Batch cooking with black liquor pretreatment
US6350348B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 19, 1999 |
| Grant date | Feb 26, 2002 |
| Priority date | — |
| Expiry date | Jul 19, 2019 |
Classification
- Technology area (CPC D)Textiles; Paper
- CPC primaryD21C3/266
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
A method of cooking pulp in an alkaline batch process (using one or more batch digesters) improves pulp bleachability. The wood material is supplied to the digester; the cellulosic material is pre-treated in the digester with a first liquor, the first liquor is displaced by a second liquor, the displaced first liquor is led to a further treatment, the cellulose material is treated with the second liquor, and the cooked pulp is removed from the digester. The second liquor is displaced as two consecutive parts, i.e. as strong black liquor and weak black liquor, and after cooling in a heat exchanger the strong black liquor thus obtained is fed into the digester as the first liquor in a subsequent batch (in the same, or a different, batch digester).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.