Search
Use the search bar or filters below to find any TAPPI product or publication.
Filters
Content Type
Publications
Level of Knowledge
Committees
Collections
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
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
Delignification and bleaching of chemical pulps with ozone: a literature review, TAPPI JOURNAL, March 1992, Vol. 75(3)
Delignification and bleaching of chemical pulps with ozone: a literature review, TAPPI JOURNAL, March 1992, Vol. 75(3)
Journal articles
Behavior of steel core in the unwinding process, TAPPI JOURNAL, October 1992, Vol. 75(10)
Behavior of steel core in the unwinding process, TAPPI JOURNAL, October 1992, Vol. 75(10)
Magazine articles
The 1992 international chemical recovery conference, TAPPI JOURNAL, September 1992, Vol. 75(9)
The 1992 international chemical recovery conference, TAPPI JOURNAL, September 1992, Vol. 75(9)
Journal articles
Improving the repulpability of wax coated corrugated paperboard, TAPPI JOURNAL, July 1993, Vol. 76(7)
Improving the repulpability of wax coated corrugated paperboard, TAPPI JOURNAL, July 1993, Vol. 76(7)
Journal articles
Dimensional stability of mechanical pulps - drying shrinkage and hygroexpansivity, TAPPI JOURNAL, June 1993, Vol. 76(6)
Dimensional stability of mechanical pulps - drying shrinkage and hygroexpansivity, TAPPI JOURNAL, June 1993, Vol. 76(6)
Journal articles
Formation of chlorinated dioxins during production of bleached kraft pulp from sawmill chips contaminated with polychlorinated phenols, TAPPI JOURNAL, March 1993, Vol. 76(3)
Formation of chlorinated dioxins during production of bleached kraft pulp from sawmill chips contaminated with polychlorinated phenols, TAPPI JOURNAL, March 1993, Vol. 76(3)
Journal articles
Bleaching and brightness stability of aspen biomechanical pulps, TAPPI JOURNAL, November 1993, Vol. 76(11)
Bleaching and brightness stability of aspen biomechanical pulps, TAPPI JOURNAL, November 1993, Vol. 76(11)
Journal articles
The effect of metal complexes in electrochemically mediated oxygen bleaching of wood, TAPPI JOURNAL, October 1993, Vol. 76(10)
The effect of metal complexes in electrochemically mediated oxygen bleaching of wood, TAPPI JOURNAL, October 1993, Vol. 76(10)