Modeling of a modified kraft process

This paper presents experimental and modeling studies on a modified kraft pulping process. The batch digester used in the laboratory is equipped with sensors to allow the measurement of cooking chemicals and dissolved lignin concentrations during the cook. Cooks are performed in such a way that the chemical concentrations and the lignin concentration can be profiled and maintained at the desired level. The modified digester achieves this goal by controlling the alkali input to the digester and withdrawing liquor out of the digester. Using the online data obtained from the experiments, a model is constructed for the bulk phase of delignification for the profiled cooks and the model parameters are obtained by an optimization technique. Model predictions are found to be in agreement with the experimental values, in the range of experimental conditions used in the laboratory.