| 摘要 |
A continuous process for digesting a lignocellulose material using a two-vessel digestion apparatus, wherein a permeation vessel is installed before a digester, the digester has, from the top towards the bottom thereof, an overhead zone, an upper digestion zone and a lower digestion zone, each zone has a strainer at its bottom, and a black digestion liquor extracted is discharged from at least one strainer to the outside of the digestion system, characterized in that use is made of a chip from a broad-leaved tree or a needle-leaved tree; an alkaline digestion liquid is added at the top of the permeation vessel which liquid contains a polysulfide type sulfur in a concentration of 3 to 20 g/L as sulfur, and contains sulfur in an amount of 45 to 100 wt % and an effective alkali in an amount of 45 to 79 wt %, both percentages being relative to the respective total amounts contained in the alkaline digestion liquid introduced to the above digestion system; an alkaline digestion liquid which contains a specific amount of a quinone compound per the weight of an absolutely dried chip is fed to the permeation vessel or to the upper digestion zone at its bottom. The process can be employed for lowering the kappa value for the same percentage of addition of an effective alkali and also for improving the yield of pulp for the same kappa value. |
