Mass transfer coeficients in pulsed perforated-plate extraction columns

Abstract

-This study examined the mass transfer performance in a pulsed perforated-plate extraction column with diameter of 50 mm using two different liquid systems. Mass transfer coefficients have been interpreted in terms of the axial diffusion model. The effects of pulsation intensity and dispersed and continuous phase velocities on the mass transfer performance have been investigated. Three different operating regimes, namely mixer-settler, transition, and emulsion regimes, were observed when the input energy was changed. Effective diffusivity is substituted for molecular diffusivity in the Gröber equation for prediction of dispersed phase overall mass transfer coefficients. A single correlation is derived in terms of Reynolds number, Eötvös number and dispersed phase holdup for prediction of the enhancement factor in all operating regimes. The prediction of overall mass transfer coefficients from the presented model is in good agreement with experimental results.

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

“…The results show that the mass transfer rate is directly proportional to the dispersed phase flow rate. In fact, the impact of the flow rate of the dispersed phase on H oc is found to be great- er than that of the continuous phase, in accordance with the observations of Torab-Mostaedi et al [33] in a standard vertical pulsed sieve-plate column, of Panahinia et al [26] and Amani et al [27] in a horizontal extraction column, of Safari et al [21] in a pulsed packed column, and of Harikrishnan et al [34] in a reciprocating-plate column. This phenomenon can be linked to the fact that incrementing the dispersed phase flow rate resulted in the increase of the drag forces between the phases, intense drops coalescence, and a higher droplet population density; consequently, the droplets obtain a particular drop size distribution regarding the pulsation intensity, the net superficial velocity of both phases, and perforation diameter of the plates, resulting in a higher interfacial area.…”

Mass transfer into/from nanofluid drops in a spray liquid‐liquid extraction column

“…To explain the reason of this observation, it should be considered that efficiency of liquid-liquid contactors is primarily dependent on the degree of turbulence imparted to the system and the interfacial area available for mass transfer. 57 As the results of the present research showed that nanoparticles do not have any significant influence on the hydrodynamics parameters such as interfacial area, it seems that the effect of nanoparticles is due to the internal turbulence of drops. As the continuous phase resistance is negligible within the concentration range used, mass-transfer resistance mostly existed in the dispersed phase for the system in this work.…”

The influence of silica nanoparticles on hydrodynamics and mass transfer in spray liquid–liquid extraction column

“…A decreasing trend is observed by increasing the nano-silica particles concentrations further. To explain the reason of this observation, it should be considered that efficiency of liquid-liquid contactors is primarily dependent on the degree of turbulence imparted to the system and the interfacial area available for mass transfer [46]. Since the results of the present research showed that nanoparticles do not show significant influence on the hydrodynamic parameters such as interfacial area, it seems that the effect of nanoparticles on extraction efficiency is due to the internal turbulence of drops.…”