Development of the Pressure Screen Foil

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  • Topic: Efficient energy use, Mass flow rate, Volumetric flow rate
  • Pages : 17 (5503 words )
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  • Published : January 21, 2013
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Saimaa University of Applied Sciences Technology, Imatra Paper Technology

Loan Dinh

Development of the Pressure Screen Foil

Bachelor’s Thesis 2012

Abstract
Loan Dinh Development of the Pressure Screen foil, 60 pages, 12 appendices Saimaa University of Applied Sciences Technology, Imatra Paper Technology Bachelor’s Thesis 2012 Instructors: Mr Ari Pelkiö, Chief Technology Manager, Andritz Mr Pekka Karppinen, Product Manager, Andritz Mr Jarkko Männynsalo, MSc, Senior Lecturer, Saimaa UAS Mr Tapio Tirri, Director, MUAS FiberLaboratory Mr Jari Käyhkö, Research Director, MUAS FiberLaboratory

The purpose of the research was to develop new foils model for headbox screen on higher consistency level of the feed flow than foil that is used today with target feed/accept consistency being approximately 2.0%. However, energy consumption and pulsation level should be in same range as today’s foil type has. The study was commissioned by Andritz. The study was carried out at Fiber-Laboratory in Savonlinna. The work was divided into four parts. First part was the test of Dolphin D foil and Bump foil. Second part was the test of new foil with different position on the rotor. Third part was the test of three new foils which were designed from new original foil. Last part was the test of new HB foil. The purpose was to find out which one has the best condition for using in headbox screen of the paper machine. The data for this thesis were collected from the control room of the laboratory. The information was gathered from literature, newspapers, journal, theses and the internet. The final result of this thesis was that Bump had the most suitable condition for working in headbox screen. However, if concentrating on the results of new foil, new designed foils and HB foil, No8 (new designed foil with two cutting edges) had the most suitable condition with low pulsation, good runnability, low thickening factor and low power consumption.

Keywords: pressure screen, headbox screen, pressure pulsation, power consumption, screening, foil

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Contents
1 Introduction .............................................................................................................................. 5 Theoretical part ........................................................................................................................... 6 2 Pressure screen’s structure and principle ........................................................................... 6 3 Screening parameters ............................................................................................................ 7 3.1 Design parameters .......................................................................................................... 7 3.1.1 Feed construction ..................................................................................................... 7 3.1.2 Rotor design .............................................................................................................. 7 3.1.2 Screen cylinder design ............................................................................................ 9 3.2 Operational parameters ................................................................................................ 11 3.2.1 Aperture velocity ..................................................................................................... 11 3.2.2 Rotor tip speed and rotor frequency .................................................................... 12 3.2.3 Feed consistency ................................................................................................... 12 3.2.4 Volumetric reject rate ............................................................................................. 13 3.3 Furnish parameters ....................................................................................................... 13 3.3.1 Temperature and pH...
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