Sökning: "Oxygen delignification"

Visar resultat 1 - 5 av 19 avhandlingar innehållade orden Oxygen delignification.

  1. 1. Pulp strength enhancement by oxygen delignification

    Författare :Claudia Esteves; Elisabet Brännvall; Olena Sevastyanova; Sören Östlund; Christine Chirat; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; fiber charge; morphology; oxygen delignification; swellability; tensile properties; dragegenskaper; fiberladdningar; morfologi; svällningsförmåga; syrgasdelignifiering; Chemical Engineering; Kemiteknik;

    Sammanfattning : Oxygen delignification is widely used in the pulp and paper industry as a part of delignification process between the kraft cook and bleaching. However, its potential has not been fully utilized. LÄS MER

  3. 2. Oxygen-Alkali Treatment of Kraft Pulp and Cellobiitol. Model Experiments and Applied Studies of Interest for Oxygen Bleaching

    Författare :Bengt Järrehult; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; selectivity; pH-levels; copper; oxygen delignification; catalytic effects; iron; alkali; cellobiitol; magnesium; yield;

    Sammanfattning : During oxygen delignification of kraft pulp the alkalinity has a decisive influence upon the selectivity, defined as viscosity at a given kappa number. Using 0.2% pulp consistency in order to achieve constant pH-levels a minimum selectivity was reached at pH 13, corresponding to 0.1 M NaOH. LÄS MER

  4. 3. Optimization of Pretreatment of Kraft Pulp with Nitrogen Oxides

    Författare :Urban Öjteg; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Kappa number; lignins; Nitric acid; Magnesium; spent liquors; viscosity; softwood; oxygen bleaching; Nitrogen dioxide; Manganese; Oxygen; Nitrogen oxides; pretreatment; Kraft pulp;

    Sammanfattning : Modified kraft pulp subjected to oxygen bleaching following pretreatment with 2% nitrogen dioxide for 140 min with the addition of oxygen resulted in low selectivity after subsequent oxygen bleaching. In contrast, pretreatment in the absence of oxygen removed more than 80% of the lignin after oxygen bleaching and still maintained high selectivity (kappa number less than 5 at viscosity 950 dm3/kg). LÄS MER

  5. 4. Aspects of extended impregnation kraft cooking for high-yield pulping of hardwood

    Författare :Helena Wedin; Mikael E. Lindström; Martin Ragnar; Jorge L. Colodette; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Yield; pulp; kraft cook; carbohydrate; xylan; oxygen delignification; Hexenuronic acid; kappa number;

    Sammanfattning : The long-term trend regarding wood is an increase in price. Because wood contributes to a large part of production costs, the efficient utilisation of wood is greatly desired to reduce production costs for kraft pulp producers. During the 1990s, the development of improved modified kraft cooking began, which led to higher yields. LÄS MER

  7. 5. The Impact of Dissolved Matter on Fiberline Processes

    Författare :Caroline Wilke; Ulf Germgård; Niclas Andersson; Juha Fiskari; Karlstads universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Bleach plant control; Carbonate; Carryover; Chlorine dioxide bleaching; COD; Dissolved lignin; Dissolved matter; Fiberline control; Filtrate; Hexenuronic acid; Hydrogen peroxide bleaching; Kappa number; Oxygen delignification; Wash loss; Chemical Engineering; Kemiteknik;

    Sammanfattning : The impact of dissolved matter on the performance of four fiberline process stages was investigated: oxygen delignification, hot acid treatment, chlorine dioxide bleaching, and hydrogen peroxide reinforced alkaline extraction. In particular the impact on delignification due to dissolved lignin was studied. LÄS MER