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Control of malodorous gases emission from wet-end white water with hydrogen peroxide, TAPPI Journal October 2021
ABSTRACT: White water is highly recycled in the papermaking process so that its quality is easily deteriorated, thus producing lots of malodorous gases that are extremely harmful to human health and the environment. In this paper, the effect of hydrogen peroxide (H2O2) on the control of malodorous gases released from white water was investigated. The results showed that the released amount of total volatile organic compounds (TVOC) decreased gradually with the increase of H2O2 dosage. Specifically, the TVOC emission reached the minimum as the H2O2 dosage was 1.5 mmol/L, and meanwhile, the hydrogen sulfide (H2S) and ammonia (NH3) were almost completely removed. It was also found that pH had little effect on the release of TVOC as H2O2 was added, but it evidently affect-ed the release of H2S and NH3. When the pH value of the white water was changed to 4.0 or 9.0, the emission of TVOC decreased slightly, while both H2S and NH3 were completely removed in both cases. The ferrous ions (Fe2+) and the copper ions (Cu2+) were found to promote the generation of hydroxyl radicals (HOœ) out of H2O2, enhancing its inhibition on the release of malodorous gases from white water. The Fe2+/H2O2 system and Cu2+/H2O2 system exhibited similar efficiency in inhibiting the TVOC releasing, whereas the Cu2+/H2O2 system showed better perfor-mance in removing H2S and NH3.
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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.
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The Mechanism of Bonding, TAPPI Journal September 2022
ABSTRACT: Three factors are involved in cellulose bonding--available area, contact, and hydrogen bonding.
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Effectiveness of masks in the suppression of COVID-19 cases during the ongoing pandemic in India, TAPPI Journal October 2022
ABSTRACT: Perhaps the worst predicament faced by humanity in the twenty-first century is the COVID-19 pandemic, which is caused by the SARS-CoV-2 virus. Most parts of the world, including India, went into lockdowns for some period because of the massive increase in cases throughout 2020. Face masks became an important counter-measure for protecting the populace, health professionals, and medics, particularly during the period prior to the mass availability of vaccines. This study intends to evaluate the effectiveness of face masks in limiting the spread of the virus. The data for the number of COVID-19 cases was analyzed from January 1, 2022 to May 31, 2022, using Python programming. This timeframe involved face mask mandates and no mask requirement, and hence was considered to be ideal for analyzing the usefulness of face masks. A decline in cases during the mandate was observed, while the opposite occurred without the mandate. The outcome of the research showed that face masks are effective additional measures against the spread of SARS-CoV-2. This study elevates the value of personal protective equipment (PPE), such as face masks, made with nonwovens and other fabrics, as lifesavers in the case of airborne diseases such as COVID-19 and other pulmonary disorders.
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Z-direction chemical analysis for new application methods, TAPPI Journal January 2023
ABSTRACT: In conventional wet-end chemical addition during paper production, chemical distribution through the z-direction of the sheet is usually not considered an important characteristic. With a nontraditional chemical dosing approach, such as foam-assisted additive addition, the chemistry can appear at different concentrations throughout the sheet, typically in a z-direction gradient. To fully understand the strength properties of the sheet, it is helpful to view or quantify the chemical distribution through the sheet in the z-direction. One qualitative method uses a dye technique along with confocal laser scanning microscopy to generate an image where the relative chemical concentration can be observed. A quantitative method involves compiling nitrogen analyses of layered subsections of the sheet into a composite graph of relative chemical concentration vs. the z-direction of the sheet. Chemical distribution analysis can be paired with traditional z-direction strength tests, such as Scott bond and z-direction tensile, to help one understand and improve the chemical addition process and its effects.
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Evaporation of process water from recycled containerboard mills, TAPPI Journal July 2023
ABSTRACT: The reduction of the specific effluent discharge volumes of paper mills leads to concentrated process waters that are difficult to treat. Evaporation is an effective water reclamation technology; however, its feasibility largely depends on the fouling behavior of the calcium rich process water. A pilot plant study was conducted to investigate fouling of an evaporator processing the production water from a recycled containerboard mill. The evaporator was operated continuously for five weeks at an evaporation temperature of 55°C and a differential temperature of 5°C, and with a recovery rate of approximately 90%. The calcium ion concentration of the circulating liquor exceeded 7,000 mg/L with a pH of 6. Despite the high fouling potential of the circulating liquor, the heat transfer coefficient did not decline over the investigated trial. The absence of deposits on large areas of the heating surfaces demonstrate that the process water does not generally form deposits under the conditions that were investigated. Calcium sulfate deposits were only found in areas where there was inadequate coverage of liquid over the heating surfaces.The findings show that evaporators can be used to effectively close the water system of recycled containerboard mills without fouling impacting the energy efficiency.
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Recovery boiler back-end heat recovery, TAPPI Journal March 2023
ABSTRACT: Sustainability and efficient use of resources are becoming increasingly important aspects in the operation of all industries. Recently, some biomass-fired boilers have been equipped with increasingly complex condensing back-end heat recovery solutions, sometimes also using heat pumps to upgrade the low-grade heat. In kraft recovery boilers, however, scrubbers are still mainly for gas cleaning, with only simple heat recovery solutions. In this paper, we use process simulation software to study the potential to improve the power generation and energy efficiency by applying condensing back-end heat recovery on a recovery boiler. Different configurations are considered, including heat pumps. Potential streams to serve as heat sinks are considered and evaluated. Lowering the recovery boiler flue gas temperature to approximately 65°C significantly decreases the flue gas losses. The heat can be recovered as hot water, which is used to partially replace low-pressure (LP) steam, making more steam available for the condensing steam turbine portion for increased power generation. The results indicate that in a simple condensing plant, some 1%•4% additional electricity could be generated. In a Nordic mill that provides district heating, even more additional electricity generation, up to 6%, could be achieved. Provided the availability of sufficient low-temperature heat sinks to use the recovered heat, as well as sufficient condensing turbine swallowing capacity to utilize the LP steam, the use of scrubbing and possibly upgrading the heat using heat pumps appears potentially useful.
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Editorial: Shaping industry and career success with TAPPI Standards involvement, TAPPI Journal May 2023
ABSTRACT: Within TAPPI, there are many ways to help advance our industry and make sure it thrives for years to come. Writing a research paper for publication or acting as peer reviewer for TAPPI Journal, presenting at a conference or helping to organize one, and becoming involved in the many committees that are part of TAPPI Divisions are just some of the ways. One other very important way to contribute to our industry is through the standards development process.
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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]).
Journal articles
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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.