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Model-Based Optimization of Economical Grade Changes for the Borealis Borstar Polyethylene Plant

Larsson, Per-Ola LU ; Åkesson, Johan LU ; Carlsson, Niclas and Andersson, Niklas LU (2012) In Computers & Chemical Engineering 46. p.153-166
Abstract
Economical grade changes are considered for a Borealis Borstar polyethylene plant model, incorporating two slurry-phase reactors, one gas-phase reactor and a recycle area with three distillation columns. The model is constructed in the Modelica language and the JModelica.org platform is used for opti- mization. The cost function expresses the economical profit during a grade change and is formulated using on-grade intervals for seven polymer quality variables such as melt index, density and reactor split factors. Additionally, incentives to produce polymer with quality variables on grade target values, not only inside grade intervals, are added. Twelve inflows and three purge flows are used at optimization. Two grade changes are thoroughly... (More)
Economical grade changes are considered for a Borealis Borstar polyethylene plant model, incorporating two slurry-phase reactors, one gas-phase reactor and a recycle area with three distillation columns. The model is constructed in the Modelica language and the JModelica.org platform is used for opti- mization. The cost function expresses the economical profit during a grade change and is formulated using on-grade intervals for seven polymer quality variables such as melt index, density and reactor split factors. Additionally, incentives to produce polymer with quality variables on grade target values, not only inside grade intervals, are added. Twelve inflows and three purge flows are used at optimization. Two grade changes are thoroughly reviewed, showing the effect of using a cost function that regards plant economy. Re- sulting trajectories can be divided into three phases with distinguishing fea- tures, and the synchronization of inflows and usage of recycle area off-gas flows are important in the grade changes. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
optimization, grade change, polymer, economy
in
Computers & Chemical Engineering
volume
46
pages
153 - 166
publisher
Elsevier
external identifiers
  • wos:000308714800014
  • scopus:84864942620
ISSN
1873-4375
DOI
10.1016/j.compchemeng.2012.06.024
project
PICLU
language
English
LU publication?
yes
id
f0b2d9bd-a33d-4b7d-8be4-194c7e6fea7a (old id 2972262)
date added to LUP
2012-08-24 10:55:13
date last changed
2017-04-09 04:10:36
@article{f0b2d9bd-a33d-4b7d-8be4-194c7e6fea7a,
  abstract     = {Economical grade changes are considered for a Borealis Borstar polyethylene plant model, incorporating two slurry-phase reactors, one gas-phase reactor and a recycle area with three distillation columns. The model is constructed in the Modelica language and the JModelica.org platform is used for opti- mization. The cost function expresses the economical profit during a grade change and is formulated using on-grade intervals for seven polymer quality variables such as melt index, density and reactor split factors. Additionally, incentives to produce polymer with quality variables on grade target values, not only inside grade intervals, are added. Twelve inflows and three purge flows are used at optimization. Two grade changes are thoroughly reviewed, showing the effect of using a cost function that regards plant economy. Re- sulting trajectories can be divided into three phases with distinguishing fea- tures, and the synchronization of inflows and usage of recycle area off-gas flows are important in the grade changes.},
  author       = {Larsson, Per-Ola and Åkesson, Johan and Carlsson, Niclas and Andersson, Niklas},
  issn         = {1873-4375},
  keyword      = {optimization,grade change,polymer,economy},
  language     = {eng},
  pages        = {153--166},
  publisher    = {Elsevier},
  series       = {Computers & Chemical Engineering},
  title        = {Model-Based Optimization of Economical Grade Changes for the Borealis Borstar Polyethylene Plant},
  url          = {http://dx.doi.org/10.1016/j.compchemeng.2012.06.024},
  volume       = {46},
  year         = {2012},
}