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Mill experience of calcium carbonate scale formation in green liquor pipelines, TAPPI Journal August 2020
ABSTRACT: Experience of hard calcite (CaCO3) scale formation in green liquor pipelines at four kraft pulp mills was systematically investigated to determine if there is any correlation between the severity of the scaling problem at each mill and the design and operating conditions of its causticizing plant. The results show that the high degree of supersaturation of calcium ions (Ca2+) in the liquor is the main contributing factor. Mills that operate at a lower green liquor total titratable alkali (TTA), higher causticity, and a larger liquor temperature drop are more likely to produce a green liquor that is supersaturated with Ca2+, and thus experience more severe scaling problems. In order to minimize CaCO3 scaling, the green liquor handling equipment should be operated as steady as possible to avoid conditions that allow Ca2+ to be supersaturated. The strategies include minimizing variations in liquor TTA, insulating the green liquor pipelines to reduce temperature gradients, and adding lime mud to weak wash to provide seeds for precipitation to occur on mud particles instead of on metal substrate.
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On-machine visible dirt measurement on moving sheets and the relationships to standard laboratory methods, TAPPI Journal August 2020
ABSTRACT: There has been a proliferation of new sensors to measure on-machine dirt specks that employ different technologies and methodologies to perform measurements. The differences in the on-machine technologies are discussed in terms of the TAPPI and ISO standard laboratory test methods with respect to dirt detection using light reflected from, or light transmitted through, the sheet. Also discussed are the requirements for measuring sta-tistically representative areas of the sheet; the difference between the dirt physical size and Equivalent Black Area (EBA) size; and the implication of these issues when specifying cleanliness acceptance criteria.This technical brief describes on-machine visible dirt measurement’s relationship to standard laboratory testing.
Journal articles
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Standards
Relating bending stiffness measurements across various free span lengths, TAPPI Journal August 2020
ABSTRACT: Bending stiffness should be an intrinsic property of a material, so it is puzzling that the TAPPI Standard Test Method T 836 “Bending stiffness, four point method” specifies span lengths when testing different types of corrugated fiberboard. These specified spans often limit the samples that can be measured with this method. To better understand the relationship between bending stiffness and span length, we performed measurements on a range of materials at different spans. The results provide a practical tool enabling comparison of bending stiffness measurements made at various span lengths. Additionally, this note discusses several areas that could serve as the foundation for more fundamental work exploring the bending behavior of corrugated board.
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Editorial: Kathleen Bennett: Opportunities for paper are pro
Editorial: Kathleen Bennett: Opportunities for paper are proliferating, TAPPI JOURNAL May 2016
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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
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Novel CaCO3-polymer nanocomposite fillers for the improvemen
Novel CaCO3-polymer nanocomposite fillers for the improvement of bagasse-based papers, November 2016 TAPPI JOURNAL
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Measurement of the dynamics of fluid sorption for tissue papers, TAPPI Journal July 2019
ABSTRACT: Liquid absorption ability belongs to the most important features of tissue papers. Due to non-homo-geneous internal and superficial structures, precise and fast evaluation of this property is challenging. The main aim of the presented research was to design an experimental device dedicated to the measurement of the kinetics of wetting phenomenon for tissue papers. The second aim was to evaluate whether it was possible to use image analysis for more precise characterization of liquid absorption properties of tissue paper. The obtained results showed that the method used, based on image analysis supported by gravimetric methods, proved to efficiently and quantitatively characterize the dynamics of liquid absorption for tissue papers. Supplementary parameters such as absorption anisotropy and in-plane velocity were obtained. Different experi-mental results were obtained for various tissue paper grades. Furthermore, water absorption capacity calculated from image analysis data correlated with results obtained according to the standard method EN ISO 12625-8:2010 “Tissue paper and tissue products—Part 8: Water-absorption time and water-absorption capacity, basket-immersion test method.” Hence, the presented device quantitatively characterizes and discriminates water absorption phenom-enon for tissue papers.
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Citrus-based hydrocolloids: A water retention aid and rheology modifier for paper coatings, TAPPI Journal July 2019
ABSTRACT: The rheological and dewatering behavior of an aqueous pigmented coating system not only affects the machine runnability but also affects the product quality. The current study describes the use of natural hydrocol-loids derived from citrus peel fibers as a rheology modifier in paper coating applications. The results were compared with carboxymethyl cellulose (CMC) in a typical paper coating system. Water retention of the coating formulation was increased by 56% with citrus peel fibers compared to a default coating, and it also was higher than a CMC-containing coating. The Brookfield viscosity of paper coatings was found to increase with citrus peel fibers. Compared to CMC, different citrus peel fibers containing coating recipes were able to achieve similar or higher water retention values, with no change or a slight increase in viscosity. Coatings were applied on linerboard using the Mayer rod-coating method, and all basic properties of paper were measured to assess the impact of citrus peel fiber on the functional value of the coatings. Paper properties were improved with coated paper containing citrus peel fibers, including brightness, porosity, smoothness, surface bonding strength, and ink absorption.
Journal articles
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Editorial: TAPPI Journal reinstates the “Technical Brief” short-form research paper, TAPPI Journal June 2019
ABSTRACT: For many years, TAPPI Journal (TJ) accepted submissions of “Technical Briefs” (also known as Technical Notes or Brief Notes) in addition to the full-length papers peer-reviewed papers that you have typically seen in more recent years. The TJ Editorial Board is once again accepting these short-form papers, as readers may have noticed in the last issue with publication of Tom Lindstrom’s short nanocellulose re-view (TAPPI Journal 18[5]: 308[2019]). Another Technical Brief appears on p. 391 of the current issue.
Journal articles
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The evolution of reel statistical methods, TAPPI Journal June 2019
ABSTRACT: Multiple statistical methods for calculating the variance partition analysis (VPA) of reel data have existed for decades. In the paper industry, VPA is also commonly known as reel statistics. VPA commonly consists of total variance (TOT) that is then divided into three components: cross direction (CD), machine direction (MD), and residual (RES). A common mathematical procedure is referred to as ANOVA (analysis of variance). TAPPI Standard Test Method T 545 “Cross-machine grammage profile measurement (gravimetric method)” addresses paper testing and includes the ANOVA equations that have also been used to analyze scanning data.In the 1990s, TAPPI published TIP 1101-01 “Calculation and partitioning of variance using paper machine scanning sensor measurements,” which contained simple formulas that were easy to implement and could be used by a nov-ice to generate statistics on a spreadsheet. All involved quality control system (QCS) suppliers agreed to support this common method in their QCS. TIP 1101 was recently revised, and this paper concerns the analysis of data collected from a scanning sensor in a QCS and the creation of a common method for the calculation of reel statistics by TAPPI’s Process Control Division.