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:
Jul. 30, 1996
Filed:
Apr. 08, 1994
Stig Andtbacka, Karlstad, SE;
Anders Bergqvist, Karlstad, SE;
Lennart Hagelquist, Varberg, SE;
Daniel Pang.lsson, Karlstad, SE;
Gunnar Wernqvist, Biot, FR;
Kvaerner Pulping Technologies AB, Karlstad, SE;
Abstract
A method of integrating bleaching and recovery in connection with the production of chemical pulp that has been digested and preferably delignified with oxygen gas using processes that retain the viscosity and strength, to kappa number less than 16 without the use of chemicals containing chlorine, and using a bleaching sequence including at least one step with sequestering agent and/or acid, and a peroxide step. According to the invention spent liquor (5) from the bleaching department is pre-evaporated in one or more evaporation units (20F, 20G), and the spent liquor (24) from the bleaching department thus pre-evaporated is combined with spent liquor (22) from the digestery and/or with pre-evaporated spent liquor (23) from the digestery obtained by pre-evaporating spent liquor (22) from the digestery in one or more evaporation units (20D, 20E) other than said evaporation units (20F, 20G) for pre-evaporating spent liquor (5) from the bleaching department, after which the mixture of spent liquors (23, 24) is subjected to final evaporation in one or more evaporation units (20A, 20B, 20C) other than said evaporation units (20F, 20G, 20D, 20E) used for pre-evaporation.