The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 15, 2007
Filed:
Dec. 04, 2002
Catrin Gustavsson, Karlstad, SE;
Mikael Lindstrom, Stockholm, SE;
Krister Olsson, Karlstad, SE;
Vidar Snekkenes, Karlstad, SE;
Catrin Gustavsson, Karlstad, SE;
Mikael Lindstrom, Stockholm, SE;
Krister Olsson, Karlstad, SE;
Vidar Snekkenes, Karlstad, SE;
Kvaerner Pulping AB, Karlstad, SE;
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, T, and cooked at a predetermined cooking temperature, T, 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.