Paper making and fiber liberation – Processes of chemical liberation – recovery or purification... – With regeneration – reclamation – reuse – recycling or...
Patent
1994-04-08
1996-07-30
Czaja, Donald E.
Paper making and fiber liberation
Processes of chemical liberation, recovery or purification...
With regeneration, reclamation, reuse, recycling or...
162 65, 162 78, 162 19, 162 33, 162189, 159 473, D21C 1100, D21C 1110
Patent
active
055408168
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.
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Andtbacka Stig
Bergqvist Anders
Hagelquist Lennart
P.ang.lsson Daniel
Wernqvist Gunnar
Czaja Donald E.
Fortuna Jos'e A.
Kvaerner Pulping Technologies AB
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