MODEL-BASED CONTROL OF A HIGH-PURITY DISTILLATION COLUMN

In this paper, the problem of dual product composition control of an i ndustrial high purity distillation column, a deisohexanizer (DIH), is addressed using a Generic Model Control framework. A dynamic simulatio n of the DIH was performed for preliminary studies of the performance of different controller strategies/algorithms. The performance of Gene ric Model Control incorporating different process models was studied. Process models are presented ranging from simple first order approxima tions to mechanistic short cut distillation models where a tradeoff be tween model complexity and model adaptivity is investigated. The diffe rent controllers were implemented and compared using a dynamic simulat ion of an industrial deisohexanizer (DIH) to select the best condidate controller. A controller using a nonlinear process model emerged as t he best controller and was implemented on the actual process, resultin g in improved performance over the original controller. Simulation res ults and industrial plant data are presented.