Model-based computer control of Kappa number in magnefite pulp cooking

The aim of this contribution is to present a model-based system for Kappa control in batch pulp cooking. Kappa is one of the parameters that reflect quality of the pulp. In order to keep the quality uniform, Kappa value at the end of the batch should dissipate as little as possible. Target Kappa is controlled (among others) by careful selection of cooking times which depend on charging and cooking conditions. Since appropriate industrial sensors for online Kappa measurements in batch digesters are still not available, current Kappa values have to be "sensed" by means of the mathematical model. In this paper an extended Vroom´s model is adopted for online Kappa prediction and adaptive control. A model represents the essential part of the system for digester control. Provided uniform charging conditions are guaranteed, the computer control system is shown to be able to give on average better results than manual control even if performed by experienced operators.