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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
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
Preparation and characterization of cellulose nanofibers from bleached pulp using a mechanical treatment method, TAPPI JOURNAL May 2014
Preparation and characterization of cellulose nanofibers from bleached pulp using a mechanical treatment method, TAPPI JOURNAL May 2014
Journal articles
Influence of kraft pulping on the kinetics of oxygen delignification, TAPPI JOURNAL, February 2000, Vol. 83(2)
Influence of kraft pulping on the kinetics of oxygen delignification, TAPPI JOURNAL, February 2000, Vol. 83(2)
Journal articles
Direct causticization of kraft black liquor solids with tio2 in a fluidized bed, TAPPI JOURNAL, December 2000, Vol. 83(12)
Direct causticization of kraft black liquor solids with tio2 in a fluidized bed, TAPPI JOURNAL, December 2000, Vol. 83(12)
Journal articles
Deinking of newspaper assisted by steam explosion, TAPPI JOURNAL, December 2000, Vol. 83(12)
Deinking of newspaper assisted by steam explosion, TAPPI JOURNAL, December 2000, Vol. 83(12)
Journal articles
Wood quality ranking of plantation trees, TAPPI JOURNAL, December 2000, Vol. 83(12)
Wood quality ranking of plantation trees, TAPPI JOURNAL, December 2000, Vol. 83(12)
Journal articles
Calcium in pulping and bleaching, TAPPI JOURNAL, December 2000, Vol. 83(12)
Calcium in pulping and bleaching, TAPPI JOURNAL, December 2000, Vol. 83(12)
Journal articles
Water minimization in the washing section of a paperboard mill, TAPPI JOURNAL, September 2000, Vol. 83(9)
Water minimization in the washing section of a paperboard mill, TAPPI JOURNAL, September 2000, Vol. 83(9)
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)