Controlling of chemical recovery and causticizing process using online analysers

摘要

Production of cellulose in the sulphate cooking plant is accompanied by the recovery of Green Liquor. On-line measurements control this causticizing step with financial and production benefits. Metrohm Applikon has built and installed several on-line monitoring analysers to control causticizing process. In the presentation, all studies were made in Scandinavia, Northern Europe. Measurements in the chemical recovery process include: Effective Alkali (EA), Active Alkali (AA), Total Titratable Alkali (TTA) and the degree of causticizing. These measurements were made according Scandinavian pulp, paper and board standards. EA, AA, TTA and the degree of causticizing were measured according standard SCAN N30:85 in green liguor, lime milk and white liquor. Measuring sulphate concentrations was made according standard SCAN N6:85 in green liquor. Sulphate content was also measured with the latest innovation method to measure sulphate content in green liquor using rapid thermometric titration. Thermometric titration measures enthalpy, temperature changes, in the reaction and can be used with several endothermic and exothermic reactions. Study includes description of on-line analysis methods according SCAN N30:85 and SCAN N6:85 standards.