DOCTORAL THESES

Modeling chlorine dioxide bleaching of chemical pulp (Aalto University)

ABSTRACT This doctoral thesis deals with the phenomenon-based modeling of pulp bleaching. Previous bleaching models typically utilize one or two empirical correlations to predict the kinetics in kappa number development. Empirical correlations are simple to develop, but their parameters are often tied to the validation system. A major benefit of physico-chemical phenomenon models is that they are valid regardless of…

Impregnation, vapor phase and methanol as means of intensifying the softwood kraft pulping process (Helsinki University of Technology)

ABSTRACT The objective of the research was to find ways to shorten the cooking time, i.e. intensify the kraft pulping process. The reason for undertaking such a study lies in the long standing trend of ever increasing reactor size in the kraft pulping industry. The huge digester size in use presently has lead to severe problems in understanding the behavior…

Studies on industrial digesters and cooking performance – Methods and applications (Helsinki University of Technology)

ABSTRACT Industrial pulp cooking reactors, digesters, were introduced in the early stages of chemical pulping technology for chemical liberation of fibres from wood chips and other lignocellulosic materials. With cooking temperatures of 20 – 80 °C above the boiling point of water and strong chemicals such as sodium hydroxide, suiphide or suiphite, digesters had to be sturdy and big. When…

Chemical characterization of lignosulfonates (North Carolina State University)

ABSTRACT Softwood (pinus silvestris) lignosulfonates from the acidic stage of a three-stage sulfite cook were fractionated and purified by ultrafiltration and ion exclusion chromatography. The fractions were characterized by 13C NMR spectroscopy together with conventional chemical methods. In order to ascertain correct signal assignment of the 13C NMR spectra of lignosulfonate fractions, the chemical shifts of model compounds were studied. It was…