Patent ID: 6048510
Filing Date: 2000-04-11
Classification: B01D,F23J

Abstract:
A method of reducing the concentration of nitrogen oxides (NO.sub.x) in an effluent gas stream from the combustion of carbonaceous fuel in a boiler or furnace, comprising the steps of:identifying a gas combustion temperature zone within said boiler or furnace which ranges from about 1700.degree. F. to 2000.degree. F.;injecting an aqueous solution into contact with an effluent gas stream in said gas combustion temperature zone within said boiler or furnace, said aqueous solution comprises a dissolved or dispersed reducing agent selected from the group consisting of urea, ammonia, and an ammonia precursor, said step of injecting being performed with at least one injector, said step of injecting being performed with a nozzle that forms a flat, planar, fan shaped spray pattern which is oriented perpendicular to said effluent gas stream;producing droplets of a non-uniform variable size ranging from 10 .mu.m to 1000 .mu.m where a mean and maximum size of said droplets depend on dimensions of said furnace or boiler, said producing step taking place during said injecting step by varying hydraulic and air atomizing pressures in said injector in order to permit distribution and vaporization of different sized droplets at different locations within said gas combustion temperature zone; andadjusting a position of an injector droplet outlet of said injector within said boiler or furnace based on an outer edge of said gas combustion temperature zone identified in said identifying step, said adjusting step positioning said injector droplet outlet adjacent to said outer edge of said gas combustion temperature zone identified in said identifying step.