EFFECTS OF PULPING CONDITIONS AND BLACK LIQUOR ON VISCOSITY OF SOFTWOOD KRAFT BLACK LIQUORS - PREDICTIVE MODELS

The effects of pulping conditions and black liquor composition on the kinematic viscosity of slash pine kraft black liquors from statistical ly designed pulping experiments have been studied. Very accurate predi ctive equations requiring five parameters at most were obtained using nonlinear regression procedures. These correlations can be used to est imate the viscosity of slash pine black liquors at process conditions from knowledge of pulping variables or black liquor solids composition . The analysis, using quadratic response model, indicates that the vis cous response of black liquor to both pulping variables and black liqu or solids composition is highly nonlinear, and higher-order interactio ns are important when a predictive model is needed. Predictive models (of ten parameters) for viscosity behaviour of slash pine black liquor s at low solids concentrations (less than or equal to 50% solids) as a function of the cooking conditions and composition of the liquors wer e obtained by using general linear regression models and using differe nt statistical criteria.