CONSTRAINED MULTIVARIABLE CONTROL OF A WOOD CHIP REFINER - TRANSFER SCREW SPEED ADJUSTMENTS LINKED TO DESIGN FLEXIBILITY

This paper presents the design of a constrained multivariable adaptive controller for a wood chip refiner in the thermomechanical pulping (T MP) process. The control algorithm is based on Generalized Predictive Control (GPC) with consideration for the constraints on process variab les. The control objective is to maintain two output variables - refin er motor load and blow-line consistency - at their setpoints by adjust ing three manipulated variables: transfer screw speed, refiner hydraul ic pressure and dilution flow-rate. Computer simulations are presented to demonstrate the advantages of the proposed control algorithm.