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US 6,485,289 B1Granted
Ultra reduced NOx burner system and process
AssigneeAltex Technologies Corporation
InventorsJohn T. Kelly, Mehdi Namazian
Life of this patent
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AssigneeAltex Technologies Corporation
InventorsJohn T. Kelly, Mehdi Namazian
Estimating the term…
A NOx reduction burner system and process. Fuel modification and fuel rich reactor zone gases are brought together with products from a fuel lean reactor zone in a low temperature burnout and NOx reduction reactor zone. The fuel modification fuel rich reactor stabilizes combustion through recirculation of hot gases to the reactants. Nitrogenous species decay reactions in the fuel rich zone controls the production of NOx. The nitrogenous species from the fuel rich zone and the NOx from the fuel lean zone then react in the burnout zone at an optimal temperature and nitrogenous species mix where NOx is minimized. Temperature in all zones, and in particular the burnout zone, can be controlled by furnace gas entrainment, induced flue gas recirculation, forced flue gas recirculation and active cooling by radiative and/or convective heat transfer. NOx can be even further reduced by introducing ammonia, or a like amine species, into the low temperature burnout zone. By balancing combustion and emissions control reactions over several zones, low emissions can be achieved under good flame stability, turndown, heat transfer and noise characteristics.
A combustion and emissions control system of apparatus comprising a first reaction chamber, means for injecting into the first reaction chamber fuel and air in amounts which produce a first mixture having a total fuel to air equivalence ratio which is sufficiently greater than one to cause combustion and nitrogenous species decay reactions over a residence time and temperature which are sufficient to produce first combustion products comprising partially oxidized fuel, decayed levels of nitrogenous species, nitrogenous NOx reducing species and nitrogen oxides, a second reaction chamber, means for injecting into the second reaction chamber additional fuel and air in amounts which produce a second mixture having a total fuel to air equivalence ratio which is sufficiently less than one to cause combustion in the mixture over a residence time and low temperature which are sufficient to produce second combustion products mixed with a minimum amount of nitrogen oxides, means for combining the first and second combustion products into a third mixture, and means for generating burnout reactions in the third mixture over a residence time, temperature and oxygen concentrations which are sufficient to complete reaction of any remaining fuel and to promote reaction between nitrogenous reducing species and nitrogen oxides to produce an exhaust with a low amount of nitrogen oxides.
A method of combusting fuel and air to produce products of combustion with low amounts of NOx, comprising the steps of providing a first mixture of fuel and air, combusting the first mixture in a first zone, the first mixture having a total fuel to air equivalence ratio which is sufficiently greater than one to cause the combustion of the first mixture to produce nitrogenous species decay reactions over a residence time and temperature which are sufficient to produce first combustion products comprising partially oxidized fuel, decayed levels of nitrogenous species, nitrogenous NOx reducing species and nitrogen oxides, providing a second mixture of additional fuel and air, combusting the second mixture in a second zone, the second mixture having a total fuel to air equivalence ratio which is sufficiently less than one to cause the combustion of the second mixture to proceed over a residence time and low temperature which are sufficient to produce second combustion products mixed with a minimum amount of nitrogen oxides, combining the first and second combustion products into a third mixture, and causing burnout reactions of the first and second combustion products in the third mixture to proceed over residence time, temperature and oxygen concentrations which are sufficient to complete reaction of any remaining fuel and to promote reaction between nitrogenous reducing species and nitrogen oxides to produce an exhaust with low amounts of nitrogen oxides.
Dependencies are inferred from the claim text.