Hierarchical computer system for retention control in the wet end of a paper machine

The authors present a hierarchical data acquisition and control system for controlling retention in the paper machine wet end. Special methods were developed for retention control. The use of a hierarchical control system and these methods produced good results in retention control on a Finnish paper machine. Retention control tests were performed and measurements of the final paper quality were closely monitored. Controlling the retention decreased variations in the paper formation.<>