EFFECT OF COOKING STAGE EA CONCENTRATION PROFILES ON SOFTWOOD KRAFT PULPING

The aim of the study was to investigate the effect of different cookin g stage EA profiles and concentrations on softwood kraft pulping. It w as found that when the EA concentration in the cooking stage as a whol e was increased, the H-factor needed to reach a given kappa number dec reased, while pulp strength, homogeneity and bulk increased. There wer e also improvements in brown stock brightness and bleachability. The d isadvantages were decreases in yield, beatability and viscosity. When the EA profile was changed and the EA concentration was raised only at the end of the cook, the yield loss almost disappeared and viscosity increased. Other properties remained about the same. A new continuous cooking process, ''Enhanced Alkali Profile Cooking (EAPC)'': has been developed on the basis of This lab study and process simulations have been carried out by Ahlstrom Machinery, The objective was to be able t o control the EA profile during kraft cooking without increasing white liquor consumption. This would allow pulp mills to adjust their kraft pulp properties according to different customer requirements.