Retention Modelling and Control in the Paper Machine WET End

Retention control has largely remained unsolved, although it is one of the most important control loops still to be closed in the paper machine. In this paper retention modelling is done using multivariable time-series approach. Based on careful selection of vanables and model structure, several new control strategies are developed. Different feedback controls are successfully tested on a pilot paper machine. It is believed to be the first time when successful retention control has been reported in the literature.