Optimal grade transition and selection of closed-loop controllers in a gas-phase olefin polymerization fluidized bed reactor

作     者：Chatzidoukas, C Perkins, JD Pistikopoulos, EN Kiparissides, C 

作者机构：Aristotle Univ Thessaloniki Chem Proc Engn Res Inst Dept Chem Engn Thessaloniki 54006 Greece Univ London Imperial Coll Sci Technol & Med Ctr Proc Syst Engn Dept Chem Engn London SW7 2BY England 

出 版 物：《CHEMICAL ENGINEERING SCIENCE》 (化学工程科学)

年 卷 期：2003年第58卷第16期

页      面：3643-3658页

核心收录：

学科分类：0817[工学-化学工程与技术] 08[工学] 

基　　金：European Commission, EC, (G1RD-CT-2000-00422) European Commission, EC 

主　　题：gas-phase olefin polymerization optimal grade transition optimal control structure selection mixed integer dynamic optimization gPROMS((R)) simulator 

摘      要：To satisfy the diverse product quality specifications required by the broad range of polyolefin applications, polymerization plants are forced to operate under frequent grade transition policies. Commonly, the optimal solution to this problem is based on the minimization of a suitable objective function defined in terms of the changeover time, product quality specifications, process safety constraints and the amount of off-spec polymer, using dynamic optimization methods. However, considering the great impact that a given control structure configuration can have on the process operability and product quality optimization, the time optimal grade transition problem needs to be solved in parallel with the optimal selection of the closed-loop control pairings between the controlled and manipulated variables. In the present study, a mixed integer dynamic optimization approach is applied to a catalytic gas-phase ethylene-1-butene copolymerization fluidized bed reactor (FBR) to calculate both the best closed-loop control configuration and the time optimal grade transition policies. The gPROMS/gOPT computational tools for modelling and dynamic optimization, and the GAMS/CPLEX MILP solver are employed for the solution of the combined optimization problem. Simulation results are presented showing the significant quality and economic benefits that can be achieved through the application of the proposed integrated approach to the optimal grade transition problem for a gas-phase polyolefin FBR. (C) 2003 Elsevier Ltd. All rights reserved.