Modelling of a modified kraft process

This paper presents experimental and modelling studies on a modified kraft pulping process. The batch digester used in the laboratory was equipped wit h sensors to allow the measurement of cooking chemicals and dissolved ligni n concentrations during the cook. Cooks were performed in such a way that t he chemical concentrations and the lignin concentration could be profiled a nd maintained at the desired level. The modified digester achieved this goa l by controlling the alkali input to the digester and withdrawing liquor ou t of the digester. Using the on-line data obtained from the experiments, a model was constructed for the bulk phase of delignification for the profile d cooks and the model parameters were obtained by an optimization technique . Model predictions were found to be in agreement with the experimental val ues in the range of experimental conditions used in the laboratory.