Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • 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
Evaluation of Furnishes for Tissue Manufacturing
Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering. (Paper technology)
2012 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Water removal on a tissue machine becomes progressively more difficult and expensive in each successive zone. Since a big part of the cost is allocated to the drying section, improved water removal in the wet end may lead to huge savings in the manufacturing process. This can be accomplished by selecting proper raw materials and optimizing the treatment of the fibres in the furnish.

The aim of the work described in this thesis was to investigate the influence of three particular furnish properties on dewatering of low grammage papers in the forming and press section; fibre species, beating and additives. The focus was to evaluate how the solids content varies as these furnish properties are changed, but also how the quality of the end product is affected.

Water removal during suction is affected by the choice of pulp which can be explained by structural differences in the networks caused by differences in the morphology of the fibres. The total area of straight pores between the fibres is much higher for softwood pulps compared to hardwood pulps which will facilitate transport of both water and air through the sheet. Beating has a negative effect on the solids content reached in vacuum dewatering which can be coupled to internal and external fibrillation of the fibres.

Water removal during pressing is affected by the choice of pulp controlled by the pore structure of the fibres and the ability to sorb water. More available water before pressing lead to that more water can be removed. Beating mainly delaminates macropores with small effects on micropores. Both water between the fibres and water in macropores is removed during wet pressing.  

The dryness after wet pressing is increased by addition of a wet strength agent (PAE) to the stock, probably due to crosslinking in the fibre wall. PAE-resins decrease the volume of both micro- and macropores which will leave less water deposited in the fibre wall. Tensile strength is increased with a wet strength agent and further increased by addition of a flocculant and a micropolymer to the stock. A lower absorption capacity is achieved with addition of PAE-resins due to formation of covalent bonds in the fibre wall.

Place, publisher, year, edition, pages
Karlstad: Karlstads universitet, 2012. , 51 p.
Series
Karlstad University Studies, ISSN 1403-8099 ; 2012:42
National Category
Chemical Engineering
Research subject
Chemical Engineering
Identifiers
URN: urn:nbn:se:kau:diva-14544ISBN: 978-91-7063-449-9 (print)OAI: oai:DiVA.org:kau-14544DiVA: diva2:545882
Presentation
2012-10-19, 9C204, Karlstads Universitet, Karlstad, 10:15 (English)
Opponent
Supervisors
Available from: 2012-10-15 Created: 2012-08-21 Last updated: 2014-10-28Bibliographically approved
List of papers
1. Evaluation of furnishes for tissue manufacturing; suction box dewatering and paper testing
Open this publication in new window or tab >>Evaluation of furnishes for tissue manufacturing; suction box dewatering and paper testing
2012 (English)In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, no 1, 143-150 p.Article in journal (Refereed) Published
Abstract [en]

Water removal on a tissue machine becomes progressively more difficult and expensive in each successive zone. A good way to reduce cost can therefore be to improve the dewatering prior to evaporative drying. This can be done by selecting proper raw materials and optimizing the treatment of the fibres in the furnish.

In this work, four pulps beaten to different levels were studied in vacuum dewatering trials. Mixing of the pulps, common in tissue manufacturing, was also performed. To simulate the suction boxes on a tissue machine, bench-scale laboratory equipment was used. Conditions typically used on a tissue machine regarding dwell times and vacuum levels were chosen. Paper properties relevant for tissue, like wet strength and absorption were measured on non-creped papers. To obtain information about the fibre properties, fibre characterization and microscope studies were also conducted.

Vacuum dewatering in tissue manufacturing is shown to be affected by the choice of pulp which can be explained by structural differences in the networks caused by variations in fibre properties. Beating has a strong negative impact on the solids contents reached, which is believed to be an effect of both internal and external fibrillation. These results, together with additional data from mixing and paper testing, give a better understanding of how the furnish should be prepared to reduce energy use in the process and still fulfil consumer requirements on properties.

Place, publisher, year, edition, pages
Stockholm: Nordic pulp and paper, 2012
Keyword
Beating, Fibre properties, Mixing, Solids content, Suction box dewatering, Tissue, Water removal
National Category
Chemical Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-14541 (URN)10.3183/NPPRJ-2012-27-01-p143-150 (DOI)000311019900017 ()
Available from: 2012-08-21 Created: 2012-08-21 Last updated: 2017-12-07Bibliographically approved
2. Evaluation of furnishes for tissue manufacturing: wet pressing
Open this publication in new window or tab >>Evaluation of furnishes for tissue manufacturing: wet pressing
2012 (English)In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, no 5, 947-951 p.Article in journal (Refereed) Published
Abstract [en]

Wet pressing is the last operation on the tissue machine in which water can be removed prior to the expensive evaporative drying of the web. An increase in dryness at this stage can lead to major savings during the manufacturing process. A higher solids content can be achieved by suitable selection of raw materials and by optimizing the treatment of the fibres in the furnish. In this work, wet pressing was evaluated with four pulps beaten to different levels in a PFI mill. Wet pressing was done in a dynamic press simulator and conditions representative of tissue machines with regard to nip pressures and dwell times were chosen. Water retention and thermoporometry were used to determine the pore structure of the fibres. Thickness measurements were made to determine the permanent deformation of the sheets after the pressure pulse.

Wet pressing in tissue manufacturing is shown to be affected by the choice of pulp, which can be explained by differences in pore structure of the fibres and consequently differences in ability to retain water. More water available before pressing leads to more water that can be removed. Beating has a negative impact on the solids contents reached after pressing, which is believed to be an effect of both internal and external fibrillation. These effects of beating seem mainly to affect the dryness after vacuum dewatering, which is also reflected after pressing. Beating delaminates macropores in the fibre wall but has a minor effect on micropores. Both water between the fibres and water in macropores are removed during pressing. These results give knowledge of how the furnish should be prepared in order to reduce energy consumption in the process.

Place, publisher, year, edition, pages
Mittuniversitetet, 2012
Keyword
Beating, Pore structure, Solids content, Thermoporosimetry, Tissue, Water removal, Water retention value, Wet pressing
National Category
Chemical Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-14542 (URN)10.3183/NPPRJ-2012-27-05-p947-951 (DOI)000313375400015 ()
Available from: 2012-08-21 Created: 2012-08-21 Last updated: 2017-08-15Bibliographically approved
3. Evaluation of furnishes for tissue manufacturing; additives
Open this publication in new window or tab >>Evaluation of furnishes for tissue manufacturing; additives
(English)Article in journal (Refereed) Submitted
Abstract [en]

Additives are widely used in the tissue manufacturing process to facilitate the operation of the tissue machine and to improve tissue paper properties like wet strength, softness and water absorbency. Chemical retention and drainage programs are created to enhance the runnability of the tissue machine. A raise in dryness in the wet end of the tissue machine can lead to huge savings during the manufacturing process.

In this work, the effect of 4 different additives on vacuum dewatering, wet pressing and paper properties was evaluated. Conditions representative for tissue machines regarding vacuum levels and dwell times were chosen. Paper properties relevant for tissue, like wet strength and absorption were measured on non-creped papers. Water retention and thermoporometry were used to determine the pore structure of the fibres.

The solids content after vacuum dewatering and wet pressing is shown to be unaffected by addition of any of the four additives used in this study. The dryness after wet pressing is however increased by addition of a PAE-resin to the stock which probably is due to crosslinking in the fibre wall. Thermoporometry shows that the PAE-resin reduces the volume of both micro- and macropores which will leave less water deposited in the fibre wall. Tensile index is increased with the PAE-resin and further increased by addition of a flocculant and a micropolymer to the stock. Wet strength is increased while absorption capacity is decreased with the PAE-resin. No further effect on the two properties can be seen with additional chemicals in the furnish.

National Category
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-14543 (URN)
Available from: 2012-08-21 Created: 2012-08-21 Last updated: 2015-09-03Bibliographically approved

Open Access in DiVA

KUS_2012_42(2628 kB)1886 downloads
File information
File name FULLTEXT01.pdfFile size 2628 kBChecksum SHA-512
64a86570a1aae12ade964a539674dae15e0511dad716d4c72b66e94726b7d102940950b0e056a45d66b239ad7f379bec64ddd9b0436fe3f4d13f5da7b7f2a542
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Kullander, Johan
By organisation
Department of Chemical Engineering
Chemical Engineering

Search outside of DiVA

GoogleGoogle Scholar
Total: 1886 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 577 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • 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