Numerical simulations of pressure pulses produced by a pulp screen solid core rotor

Thumbnail Image

URL

Journal Title

Journal ISSN

Volume Title

Helsinki University of Technology | Master's thesis
Checking the digitized thesis and permission for publishing
Instructions for the author
Location:
P1 Ark TKK

Authors

Date

2007

Department

Konetekniikan osasto

Major/Subject

Lujuusoppi

Mcode

Kul-49

Degree programme

Language

en

Pages

65

Series

Abstract

Pulp and paper manufacturing is an energy-intensive industry. One high-energy process is pressure screening to remove contaminants from the pulp. The screen is equipped with a rotor with hydrodynamic elements, which accelerates and keeps the pulp at a high tangential velocity. The pulp is forced through narrow apertures in the screen, which serves as a barrier to contaminants and oversized fibers. Pressure screens are critical in ensuring high quality pulp, which in return affects the quality, appearance and strength of the resulting paper products. The goal of this study was to reduce rotor energy consumption by optimizing the hydrodynamic element shape. The optimization was conducted using computational fluid dynamics (CFD) simulations done with FLUENT. Element performance was evaluated with the max. and min. pressure coefficient value, Cp, and vorticity around the element which creates drag. The element shape was controlled by four variables; chord length, position of maximum height, leading and trailing edge angles. The effect of rotor variables, element height, gap, rotor diameter and tip speed, were studied as well. The results show a -11% increase in the negative Cp peak and a -5% decrease in the positive Cp peak. Increase in the negative Cp peak results as a -15% decrease in rotor power consumption. The vorticity around the element was significantly reduced. In addition to these results, this study has shown that CFD is a powerful tool to research and develop specific rotor designs for industrial pressure screens.

Description

Supervisor

Tuhkuri, Jukka

Thesis advisor

Olson, James

Keywords

pulp, pressure screen, pressure pulse, rotor, computational fluid dynamics, model, optimization, energy

Other note

Citation

Permanent link to this item

https://urn.fi/URN:NBN:fi:aalto-2020120553438

Collections

[dipl] Teknillinen korkeakoulu / TKK