Residence time distribution measurements in an industrial-scale pulp digester using technetium-99m as radiotracer

This paper describes measurement of residence time distributions (RTD) of the liquid phase in an industrial-scale continuous pulp digester. The objective of the study was to quantify the degree of mixing of the liquid phase and optimization of operating conditions of digester. Technetium-99m (^99mTc) was used as radiotracer to measure the RTD of liquid phase. A combined model was proposed for the simulation of experimental RTD curve. The quality parameter of pulping process was measured using chemical methods. From the comparison of pulping and mixing parameters the optimum operating condition of digester was identified. (author)