Abstract: Various methods for decreasing the amount of nitrogen oxides released to the atmosphere as a component of combustion gas mixtures are provided. The methods specifically provide for the removal of nitric oxide and nitrogen dioxide (NOx) from gas mixtures emitted from stationary combustion systems. In particular, methods for improving efficiency of nitrogen oxide reduction from combustion systems include injecting metal-containing compounds into the main combustion zone and/or the reburning zone of a combustion system. The metal containing compounds react with active combustion species, and these reactions change radical concentrations and significantly improve NOx conversion to molecular nitrogen. The metal-containing additives can be injected with the main fuel, in the main combustion zone, with secondary or reburning fuel addition, or at several locations in the main combustion zone and reburning zone.

Abstract: Methods are provided for decreasing the amount of nitrogen oxides released to the atmosphere as a component of combustion emissions. The methods are carried out by forming a combustion flue gas in a combustion zone, the combustion flue gas including nitrogen oxides, injecting overfire air and droplets of a solution or a powder of a selective reducing agent into a burnout zone, and contacting the combustion flue gas with the overfire air and the selective reducing agent in the burnout zone to thereby decrease the concentration of nitrogen oxides therein. The selective reducing agent is provided in an aqueous solution or powder which is injected into the overfire air in optimized droplet or particle form prior to or concurrently with injection of the overfire air into the burnout zone.

Abstract: A method and system for the use of waste coal fines to reduce nitrogen oxides emissions from a coal-fired cyclone boiler. A coal water slurry including waste coal fines is injected as a co-firing fuel into a cyclone barrel of the cyclone boiler to partially oxidize the coal water slurry in a central portion of the cyclone barrel where injected. This produces a reducing zone having reducing gas species that convert nitrogen oxides to diatomic nitrogen. The coal water slurry can alternatively be injected into the cyclone barrel from a secondary combustion air conduit. The evaporation of the water from the coal water slurry reduces the overall combustion temperature in the cyclone barrel, further reducing the production of nitrogen oxides.

Abstract: An improved methods and systems are provided for transferring heat in a combustion system. The methods and systems provide for alternately exposing a reducing gas and a gas containing molecular oxygen to an unmixed combustion catalyst to respectively reduce and oxidize the unmixed combustion catalyst. The unmixed combustion catalyst is readily reducible when in its oxidized state and is readily oxidized when in its reduced state. The alternating reduction and oxidation reactions enable the unmixed combustion catalyst to efficiently release heat to a heat receiver in efficient thermal contact with the unmixed combustion catalyst. In most embodiments of the present invention, the unmixed combustion catalyst is in a reactor bed of a combustion system.

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: The present invention is related to a method for preventing the formation of NH.sub.4 HSO.sub.4 during the noncatalytic reduction of nitric oxide by ammonia or ammonia precursors in combustion effluents. The present invention is also related to a method for preventing the formation of H.sub.2 SO.sub.4 in the absence of ammonia or its precursors. The formation of these corrosive substances is extremely detrimental. NH.sub.4 HSO.sub.4 formation is a limitation upon the usefulness of nitric oxide reduction processes, particularly in boilers, furnaces, and other combustion devices. The formation of H.sub.2 SO.sub.4 limits effective heat recovery in combustion equipment.The present invention specifically teaches the use of methanol to reduce SO.sub.3 in the effluent stream to SO.sub.2. The noncatalytic reduction of SO.sub.3 by methanol is selective in that a large fraction of the SO.sub.3 is converted to SO.sub.2, while on a percentage basis very little oxygen is consumed.