Azeotropic Distillation is a complex separation process with possibility of existence of multiple steady states for both homogeneous and heterogeneous modes of operation. Computationally intensive continuation methods are usually applied to rigorous models of such columns to identify the number and character of steady states. Geometric methods using residue curves and distillation lines offer an alternate and computationally simpler method to analyze the occurrence of steady states in heterogeneous azeotropic distillation columns. Distillation lines are observed to be difficult to generate and there exists no reported systematic approach for using residue curves for analyzing the heterogeneous azeotropic distillation (HETAD) columns, specifically, in the two liquid phase region. A simplified method using residue curves and vapor line is proposed for the analysis of HETAD columns. The workability of the method has been discussed for different configuration possibilities of continuous heterogeneous distillation columns. Steady state and dynamic simulation have been used to study behavioural characteristics of each of the reported steady states and controllability of a chosen steady state. A conceptual framework of an Integrated System for design, analysis and control of azeotropic distillation columns is presented.

Keywords: Heterogeneous, azeotropic, multiple steady states, residue curve, vapor line

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