Nonuniformity of Carbohydrate Degradation during Kraft Pulping−Measurement and Modeling Using a Modified G-Factor

Abstract

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Increasing pulp yield in kraft cooking of softwoods by high initial effective alkali concentration (HIEAC) during impregnation leading to decreasing secondary peeling of cellulose

“…In the two latter cases, higher degrees of delignification led to an increased fraction of higher MM cellulose. This corroborates well with the viscosity distribution through wood chips proposed by Li et al (2000). The cellulose molecules closer to the surface have been exposed to alkaline hydrolysis to 100 000 1 000 000 10 000 000 100 000 000 1E+09…”

“…Unfavorable impregnation conditions may result in viscosity profiles through the chip, illustrated by the red dotted line in Figure 6, while an even impregnation would have more similar viscosity values in all parts of the chip, illustrated by the blue line. The occurrence of viscosity profiles has been measured and modeled by Li et al (2000).…”

Heterogeneous Kinetic Model for the Methylglucuronic and Hexenuronic Acids Reactions during Kraft Pulping of Eucalyptus globulus

“…The reaction rates are identified as follows: r 1 and r 2 are the rates of degradation of the fast and slow GlcA, r 3 is the rate of HexA formation from GlcA s , and r 4 is the HexA degradation rate, with α being the stoichiometric factor for the HexA formation reaction. It is well-established ,, that the carbohydrates kinetics of kraft pulping can be expressed in the form of ordinary power law kinetic equations. It was also assumed that all these reactions are dependent on temperature, wood component content, and effective alkali and hydrogen sulfide ion concentrations.…”