GPEC: A Program for Global Phase Equilibrium Calculations in Binary Systems

MARTÍN CISMONDI; DIEGO N. NUÑEZ; MARCELO S. ZABALOY; ESTEBAN A. BRIGNOLE; MICHAEL L. MICHELSEN; JØRGEN M. MOLLERUP

Morelia, Michoacán, México

Conferencia; EQUIFASE 2006: VII Conferencia Iberoamericana sobre Equilibrio entre Fases para el Diseño de Procesos; 2006

A general algorithm for the calculation of global phase equilibrium diagrams for binary systems has been recently developed [i]. It integrates the calculation of critical lines, liquidliquid- vapour (LLV) lines and critical end points and constitutes the basis for the new software program GPEC: Global Phase Equilibrium Calculations. This program allows, after specifying a binary system and choosing an equation of state (EOS) and values for its parameters, to calculate and plot the predicted global phase equilibrium diagram on different projections of the temperature-pressure-composition-density space. These projections show the boundaries for complete miscibility regions, and for different types of phase equilibria. Additionally, complete Pxy and Txy diagrams can also be generated using GPEC. The methods and computational strategy for their automated construction from the points given by the global phase equilibrium diagram are presented in a separate work [ii]. We illustrate the use of GPEC considering different types of EOSs. The program is shown to be a powerful tool for a thorough understanding of different types of phase behaviour that can be calculated with an EOS and the transitions between them. It allows a straightforward study of the influence of a given parameter on the predicted global phase behaviour for a given binary system. Finally, when having a model and parameters capable of a good representation of experimental data in wide ranges of conditions, the program becomes a useful tool in the search for promising operating conditions for specific applications.