Catalytic combustor for substantially eliminating nitrous oxide emissions

#The present invention relates generally to gas powered turbines for generating power, and more particularly to a low nitrous oxide emission combustion system for gas powered turbine systems.

#It is generally known in the art to power turbines with gases being expelled from combustion chambers. These gas powered turbines can produce power for many applications such as terrestrial power plants. In the gas powered turbine a fuel, such as a hydrocarbon (for example methane or kerosene) or hydrogen, is combusted in an oxygen rich environment. Generally, these combustion systems have high emissions of undesirable compounds such as nitrous oxide compounds (NOX) and carbon containing compounds. It is generally desirable to decrease these emissions as much as possible so that undesirable compounds do not enter the atmosphere. In particular, it has become desirable to reduce NOX emissions to a substantially low amount. Emissions of NOX are generally desired to be non-existant, and are accepted to be non-existent, if they are equal to or less than about one part per million volume of dry weight emissions.

#In a combustion chamber fuel, such as methane, is combusted in atmospheric air where temperatures generally exceed about 2600° F. (about 1427° C.). When temperatures are above 2600° F., the nitrogen and oxygen compounds, both present in atmospheric air, undergo chemical reactions which produce nitrous oxide compounds. The energy provided by the high temperatures allows the breakdown of dinitrogen and dioxygen, especially in the presence of other materials such as metals, to produce NOX compounds such as NO2 and NO.

#The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

#FIG. 1 is a partial cross-sectional perspective view of a gas powered turbine including a combustor according to the present invention;

#FIG. 2 is a partial cross-sectional perspective view of a single combustor according to the present invention;

#The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.

#A gas powered combustion turbine 10 may use several different gaseous fuels, such as hydrocarbons (including methane and propane) and hydrogen, which are combusted and expand to move portions of the gas powered turbine 10 to produce power. An important component of a gas powered turbine 10 is a compressor 12 which forces atmospheric air into the gas powered turbine 10. Also, the gas powered turbine 10 includes several combustion chambers 14 for combusting fuel. The combusted fuel is used to drive a turbine 15 including turbine blades or fans 16 which are axially displaced in the turbine 15. There are generally a plurality of turbine fans 16, however, the actual number depends upon the power the gas powered turbine 10 is to produce. Only a single turbine fan is illustrated for clarity. In general, the gas powered turbine 10 ingests atmospheric air, combusts a fuel in it, and powers the turbine fans 16. Essentially, air is pulled in and compressed with the compressor 12, which generally includes a plurality of concentric fans which grow progressively smaller along the axial length of the compressor 12. The fans in the compressor 12 are all powered by a single axle. The high pressure air then enters the combustion chambers 14 where fuel is added and combusted. Once the fuel is combusted, it expands out of the combustion chamber 14 and engages the turbine fans 16 which, due to aerodynamic and hydrodynamic forces, spins the turbine fans 16. The gases form an annulus which spin the turbine fans 16, which are in turn affixed to a shaft (not shown). Generally, there are at least two turbine fans 16. One or more of the turbine fans 16 engage the same shaft that the compressor 12 engages. The gas powered turbine 10 is self-powered since the spinning of the turbine fans 16 also powers the compressor 12 to compress air for introduction into the combustion chambers 14. Other turbine fans 16 are affixed to a second shaft 17 which extends from the gas powered turbine 10 to power an external device. It will be understood that the gas powered turbines are used for many different applications such as engines for vehicles and aircraft or for power production in a terrestrially based gas powered turbine 10. After the gases have expanded through the turbine fans 16, they are expelled out the exhaust portion which includes an exhaust port 18.

#The gases which are exhausted from a gas powered turbine 10 include many different chemical compounds that are created during the combustion of the atmospheric air in the combustion chambers 14. If only pure oxygen and pure hydrocarbon fuel, were combusted, absolutely completely and stoichiometrically, then the exhaust gases would include only carbon dioxide and water. Atmospheric air, however, is not 100% pure oxygen and includes many other compounds such as nitrogen and other trace compounds. Therefore, in the high energy environment of the combustion chambers 14, many different compounds may be produced. All of these compounds exit the exhaust port 18. It is generally known in the art that an equivalence ratio is determined by dividing the actual ratio of fuel and air by a stoichiametric ratio of fuel to air (where there is not an excess of one starting material). Therefore, a completely efficient combustion of pure fuel and oxygen air would equal an equivalence ratio of one.