Distillation column dynamics and control have been viewed by many as a very mature or even dead field. However, as is discussed in this paper significant new results have appeared over the last 5-10 years. These results include multiple steady states and instability in simple columns with ideal thermodynamics (which was believed to be impossible), the understanding of the difference between various control configurations and the systematic transformation between these, the feasibility of using the distillate-bottom structure, for control (which was believed to be impossible), the importance of flow dynamics for control studies, the fundamental problems in identifying models from open-loops responses, the use of simple regression estimators to estimate composition from temperatures, and an improved general understanding of the dynamic behavior of distillation columns which includes a better understanding of the fundamental difference between internal and external flow, simple formulas for estimating the dominant time constant, and a derivation of the linearizing effect of logarithmic transformations. These issues apply to all columns, even for ideal mixtures and simple columns with only two products. In addition, there have been significant advances for cases with complex thermodynamics and complex column configurations. These include the behavior and control of azeotropic distillation columns, and the possible complex dynamics of nonideal mixtures and of interlinked columns. However, both for the simple and more complex cases there are still a number of areas where further research is needed.

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Dynamics and control of distillation columns : a critical survey

https://www.mic-journal.no/PDF/1997/MIC-1997-3-1.pdf

Dynamics and Control of Distillation Columns - A Critical Survey

Optimal design and control of a high-purity industrial distillation system

Analyse phenomenologique de la dynamique d'un certain nombre de systemes a parametres distribues du genie chimique montrant un comportement dynamique simple de ces systemes malgre la complexite des modeles des procedes non lineaires. Description de la dynamique de la plupart des procedes consideres avec suffisament de precision par trois modeles structuraux servant de base a l'analyse theorique des systemes. Etude des proprietes caracteristiques des ondes propagees et des mecanismes responsables de la formation de ces ondes. Etudes montrant que la connaissance etendue de ces procedes peut etre appliquee a la resolution des problemes d'interet technique

Wellenausbreitung in verfahrenstechnischen Prozessen

Untersuchungen zur stochastischen Online Optimierung kontinuierlicher Destillationsprozesse unter Unsicherheiten

In order to achieve optimal energy-saving, load-dependent operation of rectification columns, development and implementation of model-based control concepts are necessary. This paper reports on the design and step-by-step testing of a state observer for the estimation of two state variables which cannot be measured directly, namely the vapour rate and the location of mass transfer zone (temperature front) in the stripping section of a production column. The procedure is described, and the relevant simulation and operation results are presented and discussed. Initial experience, gained when the concept was put into practical operation, is reported.

Manfred Köhne

Papers

Design and analysis of a state observer for the temperature front of a retification column