Exploiting Homogeneous Azeotropes

Exploitation of Homogeneous Azeotropes Homogeneous azeotropic distillation refers to a flowsheet structure in which azeotrope formation is exploited or avoided in order to accomplish the desired separation in one or more distillation columns. The azeotropes in the system either do not exhibit two-hquid-phase behavior or the hquid-phase behavior is not or cannot be exploited in the separation sequence. The structure of a particular sequence will depend on the geometry of the residue curve map or distillation region diagram for the feed mixture-entrainer system. Two approaches are possible ... 

Exploitation of Pressure Sensitivity The breaking of homogeneous azeotropes that are part of a distiUation boundary (that is, into produc ts in different distillation regions) requires that the boundaiy... 

As an example. Van Dongen (Ph.D. Thesis, University of Massachusetts, 1983) considered the separation of a methanol-methyl acetate mixture, which forms a homogeneous azeotrope, using n-hexane as an entrainer. The distillation boundaries for this system (Fig. 13-87a) are somewhat curved. A separation sequence that exploits this boundary curvature is shown in Fig. 13-87b. Recycled methanol—methyl acetate binary azeotrope and methanol-methyl acetate—hexane ternary azeotrope are added to the original feed FO to produce a net feed com-... 

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