kraftkokning med vitlut tillsatt till tvaettcirkulationen.

摘要

In the continuous kraft pulping of comminuted cellulosic fibrous material (e.g. wood chips) to produce paper pulp, viscosity for a given Kappa Number is significantly increased (e.g. at least about 20%) by adding kraft white liquor to the wash recirculation loop (38-40) in a continuous digester (19). Optimum results are obtained when kraft white liquor is also added to a recirculation loop (28-30) at a central portion of the digester, so that the majority of the digester has countercurrent flow between white liquor and cellulosic material. About 5-20% of the total white liquor necessary to effect kraft cooking is introduced in the wash circulation, and about 10-20% is introduced into the central portion recirculation. The temperature in the wash zone is maintained at about 140-175 DEG C. IMAGE