Abstract: Method for controlling N.sub.2 O emissions from stationary combustion systems having variable flue gas temperatures are disclosed. The N.sub.2 O emissions are controlled by the introduction of a N.sub.2 O control agent, such as an alkaline compound, into the effluent stream. In addition, the present invention discloses methods for controlling N.sub.2 O emissions from stationary combustion systems having variable flue gas temperatures while reducing NO.sub.x emissions. Use of an NO.sub.x reducing agent and an N.sub.2 O control agent, such as urea and monosodium glutamate, enlarges the temperature window for effective selective noncatalytic NO.sub.x reduction while significantly eliminating N.sub.2 O emissions commonly experienced with urea injection. Further, the present invention discloses methods for controlling N.sub.2 O emissions from stationary combustion systems having variable flue gas temperatures while reducing SO.sub.x emissions. Use of an NO.sub.x reducing agent, an SO.sub.

Abstract: Techniques for enhancing the burnout zone chemistry for NO.sub.x reduction are disclosed. The key parameters for the enhancement of burnout zone chemistry are: (a) a reaction temperature in the range from about 1300.degree. F. to about 1900.degree. F., and optimally in the range from 1400.degree.-1700.degree. F.; (b) a carbon monoxide concentration below about 0.5 percent; and (c) the presence of nitrogenous reducing species. By controlling the stoichiometry associated with reburning to produce a slightly fuel-rich region for selective reducing agent injection, reductions can be achieved at relatively low temperatures which approach those obtained by conventional catalytic reduction.

Abstract: Methods for reducing NO.sub.x emissions from stationary combustion systems having variable flue gas temperatures are disclosed. Use of an annonium salt of an organic acid enlarges the temperature window for effective selective noncatalytic NO.sub.x reduction thereby accounting for variable flue gas temperatures. Currently preferred ammonium salts of organic acids include ammonium formate, ammonium acetate, and ammonium oxalate. Mixtures of urea and either an ammonium salt of an organic acid or a metallic salt of an organic acid provide an even greater temperature window for NO.sub.x reduction. Currently preferred metallic salts of organic acids include Ca(COOH).sub.2, Ca(CH.sub.3 COO).sub.2, Ca(C.sub.2 H.sub.5 COO).sub.2, Mg(COOH).sub.2, Mg(CH.sub.3 COO).sub.2, and Mg(C.sub.2 H.sub.5 COO).sub.2.