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Gap mechanics in pulp refiners, TAPPI Journal June 2025

ABSTRACT: Studies of pulp refining have shown that a single bar impact on pulp has only a 1%•5% probability of producing a successful refining effect. This study has explored the reason why. An analysis of refining kinetics suggested that small segments of a fiber length, about a fiber diameter in size, are treated during each impact. Measurements of localized swelling along fiber lengths caused by refining supported this finding. Based on these findings, it was postulated that force transmittal through fiber networks occurred primarily at fiber crossings. The small size of fiber diameters relative to fiber lengths accounts for the low probability of a successful refining event at each impact. This probability, and the probability of fibers being captured and impacted during passage through a refiner, account for the need for multiple bar crossings to refine pulps.

Mitigating Malodors at Pulp and Paper Production Plants, Paper360º July/August 2024

Continuous digester rapid thinning, TAPPI Journal June 2024

ABSTRACT: Carbon steel continuous digesters built after the early 1980s are fully stress relieved, so stress corrosion cracking has been less of a concern. However, these newer digesters were designed to run modified cooking processes that have turned out to be much more corrosive than those running with conventional cooking. This corrosion is mainly associated with softwood digesters and appears to be flow related. Average corrosion rates of 40 mil/year are possible on the exposed shell between the wash and extraction screens. The corrosion patterns are visually distinct from surfaces in the upper digester and below the wash screens. This paper goes into practical detail on where it occurs, the causes, visual identification, inspection planning and results evaluation, and finally, how to mitigate this damage, which consists of applying a corrosion resistant barrier. Some discussion on dealing with general corrosion throughout the digester is included.

Pulping and bleaching of Malaysian oil palm empty fruit bunc

Pulping and bleaching of Malaysian oil palm empty fruit bunches, TAPPI JOURNAL June 2017

Paper Chemistry: What’s New, What’s Next, Paper360º March/

Paper Chemistry: What’s New, What’s Next, Paper360º March/April 2017

Facing the Market, Paper360 May/June 2019

Facing the Market, Paper360 May/June 2019

The Shortest Route to Fiber Quality, Paper360 May/June 2019

The Shortest Route to Fiber Quality, Paper360 May/June 2019

7 Water Waste Reduction Strategies to Improve Pump Reliability/Black Liquor Processing, Paper360º November/December 2019

7 Water Waste Reduction Strategies to Improve Pump Reliability/Black Liquor Processing, Paper360º November/December 2019

Hydrogen peroxide and caustic soda: Dancing with a dragon while bleaching, TAPPI JOURNAL July 2013

Authors: Peter W. Hart; Carl Houtman; and Kilby Hirth | ABSTRACT: When hydrogen peroxide is mixed with caustic soda, an auto-accelerating reaction can lead to generation of significant amounts of heat and oxygen. On the basis of experiments using typical pulp mill process concentration and temperatures, a relatively simple kinetic model has been developed. Evaluation of these model results reveals that hydrogen peroxide-caustic soda systems are extremely sensitive to hydrogen peroxide:caustic soda ratio, transition metal contamination, and temperature. Small changes in initial conditions can result in a closed system becoming explosive. Analysis of model results was used to develop guidelines for safer application of hydrogen peroxide in a mill setting.

Wood Pulp: The New Cotton for the Garment Industry?, Paper360 May/June 2019

Wood Pulp: The New Cotton for the Garment Industry?, Paper360 May/June 2019