_{c}}^{2}} u_{ic} ∆ d ∆ t k < j \\ 1 goodbreak- g ((), d_{j}) ∆ t k goodbreak= j & <...> \end{matrix})

…”

Section: Mathematical Modelmentioning

confidence: 99%

“…Such empirical correlations have been reported, 1,42,43 but there are limited studies on droplet movement in APCs. Thus, V i has been calculated in this study from V x =x d,i , and a correlation of x d which includes the drop size as a predictor variable has been developed based on our previous study 14 and the study by Kumar and Hartland. 44…”

Section: Population Balance Equationmentioning

confidence: 99%

“…It is expected to be capable of achieving the formation of smaller droplets with a narrow size distribution compared to other conventional pilot plant columns. Our previous studies on the hydraulics 13,14 and axial dispersion characteristics 15 have shown that APC provides much higher interfacial area while with similar axial dispersion coefficients compared with the conventional extraction columns. Furthermore, a DN32 APC has shown high hydrodynamic throughput and nearly twice as high mass transfer efficiency as that of Kühni's column of the same scale 16,17 .…”

Section: Introductionmentioning

confidence: 99%

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Modeling the axial distribution of mass transfer coefficient in an agitated‐pulsed extraction column

Tan

Wang

et al. 2022

AIChE Journal

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The dispersed phase holdup and drop size in solvent extraction columns vary along the column height and this affects the mass transfer coefficient and interfacial area. In this article, mass transfer study was performed experimentally using a 25 mm diameter agitated pulsed column. The axial distribution of mass transfer coefficient was determined by coupling population balance equation and axial dispersion model by taking the longitudinal variation in hydrodynamic performance into consideration. Feasibility of different mass transfer models in predicting concentration profiles was evaluated and a novel correlation based on effective diffusivity was developed. The results showed that both overall and volumetric mass transfer coefficients have significant change along the column height and greatly depends on the agitation speed and pulsation intensity. Increasing dispersed phase velocity also augments the overall mass transfer coefficient. The maximum number of transfer unit was measured to be 10 m−1 at agitation speed of 1000 rpm.

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Mass transfer performance of pulsed disk and doughnut column (PDDC) in the extraction of active ingredients in peppermint extract obtained by hot percolation

Hosseini,

Bahmanyar,

Rahimpour

et al. 2024

Can J Chem Eng

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The active ingredients in peppermint are widely used in the pharmaceutical, food, cosmetic, and other industries. The traditional methods for producing peppermint extract through hydrodistillation (HD) and percolation are long process with low efficiency. The aim of this study is the improvement of the extraction performance and the efficiency of the extract obtained from hot percolation via pulsed disk and doughnut columns (PDDC), which is one of the most important pieces of liquid–liquid extraction (LLE) equipment. Peppermint extract was used as the continuous phase in the PDDC. n‐Hexane was considered as the dispersed phase in this column. In this study, the effects of three operating parameters were investigated, including the pulse intensity, continuous phase height, and dispersed phase flow rate, on the extraction efficiency of active ingredients in peppermint. The response surface method (RSM) was used to investigate the effect of these parameters on the extraction efficiency. The efficiency of this column in the extracting of active ingredients from peppermint was measured by UV–vis spectrophotometry, via the absorption rate of the main active ingredients of peppermint (menthol) in the samples, and the efficiency was 75% on average. The experimental and theorical of dispersed phase mass transfer coefficient were evaluated and compared. The results showed that the PDDC improved the extraction and mass transfer. By increasing the flow rate of the dispersed phase and the height of the continuous phase, the extraction efficiency and the mass transfer coefficient were increased.

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Dispersed‐Phase Holdup and Characteristic Velocity in an Agitated‐Pulsed Solvent Extraction Column

Cited by 11 publications

References 38 publications

Study on Dispersed-Phase Axial Dispersion in an Agitated–Pulsed Solvent Extraction Column with a Step Tracer Injection Technique

Study on Dispersed-Phase Axial Dispersion in an Agitated–Pulsed Solvent Extraction Column with a Step Tracer Injection Technique

Modeling the axial distribution of mass transfer coefficient in an agitated‐pulsed extraction column

Mass transfer performance of pulsed disk and doughnut column (PDDC) in the extraction of active ingredients in peppermint extract obtained by hot percolation

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