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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.
Journal articles
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Lignin carbohydrate complex studies during kraft pulping for producing paper grade pulp from birch, TAPPI Journal September 2020
ABSTRACT: Paper grade pulp production across the globe is dominated by the kraft process using different lignocellulosic raw materials. Delignification is achieved around 90% using different chemical treatments. A bottleneck for complete delignification is the presence of residual covalent bonds that prevail between lignin and carbohydrate even after severe chemical pulping and oxygen delignification steps. Different covalent bonds are present in native wood that sustain drastic pulping conditions. In this study, 100% birch wood was used for producing paper grade pulp, and the lignin carbohydrate bonds were analyzed at different stages of the kraft cook. The lignin carbohydrate bonds that were responsible for residual lignin retention in unbleached pulp were compared and analyzed with the original lignin-carbohydrate complex (LCC) bonds in native birch wood. It was shown that lignin remaining after pulping and oxygen delignification was mainly bound to xylan, whereas the lignin bound to glucomannan was for the most part degraded.
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Quantification of vegetable oil in recycled paper, TAPPI JOURNAL September 2020
ABSTRACT: Vegetable soybean oil is commonly used in cooking foods that are packaged in takeaway paper-board containers. Vegetable oil is hydrophobic, and in sufficiently high concentration, could interfere with interfiber bonding and result in paper strength loss. In order to quantify the effect of oil on the resulting paperboard strength, it is necessary to quantify the oil content in paper. A lab method was evaluated to determine the soybean oil content in paper. Handsheets were made with pulps previously treated with different proportions of vegetable oil. Pyrolysis gas chromatography-mass spectrometry (pyGCMS) was used to quantify the amount of oil left in the handsheets. The results revealed a strong correlation between the amount of oil applied to the initial pulp and the amount of oil left in the handsheets.In addition, the effect of vegetable oils on paper strength may be affected by the cooking process. Vegetable oil is known to degrade over time in the presence of oxygen, light, and temperature. The vegetable oil was put in an oven to imitate the oil lifecycle during a typical pizza cooking process. The cooked oil was then left at room temperature and not protected from air (oxygen) or from normal daylight. The heated, then cooled, oil was stored over a period of 13 weeks. During this time, samples of the aged oil were tested as part of a time-based degradation study of the cooked and cooled oil.
Journal articles
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Editorial: TAPPI Journal 2024 Best Research Paper focuses on realistic potential for using nonwood residues in sustainable packaging, TAPPI Journal April 2025
ABSTRACT: Each year, the TAPPI Journal Editorial Board honors outstanding content by nominating and voting for the Best Research Paper published the previous year based on scientific merit, innovation, creativity, and clarity. TAPPI and the TAPPI Journal Editorial Board would like to congratulate the authors of the 2024 TAPPI Journal Best Research Paper: Antonio Suarez, Ashok Ghosh, Fritz Paulsen, and Peter W. Hart of Smurfit Westrock (formerly WestRock). The winning paper, “Life cycle carbon analysis of packaging products containing nonwood residues: A case study on linerboard and corrugating medium,” was published in the March 2024 issue.
Journal articles
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Numerical analysis of the impact of rotor and screen hole plate design on the performance of a vertical pulper, TAPPI Journal April 2025
ABSTRACT: The dissolving of mechanical pulp is one of the most important process steps in stock preparation, since pulping occurs at the very beginning of the papermaking process. Efficient mixing of the pulp in a short amount of time is essential to achieve high furnish volume flow rates. The design of the rotor, as well as the pulper vat and inserts, significantly affects the overall performance of the pulper, such as mixing efficiency and power demand. Using advanced numerical methods such as computational fluid dynamics (CFD) can accelerate the development process. The CFD simulations allow for detailed analysis of flow phenomena, making it possible to study a real-size machine numerically. This approach is particularly advantageous because it can reduce the need for timeconsuming and costly experiments associated with scaling up test rigs. In this study, we compared two different rotor designs utilized in a vertical pulper and evaluated the numerical results with experimental data. Rotor A is designed for low turbulence and low power demand, while rotor B is designed for high turbulence with high power demand. The CFD results showed good agreement with the experimental measurements. We investigated how the rotor design influences the free fluid surface and the mixing efficiency. Our study also highlights the differences in results depending on whether water or furnish is simulated, which exhibit Newtonian or, respectively, non-Newtonian fluid behavior. Additionally, a detailed numerical investigation of various screen hole plate designs revealed that the newly developed hole design significantly reduces pressure loss compared to a standard drilled hole. This outcome was consistent for both types of fluids investigated: water and furnish.
Journal articles
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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
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Dynamic compression characteristics of fiber-reinforced shoe press belts, TAPPI Journal April 2025
ABSTRACT: Shoe press belts contribute significantly to the overall dewatering performance in the press section of a paper machine. Within the shoe press nip, the press belt faces a dynamic and multidimensional load that mainly leads to a compression of the structure. As this will cause a loss in void volume, knowledge of the dynamic compression characteristics of shoe press belts is crucial for optimized dewatering. A novel method was developed to examine the dynamic compression characteristics of grooved polyurethane press belts. Therefore, an experimental setup allowing realistic boundary conditions to test specimens was placed in a servo-hydraulic testing machine. Press belt specimens with different matrix material formulations and groove patterns were tested under varying load rates equivalent to different paper machine operational speeds. The results showed an evident sensitivity of the dynamic compression stiffness to the operational speed of the paper machine. This behavior was seen to be more sensitive to changes in the matrix material formulation than to adaptions of the groove pattern. As a result, the compression of the press belt within a shoe press nip is not only influenced by the peak pressure within the shoe press nip but also depends on the operational speed of the paper machine.
Journal articles
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Comparing a linear transfer function-noise model and a neural network to model boiler bank fouling in a kraft recovery boiler, TAPPI Journal, July 2024
ABSTRACT: Boiler bank fouling reduces heat transfer efficiency in kraft recovery boilers. Here, we model the relationships between boiler parameters and boiler bank pressure drop, an indicator of fouling, based on recovery boiler operating data. We compared two models: an autoregressive integrated exogenous (ARIX) model and a feedforward neural network. The ARIX model better simulates boiler bank pressure drop compared to the neural network (R2 of 0.64 vs. 0.58). Based on the ARIX model, we identified six boiler parameters that significantly influence boiler bank fouling and their relative contributions. Finally, we demonstrate how the models can simulate boiler bank pressure drop given artificial perturbations in boiler parameters.
Journal articles
Magazine articles
Effects of different soda loss measurement techniques on brownstock quality, TAPPI Journal July 2024
ABSTRACT: The efficiency of the kraft recovery plant, bleaching process, and paper machine are affected when black liquor carryover from the brownstock washers is not controlled well. Measuring soda loss within a mill can vary from using conductivity, either in-situ or with a lab sample of black liquor filtrate squeezed from the last stage washer, to measuring absolute sodium content with a lab sodium specific ion probe or spectrophotometer. While measuring conductivity has value in tracking trends in black liquor losses, it is not an acceptable method in reporting losses in absolute units, typically in lb/ton of pulp. This is further complicated when trying to benchmark soda loss performance across a fleet of mills with multiple washer lines. Not only do the testing methods vary, but the amount of bound soda on high kappa pulps can be significant. This variability creates inconsistent results, and studies are needed to understand the effect of different testing methods on the pulp quality. In this study, soda loss is expressed as sodium sulfate (Na2SO4). Four different methods to measure soda content in pulp off commercial brownstock washers were studied: full digestion (FD), washing soaking overnight and washing (WSW), soaking in boiling water and stirring 10-min (SW-10), and squeeze-no wash (Sq). Total, washable, and bound sodium sulfate calculations were determined for each soda content measuring technique using inductively coupled plasma-optical emission spectroscopy (ICP-OES). Results showed bound and washable sodium sulfate amounts significantly depend on which soda measurement technique was used. In addition, the soda results were correlated with the pulp kappa numbers. As the kappa number increases, bound soda increases, regardless of the soda measurement method used. Impacts of high sodium sulfate in brownstock are also discussed.
Journal articles
Magazine articles
A new and quick testing method for evaluating commercial OCC recycled pulp, TAPPI Journal July 2024
ABSTRACT: In this paper, a new and quick testing method for evaluating commercial old corrugated cardboard/containers (OCC) pulp was developed and used by a large Chinese boxboard manufacturer for quality control of imported OCC pulp.