Paper making and fiber liberation – Processes of chemical liberation – recovery or purification... – With regeneration – reclamation – reuse – recycling or...
Patent
1995-03-14
1997-08-26
Czaja, Donald E.
Paper making and fiber liberation
Processes of chemical liberation, recovery or purification...
With regeneration, reclamation, reuse, recycling or...
162248, D21C 714, D21C 326
Patent
active
056606869
ABSTRACT:
A method and continuous digester system provide for a high Na.sub.2 S concentration in the beginning of the cook of comminuted cellulosic fibrous material to produce cellulose pulp, providing a more selective cook and potential to lower cooking kappa. Two different streams of spent (e.g. "sulphurous" and "black") liquor are removed from different screens associated with continuous digesters. The spent liquor removed from the uppermost screen has a relatively high effective alkali and Na.sub.2 S concentration. The second spent liquor, removed from the second screen, has effective alkali and Na.sub.2 S concentrations which are at least 25% less than for the first spent liquor. The first spent liquor is circulated to an impregnation vessel, or other part of a chip feed system, to enhance the amount of sulphur present at the beginning of the cooking stage in the digester. The second spent liquor may be used in a number of ways, including--with or without first passing it through a flash tank--circulating it to a chip slurrying system for slurrying the chips so that they can be fed to the digester. The steaming and slurrying system may include only an unpressurized chip bin, chip feeder, slurrying vessel, and high pressure feeder, thus being simpler than conventional constructions.
REFERENCES:
patent: 5053108 (1991-10-01), Richter
patent: 5080755 (1992-01-01), Backlund
patent: 5256255 (1993-10-01), Fagerlund
patent: 5522958 (1996-06-01), Li
Nils Hartler, "Extended Delig . . . New Concept", 1978 Svensk Pappersidning 15:483 (pp. 1-2) 1978.
Johan Engstrom, "Black Liquor . . . Kraft Cooking", Paper and Timber vol. 76, pp. 59-66 Jan. 2, 1994.
Disa Tormund, "New Findings . . . Pulping Liquors", Tappi Journal, pp. 205-210 May 1989.
Henricson Kaj O.
Tervola Pekka
Ahlstrom Machinery Inc.
Czaja Donald E.
Nguyen Dean T.
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