Distillation of non-ideal mixtures

In this brief, theoretical and practical elements are applied to design distillation units for separating non-ideal mixtures, including azeotropic mixtures with minimum bubble temperature (noted T _min ), azeotropic mixtures with maximum bubble temperature (noted T _max ) and mixtures with close relative volatility.

These concepts, presented in the previous dossier "Distillation of non-ideal mixtures. Residue curves and other design tools" [J 2 611] , are as follows:

• residue curve, similar to the composition profile of a continuous distillation column operating at full reflux, indicating the distillate possible in batch distillation;

• relationship between the stability of singular points, pure bodies and azeotropes, and their boiling temperature within a distillation region ;

• properties of residue curve networks with distillation boundaries separating distillation regions ;

• classification of residual curve networks ;

• univolatility curve identifying the regions of order of volatility in composition diagrams and therefore the ability of a pure body to be at the top or bottom of a column;

• unidistribution curve associated with the shape and curvature of residual curves.

While distillation with pressure change is mentioned, the dossier focuses on azeotropic or extractive distillation, which requires the addition of a third E-body/entrainer.