Dynamic modeling of carbohydrates degradation in kraft pulping of hardwood

The degradation of carbohydrates during the kraft pulping process is of significant economic importance since it is related to the pulp yield. While there are numerous studies of carbohydrate degradation chemistry, there are relatively few dynamic models of carbohydrate kinetics that allow predictions of yield. In this work a dynamic model of carbohydrates dissolution was developed using data from batch kraft cooks of a Southern U.S. hardwood (red oak). On line measurement of cooking liquor properties allowed for the estimation of liquor component concentrations in real time. These data were used with appropriate mass balances to construct a dynamic model of carbohydrate degradation during the course of the cooks. Carbohydrate dissolution and possible reprecipitation during the later stages of cook were observed in this study; the mode is able to predict these phenomena. A separate model was developed that predicts the loss of pulp viscosity during batch kraft cooks of hardwood. These models along with previously developed delignification and effective alkali models will assist in full optimization of kraft batch digesters.