Non-Interactive Distillation Tower Analyzer Control

This paper discusses a novel but simple way of decoupling overhead and bottoms tower product quality controllers without the aid of a towe model. This approach also linerizes the relationship between tower manipulated variables (reboiler duty and reflux ratios) and the product impurity levels. The paper first discusses the base level tower controls including: reflux-to-feed ratio control, reboiler-to-feed ratio control and temperature control. The paper will also discuss conventional analyzer controls for dual product quality control. The paper then discusses a new approach which uses combinations of overhead and bottoms impurity levels to calculate indices of tower cut and fractionation. The cut and fractionation indices are then controlled using conventional control schemes.