This paper addresses the addition of internal heat integration to the pressure-swing distillation (PSD) process used in the separation of binary pressure-sensitive azeotropes. The primary step in the process design is to determine the pressure elevation from the low-to high-pressure distillation columns, followed by the design of internal heat integration between the two distillation columns. A general procedure is suggested and illustrated through the separation of an acetonitrile-water binary mixture, which forms pressure-sensitive minimum-boiling azeotropes. Comparisons are made between the conventional and the internally heat integrated PSD processes. It is demonstrated that breaking pressure-sensitive azeotropic mixtures can be made more economical than the current practice with conventional PSD processes. However, the degree of cost reduction is strongly dependent upon the properties of the mixtures to be separated.
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