Model based optimal reactor design applied to a free radical polymerization process

• Published in: Computer Aided Chemical Engineering Vol. 31; pp. 1185 - 1190
• Main Authors: Klimantos, P., Hillestad, M.
• Format: Book Chapter
• Language: English
• Published: 2012
• Subjects: free-radical mechanism; optimization; reactor design; reactor design; optimization; free-radical mechanism
• ISBN: 9780444595058; 0444595058
• ISSN: 1570-7946
• DOI: 10.1016/B978-0-444-59506-5.50068-7

A computational framework is presented for model based optimal design of chemical reactors and applied to a multistage ethylene polymerization process. Design alternatives are generated on the basis of a state space composite model, accounting for fluid mixing, heat transfer, multiple and distributed feeds, initiator efficiency and others. A free radical polymerization kinetic mechanism is superimposed into the framework to describe the molecular and morphological polymer properties.The complexity of the kinetic mechanism due to the associated infinite dimensional population balance model (large stiff system of ODEs) is reduced by applying a continues variable approximation scheme over the discrete chain length domain. Finally an optimization problem is formulated by dis-cretizing the resulting differential algebraic equation (DAE) system into an NLP model by applying a complete parametrization (CP) technique. Optimal reactor designs and operating modes are identified that minimize an objective function subject to technical and product quality constraints.