Methods for controlling N2O emissions and for the reduction of NOx and SOx emissions in combustion systems while controlling N2 O emissions

Method for controlling N2O emissions from stationary combustion systems having variable flue gas temperatures are disclosed. The N2O emissions are controlled by the introduction of a N2O control agent, such as an alkaline compound, into the effluent stream. In addition, the present invention discloses methods for controlling N2O emissions from stationary combustion systems having variable flue gas temperatures while reducing NOx emissions. Use of an NOx reducing agent and an N2O control agent, such as urea and monosodium glutamate, enlarges the temperature window for effective selective noncatalytic NOx reduction while significantly eliminating N2O emissions commonly experienced with urea injection. Further, the present invention discloses methods for controlling N2O emissions from stationary combustion systems having variable flue gas temperatures while reducing SOx emissions. Use of an NOx reducing agent, an SOx reducing agent, and an N2O control agent, such as urea, an alkaline-earth metal compound, and an alkali-metal compound, respectively, enlarges the temperature window for effective NOx and SOx reductions while significantly eliminating N2O emissions.