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Combustion behavior of kraft black liquor droplets from hot
Combustion behavior of kraft black liquor droplets from hot water pretreated hardwood and softwood chips, November 2016 TAPPI JOURNAL
Journal articles
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Repulping of wet strength paper towel with potassium monopersulfate, TAPPI Journal September 2020
ABSTRACT: Potassium monopersulfate (KMPS) was used in repulping of polyamide-epichlorohydrin (PAE)-containing paper towel. The effectiveness of the repulping aid was compared with that of sodium hypochlorite. Addition of a 2.4% KMPS repulping aid achieved complete repulping of the paper towel, resulting in 88% screen yield and about 5% rejects. To reach a similar pulping result, two times the oxidative equivalent amount of sodium hypochlorite had to be used. Compared to the pulp fibers obtained from sodium hypochlorite repulping, those obtained from KMPS repulping had higher physical strength, longer fiber length, and lower fines content. This study demonstrated that KMPS was superior to sodium hypochlorite in repulping of PAE-containing paper towel in terms of effectiveness and pulp quality.
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Editorial: TAPPI Journal Best Research Paper for 2023 focuses on black liquor concentration using graphene oxide membranes, TAPPI Journal February 2024
ABSTRACT: TAPPI and the TAPPI Journal (TJ) Editorial Board would like congratulate the authors of the 2023 TAPPI Journal Best Research Paper Award and Honghi Tran Prize: Sam Rae, Ella V. Richards, Max Kleiman-Lynch, Brent D. Keller, and Brandon I. Macdonald. Their paper, “Pilot scale black liquor concentration using pressure driven membrane separation,” appeared on p. 223 of the April 2023 issue. This kraft recovery cycle research was recognized by the TAPPI Journal Editorial Board for its innovation, creativity, scientific merit, and clear expression of ideas.
Journal articles
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Fate of phosphorus in the recovery cycle of the kraft pulping process, TAPPI Journal March 2020
ABSTRACT: The accumulation of nonprocess elements in the recovery cycle is a common problem for kraft pulp mills trying to reduce their water closure or to utilize biofuels in their lime kiln. Nonprocess elements such as magnesium (Mg), manganese (Mn), silicon (Si), aluminum (Al), and phosphorus (P) enter the recovery cycle via wood, make-up chemicals, lime rock, biofuels, and process water. The main purge point for these elements is green liquor dregs and lime mud. If not purged, these elements can cause operational problems for the mill. Phosphorus reacts with calcium oxide (CaO) in the lime during slaking; as a result, part of the lime is unavailable for slaking reactions. The first part of this project, through laboratory work, identified rhenanite (NaCa(PO4)) as the form of P in the lime cycle and showed the negative effect of P on the availability of the lime. The second part of this project involved field studies and performing a mass balance for P at a Canadian kraft pulp mill.
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How do mud balls form in lime kilns?, TAPPI Journal April 2023
ABSTRACT: Mud ball formation in lime kilns has been a persistent problem in many kraft mills, particularly for older kilns that are equipped with chains. A systematic laboratory study was conducted to examine how mud balls are formed and the key factors that affect ball formation. The results confirm the general mill experience that high moisture and high sodium contents in lime mud are the main contributing factors to ball formation. The high moisture content allows lime mud to agglomerate and grow to form balls, while the high sodium content helps make the balls hard and retain their shape. A ball formation mechanism is proposed to explain how mud balls form and grow near the kiln feed end.
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Editoral: Investing in the future: Writing and peer-reviewing for TAPPI Journal, TAPPI Journal July 2024
ABSTRACT: Those who actively participate in TAPPI realize how much there is to gain from the networking, educational resources, career development, and other opportunities that come with this involvement. One important opportunity is the ability to share your work and expertise with others in your field, and an excellent way to do this is by taking part in the TAPPI Journal peer-review process, either as an author or a reviewer or both.
Journal articles
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Effects of varying total titratable alkali and causticizing efficiency targets on kraft pulp mill productivity, TAPPI Journal March 2024
ABSTRACT: The kraft mill causticizing area is often overlooked and undervalued when it comes to mill optimization; however, the operation of the causticizing plant has downstream effects on the entire liquor cycle. Setting the right targets for the causticizing plant can have a tremendous effect on mill operating costs, as well as push the production bottleneck from one unit operation to another. The key performance parameters associated with the causticizing plant itself are liquor total titratable alkali (TTA) and causticizing efficiency. Individual facilities choose their TTA and causticizing efficiency targets based on their goals, the limits of their equipment, and past experiences. This gives a variety of operating strategies in practice, but what are the implications for optimizing total titratable alkali and causticizing efficiency, and what level of optimization can be achieved through implementation of modern technology? This paper reviews the results of several different operational strategies and models the effects of these different approaches on kraft mill liquor cycle.
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Factors affecting deposit formation in foul condensate stripping systems, TAPPI Journal June 2024
ABSTRACT: In kraft pulp mills, foul condensates are often steam-stripped to produce clean condensate for use as process water. The formation of organic deposits in the stripped condensate is a common problem. A systematic study was conducted to examine the deposit composition and the most likely operating parameters responsible for stripped condensate contamination experienced at a kraft mill in Brazil. Daily averaged data of 170 operating parameters over a 15-month period were analyzed by means of multivariate discriminant analysis and random forest classification analysis. The results showed that the deposit formation is related to high temperature, pressure, and dry solids operations in various evaporator effects. These conditions, combined with the poor demisting efficiency in these effects, may have increased black liquor carryover mist in the vapor. Deposit formation also appeared to be related to increased throughput of the foul condensate stripping system and increased pressure in the stripper. Results of Fourier transform infrared spectroscopy (FTIR) and pyrolysis-gas chromatography mass spectrometry (Py-GCMS) analyses show that the deposit consists of mostly organic matter that likely originated from wood extractives and lignin.
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Critical parameters for tall oil separation I: The importance of ration of fatty acids to rosin acids, TAPPI Journal September 2019
ABSTRACT: Tall oil is a valuable byproduct in chemical pulping of wood, and its fractions have a large spectrum of applications as chemical precursors, detergents, and fuel. High recovery of tall oil is important for the economic and environmental profile of chemical pulp mills. The purpose of this study was to investigate critical parameters of tall oil separation from black liquor. To investigate this in a controlled way, we developed a model test system using a “synthetic” black liquor (active cooking chemicals OH- and HS- ions), a complete process for soap skimming, and determination of recovered tall oil based on solvent extraction and colorimetric analysis, with good reproducibility. We used the developed system to study the effect of the ratio of fatty acids to rosin acids on tall oil separation. When high amounts of rosin acids were present, tall oil recovery was low, while high content of fatty acids above 60% significantly promoted tall oil separation. Therefore, manipulating the content of fatty acids in black liquor before the soap skimming step can significantly affect the tall oil solubility, and hence its separation. The findings open up chemical ways to improve the tall oil yield.
Journal articles
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Soybean peroxidase treatment of ultra-high kappa softwood pulp to enhance yield and physical properties, TAPPI Journal September 2020
ABSTRACT: The working hypothesis serving as basis for this study is that pulping to a higher kappa number will produce a higher yield pulp, and then treating that pulp with a surface reactive lignin peroxidase to ablate surface lignin will increase specific bonding area. In the present case, the working hypothesis was modified so that soybean peroxidase (SBP) works like lignin peroxidase to modify surface lignin on high-kappa, high-yield softwood pulps to facilitate enhanced fiber-to-fiber bonding such that the resulting paper strength is similar to the lower kappa soft-wood pulp generally used to make linerboard. Soybean peroxidase is actually a plant peroxidase that exhibits lignin peroxidase-like activity. It is not a lignin peroxidase derived from white rot fungus. The current work did show a significant improvement in pulp yield (62.2% vs. 55.2% yield for a 103-kappa control linerboard grade sheet), while treatment with SBP showed that tensile, burst, and STFI properties of the pulp were improved, although more convincing data needs to be obtained.