The University of British Columbia

This paper investigates the development and industrial application of a multi-input/single-output adaptive-predictive Kamyr digester chip level controller based on Generalized Predictive Control (GPC). The controller simultaneously manipulates the blow flow and the chip meter to control the chip level. The chip meter is manipulated in a way which tends to maintain the desired production rate, while still leaving some room for control. The idea was to use the chip meter as a second input variable to reduce blow flow manipulation and, thereby, reduce disruptions to the chip column movement. The two-input strategy decreased blow flow manipulation by more than 50% (compared to an otherwise equivalent one-input scheme) without sacrificing output performance. However, the anticipated improvements in permanganate-number variability were not achieved. The multi-input strategy was discontinued after six months of operation.