Rapid generation of composition profiles for reactive and extractive cascades

Abstract

A quick method for estimating composition profiles for reactive and extractive cascades in a double-feed column without stage calculations is presented. This profile estimation is based on the feasibility and pinch point analyses. The trajectories of pinch points are determined with material balance equations and phase and reaction equilibrium data. From these pinch point trajectories, the ranges of feasible external reflux ratios and required entrainer flow rates are calculated for a given reaction extent and product purity. Then, for given external reflux ratios, heat balance constraints are imposed to determine the positions of pinch points. Finally, using the internal reflux ratios of these pinch points, manifolds of possible composition profiles are generated. Composition profiles of a reactive/extractive cascade can lie in the section of the reaction equilibrium surface where the internal reflux ratio of a saddle pinch is between the upper and lower bounds of the internal reflux ratio. (C) 2005 American Institute of Chemical Engineers.