An Analytical Approach to Approximate Dynamic Modeling of Distillation Towers.

Abstract

This paper presents analytical expressions for predicting distillate and bottoms composition transient reponses due to changes in manipulative and disturbance variables of a tower. The authors in an earlier paper showed that towers are inherently recycle structures and linearization techniques should be applied at perturbed conditions of tower models to evaluate realistic tower time constants. In this earlier paper, a numerical approach to estimating time constants was presented. The numerical approach is extended in this paper to an analytical approach that requires only steady state and design information of a tower. The analytical approach is relatively simple to use and much less time consuming compared to dynamic simulation. Further, the analytical technique gives insight into why towers respond nonlinearly.