PERIODIC PROCESS OF PRODUCTION OF KRAFT PULP (VERSIONS) Russian patent published in 1999 - IPC

FIELD: production of kraft pulp. SUBSTANCE: process includes that some quantity of green liquor or its derivative is introduced at the stage of impregnation or/and preliminary treatment of cellulose material. Derivative may be in the form of mother liquor produced by crystallization of carbonate from green liquor. Periodic methods include displacement of liquor used for impregnation with new volume of used cooking liquor and preliminary treatment of material with this liquor. Then, liquor used for preliminary treatment is displaced with hot cooking liquor and cooking of material is performed in this liquor. Further, liquor is displaced with washing filtrate used for cooking. EFFECT: mild conditions at the end of cooking stage and short period of cooking; higher process productivity; good preservation of chemical substances balance. 10 cl, 1 dwg, 13 tbl