METHOD AND APPARATUS FOR COOKING SULFATE CELLULOSE (VERSIONS), AND SULFATE CELLULOSE PRODUCED BY THIS METHOD Russian patent published in 1999 - IPC

FIELD: pulp-and-paper industry. SUBSTANCE: sulfate cellulose with elevated strength and bleaching capacity can be obtained with reduced consumption of effective alkali and at lower H value by way of maintaining low concentration of dissolved organics during essentially all sulfate cooking time including extraction of lye with liquid having low level of dissolved organics from at least one part of continuous cooking kettle and replacement of this lye with liquid having much lower level of dissolved organics. Existing grinders for crude cellulose equipped by double-reservoir hydraulic or single-reservoir hydraulic and other systems can be modified to provide extractions and additional feeds of diluted lye with low concentration of dissolved organics (including white lye essentially free of dissolved organics). In addition, industrial-scale (at least 8 t crude cellulose per day) periodic cooking kettles can be run with lye having low concentration of dissolved organics to produce crude cellulose with increased strength. EFFECT: increased strength and/or reduced H value and alkali consumption. 50 cl, 2 tbl