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Simultaneous cyclic scheduling and optimal control of polymerization reactors
Author(s) -
TerrazasMoreno Sebastian,
FloresTlacuahuac Antonio,
Grossmann Ignacio E.
Publication year - 2007
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.11247
Subject(s) - discretization , mathematical optimization , nonlinear system , sensitivity (control systems) , mathematics , dynamic programming , optimal control , nonlinear programming , control variable , integer programming , continuous stirred tank reactor , orthogonal collocation , control theory (sociology) , collocation method , computer science , engineering , control (management) , chemical engineering , differential equation , mathematical analysis , artificial intelligence , ordinary differential equation , statistics , physics , quantum mechanics , electronic engineering
The simultaneous solution of the optimal sequencing and optimal dynamic transitions of two multigrade polymerization continuous stirred‐tank reactors (CSTRs) is presented. The simultaneous formulation leads to a mixed‐integer dynamic optimization (MIDO) problem. The profiles of the state variables during dynamic transitions are discretized using orthogonal collocation on finite elements, transforming the MIDO problem into a mixed‐integer nonlinear programming (MINLP) problem. The objective of this formulation is to maximize the profit of the manufacturing operation, considering polymer sales, inventory costs and transition costs. The transition cost term is determined by the duration of the transition stages and the manipulated variable profile during transitions. Two industrial reaction systems are used to analyze the optimal solution and compare it to other solutions obtained using different methods. Finally, a sensitivity analysis is carried out to describe the impact of changes in certain problem parameters. © 2007 American Institute of Chemical Engineers AIChE J, 2007