SELECTION OF KAPPA NUMBER TARGET FOR BLEACHED KRAFT PULP-MILLS

An optimum production cost can be obtained by altering pulping conditions without causing any significant effect on pulp quality. Lifting the Kappa target at the digester is the best option when mill operation is limited by either the capacity of the chemical recovery or the causticizing plant. However a downturn of the target Kappa is a preferable choice if the bleach plant effluent discharge is already at its allowable limit and the mill has excess capacities for chemical recovery and causticizing. The above perception, which is quantitatively analysed in this paper, can be extended and applied to a more complicated setting, where the mill is producing more than one pulp grade and is equipped with more than one chemical recovery system.