FIELD: pulp-and-paper industry. SUBSTANCE: method involves feeding ground cellulose fibrous material in white sulfate liquor into upper section of boiling flow; extracting black sulfate liquor from at least one region between upper and central sections of boiler; discharging and recirculating liquid in recirculation circuit in boiler central section; adding washing liquid in lower section of boiler and discharging kraft-pulp from lower section. Liquid is discharged from lower section and recirculated in washing recirculation circuit while white sulfate liquor is added. Recirculated liquor is ascended in boiler in countercurrency to material flow, with amount of added liquor and temperature mode in washing circuit being regulated. EFFECT: increased efficiency and improved quality of boiled material. 9 cl, 3 dwg, 1 tbl
