Liquid‐liquid extraction in laminar slug flow

Abstract

The hydrodynamics of liquid‐liquid slug flow have been studied for several organic components in water, in vertical tubes of diameters between 4.08 and 18.99 mm. Under conditions such that the slug flow is laminar and stable, mass transfer of sparingly soluble organic components (n‐butanol, n‐pentanol and methyl i‐butyl ketone) to water has been measured by observing the shrinkage rates of slugs. The observations are compared with predictions based upon the Higbie penetration model and the calculated velocity profile due to slug flow. It is concluded that the slug flow technique could be useful in studying the rates of reaction‐accompanied extraction.

Liquid‐liquid extraction by a suspended slug

“…A "free slug" apparatus (Krovvidi (1980)) was also used in some of the experiments. This closely resembled the simple vertical tube arrangement of Baird and Ho (1979) except that the internal diameter of the main tube section was 12.4 mm, rather than the 4 or 6 mm diameters used earlier.…”

“…As discussed by Wallis (1969), a slug of light phase may rise through a denser phase in a vertical tube according to several different flow regimes. This work and its precursor (Baird, Ho (1979)) are concerned with the "capillary regime" in which the interfacial tension greatly restricts the slug velocity. Thus in the case of !I-heptane and water (Ap = 318 kg/m3, a = 43.4 rnN/m) the critical tube diameter for total prcvenrion of plug flow is given by Bretherton's (1961) relationship:…”

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his paper describes a refined version of the laboratory T extraction device developed by Baird and Ho (1979).As noted by these authors, there is a need for laboratory extractors whose performance can be predicted from hydrodynamic principles. Such a device must ensure controlled laminar flow conditions and must be simple enough to allow ready cleaning to remove surface active contaminants.

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“…his paper describes a refined version of the laboratory T extraction device developed by Baird and Ho (1979).…”

“…The procedure with the "free slug" apparatus basically followed that of Baird and Ho (1979) in regard to the introduction of the organic phase. The slug was removed for analysis as described above.…”