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AssigneeKamyr, Inc.
InventorsBruno S. Marcoccia, J. Robert Prough, Richard O. Laakso, Joseph R. Phillips, Rolf C. Ryham, Jan T. Richardsen, R. Fred Chasse
Estimating the term…
Kraft pulp of increased strength (e.g. at least about 15% greater tear strength at a specified tensile for fully refined pulp, and as much as about 27%) is produced by keeping the dissolved organic material (DOM) concentration below about 100 g/l (e.g. <50 g/l) throughout substantially the entire kraft cook. This may be done by extracting liquor containing a level of DOM substantial enough to adversely affect pulp strength, and replacing some or all of the extracted liquor with liquor containing a substantially lower effective DOM level than the extracted liquor, so as to positively affect pulp strength. The replacement liquor may be water, white liquor, pressure heat treated black liquor, washer filtrate, cold blow filtrate, or combinations, or the extracted liquor can be treated to remove or passivate the DOM (e.g. by precipitation, ultrafiltration, or absorption). The extraction and dilution provided is practiced at a number of different stages during kraft cooking, such as at three or more different levels in a continuous digester, or by continuously flowing low DOM concentration liquor through a batch digester.
A method of draft cooking comminuted cellulose fibrous material at a rate of at least 100 tones of pulp per day by keeping the effective dissolved organic material concentration at 100 grams per liter or less throughout substantially the entire kraft cook, and wherein the effective concentration of dissolved organic material is obtained by continuously passing substantially dissolved organic material-free cooking liquor into and out of contact with the cellulose material until completion of the kraft cook thereof.
A method of producing kraft pulp by cooling comminuted cellulosic fibrous material comprising the steps of continuously, at a plurality of different stages during draft cooking of the material to produce pulp and liquor surrounding the pulp which contains dissolved organic material:
A method of kraft cooking comminuted cellulose fibrous material in a digester, comprising the steps of continuously, at a plurality of different stages during kraft cooling of the material to produce pulp and liquor surrounding the pulp which contains dissolved organic material:
Dependencies are inferred from the claim text.