Strategies for separating pressure sensitive binary azeotropes

Abstract

The separation of azeotropic mixtures, particularly, pressure sensitive azeotropes is intriguing, challenging, and inevitable in chemical industries in comparison to pressure insensitive azeotropic mixtures. The main bottleneck for separating pressure sensitive azeotropes lies in the pressure selection and sequencing of distillation columns. A conundrum in pressure swing distillation for both minimum and maximum boiling azeotropes primarily about the feasibility of column configurations has been discussed in this work. The two column configurations, Low pressure Column-High Pressure Column (LPC-HPC) and High Pressure Column-Low Pressure Column (HPC-LPC) are found to be dependent on the feed composition, type of azeotrope (whether, minimum or maximum), and the effect of pressure on azeotropic composition. This article has explored concomitantly pressure swing distillation technique (continuous one) and the effect of various feed compositions on the column sequencing and process feasibility. A comprehensive strategy for both minimum and maximum boiling azeotropes has been proposed depending upon the effect of pressure on azeotropic composition. Two example case studies have been also presented in support of the proposed strategies for pressure swing distillation technique.

Keywords

• Azeotropic composition
• Column configuration
• Minimum boiling azeotrope
• Maximum boiling azeotrope
• Feed composition