Search
Use the search bar or filters below to find any TAPPI product or publication.
Filters
Content Type
Publications
Level of Knowledge
Collections
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
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.
Magazine articles
The r & t system: everyone is responsible for innovation, TAPPI JOURNAL, September 2000, Vol. 83(9)
The r & t system: everyone is responsible for innovation, TAPPI JOURNAL, September 2000, Vol. 83(9)
Magazine articles
The role of science in setting the environmental agenda, TAPPI JOURNAL, September 2000, Vol. 83(9)
The role of science in setting the environmental agenda, TAPPI JOURNAL, September 2000, Vol. 83(9)
Magazine articles
A financial analysis of north american pulp and paper companies, TAPPI JOURNAL, July 2000, Vol. 83(7)
A financial analysis of north american pulp and paper companies, TAPPI JOURNAL, July 2000, Vol. 83(7)
Magazine articles
Calcium based sulfur recovery process for kraft black liquor gasification - proof of concept', TAPPI JOURNAL, July 2000, Vol. 83(7)
Calcium based sulfur recovery process for kraft black liquor gasification - proof of concept', TAPPI JOURNAL, July 2000, Vol. 83(7)
Magazine articles
Taiwan holds first symposium on environmentally friendly and emerging technologies for a sustainable industry, TAPPI JOURNAL, September 2000, Vol. 83(9)
Taiwan holds first symposium on environmentally friendly and emerging technologies for a sustainable industry, TAPPI JOURNAL, September 2000, Vol. 83(9)
Magazine articles
Laccase n-hydroxybenzotriazole full sequence bleaching with hydrogen peroxide and chlorine dioxide, TAPPI JOURNAL, September 2000, Vol. 83(9)
Laccase n-hydroxybenzotriazole full sequence bleaching with hydrogen peroxide and chlorine dioxide, TAPPI JOURNAL, September 2000, Vol. 83(9)
Magazine articles
Environmental issues continue to be a major industry concern, TAPPI JOURNAL, September 2000, Vol. 83(9)
Environmental issues continue to be a major industry concern, TAPPI JOURNAL, September 2000, Vol. 83(9)
Journal articles
Magazine articles
Preparing prehydrolyzed kraft dissolving pulp via phosphotungstic acid prehydrolysis from grape branches, TAPPI Journal January 2022
ABSTRACT: Dissolving pulp was successful prepared via phosphotungstic acid (PTA) prehydrolysis kraft (PHK) cooking followed by an elementary chlorine-free (ECF) bleaching process from grape branches. The effects of prehydrolysis temperature, reaction time, and PTA concentration that potentially affect the quality of dissolving pulp product on chemical components of pulp were studied via an orthogonal experiment. The structure of lignin was activated during the PTA prehydrolysis phase, and lignin was easily removed during the following cooking process. Thus, relatively mild conditions (140°C, 100 min) can be used in the cooking process. During the prehydrolysis phase, temperature exhibited the most significant influence on the cellulose purity of the obtained pulp fiber, followed by reaction time and PTA concentration. The optimized prehydrolysis conditions were as follows: prehydrolysis temperature, 145°C; reaction time, 75 min; and PTA concentration, 1 wt%. Whether the excessively high prehydrolysis temperature or prolonging the reaction time did not favor the retention of long chain cellulose, the delignification selectivity for the cooking process could not be further improved by excessive PTA loading. Under these prehydrolysis conditions, 94.1% and 29.0% for a-cellulose content and total yield could be achieved after the given cooking and bleaching conditions, respectively. Moreover, the chemical structure and crystal form of cellulose were scarcely changed after PTA prehydrolysis, which could be confirmed by results from Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). PTA prehydrolysis could be considered as an alternative method for preparing PHK dissolving pulp under relatively mild cooking conditions.