Industrial & Engineering Chemistry Research, Vol.36, No.10, 4114-4125, 1997
Kinetic Modeling of Kraft Delignification of Eucalyptus-Globulus
A kinetic model for the kraft pulping delignification of Eucalyptus globulus is proposed. This model is discriminated among some kinetic expressions often used in the literature, and the kinetic parameters are determined by fitting of experimental results. A total of 25 isothermal experiments at liquor-to-wood ratios of 50 and 5 L kg-1 have been carried out. Initial, bulk, and residual delignification stages have been observed during the lignin removal, the transitions being, referring to the lignin initial content, about 82 and 3%. Carbohydrate removal and effective alkali-metal and hydrosulfide consumption have been related with the lignin removal by means of effective stoichiometric coefficients for each stage, coefficients also being calculated by fitting of the experimental data. The kinetic model chosen has been used to simulate typical kraft, pulping experiments carried out at nonisothermal conditions, using a temperature ramp. The model yields simulated values close to those obtained experimentally for the wood studied and also ably reproduces the trends of the literature data.
Keywords:WOOD