Kraft continuous digester cooking control - DMT controls effective alkali, reduces kappa number variability

The control objective of a continuous pulp digester is to achieve maximum pulp production at a specified kappa number with a minimum of chemicals and energy input. Reducing the variability of effective alkali through closed loop control is believed to contribute to smoother digester operation and reduced kappa number variation. This paper describes the application of a dynamic modelling technology (DMT) predictive adaptive process controller that was able to provide closed loop control of effective alkali and resulted in reduced Kappa number variability, which resulted in annual savings in excess of $100 000.