Modeling ultrafiltration and filtration phenomena applied in chemical pulping processes

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en Kovasin, Kari 2012-01-24T14:36:51Z 2012-01-24T14:36:51Z 2003-02-07
dc.identifier.isbn 951-22-6316-5
dc.identifier.issn 1236-875X
dc.description.abstract This thesis is based on seven publications dealing with separation processes applied in the manufacturing of chemical pulp. The first part discusses the correlation of mass transfer phenomena in the ultrafiltration of spent cooking liquor. The second part focuses on the fiber mat formation that takes place in pulp washers and thickeners. The main interest throughout the thesis is to develop useful and scientifically justified methods for correlating mass transfer and filtration mechanisms in order to interpret the phenomena taking place in the studied unit operations. The methods presented can be used in the designing and dimensioning of industrial-scale equipment and systems. Two types of basic mass transfer models, the film model and a more complete approach utilizing an integral solution for two-dimensional diffusion, have been introduced for the calculation of the macrosolute concentration at the surface of the ultrafiltration membrane. A pilot-scale test rig was used to measure ultrafiltration of spent cooking liquor. Mass transfer correlations to estimate the permeate flux have been developed based on both models to be used for plant design calculations. The modeling studies indicated that the integral solution method gave a physically more realistic behavior for the macrosolute concentration at the membrane wall than the widely used film model. It was further shown that dynamic programming may be effectively used to optimize a multistage industrial-scale ultrafiltration-diafiltration process. This method required a shorter calculation time and resulted in slightly better optimal conditions than the direct search algorithm. The studies on mat formation during pulp washing showed that the washing tester is a useful tool to obtain the required information for the washer. A calculation procedure has been developed to obtain design parameters for the dimensioning of industrial pulp washers. The suggested theory was based on Darcy's law under the conditions of constant pressure filtration of incompressible beds and reasonable accuracy was obtained for purposes of washer design. A more accurate approach for the modeling of the mat formation stage was formulated on the fundamental filtration theory of compressible fiber beds. Two such methods were discussed. In the more general model of mat formation, the equation of continuity during filtration was also taken into account. This model was then used for evaluating the effect of various operational parameters on drum washer performance. This model was also able to predict earlier generated experimental test data rather well. A new method for considering the additional filtration resistance due to suspended gases (e.g. air) was also suggested. en
dc.format.extent 49, [57]
dc.format.mimetype application/pdf
dc.language.iso en en
dc.publisher Helsinki University of Technology en
dc.publisher Teknillinen korkeakoulu fi
dc.relation.ispartofseries Chemical engineering report series en
dc.relation.ispartofseries Kemian laitetekniikan raporttisarja fi
dc.relation.ispartofseries 44 en
dc.relation.haspart Kovasin, K. and Nordén, H. V., 1984. Determination of lignosulphonate rejection from test results in the ultrafiltration of spent sulphite liquor. Svensk Papperstidning 87, No. 6, R44-R47. [article1.pdf] © 1984 Svensk Papperstidning. By permission.
dc.relation.haspart Kovasin, K. K. and Hill, C. G., Jr., 1986. A method for correlating permeate flux in the ultrafiltration of macrosolutes. Journal of Pulp & Paper Science 12, No. 4, J119-J125. [article2.pdf] © 1986 PAPTAC. By permission.
dc.relation.haspart Kovasin, K. K., Hughes, R. R. and Hill, C. G., Jr., 1986. Optimization of an ultrafiltration-diafiltration process using dynamic programming. Computers and Chemical Engineering 10, No. 2, pp. 107-114. [article3.pdf] © 1986 Elsevier Science. By permission.
dc.relation.haspart Hakamäki, H. and Kovasin, K., 1985. The effect of some parameters on brown stock washing: A study made with a pulp tester. Pulp & Paper Canada 86, No. 9, T243-T249. [article4.pdf] © 1985 PAPTAC. By permission.
dc.relation.haspart Kovasin, K. and Tuomi, A., 1986. Entwicklung der Holzschliffeindickung bei hohen Temperaturen. Wochenblatt für Papierfabrikation 114, No. 7, pp. 230-234. [article5.pdf] © 1986 Deutscher Fachverlag GmbH. By permission.
dc.relation.haspart Kovasin, K., Nordén, H. V. and Ahonen, L., 1988. Modelling the filtration stage of a pulp washer. Filtration & Separation 25, No. 1, pp. 42-45. [article6.pdf] © 1988 Elsevier Science. By permission.
dc.relation.haspart Kovasin, K. and Aittamaa, J., Factors defining the capacity of pulp washers. Paperi ja Puu, accepted for publication on 21.08.2002. To be published in 2003.
dc.subject.other Paper technology en
dc.subject.other Chemistry en
dc.title Modeling ultrafiltration and filtration phenomena applied in chemical pulping processes en
dc.type G5 Artikkeliväitöskirja fi
dc.description.version reviewed en
dc.contributor.department Department of Chemical Technology en
dc.contributor.department Kemian tekniikan osasto fi
dc.subject.keyword pulping en
dc.subject.keyword fiber en
dc.subject.keyword spent cooking liquor en
dc.subject.keyword mass transfer en
dc.subject.keyword ultrafiltration en
dc.subject.keyword filtration en
dc.subject.keyword optimization en
dc.subject.keyword washing en
dc.identifier.urn urn:nbn:fi:tkk-000224
dc.type.dcmitype text en
dc.type.ontasot Väitöskirja (artikkeli) fi
dc.type.ontasot Doctoral dissertation (article-based) en
dc.contributor.lab Laboratory of Chemical Engineering and Plant Design en
dc.contributor.lab Kemian laitetekniikan ja tehdassuunnittelun laboratorio fi

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