Reduced-order models for separation columns—V. Selection of collocation points

Abstract

In the earlier parts of this paper, a method for developing reduced-order models for separation columns was presented. This article presents some guidelines for determining the degree of order reduction achievable for a given column. An index called ORP (Order Reduction Parameter) is developed to predict a priori, the extent of order reduction achievable and to provide guidelines for choosing a reduced-order model of the appropriate size. This, combined with a comparison with a steady state solution, can provide the engineer with a good estimate of the number and location of collocation points to be used in the reduced-order model. The method is developed using a simple binary absorber and illustrated by application to a more complex, multicomponent distillation column.