EP 0476230 A2 19920325 - Extended kraft cooking with white liquor added to wash circulation.
Title (en)
Extended kraft cooking with white liquor added to wash circulation.
Title (de)
Verlängertes Kraftkochen mit dem Waschkreislauf zugefügter Weisslange.
Title (fr)
Cuisson kraft complète avec lessive ajoutée à la circulation de lavage.
Publication
Application
Priority
US 58304390 A 19900917
Abstract (en)
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>
IPC 1-7
IPC 8 full level
D21C 3/02 (2006.01); D21C 3/24 (2006.01); D21C 7/00 (2006.01); D21C 7/14 (2006.01); D21C 9/147 (2006.01); D21C 9/153 (2006.01); D21C 9/16 (2006.01)
CPC (source: EP)
D21C 3/02 (2013.01); D21C 3/24 (2013.01); D21C 7/00 (2013.01); D21C 9/147 (2013.01); D21C 9/153 (2013.01); D21C 9/163 (2013.01)
Designated contracting state (EPC)
AT DE FR GB IT SE
DOCDB simple family (publication)
EP 0476230 A2 19920325; EP 0476230 A3 19930609; EP 0476230 B1 19961218; AT E146538 T1 19970115; AU 647129 B2 19940317; AU 7830591 A 19920319; BR 9103650 A 19920519; CA 2037717 A1 19920318; CA 2037717 C 19960305; DE 69123670 D1 19970130; FI 103815 B1 19990930; FI 103815 B 19990930; FI 914353 A0 19910917; FI 914353 A 19920318; JP 3029492 B2 20000404; JP H04300378 A 19921023; NO 179918 B 19960930; NO 179918 C 19970108; NO 913639 D0 19910916; NO 913639 L 19920318; RU 2089694 C1 19970910; ZA 912117 B 19911127
DOCDB simple family (application)
EP 91108241 A 19910522; AT 91108241 T 19910522; AU 7830591 A 19910612; BR 9103650 A 19910826; CA 2037717 A 19910307; DE 69123670 T 19910522; FI 914353 A 19910917; JP 23050191 A 19910910; NO 913639 A 19910916; SU 5001635 A 19910916; ZA 912117 A 19910321