Foam as a medium for gas absorption

Helsby, F. W.; Birt, D. C. P.

doi:10.1002/jctb.5010050708

Cited by 9 publications

(1 citation statement)

References 1 publication

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“…In addition, pneumatic foams are used to enhance gas absorption in gas–liquid contacting processes . For the latter application, it has been experimentally demonstrated that a foam of higher liquid fraction favors mass transfer, but if the gas rate is too high, a change in flow regime can cause a reduction in performance. , This work addresses what the maximum liquid fraction of foam is before the flow regime changes and develops a theoretical model, albeit empirical with respect to liquid drainage rate, to predict the hydrodynamic conditions for the regime change.…”

Section: Introductionmentioning

confidence: 99%

Flooding in a Vertically Rising Gas–Liquid Foam

Wang

Evans

Stevenson

2014

Ind. Eng. Chem. Res.

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The maximum liquid fraction that stable pneumatic foam can support is studied in this paper in order to illuminate change of flow regime from turbulent foam flow to the “emulsion regime” in which the distinct interface between the foam layer and the bubbly liquid is lost; this regime transition is nominated as “flooding”. With further increases in gas flow rate, large (or “gross”) bubbles can appear and rise in the column, the existence of which depends on the absolute pressure at the column bottom. Experiments are carried out using foam stabilized by sodium dodecyl sulfate, and the liquid fraction of both the foam layer and the bubbly liquid are measured using a pressure gradient method. The maximum liquid fraction is found to be at a critical point when the interface between the foam and the bubbly liquid layer disappears. The predicted maximum liquid fraction in the foam is given by ε* = (n – 1)/(n + 1), where n is an adjustable constant that depends upon the characteristics of the gas–liquid interface, and the predictions have been experimentally verified.

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Section: Introductionmentioning

confidence: 99%

Flooding in a Vertically Rising Gas–Liquid Foam

Wang

Evans

Stevenson

2014

Ind. Eng. Chem. Res.

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Gas–Liquid Mass Transfer in Foam

Stevenson

2012

Foam Engineering

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Mass transfer in horizontally moving stable aqueous foams

Weissman¹,

Calvert²

1965

AIChE Journal

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A n efficient gas absorption device has been developed based on a stable aqueous foam moving in a horizontal duct, with a gas-liquid interaction that causes only negligible pressure drops.The study of a liquid-phase and a mostly gas-phase-controlled system has indicated that their mass transfer performance can be predicted. This is based on hydrodynamic data for flowing foams, obtained in a preliminary study published elsewhere.The influence of geometry, foaming solution properties, and surfactant-caused interfacial resistance are included i n the analysis.Foaming systems have lately been receiving increased attention for heat and mass transfer applications owing to the large interfacial areas they offer from relatively low amounts of liquid.Work drops. This is particularly the case for highly intensified gas-liquid contacting, that is high flow rates and pure liquids (no surfactants added). Such dynamically stable foams collapse below a critical gas flow rate. Some different approaches have also been published. Workman ( 4 8 ) reported on sieve plate arrangements with and without egg crate supports for the froths that were formed. Ungemach ( 4 3 ) published a brief note on an inclined baffled tube arrangement, and an application to heat exchange (29) is under study. This paper treats the gas desorption from a moving aqueous foam. In the present case, however, the foam has been generated by pretreatment of the liquid phase (water) with a small amount of a surface-active agent (saponin) * prior to contacting with a gas phase. Thus, a suitable surface activity has been induced in the liquid, and high rates of momentum transfer are no longer necessary for the obtention of a stable foam. APPARATUS AND PROCEDUREThe desorption of carbon dioxide from water (liquidphase controlled system) and of ammonia from water (almost gas-phase controlled) were studied under identical sets of operating conditions and geometries. The stripping gas was air [containing 350 p.p.m. carbon dioxide ( 4 6 ) l . It also made the solution foam and was presaturated with water at the run temperature ( 30" C. ) .* Saponin is an extract of naturally occurring glucosides, nonionic in character, and known to produce very stable slow-draining foams. An 0.2% concentration by weight was found to be the minimum ameunt permitting good operation of the foam apparatus over a wide range oi gas and liquid Bow rates while not affecting the equilibrium relationships carbon dioxide-water and ammonia-water ( 4 6 ) .

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Foam as a medium for gas absorption

Cited by 9 publications

References 1 publication

Flooding in a Vertically Rising Gas–Liquid Foam

Flooding in a Vertically Rising Gas–Liquid Foam

Gas–Liquid Mass Transfer in Foam

Mass transfer in horizontally moving stable aqueous foams

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