Method of removing nitrogen oxides from recovery boiler flue gases
US6146604A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 11, 1999 |
| Grant date | Nov 14, 2000 |
| Priority date | — |
| Expiry date | May 11, 2019 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02A50/20
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
A method of removing nitrogen oxides from flue gases of a cellulose pulp mill recovery boiler does so in a cost effective and environmentally friendly manner. In the heat recovery section of the recovery boiler, a peroxide solution (e.g. a water solution containing about 1-35% hydrogen peroxide) is brought into contact with (e.g. sprayed into) the flue gases in the heat recovery section, so that the flue gases and the peroxide remain in contact between about 0.5-5 (preferably between about 1-2) seconds. The majority (e.g. about 60-90%) of the nitrogen oxides are converted to nitrogen dioxide. The temperature of the flue gases at the time of contact with the peroxide solution is between about 300-800.degree. (preferably 400-600.degree.) C. The nitrogen dioxide is removed by scrubbing the flue gases, downstream of the recovery boiler, with an alkaline liquid (e.g. a liquid otherwise used in the pulp mill having a pH of greater than 9) to convert the majority of the nitrogen dioxides into nitrate. The nitrate may be used as a nutrient in a biological effluent treatment plant within the pulp mill.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.