Model based control of a high purity distillation column

In this paper, the problem of dual product composition control of an industrial high purity distillation column, a deisohexanizer (DIH), is addressed using a Generic Model Control framework. A dynamic simulation of the DIH was performed for preliminary studies of the performance of different controller strategies/algorithms. The performance of Generic Model Control incorporating different process models was studied. Process models are presented ranging from simple first order approximations to mechanistic short cut distillation models where a tradeoff between model complexity and model adaptivity is investigated. The different controllers were implemented and compared using a dynamic simulation of an industrial deisohexanizer (DIH) to select the best condidate controller. A controller using a nonlinear process model emerged as the best controller and was implemented on the actual process, resulting in improved performance over the original controller. Simulation results and industrial plant data are presented. Dans cet article, on etudie a l'aide d'un schema de «controle generique des modeles» le probleme du controle de la double composition des produits dans une colonne a distiller a haute purete industrielle, soit un deisohexaniseur (DIH). On a realise une simulation dynamique du DIH en vue d'etudes preliminaires de la performance des differentes strategies ou algorithmes de controle. La performance du controle generique des modeles a ete etudiee en utilisant plusieurs modeles de procedes. On presente les differents modeles de procedes qui vont de la simple approximation du premier ordre jusqu'au modele mecanistique de distillation en petites coupes, et on etudie le compromis entre la complexite des modeles et leur adaptabilite. On a applique et compare les differents controleurs au moyen d'une simulation dynamique d'un deisohexaniseur dans le but de selectionner le meilleur controleur possible. Un controleur base sur un modele de procede non lineaire s'est revele le meilleur et a ete applique au processus reel, ce qui a donne une amelioration de la performance par rapport au controleur original.