Reliable Phase Stability Analysis for Cubic Equation of State Models


J. Z. Hua, J. F. Brennecke, and M. A. Stadtherr


The reliable prediction of phase stability is a challenging computational problem in chemical process simulation, optimization and design. The phase stability problem can be formulated either as a minimization problem or as an equivalent nonlinear equation solving problem. Conventional solution methods are initialization dependent, and may fail by converging to trivial or nonphysical solutions or to a point that is a local but no global minimum. Thus there has been considerable recent interest in developing more reliable techniques for stability analysis. In this paper we demonstrate, using cubic equation of state models, a technique that can be solve the phase stability problem with complete reliability. The technique which is based on interval analysis, is initialization independent, and if properly implemented provided a mathematical guarantee that the correct solution to the phase stability problem has been found.

Comput. Chem. Eng., 20, S395-S400 (1996)

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