Computing homogeneous azeotropes using interval analysis

Determining the existence of homogeneous azeotropes, together with their co mposition and temperature, is important from both theoretical and practical standpoints in the analysis of phase behavior and in the synthesis and des ign of separation systems employing distillation. We describe here a new me thod that reliably locates any and all homogeneous azeotropes for multicomp onent mixtures, and also verifies the nonexistence of homogeneous azeotrope s if none are present. The method is based on interval analysis, and provid es a mathematical and computational guarantee that all azeotropes are locat ed. The technique is general purpose and can be applied in connection with any thermodynamic model describing vapor-liquid equilibrium. An example usi ng a five-component mixture modeled with the NRTL equation is presented.