METHOD AND APPARATUS FOR BLEACHING PULP WITH A GASEOUS BLEACHING REAGENT

摘要

A method and apparatus for bleaching pulp with a gaseous bleaching reagent. The pulp (18) is intensively mixed in the presence of the bleaching reagent within an upstream vessel comprising a fluffer/blower (12). Next, the pulp is agitated in the presence of the bleaching reagent within an intermediate vessel comprising an agitated mixer reactor (14). The pulp is then discharged to a downstream vessel, comprising a porous bed reactor (16), where it is further reacted with the bleaching reagent. The concentration of the gaseous bleaching reagent supplied to each vessel is separately controlled which, in combination with a controlled pulp residence time within at least the agitated mixer reactor and the porous bed reactor, results in an economy of energy utilization, a minimization of pulp particle damage due to mechanical mixing, and uniformity of pulp bleaching.