Reducing NO.sub.x emissions from an engine by temperature-controlled urea injection for selective catalytic reduction
US5976475A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 2, 1997 |
| Grant date | Nov 2, 1999 |
| Priority date | — |
| Expiry date | Apr 2, 2017 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02T10/40
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
A safe, reliable SCR system for reducing NO.sub.x emissions from a lean-burn internal combustion engine utilizes urea in aqueous solution. Overheating and hydrolysis of the solution are prevented by maintaining the temperature of the urea solution sufficiently low that it is not permitted sufficient time at elevated temperature to hydrolyze the urea to such an extent that solids precipitate. In a preferred embodiment, an injector system similar to those used for fuel injection provides a constant feed to injectors and a return line. The feed and injection can be controlled to provide sufficient urea for NO.sub.x reduction and sufficient cooling capacity for the feed and injection system to avoid hydrolysis and deposits of hydrolysis products.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.