Zero discharge mill distillation, salt recovery, and water management
US5518583A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 21, 1993 |
| Grant date | May 21, 1996 |
| Priority date | — |
| Expiry date | Oct 21, 2013 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S162/08
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
In minimizing effluents from a cellulose pulp mill, liquid effluents from a bleach plant are concentrated, and then incinerated to produce a residue including sodium, sulfate, and sodium chloride. This residue is distilled with sulfuric acid to produce gaseous hydrogen chloride and remaining residue, the HCl being used in chloride dioxide production for the bleach plant, while the remaining residue is passed to the recovery loop (e.g. recovery boiler). Sulfur containing gases from the non-condensible gas system may be combusted to produce gaseous sulfur dioxide, which is then converted to sulfuric acid, to distill the residue. Where a non-chlorine bleach plant is provided, the liquid effluents may be concentrated in evaporators and then passed directly to the recovery boiler. The liquid streams in the mill are managed by a cascade principle to reserve the cleanest water for only those processes where it is needed while minimizing its use where it is not necessary.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.