EVALUATION OF MODELS FOR THE STEAM SUPPLY SYSTEM TO IMPROVE CONTROL OF THE PAPER DRYER

摘要

The possibility of reducing the transient times at grade changes in paper production and machine start-ups on thernpaper machines has highlighted the need for increased knowledge of the steam supply system. Models in thisrnarea have been presented in previous work (1,2) and it is of interest to compare these models with each other andrnevaluate them against experimental data. This paper reports on the results obtained from measurements on anrnindustrial paper dryer. Step responses as well as the dynamic changes caused by new set points for the controlrnsystem are examined. The two models are derived from different disciplines and comparison between these willrnbe presented. The first model (1) will provide estimations of the heat transfer coefficients in the condensate layerrnas well as the coefficient between the cylinder and the paper. This model is based on physical properties and firstrnprinciples. The second model is a linear process model, written in the Laplace operator as a transfer function.rnThis model is based on input-output data, a black box model, where the input and the output are the experimentalrndata from the paper machine. This model has been discussed in previous work (2,3).