BLEACHING OF PULP

摘要

The present invention relates to a method for parent control of bleaching of pulp with chlorine dioxide, which is characterized by that the pulp is transported, via a mixer where chlorine dioxide is added, to an up-flow reactor wherein an essential part of the bleaching is performed, whereupon the pulp is transported to a down-flow reactor and that a regulation of the total dwell time in the reactors is controlled so that you may always be able to apply optimal time and temperature for production of different products at different production levels. The method according to the present invention may be used in a bleaching system for chlorine dioxide bleaching of pulp, a bleaching step, comprising a mixer for adding of chlorine dioxide to the pulp which leads to a smaller up-flow reactor where the most part of the bleaching is performed, which in turn leads the pulp to a down-flow reactor for final reactions.