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Quantification of hardwood black liquor contamination in pine black liquor, TAPPI Journal February 2024
ABSTRACT: The presence of hardwood black liquor contamination in pine black liquor can negatively impact brownstock washer and evaporator operation, as well as reduce soap separation and yield. It is also believed to negatively impact commercial kraft lignin production. It was desired to develop a method of quantitatively determining the amount of low-level hardwood liquor contamination in pine black liquor. A method employing pyrolysis-gas chromatography mass spectrometry (py-GCMS) was developed to perform the desired measurement. Laboratory cooks with carefully controlled blends of pine and hardwood chips were prepared, and the resulting liquor was measured using this technique. Additionally, samples of pine and hardwood black liquors were blended in known quantities and analyzed. All these samples were submitted as blind samples. The resulting analysis suggests the py-GCMS method was able to accurately determine the level of hardwood contamination between 1% to 10% hardwood liquor using a low-level calibration curve prepared with coniferyl alcohol and sinapyl alcohol as standards.
Journal articles
Magazine articles
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
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
Magazine articles
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
Effect of pulp refining on thixotropy of cellulose fiber suspensions, TAPPI Journal September 2025
ABSTRACT: This paper presents results on the thixotropic behavior of low-consistency bleached eucalyptus fiber suspensions that had been mechanically treated. The pulps were refined in a PFI mill at different numbers of revolutions (0, 3000, and 6000) to study the effect of refining intensity on the viscosity time-response of fiber suspensions. In steady rheological tests, all the suspensions exhibited shear thinning behavior and no significant differences were observed after mechanical treatment. Stepwise experiments showed that viscosity continuously increased with time when shear rate was suddenly reduced. Additionally, a delay in time evolution of viscosity was observed as the pulp was more refined. A stretched exponential model was fitted to the experimental results of viscosity.
Journal articles
The effect of Stachys floridana Shuttlew.ex Benth extract as an additive on the chemical properties of chitosan biodegradable film, TAPPI Journal June 2025
ABSTRACT: The purpose of this study is to explore chitosan with Stachys floridana Shuttlew. ex Benth (SFSB) extract as an additive to prepare an active film. The effects of the SFSB extract on the physical, antioxidant, and bacteriostatic properties of chitosan biodegradable films were studied. The results showed that the addition of SFSB extract significantly improved the antioxidant and antibacterial properties of the film, and its biodegradation rate increased rapidly. Compared to the control film, the water solubility was lower at 19.40%, the expansion degree was higher at 288.90%, the water vapor permeability (WVP) was 0.364 g·mm/(m²·d·kPa), the surface hydrophobicity increased, and the mechanical strength was also improved. The contact angle increased to 89.3°. In addition, as the amount of SFSB increased, the thermal stability of chitosan-Stachys floridana Shuttlew. ex Benth (CS-SFSB) films also increased significantly, and their ultraviolet (UV) blocking ability was gradually enhanced. The results indicate that CS-SFSB has potential as a food packaging material.
Journal articles
Magazine articles
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
Magazine articles
Continuous digester process safety improvements • Stress corrosion cracking and overpressure protection lessons learned and opportunities, TAPPI Journal October 2024
ABSTRACT: Georgia-Pacific has recent experience with continuous digester stress corrosion cracking (SCC) repairs where the extent of SCC was more than previous spot inspections had predicted (one digester had anodic protection, one did not). This paper offers case studies of reviewed and improved digester inspections by use of “boat” samples to quantify the depth of cracking mechanism. Boat sample test data is used to support repair recommendations based on hardness testing. Georgia-Pacific also reviewed overpressure protection systems and corrected gaps found in these systems. These included updating to the latest original equipment manufacturer (OEM) designs and formalizing functional testing procedures and practices. This review of digester inspection, testing, and repairs since 2020 provides: (1) a basis for including a 3rd party corrosion expert to be a part of inspections; (2) removes the use of power-wire brushes; (3) enhances digester inspection with 100% phased-array ultrasonic testing to detect SCC; and (4) ensures overpressure protection design and testing is aligned with corporate needs and the site-specific challenges.
Journal articles
Magazine articles
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
Editorial: Special pulping and engineering issues of TAPPI Journal yield important recovery cycle research, TAPPI Journal June 2024
ABSTRACT: The June issue of TAPPI Journal, which is dominated by recovery cycle topics, is the last PEERS issue organized by Dr. Peter Hart, the fomer editor-in-chief who passed away this past May. Peter, who was heavily involved with TAPPI’s Pulp Manufacture Division and various pulping-related committees, also started working with conference technical program planning starting in 2005 with the Engineering, Pulping and Environmental (EPE) Conference, which was the precursor to the more recent Pulping, Engineering, Environmental, Recycling and Sustainability (PEERS) Conference. He was also involved with other conference planning, including that for the International Pulp Bleaching Conference. In addition, Peter was a yearly attendee of such conferences starting as far back as 1990.