Reaction kinetic study and determination of controlling resistances during alkaline sulfite/anthraquinone pulping

Graduation date: 1987A survey of the pulping literature indicated\ud that although the kinetics of the Kraft Pulping\ud process has been studied in detail , very few studies\ud have been reported for Alkaline Sulfite /\ud Anthraquinone (ASAQ) pulping process. There is no\ud existing rate model for this pulping process. Hence,\ud the objectives of this thesis were to obtain a kinetic\ud rate data and to determine the controlling resistances\ud for this process.\ud Delignification rate data were obtained using a\ud softwood - chip mixture containing balsam, spruce,\ud and northern pine. Time, temperature, and chip size\ud were chosen as the independent variables in this study.\ud The concentrations of pulping chemicals were kept\ud constant during the cooks. The rate data obtained was\ud then analyzed using different techniques to establish the controlling resistances during this process.\ud From the results obtained, it was concluded that\ud during this process, ASAQ delignification occurs in\ud the mixed regime with internal diffusion resistance\ud and chemical reaction resistance controlling the rate\ud of reaction. The internal diffusion resistance is the\ud prominent resistance for most of the chip sizes used\ud in this study. The smallest chip size, however, shows\ud that chemical reaction resistance is prominent in this\ud case. Since the chips used in this study are smaller\ud than the commercial chips, we expect that the rate of\ud delignification for commercial pulping is controlled\ud mainly by internal diffusion although the\ud delignification reaction itself becomes important for\ud the smaller chips, and at higher conversions