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Journal articles
Burning mill sludge in a fluidized-bed incinerator and waste-heat-recovery system, TAPPI JOURNAL, March 1991, Vol. 74(3)
Burning mill sludge in a fluidized-bed incinerator and waste-heat-recovery system, TAPPI JOURNAL, March 1991, Vol. 74(3)
Journal articles
Reducing discharges from sulfite pulp bleach plants, TAPPI JOURNAL, May 1991, Vol. 74(5)
Reducing discharges from sulfite pulp bleach plants, TAPPI JOURNAL, May 1991, Vol. 74(5)
Journal articles
Development and application of a real-time recovery boiler expert system, TAPPI JOURNAL, November 1991, Vol. 74(11)
Development and application of a real-time recovery boiler expert system, TAPPI JOURNAL, November 1991, Vol. 74(11)
Journal articles
ASAM pulping of douglas-fir followed by a chloring-free bleaching sequence, TAPPI JOURNAL, November 1991, Vol. 74(11)
ASAM pulping of douglas-fir followed by a chloring-free bleaching sequence, TAPPI JOURNAL, November 1991, Vol. 74(11)
Journal articles
Wood recovery with In-woods flailing and chipping, TAPPI JOURNAL, September 1991, Vol. 74(9)
Wood recovery with In-woods flailing and chipping, TAPPI JOURNAL, September 1991, Vol. 74(9)
Journal articles
Comparison and combination of ozone and fungal treatments of a kraft bleachery effluent, TAPPI JOURNAL, September 1991, Vol. 74(9)
Comparison and combination of ozone and fungal treatments of a kraft bleachery effluent, TAPPI JOURNAL, September 1991, Vol. 74(9)
Journal articles
On management: Does the pulp and paper industry have to lose the race?, TAPPI JOURNAL, January 1998, Vol. 81(1)
On management: does the pulp and paper industry have to lose the race?, TAPPI JOURNAL, January 1998, Vol. 81(1)
Journal articles
Magazine articles
Optimizing OCC refining with defloccing, TAPPI Journal April 2025
ABSTRACT: Subjecting pulp to a high shear zone immediately after refining results in more efficient refining. This phenomenon was originally observed to benefit softwood pulp refining. It was attributed to floc reduction based on floc measurements in mill refiners and the observation of reduced headbox plugging. Hence, this phenomenon has been termed “defloccing.” The present work shows this technology also benefits refining of North American old corrugated containers (OCC). The combined results of several mill trials with OCC defloccing demonstrate the interactions between OCC refining intensity, defloccing technology, and other state-of-the-art refining improvements. At the same refining intensity, defloccing OCC on 100% recycled machines increases OCC refining efficiency by 15%, with greater efficiency improvement on machines that use softwood as well as OCC. Furthermore, it is shown that the benefits of defloccing are additive to refining improvements made in the refining zone of a refiner plate. Most OCC refiner plate designs can therefore benefit from the addition of a defloccing feature.
Journal articles
Conversion of paper-grade pulp from rice straw into dissolving pulp, TAPPI Journal June 2025
ABSTRACT: About 1,165 million metric tons of rice straw is generated every year worldwide, which can be a good source for the circular bioeconomy. In this research paper, the paper-grade pulp from rice straw was converted to dissolving-grade pulp by fractionation in a biorefinery initiative. Rice straw was cooked at an optimum condition of 8% potassium hydroxide (KOH) charge for 120 min at 150°C and produced a pulp yield of 47.2% with a kappa number of 18.5. Subsequently, D0(EP)D1 bleaching was carried out for the produced pulp, and the brightness of the pulp reached to 82.4%. From the black liquor, 16.5% of the lignin and 11.9% of the hemicellulose were isolated for producing biobased products and chemicals, and then the spent liquor was used for soil amendment. The bleached pulp was fractionated in a Bauer McNett fiber classifier. The pulp fibers retained on 16-, 30-, and 50-mesh screens were used as a longer fiber fraction pulp, and pulp fibers retained on 100- and 200-mesh screens were used as a shorter fiber pulp. The longer and shorter fiber fraction pulps were analyzed for cellulose, R10, pentosan, and viscosity. The long fiber fraction pulps were characterized by higher cellulose (88.2% vs. 83.1%) and lower pentosan (11.3% vs. 13.0%) content than the shorter fiber fraction pulps. The longer fiber fraction was further treated with cold KOH to remove residual hemicellulose. The KOH extraction reduced pentosan content in pulp to 6.3% and increased á-cellulose content to 91.3%. The short fiber fraction was converted to monomeric sugars using cellulase enzymes with varying reaction time, temperature, and consistency. The efficiency of cellulase activity was assessed through glucose yield and residual dry weight. A temperature of 45°C, 5.0 pH, 5% consistency, and 6 filter paper units/gram (FPU/g) o.d. pulp resulted in maximum sugar conversion of 85.7%.
Journal articles
Magazine articles
Black liquor evaporator upgrades— life cycle cost analysis, TAPPI Journal March 2021
ABSTRACT: Black liquor evaporation is generally the most energy intensive unit operation in a pulp and paper manufacturing facility. The black liquor evaporators can represent a third or more of the total mill steam usage, followed by the paper machine and digester. Evaporator steam economy is defined as the unit mass of steam required to evaporate a unit mass of water from black liquor (i.e., lb/lb or kg/kg.) The economy is determined by the number of effects in an evaporator train and the system configuration. Older systems use four to six effects, most of which are the long tube vertical rising film type. Newer systems may be designed with seven or even eight effects using falling film and forced circulation crystallization technology for high product solids. The median age of all North American evaporator systems is 44 years. Roughly 25% of the current North American operating systems are 54 years or older. Older systems require more periodic maintenance and have a higher risk of unplanned downtime. Also, older systems have chronic issues with persistent liquor and vapor leaks, shell wall thinning, corrosion, and plugged tubes. Often these issues worsen to the point of requiring rebuild or replacement. When considering the age, technology, and lower efficiency of older systems, a major rebuild or new system may be warranted. The intent of this paper is to review the current state of black liquor evaporator systems in North America and present a basic method for determining whether a major rebuild or new installation is warrant-ed using total life cycle cost analysis (LCCA).