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Magazine articles
Displacement washing of softwood pulp cooked to various levels of residual lignin content, TAPPI Journal September 2021
ABSTRACT: This study investigates the influence of the degree of delignification of kraft spruce pulp cooked at seven different kappa numbers, ranging from 18.1 to 50.1, on the efficiency of displacement washing under laboratory conditions. Although the pulp bed is a polydispersive and heterogeneous system, the correlation dependence of the wash yield and bed efficiency on the Péclet number and the kappa number of the pulp showed that washing efficiency increased not only with an increasing Péclet number, but also with an increasing kappa number. The linear dependence between the mean residence time of the solute lignin in the bed and the space time, which reflects the residence time of the wash liquid in the pulp bed, was found for all levels of the kappa number. Washing also reduced the kappa number and the residual lignin content in the pulp fibers.
Journal articles
Magazine articles
Effects of phosphogypsum whiskers modification with calcium stearate and their impacts on properties of bleached softwood paper sheets, TAPPI Journal September 2021
ABSTRACT: By combining the structural properties and characteristics of phosphogypsum whiskers, a preliminary study on the modification of phosphogypsum whiskers and their application in papermaking was carried out. The effects of reaction temperature, reaction time, and reaction concentration on the solubility and retention of modified phosphogypsum whiskers and the effects of phosphogypsum whiskers on the physical properties of paper under different modified conditions were explored. The research results show that, after the phosphogypsum whiskers are modified with calcium stearate, a coating layer will be formed on the surface of the whiskers, which effectively reduces the solubility of the phosphogypsum whiskers. The best modification conditions are: the amount of calcium stearate relative to the absolute dry mass of the phosphogypsum whisker is 2.00%; the modification time is 30 min, and the modification temperature is 60°C. The use of modified phosphogypsum whiskers for paper filling will slightly reduce the whiteness, folding resistance, burst resistance, and tensile strength of the paper, but the tearing degree and retention of the filler will be increased to some extent.
Journal articles
Preparing Corrugating Adhesive with Untreated Flexo Wash Wat
Preparing Corrugating Adhesive with Untreated Flexo Wash Water in an Automated, High Shear Mixer, 1990 Corrugated Containers Conference Proceedings
Journal articles
Investigation of the Relationship Between Board Cure Time an
Investigation of the Relationship Between Board Cure Time and Top-To-Bottom Compression Performance, 1994 Corrugated Containers Conference Proceedings
Journal articles
Corrugated medium strength assessments in different flute structures, TAPPI Journal April 2026
ABSTRACT: Recent advancements in our ability to evaluate papers and our understanding of the mechanics of box failure have brought a renewed focus on measuring the performance of corrugated medium and an associated evolution of paper measurement approaches. This study evaluates the load curves, Hardness (where the fluted structure’s loading shifts away from an elastic response), and Concora medium crush test (CMT) values for a range of corrugated mediums in different common flute geometries. The shape of the load curve is a function of the geometry of the fluting profile and the relative stiffness of the paper, with smaller flutes and heavier papers reaching both the Hardness value and the ultimate load at lower deformation. Nonetheless, while the specific dynamics during the loading process vary, Hardness and CMT values correlate linearly between flute structures, even when testing specimens after different equilibration periods post-fluting. These correlations confirm the applicability of the standard A-flute CMT test to a broad range of papers and potential combined board flute structures, supporting quality assurance processes for medium production and optimization in corrugated board manufacturing.
Journal articles
Optimization of energy efficiency and condensate production in evaporation plants for a modern softwood pulp mill, TAPPI Journal April 2026
ABSTRACT: To meet the need to further improve thermal efficiency and environmental performance of kraft pulp mills, new systems and techniques have been developed within the evaporation plant. This paper describes these novel approaches and how they were implemented in a project completed in 2018 for a new evaporator and condensate treatment system supplied by Valmet at the SCA Östrand market pulp mill in Sweden. This project was part of a stepwise upgrade of the complete mill to increase the production capacity of the mill from 430,000 to 900,000 air-dried metric tons/year (ADt/y). As part of this upgrade, the mill had the objectives to increase the energy efficiency of the pulp mill and to minimize the air emissions as much as possible, the effluent volume, and the water usage in the mill. The mill also wanted to have the disposal of the biosludge in the black liquor, and the production of tall oil from black liquor soap, liquid methanol, and turpentine. This required that the new evaporation and condensate treatment system be very closely integrated into the other process departments of the mill, including integration of the hot weak black liquor flash vapor from the digester directly into the evaporator train and the production of multiple streams of clean evaporation plant condensate at the correct temperature for the bleach plant. Heat and mass balance calculation values, which were found to do very well in predicting the effect on actual mill operation, are also presented in this paper.
Journal articles
A systems approach for process debottlenecking towards a sustainable pulp and paper industry, TAPPI Journal April 2026
ABSTRACT: Increasing the competitiveness of the pulp and paper industry requires an effective optimization of its existing assets in line with a long-term vision for process transformation, production upgrade, and product diversification. Currently, pulp production increase is one of the main sources of additional revenue for the kraft industry. Likewise, energy efficiency is often employed as a cost-effective approach to reduce operating costs, enhancing the possibilities to lower fossil fuel consumption and contributing to a low-carbon economy. On the other hand, reaching higher production targets and facilitating process transformation, such as biorefinery implementation, heavily depend on the status and performance of a mill’s current infrastructure; therefore, a system analysis is needed to assess the new production requirements, the bottlenecks, and the interactions across departments. In order to obtain practical improvement solutions, direct and indirect impacts on process performance and resource utilization should be considered. This work provides an overview of the key challenges that need to be addressed for production increase and energy efficiency improvement. The methodology starts by a scope analysis for debottlenecking and screening capacity limitations vs. mill targets, followed by their ranking (bottleneck ranking diagram). Benchmarking, gap analysis, and root-cause techniques are applied to diagnose system inefficiencies. This mill-wide debottlenecking assessment is then used to guide the selection of a long-term sustainable operation and design a portfolio of improvement projects by avoiding cross effects of the short-term projects on the long term. A case study of a kraft pulp mill is used to illustrate the proposed methodology.
Journal articles
Examination of scoring parameters of corrugated fiberboard, TAPPI Journal August 2026
ABSTRACT: One of the less interrogated aspects of corrugated packaging are scoring and scoring profiles, the intentional localized crushing of flutes to accommodate package folding and closure. This study explores the effect of scoring parameters on box compression test strength (BCT) of two balanced corrugated boards. Scoring differences produced BCT that varied by 10% for one board and less for the other board. Parameters from 4-point bending of scored specimens showed some correlation with BCT, while eccentricity and torsion parameters had less correlation. Different scores produced BCT differences that were not strongly predicted by most standard tests in the current study, implying other tests may be needed to examine the actual boundary conditions on a box during compression. In a few cases, aggressive scoring produced cracked score lines, and those containers had lower BCT than containers with uncracked score lines.
Journal articles
Investigating the causes of severe economizer tube thinning in a spent sulfite liquor (SSL) boiler, TAPPI Journal August 2026
ABSTRACT: In this study, the causes of tube thinning in the economizer of an ammonia-based spent sulfite liquor (SSL) boiler in a Canadian pulp mill are investigated. The tube thinning was most severe in the upper tube rows of the lowest economizer sections where the tube surface temperature ranges between about 180°C and 210°C. The location, the temperature range, and the results of a tube failure analysis indicate that some form of corrosion- erosion is the main cause for the tube thinning. The process is likely initiated by the formation of potassium bisulfate in tube deposits. We hypothesize that some areas in the economizer, including gaps in tube shields, have allowed for temporary buildup of deposits that were not fully removed by sootblowing. Potassium bisulfate is highly hygroscopic, so it readily absorbs moisture, forming an acidic solution leading to corrosion. The corrosion products are removed by the erosive effects of high velocity gas movement, causing the tube thinning. The high-speed fluid flow may be a result of sootblower action and/or enhanced flue gas velocity due to channeling. The tube thinning eventually leads to perforation and leakage.
Journal articles
Editorial: TAPPI Journal research themes in 2025 highlighted sustainability and process efficiency, TAPPI Journal February 2026
Each year, the pages of TAPPI Journal offer more than a collection of technical papers -- they provide a sanpshot of where our industry is appling its intellectual energy in research. Looking back at the January through November 2025 issues, there was a distant focus on improving materials performance, strenghtening process efficiency, and integrating sustainability considerations into existing manucaturing processes. A majority of this focus was centered on packaging for a variety of applications.