Reliable computation of reactive azeotropes

The determination of the existence and composition of reactive azeotropes i s important from both theoretical and practical standpoints in the analysis of combined reaction and phase equilibrium and in the synthesis and design of reactive separation systems. We present here a new method for reliably locating, from given thermodynamic models, any and all reactive azeotropes for multicomponent mixtures. The method also verifies the nonexistence of r eactive azeotropes if none are present. The method is based on interval ana lysis, in particular an interval-Newton/generalized-bisection algorithm tha t provides a mathematical and computational guarantee that all reactive aze otropes are located. The technique is general purpose and can be applied in connection with any thermodynamic models. We illustrate the technique here using several example problems. In two cases, the liquid phase is modeled as ideal; in the other cases, liquid phase nonideality is modeled using eit her the Wilson or NRTL equation. In one problem, self-association of a comp onent in the vapor phase is also included. (C) 2000 Elsevier Science Ltd. A ll rights reserved.