Mass transfer liquid foam fractionation

Phases gas-liquid, liquid-liquid. Gas liquid residence tune, short. Use for very fast reactions all reaction is in the liquid film and is mass transfer-controlled. Gas-liquid surface area, max. observed 800 m /m with the usual range 200 to 500 m /m or slightly higher than a bubble column. Target species Henry s law constant <10 kPa/mol fraction feed gas concentration <1 vol%. Not for foaming, corrosive, or particulates. Liquid-liquid can operate as gravity flow or with fluid pulsed operation. For pulsed operation surface area 75 to 3000 m /m. Related topics are solvent extraction (Section 16.11.4.10). 

A design will typically be required to meet specified rates pf gas-liquid mass transfer and heat transfer and achieve suitable mixing of the liquid and gas phase at a certain throughput (or batch size). The designer will need to know the power consumption, gas holdup (voidage) fraction, C( . and foam height associated with such duty. 

The higher the surface tension the more likely it is to make foam during distillation and this can result in filling the column with a stable froth which will prevent fractionation. A tray column, that creates mass transfer by bubbling vapour through liquid, is much more vulnerable to foam formation than a packed column which does not rely upon bubbling. 

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