Continuous digester with dissolved solids handling
US5662775A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 7, 1995 |
| Grant date | Sep 2, 1997 |
| Priority date | — |
| Expiry date | Jun 7, 2015 |
Classification
- Technology area (CPC D)Textiles; Paper
- CPC primaryD21G7/00
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
Digester systems for producing paper pulp from comminuted cellulosic fibrous material take into account the level of dissolved organic materials (DOM), such as lignin, hemi-cellulose, and cellulose, maintaining the DOM level at about 100 g/l throughout the cook (particularly kraft cook). In order to make sure there is sufficient liquid to slurry the material in the feed system of a two vessel system, some liquid is withdrawn from the circulation conduits between the digester and impregnation vessel, cooled, and fed to the feed system. In a vapor phase digester, the level of liquid at the top of the digester is more precisely controlled by circulating some of the withdrawn liquid from a circulatory loop of the digester to the level tank associated with the feed system. An in-line drainer may be provided in the feed system between a make-up liquor pump and a liquid inlet conduit leading to the top of an impregnation vessel. Within the digester, a set of extraction/dilution screens is provided specifically positioned and spaced from each other, and with respect to a reintroduction conduit opening, so that mixing of different DOM concentration liquids is minimized.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.