| 摘要 |
This invention relates to a new and improved way of continuously cooking fibre material, wherein temperatures and alkaline levels are controlled to be maintained within specific levels in different zones of the digesting process in order to optimise chemical consumption and heat-economy and at the same time achieve very good pulp properties. The fibre material is heated and impregnated by the aid of black liquor to a temperature less than 140 DEG C and passed in con-current in an impregnation zone (A). The heated and impregnated fibre material is transferred to a con-current cooking zone (B) in the upper part of a digester (6). At least 60 % of the quantity of liquor (F) required for the cooking reaction is supplied in the up-stream end of the con-current cooking zone (B) in order to obtain a level of effective alkali exceeding 35 g/l. The cooking temperature in the con-current cooking zone (B) is lower than 160 DEG C. Spent liquor (E), with an amount of effective alkali of at least 13 g/l, is withdrawn from a strainer girdle (8). A substantial part of the spent liquor is supplied to the impregnation zone. |
