Azeotropic Distillation Without an Entraining Agent

Certain binary systems form vapor azeotropes that, when condensed, form a two phase liquid without the presence of a third component. The separation is achieved with the combination of an organic column and an aqueous column coupled with a decanter. This is shown schematically in Figure 24.

The vapors from each column are condensed, and the resulting two phase liquids are combined and decanted in a single vessel. The organic phase is returned as reflux to the organic column and the aqueous phase is returned as reflux to the aqueous column. The feed should enter the columns at a point that corresponds most closely to its composition. If the feed is at or close to the azeotrope, the feed point can be the decanter. In this process, the high purity products, which are usually water and organic, are removed from the base of the two columns.

APV has supplied this type of design for the dehydration of butyl alcohol and cyclohexanone.

Distillation Alcohol

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