Broadening the Polyethylene Molecular Weight Distribution by Periodic Variation of the Hydrogen Feed Rate

The ability to control the molecular weight distribution of the created polyethylene in gas‐phase fluidized‐bed reactors is discussed. This objective is achieved via nonlinear model predictive controller utilizing the hydrogen feed rate as the only manipulated variable. The idea for limited usage of...

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Veröffentlicht in:Macromolecular reaction engineering Jg. 5; H. 2; S. 85 - 95
Hauptverfasser: Al-haj Ali, Mohammad, Ali, Emad M.
Format: Journal Article
Sprache:Englisch
Veröffentlicht: Weinheim WILEY-VCH Verlag 11.02.2011
WILEY‐VCH Verlag
Wiley-VCH
Schlagworte:
Applied sciences
Exact sciences and technology
modeling
molecular weight distribution/molar mass distribution
Organic polymers
Physicochemistry of polymers
polyethylene (PE)
Polymerization
Preparation, kinetics, thermodynamics, mechanism and catalysts
Fluidized bed reactor
Polyethylene
Polydispersed polymer
Chain transfer
Gas polymerization
Molecular weight distribution
Hydrogen
Theoretical study
Complex catalyst polymerization
Property processing relationship
Modeling
Predictive control
ISSN:1862-832X, 1862-8338
Online-Zugang:Volltext
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Zusammenfassung:The ability to control the molecular weight distribution of the created polyethylene in gas‐phase fluidized‐bed reactors is discussed. This objective is achieved via nonlinear model predictive controller utilizing the hydrogen feed rate as the only manipulated variable. The idea for limited usage of manipulated variables is to avoid economically unfavorable operations such as excessive purge and/or reduced production rate. The simulation results indicated successful implementation of the control algorithm to attain the desired molecular weight distribution. The success depends on the improved hydrogen activities inside the reactor by employing a modified catalyst that is responsive to hydrogen variation and allowing a wider range for hydrogen feed rates. Polyethylene with a pre‐specified molecular weight distribution is produced in a single fluidized‐bed reactor using a multi‐site Ziegler‐Natta catalyst. The control objective is successfully achieved, which requires forcing reactor input into cyclic operation using a nonlinear model predictive algorithm. The hydrogen‐to‐monomer molar ratio is successfully altered by regulating the hydrogen feed while keeping monomer feed rate constant, which makes reactor operation easier.
Bibliographie:istex:E1BBB2F3993EFC4C831ECE1A464E37B150DA05DF
ArticleID:MREN201000039
Research Center of College of Engineering in King Saud University
ark:/67375/WNG-646RMMMX-L
ISSN:1862-832X
1862-8338
DOI:10.1002/mren.201000039