Product Composition Regions for Azeotropic Three-Component Mixtures

Product Composition Regions for Azeotropic Three-Component Mixtures 

Let s examine three-component azeotropic mixtures with one binary azeotrope and with two regions of distillation at infinite reflux Reg°° (Fig. 3.6a). There is some region (triangle to the right of separatrix) where two points of the bottom product corresponding to one top product point exist. This fact is explained by the 5-shape of c-hnes in this region (Fig. 3.6b, points xb(2) and xb(3 ). 

The main difference between the azeotropic mixtures (and also nonideal zeo-tropic mixtures) and the ideal ones are that, to determine possible sphts of an azeotropic mixture, special analysis is required. The availability of a few distillation regions under the infinite reflux Reg can result in sharp separation becoming completely impossible or in a decrease in sharp splits number. Let s note that for ideal mixtures the fine of possible products compositions atR = ooandiV=oo and set feed composition goes partially inside the concentration simplex and partially along its boundary elements. For azeotropic mixtures, this line can go along the boundary elements of the distillation region (Fig. 3.6a, line 2). 

The question about feasible splits is one of the principal questions in the distillation theory. The understanding of this question was gradually transformed and became more precise. 

The original oversimplified view on feasible azeotropic mixtures splits consists of the following the feed point and product points have to belong to one distillation region (xd e Reg° and Xb e Reg°° if Xp e Reg° ). This view is quite accurate if the separatrix of distillation regions is linear. In a general case, at curvilinear separatrixes, the feed point can lie in one distillation region at infinite reflux and 

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