Patent ID: 6730280
Filing Date: 2004-05-04
Classification: B01D,C01C

Abstract:
A method adapted to provide a pressurized gas stream useful for an external use in removing nitrogen oxides from a combustion gas stream by SNCR (Selective Non-Catalytic Reduction), or SCR (Selective Catalytic Reduction), the method comprising:a) establishing in a reactor an aqueous solution of urea or mixtures of urea containing biuret and/or ammonium carbamate, and hydrolyzing the urea therein at temperatures and pressures sufficient to produce a gaseous product stream of ammonia, carbon dioxide and water at a rate sufficient for external use in step d), and a residual liquid phase reaction medium containing unreacted urea, biuret and/or ammonium carbamate; b) separating the gaseous product stream at a controlled pressure and flow rate; c) retaining the liquid phase reaction medium in the reactor for further conversion to gaseous ammonia and carbon dioxide, and/or recycling at least a portion of the reaction medium back into the reactor or a urea dissolver; and d) withdrawing the gaseous ammonia and carbon dioxide-containing product stream and feeding it for external use at a controlled rate which is approximately the amount necessary to the demand of said external use in removing said nitrogen oxides.