Emerging and Underutilized Technologies to Increase Kraft Mill Production, 1996 Engineering Conference Proceedings

Todd R. Brooks

Industra Inc.

Fred T. Marcinek

MARTECH

A comparison of engineering alternatives to increase kraft pulping and/or recovery capacity is presented. The authors identify options available to companies seeking increased pulp mill tonnage that are often overlooked because they are not now in common use in the pulp and paper industry in North America. Many mills can benefit from elimination, or reduction, of a recovery capacity bottleneck through expan-sion of the existing recovery unit, installation of a mini recovery boiler, or use of a gasification unit. Implementation of one of these recovery capacity options can provide an increase in mill pulp production up to 20% with an ROI of 40%. Kraft pulping production benefits utilizing polysulfide (PS) and anthraquinone (AQ) digester additives have a proven track record in Japanese mills for yield and production enhancement, but have not gained wide acceptance in North America. Because the quantity of dissolved organic material generated per unit of bleached pulp when using PS/AQ is 4% to 10% less than with conventional kraft cooking, incremental production gains are possible, even in recovery-limited mills. These solutions will be evaluated and compared on both a technical and an economic basis for application under different mill operating constraints.