Oxygen Delignification - A Study of Performance Parameters, 1996 Pulping Conference Proceedings

David Carter

Tony Johnson

H.A. Simons Ltd.

Dan McKenzie

Simons Engineering Inc.

Kristina Idner

AF-IPK

Current performance data has been collected for the oxygen delignitication system at 78 different bleached kraft pulp lines around the World. Some of the key operating parameters are presented showing that levels of delignification vary from a low of 28% to a high of 67% for softwood and from 29 to 55% for hardwood; averages are 47 and 40% respectively.

Analysis of the data includes the type of cooking, incoming kappa number of pulp, high and medium consistency, single and two stages and other variables.

Currently the analysis leads to the conclusion that there is no common factor related to performance and that operation tends to be to a mill specific target. Post oxygen stage kappa numbers reported tend to level out at 10 for softwoods and 8 for hardwoods.

The dramatic growth of oxygen delignification, as a kraft fibre line component, over the last 25 years is reviewed. The geographical distribution of systems is presented and the reasons for the growth are reviewed. Examples of both single and two stage systems are presented.