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

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Model-Based Optimization of Economical Grade Changes for the Borealis Borstar Polyethylene Plant. / Larsson, Per-Ola; Åkesson, Johan; Carlsson, Niclas; Andersson, Niklas.

I: Computers & Chemical Engineering, Vol. 46, 2012, s. 153-166.

Forskningsoutput: TidskriftsbidragArtikel i vetenskaplig tidskrift

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TY - JOUR

T1 - Model-Based Optimization of Economical Grade Changes for the Borealis Borstar Polyethylene Plant

AU - Larsson, Per-Ola

AU - Åkesson, Johan

AU - Carlsson, Niclas

AU - Andersson, Niklas

N1 - key=lar+12cace month=November project=LCCC-modeling

PY - 2012

Y1 - 2012

N2 - 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.

AB - 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.

KW - optimization

KW - grade change

KW - polymer

KW - economy

U2 - 10.1016/j.compchemeng.2012.06.024

DO - 10.1016/j.compchemeng.2012.06.024

M3 - Article

VL - 46

SP - 153

EP - 166

JO - Computers and Chemical Engineering

T2 - Computers and Chemical Engineering

JF - Computers and Chemical Engineering

SN - 1873-4375

ER -