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Considerations in managing wastewater odor at pulp and paper operations, TAPPI Journal March 2022
ABSTRACT: Many pulp and paper mills are, at least periodically, faced with the release of odors that can migrate offsite and be considered a nuisance by nearby residents. At chemical pulp mills, perceptible odors associated with reduced sulfur compounds (RSCs) are common, many of which are highly perceptible owing to their low odor thresholds. As releases of RSCs and other odorous substances from production processes are progressively controlled, the proportional contribution from wastewater treatment systems to areal odors can increase. This review paper summarizes important fundamentals of odor generation, source identification, and control. Common odorous substances are identified, and mechanisms for their generation are summarized. Approaches for measuring odorous substances are detailed to enable more effective management, and various odor control strategies are discussed.
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Development of paper quality parameter measurement in China, TAPPI Journal May 2022
ABSTRACT: Paper quality parameters are important indicators of paper production, such as paper moisture, basis weight, ash content, strength, and so on. This study focuses on the online measurement methods and development of paper basis weight, moisture, and ash measuring. First, the measurable paper parameters and quality control system products in China are analyzed. Then, the basis weight measurement methods, accuracy, and development are given in the range of 10~1000 g/m2. Third, the distinction between infrared and microwave methods for moisture measurement is discussed. Finally, the ash measurement is introduced. Production and consumption of tissue paper in China have continually increased during the past decade. Near-infrared light technology is mature for the measurement of paper parameters in the range of 10~200 g/m2 basis weight. However, the near-infrared online measurement of tissue paper is not widely used, and few tissue paper lines are equipped with this type of quality control system in China. Therefore, technology for near-infrared measurement of basis weight has a great potential market in the field of tissue paper production. This article analyzes the future development trend of near-infrared light in tissue paper basis weight measurement and summarizes the difficulties in near-infrared light measurement of tissue paper basis weight.
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The Effect of Component Removal Upon the Porous Structure of the Cell Wall of Wood. II. Swelling in Water and the Fiber Saturation Point, TAPPI Journal May 2022
ABSTRACT: The word "swelling" applied to an assemblage of fibers such as wood or wood pul p is very vague.
Journal articles
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Assessing variation in package modeling, TAPPI Journal April 2021
ABSTRACT: Predictions from empirical models are affected by variability in the input parameters for the data set used to build the models. For corrugated boxes, the difference between actual and modeled compression strength creates a real cost associated with box production, often resulting in boxes that may need to be over-designed to compensate for a lack of model precision. No work to date has attempted to assess the limitation in these compression estimates due to input parameter testing variability. In this paper we approach that problem, initially for the McKee equation and then conceptually for other box models. For our industry to do a better job at meeting the needs of our corrugated packaging customers, we need to reduce the variation in the tests we all rely on, particularly for evaluating material strength (edge crush test [ECT]) and package compression performance (box compression test [BCT]).
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Use of fines-enriched chemical pulp to increase CTMP strength, TAPPI Journal April 2021
ABSTRACT: In this study, fines-enriched pulp (FE-pulp)—the fine fraction of highly-refined kraft pulp—was benchmarked against highly-refined kraft pulp (HRK-pulp) as a strength agent in eucalyptus chemithermomechanical pulp (CTMP). Both the FE-pulp and the HRK-pulp were produced from unbleached softwood kraft pulp, and equal amounts of those strength agents were added to the original CTMP, as well as to washed CTMP, where most of the fines had been removed. The effects of the added strength agents were evaluated with laboratory handsheets.The FE-pulp proved to be twice as effective as HRK-pulp. Both HRK-pulp and FE-pulp increased the strength of the CTMP handsheets. The bulk of the handsheets decreased, however, as well as the drainability. The addition of 5% FE-pulp resulted in the same strength increase as an addition of 10% HRK-pulp, as well as the same decrease in bulk and CSF. For the handsheets of washed CTMP, the strengths were not measurable; the CTMP lost the sheet strength when the CTMP-fines content was reduced through washing. The reduced strength properties were compensated for by the addition of chemical pulp fines that proved to be an efficient strength agent. The addition of 5% FE-pulp restored the strength values, and at a higher bulk and higher drainability.
Journal articles
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Modeling and parameter optimization of the papermaking processes by using regression tree model and full factorial design, TAPPI Journal February 2021
ABSTRACT: One of the major challenges in the pulp and paper industry is taking advantage of the large amount of data generated through its processes in order to develop models for optimization purposes, mainly in the papermaking, where the current practice for solving optimization problems is the error-proofing method. First, the multiple linear regression technique is applied to find the variables that affect the output pressure controlling the gap of the paper sheet between the rod sizer and spooner sections, which is the main cause of paper breaks. As a measure to determine the predictive capacity of the adjusted model, the coefficient of determination (R2) and s values for the output pressure were considered, while the variance inflation factor was used to identify and eliminate the collinearity problem. Considering the same amount of data available by using machine learning, the regression tree was the best model based on the root mean square error (RSME) and R2. To find the optimal operating conditions using the regression tree model as source of output pressure measurement, a full factorial design was developed. Using an alpha level of 5%, findings show that linear regression and the regression tree model found only four independent variables as significant; thus, the regression tree model demonstrated a clear advantage over the linear regression model alone by improving operating conditions and demonstrating less variability in output pressure. Furthermore, in the present work, it was demonstrated that the adjusted models with good predictive capacity can be used to design noninvasive experiments and obtain.
Journal articles
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Editorial: Change, reality, and vision in the pulp and paper industry, TAPPI Journal February 2021
ABSTRACT: Change is inevitable and is a constant in our lives. Change is especially evident in this era of whirlwind, revolutionary break-throughs in communication and control technology. If nothing else, the past year has certainly made this clear.
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Editorial: Agility and adaptation in a dynamic business world, TAPPI Journal January 2021
ABSTRACT: Being agile and adaptive in this current business world is both necessary and beneficial. Throughout last year, we all continued to both directly and indirectly experience the dynamic world where we live. As we wll know, in early 2020 the pandemic gained momentum and has fundamentally altered our daily lives, both personally in how we live and professionally in how we work.
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Spraying starch on the Fourdrinier— An option between wet end starch and the size press, TAPPI Journal January 2021
ABSTRACT: Technology to apply suspensions of starch grains to the wet surface of paper, during the dewatering process, is reviewed. Though the technology is not new, it continues to attract the attention of papermakers as a means to increase bonding strength. Starch grains that are sprayed onto the wet-web of paper can be retained at levels exceeding what can be effectively added to the fiber suspension at the wet end. Unlike adding a starch solution at a size press, no additional drying capacity is required on the paper machine. To be effective, the starch needs to be able to swell and develop bonding during the paper drying process. Paperboard applications with recycled fibers appear to be a good fit. There is potential to increase bonding by processes that favor fuller gelatinization of the starch grains by the time the paper becomes dry.
Journal articles
Magazine articles
Understanding wet tear strength at varying moisture content in handsheets, TAPPI Journal January 2021
ABSTRACT: A laboratory study was conducted looking at the effects of moisture content on wet tear strength in handsheets. Three different wetting techniques were used to generate the wet tear (Elmendorf-type) data at varying moisture levels, from TAPPI standard conditions (dry) to over 60% moisture content (saturated). Unbleached hardwood and softwood fiber from full-scale kraft pulp production were used. The softwood fiber was refined using a Valley beater to reduce freeness. Handsheets were made with a blend of hardwood and softwood and with refined softwood, without the addition of wet-end chemistry. The resulting grams-force tear data obtained from the test was indexed with basis weight and plotted versus both moisture content and dryness. As moisture content levels in the handsheets increased, the wet tear strength also increased, reaching a critical maximum point. This marked a transition point on the graph where, beyond a critical moisture content level, the tear strength began to decline linearly as moisture increased. This pattern was repeated in handsheets made from a blend of hardwood and softwood and from 100% refined softwood.