Modeling and control of the DEop bleaching stages.

摘要

Optimization and control of the delignification portion of a bleach sequence may be facilitated by an accurate and robust bleaching model. A detailed model of the DEOPbleaching stages has been developed. The model includes the kinetics of the chemical reactions of chlorine dioxide and sodium hydroxide with lignin. The kinetic reactions are coupled with the non-ideal flow of pulp and liquor streams through the bleaching reactors to provide a dynamic process model of the first two stages of a bleach plant. The model is in good agreement with industrial bleach plant data. The model accurately predicts the key process outputs.;The dynamic model developed in this research was used to evaluate two candidate control strategies. The two strategies evaluated were Compensated Kappa Factor (CKF) and a Model Predictive Controller (MPC) with an estimator. The strategies were evaluated for their performance for regulatory and servo control. Trials evaluating the controllers for input kappa disturbance, production rate change, and setpoint change were performed. The MPC controller showed a greater reduction of the variability of the input kappa disturbance and was able to manage the production rate change more effectively. Both controllers performed equally well for the setpoint change. The model was shown to be an effective and useful tool in evaluating potential control strategies where multiple pathways for upgrading an existing control methodology exist.