Patent ID: 7374735
Filing Date: 2008-05-20
Classification: B01D,F23C,F23J,Y02A

Abstract:
1. A method of decreasing the concentration of nitrogen oxides in a combustion gas flowing through a vessel, said method comprising: a) generating a flue gas in a combustion zone of the vessel, the flue gas containing nitrogen oxides and carbon monoxide; b) providing initial overfire air into a burnout zone of the vessel from a first injector of the overfire air to oxidize at least some of the carbon monoxide in the flue gas; c) injecting from a second injector a selective reducing agent and additional overfire air into the flue gas flowing through the vessel, wherein the second injection is at a level in the burnout zone downstream of the first injector and downstream of oxidation of the carbon monoxide by overfire air from the first injector; and d) reacting the selective reducing agent with the flue gas to reduce the nitrogen oxides.