Pressurized Peroxide Bleaching Configuration and Process Control, 1996 Pulping Conference Proceedings

R. Detroz

A. Renders

J. Devenyns

Solvay Interox

The improved methods for metals control have prepared the way to the use of high temperature and pressure to enhance the performance of alkaline peroxide bleaching stages; such (PO) stages essentially consist of chemical and gas feed lines, MC pulp handling equipment, a pressurized reaction vessel with adequate retention, blow tank and washing.

The first part of the study deals with a systematic review of the effects of pressure, temperature, time and nature of the gas as a function of the kappa number entering the final brightening stage. Detailed examples and comparative investigations are included on (PO) bleaching of Northern softwood, European mixed hardwood and Eucalyptus. It was observed that the effects of temperature and pressure are most pronounced for softwood and Eucalyptus pulps.

Following the trend towards double/multiple vessel configurations in Oxygen delignification, the second part of the study deals with the investigation of preretention tube -reaction vessel combinations for final bleaching.

Developing from such basic (PO) design, adequate process control and optimal process configuration will both improve the performance and lower the investment.