Modelling and Parameter Estimation of a Paper Machine Drying Section Using Modelica

Abstract: In this thesis a model of the drying process in a paper mill has been adapted to paper machine 3 at Hylte Mill. The model is mainly based on a previous work by my supervisor Ola Slätteke PhD (at the Department of Automatic Control). New models have also been developed for the condensate system, e.g. condensate tanks, pumps, pipes and siphons. Models with a control system for the drying process have been implemented in the modelling based language Modelica and simulated in Dymola. Due to several unknown modelling parameters, optimisation of parameters has been a part of the work, where different optimisation routines have been investigated. Also sensitivity analysis of uncertain model parameters have been made. Step response experiments have been performed online at Hylte Mill and the results have been used for parameter optimisation and validation. Validated results show that stationary results can be modelled in a good way, even if single parameters have too high or low values. The results also show that it is difficult to use simplified physical models to describe the dynamic behaviour correctly, especially condensate removal and the dead time for paper moisture.