Computing Homogeneous Azeotropes Using Interval Analysis

Abstract

Determining the existence of homogeneous azeotropes, together with their composition and temperature, is important from both theoretical and practical standpoints in the analysis of phase behavior and in the synthesis and design of separation systems employing distillation. We describe a new method that reliably locates any and all homogeneous azeotropes for multicomponent mixtures, and also verifies the nonexistence of homogeneous azeotropes if none are present. The method is based on interval analysis, and provides a mathematical and computational guarantee that all azeotropes are located. The technique is general purpose and can be applied in connection with any thermodynamic model describing vapor-liquid equilibrium. An example using a five-component mixture modeled with the NRTL equation is presented.