Patent ID: 6153050
Filing Date: 2000-11-28
Classification: D21C,Y10S

Abstract:
A system for obtaining a substantially constant percentage of delignification of pulp across a first bleaching/delignifying stage, the system comprising:a) a computer coupled to a distributed control system (DCS) or a database, or both, for acquiring (i) data related to pulp properties prior to entrance of the pulp into a bleaching tower, where the pulp has a residence time between about 15 minutes and about 75 minutes, and (ii) data related to conditions within the bleaching tower;b) processing means comprised in the computer to process the data acquired by the computer using (i) a kinetic model to predict reagent consumption, change in kappa number, and change in brightness to determine a bleaching/delignifying reagent flow rate required to obtain the substantially constant percentage of delignification of the pulp across the first bleaching/delignifying stage, and (ii) a pulp tracking algorithm to calculate changes in kappa number at the bleaching tower outlet based on pulp flow and temperature; andc) transmitting means comprised in the computer for transmitting the bleaching/delignifying reagent flow rate required to obtain the substantially constant percentage of delignification of the pulp across the first bleaching/delignifying stage;whereby the bleaching/delignifying reagent flow rate is controlled automatically by the DCS through information transmitted from said transmitting means.