Kinetic Model for Causticizing Reaction, 1993 Pulping Conference Proceedings

Present industrial causticizing systems are operated as open stirred tank reactors at temperatures near 100°C. Lower causticizing efficiency, ineffective liquor strength control and higher energy consumption are some of the inherent problems associated with this system. Pressurized causticizing at elevated temperatures with appropriate sensors would lend itself to better control and minimize the above problems. This will result in uniform white liquor supply to the digester and in turn will result in improved pulp uniformity, productivity and overall cost efficiency.

A kinetic model has been developed which can be used to predict the causticizing efficiency and is based on easily measurable liquor properties. The model parameters are estimated using experimental data obtained from a specially designed laboratory batch pressurized causticizing reactor. This model, in combination with the liquor property measurement, allows closing of the control loop to produce uniform white liquor with improved causticizing efficiency.