Patent ID: 8449288
Filing Date: 2013-05-28
Classification: F23C,F23J,F23L

Abstract:
1. A method for reducing NOx formation, comprising the steps of: providing a staged combustion system including a furnace with a plurality of asymmetrical injection devices for introducing at least one reagent to the reactor by asymmetrical injection at predetermined, spaced apart locations; injecting fuel with primary air through a first stage prior to injection of a second air; injecting secondary air and aqueous urea solution within the reactor at temperatures above about 2000° F. through the plurality of injection devices; wherein the aqueous urea solution has a urea concentration greater than about 20% w/w and is injected at furnace locations with temperatures above about 2000° F., and wherein injection at the temperature range may be achieved without special chemicals; and creating turbulence within the reactor by controlling the asymmetrical injection of secondary air to produce the turbulence resulting in dispersion of the urea solution into the reaction system at temperatures above about 2000° F., thereby increasing the residence time of the combustion gases in the furnace and providing reduced NOx formation in the reaction process during a staged combustion system, wherein the velocity of the secondary air is such that the ratio of the velocity to the reactor width is between about 2 sec