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Refining rheological response of chemical pulp fibre suspensions

2017-10-01Lecture Open access
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dc.contributor.authorVaz, Álvaro
dc.contributor.authorSimões, Rogério
dc.contributor.authorSilvy, Jacques
dc.date.accessioned2020-02-28T15:06:54Z
dc.date.available2020-02-28T15:06:54Z
dc.date.issued2017-10-01
dc.description.abstractThe purpose of this work was to study the influence of the refining operating variables on the rheological response of chemical pulp fibre suspensions using a Valley beater. Pinus sylvestris, Eucalyptus globulus and Betula verrucosa bleached pulps were used. The normal and tangential average forces exerted on the pulp suspension in the gap clearance were evaluated, the gap between rotor and stator was measured and the apparent viscosity evolution during refining was obtained. The refining essays took place in a laboratory Valley beater, and the studied variables were the load on the roll, the rotor speed of rotation and the specific applied energy. Relationships between apparent viscosity and shear rate were tested for the three species fibre suspensions, which showed shear-thinning behaviour (Fig.1). The results were analysed in terms of fiber and flock properties. The computed crowding factors, Nc, (Kerekes and Schell) decrease from pine to eucalypt to birch. Thus, flock dimensions and resistance are significantly higher for pine. Pine had significantly wider gap, due to its greater and more resistant flocks. This produced smaller shear rate and thus higher apparent viscosity. The smaller and weaker eucalyptus and birch flocks induced smaller gaps, higher shear rates and smaller apparent viscosity. For each pulp suspension, the apparent viscosity diminished with refining time due to increased fibre flexibility and shortening, which promoted smaller flocks and reduced gap clearance (producing higher shear rates). The different rheological behaviors under the same operating conditions for different pulps lead to the inference that from the hydrodynamical point of view one should treat pulps with different morphological characteristics separately, considering the optimization of the energy transfer efficiency in pulp refining.pt_PT
dc.description.versioninfo:eu-repo/semantics/publishedVersionpt_PT
dc.identifier.citationVaz, A., Simões, R., Silvy, J., Refining rheological response of chemical pulp fibre suspensions, in Book of Abstracts of the 10th World Congress of Chemical Engineering, Barcelona, 1-5th October, p. 2859, 2017. ISBN: 978-84-697-8629-1.pt_PT
dc.identifier.isbn978-84-697-8629-1
dc.identifier.urihttp://hdl.handle.net/10400.6/9627
dc.language.isoengpt_PT
dc.peerreviewedyespt_PT
dc.publisherEFCE (European Federation of Chemical Engineering) - Spain group (ANQUE, AIQS, AEIC and SEQUI)pt_PT
dc.subjectRefiningpt_PT
dc.subjectRheological responsept_PT
dc.subjectChemical pulpspt_PT
dc.subjectFibre suspensionspt_PT
dc.titleRefining rheological response of chemical pulp fibre suspensionspt_PT
dc.typelecture
dspace.entity.typePublication
oaire.citation.conferencePlaceFira de Barcelonapt_PT
oaire.citation.startPage2859pt_PT
oaire.citation.title10th World Congress of Chemical Engineeringpt_PT
person.familyNameVaz
person.familyNameSimões
person.givenNameÁlvaro Frederico Campos
person.givenNameRogério Manuel Santos
person.identifier.ciencia-idB017-2B7B-2F19
person.identifier.ciencia-idC61A-FEC7-573C
person.identifier.orcid0000-0001-8505-8209
person.identifier.orcid0000-0001-8143-1555
rcaap.rightsopenAccesspt_PT
rcaap.typelecturept_PT
relation.isAuthorOfPublicationebb326e6-4b01-40f2-81ff-b8c38eeddcf9
relation.isAuthorOfPublication09cfc862-f9eb-4943-862c-790e0224d370
relation.isAuthorOfPublication.latestForDiscovery09cfc862-f9eb-4943-862c-790e0224d370

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