The use of secondary condensates from evaporation plant in pulp bleaching

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en
dc.contributor.advisor Vehmaa, Janne
dc.contributor.advisor Oljakka, Tuuli
dc.contributor.author Wang, Yang
dc.date.accessioned 2017-09-04T10:35:41Z
dc.date.available 2017-09-04T10:35:41Z
dc.date.issued 2017-08-29
dc.identifier.uri https://aaltodoc.aalto.fi/handle/123456789/27941
dc.description.abstract High water consumption is a key concern in pulping industry. To resolve the issue, secondary condensates from evaporation plants have been reutilized in pulp washing between the bleaching stages. In order to explore further their exploitation, secondary condensates were applied in bleaching, rather than after bleaching, in this thesis work. Pure water was partially substituted with four types of evaporation condensates as diluents in chlorine dioxide (D) and ozone (Z) bleaching stages. Mass and COD balance of the bleaching stages and the effects of secondary condensates on pulp quality and chemical composition were studied. Headspace gas chromatography - mass spectrometry was applied for quantifying volatile organic compounds (VOCs) in the condensates, bleaching filtrates and the vapor phase of the bleaching reactor. Meanwhile, COD of pulp filtrates and condensates and brightness, viscosity and kappa number of the pulps were examined to study the possible impacts of the condensate use on environmental load and pulp properties. No noticeable effect of the condensate used on pulp brightness, viscosity and kappa number in D0 and Z stages were observed. The main VOCs in the condensates were methanol, ethanol, acetone and some sulphur components, such as dimethyl disulfide. VOCs detected in pulp filtrates were mainly methanol. Also the condensate-free pulp filtrates contained significant amounts of methanol, thus secondary condensates are not the only source of methanol. It could also be formed through demethoxylation of lignin in pulp bleaching. Instead of the secondary condensates, the unbleached kraft pulp was the main source of sulphur in pulp bleaching. Secondary condensates and the methanol in them contributed quite little on COD of pulp filtrates. In conclusion, it seemed to be feasible to substitute fresh water with secondary condensates in pulp bleaching. en
dc.format.extent 44+15
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.title The use of secondary condensates from evaporation plant in pulp bleaching en
dc.type G2 Pro gradu, diplomityö fi
dc.contributor.school Kemian tekniikan korkeakoulu fi
dc.subject.keyword secondary condensate en
dc.subject.keyword chlorine dioxide en
dc.subject.keyword ozone en
dc.subject.keyword mass balance en
dc.subject.keyword ISO Brightness en
dc.subject.keyword viscosity en
dc.identifier.urn URN:NBN:fi:aalto-201709046840
dc.programme.major Biomass Refining fi
dc.programme.mcode CHEM3021 fi
dc.type.ontasot Master's thesis en
dc.type.ontasot Diplomityö fi
dc.contributor.supervisor Vuorinen, Tapani
dc.programme Master's Programme in Chemical, Biochemical and Materials Engineering fi
dc.ethesisid Aalto 9522
dc.location P1


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