Unscented Kalman filter based Nonlinear Control for the Forced-circulation Evaporation Process

The forced-circulation evaporation process plays an important role in the Bayer alumina production. Since the process has a complex dynamics, such as strong coupling, serious nonlinearity, where the conventional controller cannot meet the actual demand. Moreover, parameter uncertainties further increase degree of difficult for the above process. To address above challenge problem, an unscented Kalman filter (UKF) observer with the ability of predicting liquor heat capacity is proposed aiming at track changes of the forced-circulation process. The globally linearizing control (GLC) strategy combined with UKF is used to eliminate the coupling between the two control loops and reduce the effects of the nonlinearities on the system simultaneity. The experimental results show that the UKF observer can track the changes of the parameter uncertainty more quickly compared with the extend Kalman filter (EKF) and the proposed approach has good decoupling control performances, which provide theoretical guidance for actual production.