Conference Contribution

Calibration of a polyethylene plant for grade change optimisations

Niklas Andersson, Per-Ola Larsson, Johan Åkesson, Staffan Haugwitz, Bernt Nilsson


A polyethylene plant model coded in Modelica and based on a nonlinear MPC model currently used at Borealis AB is considered for calibration. A case study of model calibration at steady-state for four different operating points are analysed, both when looking at one operating point separately, but also to calibrate several simultaneously. Both model parameters and reactor inputs are calibrated for true plant measurement data. To solve the parameter estimation problem, the platform is used, offering tools to express and solve calibration problems. Calibration was obtained with narrow confidence intervals and shows a potential to improve the model accuracy by changing the parameter values. The results will be used for dynamic optimisations of grade changes.


Calibration, Modelica, grade change, cheical industry, polymerisation

In 21st European Symposium on Computer Aided Process Engineering, Chalkidiki, Greece, June 2011.

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