Paper making and fiber liberation – Processes of chemical liberation – recovery or purification... – With regeneration – reclamation – reuse – recycling or...
Reexamination Certificate
2007-05-15
2007-05-15
Hug, Eric (Department: 1731)
Paper making and fiber liberation
Processes of chemical liberation, recovery or purification...
With regeneration, reclamation, reuse, recycling or...
C162S019000, C162S041000, C162S042000, C162S043000, C162S017000
Reexamination Certificate
active
10494397
ABSTRACT:
The process is for continuously cooking chemical pulp in a digester system consisting of at least one vessel for impregnating and cooking comprising an inlet into which a mixture of chips and process liquid is fed. The chips are impregnated at a predetermined impregnation temperature, Timp, and cooked at a predetermined cooking temperature, Tcook, after which dissolved pulp is fed out at the outlet of the digester system. The process liquid which is continually extracted is retained outside the digester system during a dwell time, t, of at least 30 min, without any heating above 140°, and thereafter returned to the digester system to a position which is substantially at the same level as the extraction, or downstream thereof, and thereby constitute part of the process liquid in the subsequent treatment zone. The process results in improved tear strength, beatability, bleachability and reduced color reversion, and increased yield across the digester.
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Gustavsson Catrin
Lindstrom Mikael
Olsson Krister
Snekkenes Vidar
Fasth Rolf
Fasth Law Offices
Hug Eric
Kvaerner Pulping AB
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