Extreme conditions in binary reactive distillation

Abstract

In certain cases, reactive distillation can be used to avoid minimum reflux pinch points and azeotropic compositions. A pinch caused when using minimum reflux is always in the nonreactive section of the column. Its location is affected by the extent of reaction occurring elsewhere in the column. This article shows how to encounter such pinch situations by McCabe-Thiele and Ponchon-Savarit diagrams. Reactive distillation columns were designed under the extreme conditions of assuming reaction equilibrium and total reflux. Putting more than one reactive stage in such a column can be harmful to column performance for an azeotropic mixture. As a function of the magnitude of the reaction equilibrium constant, when an azeotrope can be circumvented is described. A binary reactive distillation can be bypassed only under finite reflux conditions, with the reaction equilibrium constant being greater than the reaction equilibrium constant evaluated at the azeotropic composition. A rigorous simulation of actual systems is sued to confirm the insights provided by these graphical methods.