Computer Control of a Yankee Paper Machine

This paper describes the computer control system used in the paper mill of Oy Nokia Ab in Nokia, Finland. The computer controlled Yankee Paper Machine produces paper with basis weight from 17 to 72 grams/m 2 . The operational principles of this paper machine and its control system are described. The control system software includes data collecting and reporting programs as well as supervisory programs. The most important variables and conditions of the paper machine are measured and reported. Among the control application programs the basis weight and moisture control can be considered as the most important. The target values of both moisture and basis weight are maintained by the computer. Thus the operation of the paper machine enables us to obtain maximum permissible moisture values of the produced paper. The computer also controls the non-continuous or continuous proportioning by the amounts of pulp components. Thus, an economic and exact proportioning is reached. The computer also controls the changes of grade, which are thus made accurately and fast. The computer measures continuously the lengths of the machine reel and the customer rolls on the winding machine, and tells the proper times for changes, and so the lengths are optimized. The conclusion includes the experiences we have gathered when using this computer control system.