Abstract: A method for reducing NO.sub.x in a combustion exhaust gas stream from a boiler. The method includes the steps of converting an aqueous solution of urea to ammonia by heating the urea solution to a temperature of 350.degree.-650.degree. F. The urea solution is pressurized to the pressure required to keep urea solution is pressurized to the pressure required to keep urea reaction products in the liquid phase and is contacted for a selected time with a conversion catalyst selected from the group of metals, metal oxides, or metal compounds comprising aluminum, chromium, cobalt, molybdenum, niobium, titanium, tungsten, and vanadium to provide a converted area solution. The converted area solution is injected into the combustion exhaust gas for reducing NO.sub.x.

Abstract: A method is provided for reducing NOx in a combustion exhaust gas stream from a boiler. The method includes the steps of converting an aqueous solution of urea to ammonia by heating the urea solution to a temperature of 350.degree.-650.degree. F. in an injection lance system. The urea solution is pressurized to the pressure required to keep urea reaction products in the liquid phase and is contacted for a selected time with a conversion catalyst selected from the group of metals, metal oxides, or metal compounds consisting of chromium or molybdenum to provide a converted urea solution. The converted urea solution is injected from the injection lance system into the combustion exhaust gas for reducing NOx.

Abstract: Techniques and associated systems are provided for removing oxides of nitrogen (NO and NO.sub.2, hereinafter called NO.sub.x) from combustion effluent gases. Such a system includes a nozzle and means for introducing a carrier gas and an injection chemical into the nozzle to be mixed together. The mixture is ejected from the nozzle into a flue gas duct to provide a high degree of cross-sectional coverage and intimate mixing between the injection chemical and the NO.sub.x -containing combustion effluent gas.

Abstract: This invention relates to methods and apparatus for reducing NOx in combustion effluent gases which comprise a two-stage injection process. NHi precursors (such as liquid-phase urea or ammonium hydroxide, or the like) are injected into the flue gas at temperatures greater than 1400.degree. F. in a first injection zone to reduce NO to nitrogen. This step is followed by injecting a peroxyl initiator, such as a hydrocarbon material (for example, methanol) into the flue gas at temperatures less than 1400.degree. F. to oxidize residual NO to NO.sub.2 in a second injection zone.