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Mill scale experiences of combined low dosage sulphite pre-treatment and high intensity refining of spruce
Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
SLU.
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(English)Manuscript (preprint) (Other academic)
Keywords [en]
chip pre-treatment, double disc refiner, energy reduction, refining intensity, single disc refiner, sulphite, thermomechancial pulp
National Category
Chemical Engineering
Identifiers
URN: urn:nbn:se:miun:diva-21425OAI: oai:DiVA.org:miun-21425DiVA, id: diva2:698840
Available from: 2014-02-25 Created: 2014-02-25 Last updated: 2014-03-06Bibliographically approved
In thesis
1. Reduction of refining energy during mechanical pulping: using pressurised chip compression and sulphite pre-treatment
Open this publication in new window or tab >>Reduction of refining energy during mechanical pulping: using pressurised chip compression and sulphite pre-treatment
2011 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The effects of pressurised compressive chip pre-treatment and low dosage sulphite pre-treatment were evaluated for production of thermomechanical pulp in mill scale trials using Norway spruce (Picea abies) at the Braviken paper mill (Holmen Paper AB, Sweden). The general aim of the study was to improve the energy efficiency during the production of mechanical pulps suitable for news and improved news grade papers.  The pressurised compressive chip pre-treatment performed in an Impressafiner, resulted in a reduced acetone extractive content for first stage blow line pulp by up to 24%. Furthermore, pulp produced from mechanically pre-treated chips had higher tensile- and tear indices, elongation and light scattering and lower freeness compared to pulps from untreated chips produced with equal total specific energy consumption. The total specific energy consumption was reduced by 120 kWh/bone dry ton (6%) at equal tensile index, when pulps were produced together with the Impressafiner pre-treatment. Sulphite pre-treatment increased tensile index, elongation, density and brightness and reduced light scattering and shive content compared to pulps produced with only mechanical pre-treatment at equal specific energy consumption. The increase in tensile index and reduction in light scattering followed linear relations to the dosage of sodium sulphite in the measured dosage range (0-1.2% Na2SO3). The addition of ~1.2% sodium sulphite gave a sulphur content in pulp of ~0.67% (as Na2SO3) and reduced the specific energy consumption by 210-320 kWh/bdt (12-15%) when compared at equal tensile index. However, light scattering was not retained for this energy reduction.  Further analyses showed that sulphite pre-treatment did not significantly affect the distribution of the Bauer-McNett fractions or the fibre length for pulps refined with equal specific energy consumption but did increase fibre delamination/internal fibrillation as measured by Fernando and Daniel’s (2010) version of Simons’ staining. The specific energy consumption for pulps produced with sulphite pre-treatment (1.2% Na2SO3) and double disc refining were 650 kWh/bdt (30%) lower than for pulps produced in a two stage single disc refiner line (no pre-treatment), when compared at a similar tensile index and light scattering coefficient.

Place, publisher, year, edition, pages
Uppsala: Sveriges Lantbruksuniversitet, 2011. p. 62
Keywords
Chip pre-treatment, double disc refiner, energy efficiency, Impressafiner, low dosage, Norway spruce, refining intensity, single disc refiner, sulphite pre-treatment, thermomechanical pulp
National Category
Engineering and Technology
Identifiers
urn:nbn:se:miun:diva-21428 (URN)978-91-576-9049-4 (ISBN)
Supervisors
Available from: 2014-02-27 Created: 2014-02-25 Last updated: 2017-05-03Bibliographically approved

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Nelsson, ErikSandberg, Christer

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