Importance of Homogeneity in MC Ozone Stages in TCF Bleaching Sequences, 1996 International Pulp Bleaching Conference Proceedings

Not much has been reported on how bleaching with nonchlorine chemicals is affected by inhomogeneous bleaching conditions. This paper discusses the problem of inhomogeneous ozone bleaching in an azqp* sequence’. Also, we discuss “coupled inhomogeneities,” i.E., Does inhomogeneities in a bleaching stage affect the efficiency of all the following stages in the bleach plant, or just the inhomogeneous one? Inhomogeneous ozone bleaching at medium pulp consistency does not seem to affect the pulp as negatively as we expected. Our results show that the degree of inhomogeneity, i.E., The coefficient of variation, must be higher than 30% in the ozone stage in an azqp* sequence before any negative effects on the brightness is observed. Furthermore, severe damage to brightness, and to a minor extent viscosity, does not occur until the degree of inhomogeneity reaches as high as 50%. The delignification is less sensitive to inhomogeneities than the brightness; no significant decrease in delignification is observed at a coefficient of variation of 50%.