Application of in-situ near infrared analysis for the measurement of cooking liquor components during kraft pulping

Optimization and control schemes during kraft pulping require on-line estim ation of the most important components in black liquor: The near-infrared ( NIR) technique has already achieved some success in the off-line measuremen t of black liquor However the application of NIR analysis to estimate the o n-line concentration of black liquor components in kraft digesters requires the study of important issues such as temperature variations, availability of information for calibration and the optimal selection of the path lengt h. In this paper a detailed description of the procedures to calibrate the NIR analysis in a bench-scale batch kraft digester is given, and the propos ed solutions to these problems are described.