Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Floc behaviour during roll forming
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
(English)Manuscript (Other academic)
National Category
Paper, Pulp and Fiber Technology
Identifiers
URN: urn:nbn:se:kth:diva-5219OAI: oai:DiVA.org:kth-5219DiVA: diva2:8037
Note
QC 20100901Available from: 2005-05-31 Created: 2005-05-31 Last updated: 2010-09-01Bibliographically approved
In thesis
1. Fibre flow mechanisms
Open this publication in new window or tab >>Fibre flow mechanisms
2005 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

The flow behaviour, and primarily the floc-floc interaction, of pulp paper suspensions have been studied visually. Analogy models based on these observations have been developed as well as the identification of important parameters of floc break-up in low shear rate flow fields. Floc compressions and the locations of voids (areas of lower fibre concentration) where found to influence the floc splitting mechanism. Based on this investigation an equipment for measuring the load carrying ability of fibre flocs and networks was designed, and the effect of measurement geometry, network structure and fibre suspension concentration was investigated. The load carrying ability with concentration increases rapidly when going from 1% to 2% in initial suspension concentration.

A model handling the fibre floc behaviour during extension and compression has been developed, and some basic flocculated flow mechanisms are discussed on an analogy basis. A modified Voigt element is use, describing mainly the compressional behaviour and plastic behaviour of loose fibre network structures. Further the pos- sibility of stress chain formation is discussed on a fibre level as well as on a floc level.

The effect of fibre flow (shear field) occurring in the forming zone of a roll former has been studied in detail. Basic forming mechanisms on floc scale has been investi- gated, and the effect of running parameters like dewatering pressure and jet-to-wire speed difference as well as the fibre type and concentration of the pulp suspension has been evaluated. It is evident that floc elongation increases with shear rate (jet-to-wire speed difference) and lower dewatering rate. The latter is because the fibre floc is subjected to the shear field longer due to slower immobilisation. Shorter fibre tends to create weaker networks, which promotes a higher elongation of the flocs.

Place, publisher, year, edition, pages
Stockholm: KTH, 2005. 15 p.
Series
Trita-FPT-Report, ISSN 1652-2443 ; 2006:17
Keyword
Fibre flow, floc, shear, compression, fibre network, stress chain
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-240 (URN)
Public defence
2005-06-17, Hörsal D2, Kungliga Tekniska Högskolan, Lindstedtsvägen 5, Stockholm, 14:00
Opponent
Supervisors
Note
QC 20100901Available from: 2005-05-31 Created: 2005-05-31 Last updated: 2010-09-01Bibliographically approved

Open Access in DiVA

No full text

Search in DiVA

By author/editor
Bergström, RogerNorman, Bo
By organisation
Fibre and Polymer Technology
Paper, Pulp and Fiber Technology

Search outside of DiVA

GoogleGoogle Scholar

urn-nbn

Altmetric score

urn-nbn
Total: 88 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf