MULTICOMPONENT 3-PHASE AZEOTROPIC DISTILLATION .2. PHASE-STABILITY AND PHASE-SPLITTING ALGORITHMS

A literature review of three-phase distillation calculation procedures highlights the large number of efforts that have been made to account for the appearance of a second liquid phase on a distillation tray. The numerical problems due to the introduction of a second liquid phase during an iteration scheme are summarized in a table containing the known 15 solution sets. Many of these solutions contain a liquid-phase-splitting algorithm. A new algorithm based on Michelsen's phase-stability test and phase-splitting algorithm has been developed. New procedures in the iteration method and to identify liquid-phase instability have been produced and verified. These new procedures use analytical partial derivatives which can be determined from modern thermodynamic models to describe nonideal liquid-phase behavior. The predicted separation performance of a three-phase azeotropic distillation column using this new algorithm is in good agreement with the experimental data collected in part 1 of this series. © 1990, American Chemical Society. All rights reserved.