Multi-level sulfide content white liquor production and utilization in cellulose pulping
US5326433A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 22, 1992 |
| Grant date | Jul 5, 1994 |
| Priority date | — |
| Expiry date | May 22, 2012 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S423/03
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
Paper pulp (e.g. kraft pulp) is produced utilizing at least two different supplies of cooking liquor, one having low sulfide content, and the other high sulfide content. The high sulfide content supply is typically used to impregnate the pulp or otherwise treat it first, while the second supply is used in other cooking stages (e.g. a digester), whether co-current or countercurrent. The different sulfur content liquors are obtained by heat treating (under pressure) black liquor to drive off sulfur compounds, and absorbing them into white liquor to produce a high sulfide stream. The low sulfide stream is made by conventional treatment of the black liquor after heat treating and evaporation. Utilizing multiple sulfide content supplies results in an optimum viscosity/kappa ratio and/or pulp strength properties for the pulp produced.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.