| 摘要 |
PROBLEM TO BE SOLVED: To prevent chip hanging from occurring in a two-vessel liquid-phase and vapor-phase continuous digester for producing kraft pulp. SOLUTION: The two-vessel liquid-phase and vapor-phase continuous digester is equipped with a penetration vessel V1 of a pressurized liquid phase and a digestion vessel V2 of a pressurized vapor phase for digesting a pulp raw material fed from the penetration vessel bottom through a circulation line L5. In the digestion vessel, a digestion zone B for dissolving and separating lignin in the pulp raw material from the upper position and a washing zone C for washing cellulose in the pulp raw material are formed. A digestion circulation line L6 for returning a part of a cooking liquor from a digestion circulating strainer 1 provided in the digestion zone B to the top of the digestion vessel is installed and a takeout liquor line LZ6 is branched from the digestion circulation line. Thereby, a part of a liquor Z6 is taken out of the circulating liquor of the digestion circulation line with the takeout liquor line and then fed to a cooking chemical recovering step line. As a result, the ratio of the liquors in the digestion zone B and the washing zone C is regulated. COPYRIGHT: (C)2005,JPO&NCIPI
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