Paper making and fiber liberation – Processes of chemical liberation – recovery or purification... – Gas – vapor or mist contact
Patent
1997-02-10
1999-03-16
Silverman, Stanley S.
Paper making and fiber liberation
Processes of chemical liberation, recovery or purification...
Gas, vapor or mist contact
162 66, 162 17, 162 19, 162 41, 162 47, 162 52, D21C 700, D21C 326
Patent
active
058824774
ABSTRACT:
A cellulose pulp continuous digester (e.g. for producing kraft pulp) is operated so that it has the advantages of a hydraulic digester yet has a gas-filled zone over the liquid level. A slurry of chips and cooking liquor is introduced into the top of the digester vessel through an inverted top separator. A liquid level is established below the inverted top separator, and a chips level is established below the inverted top separator (above or below the liquid level). A gas-filled zone above the liquid level includes compressed gas, and is at a temperature of less than 160 (preferably less than 120).degree.C. and at a pressure of between 50-200 (preferably 80-150) psig. The chips are heated by recirculating and heating liquid using a recirculation loop below the chips level, and a countercurrent flow zone is preferably provided.
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Annergren et al, "Neutral Sulfite Semichemical Pulping with Diffusion Washing in a Kamyr Digester", Tappi, The Journal of the Technical Association of the Pulp and Paper Industry, vol. 51, No. 5, May 1968.
"The History of Kamyr Continuous Cooking" by Johan Richter, 1981, pp. 48 through 51.
"Continuous Pulping Processes" by Sven Rydholm, Tappi Stap Series, 1970, lecture 9, pp. 121-157.
"Continuous Digesters" by Brian Greenwood, Kamyr, Inc., Apr., 1991, CPPA Tech '91 Kraft Pulping Course, pp. 2.1-2.14.
Laakso Richard
Stromberg C. Bertil
Ahlstrom Machinery Inc.
Fortuna Jos'e A.
Silverman Stanley S.
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