Injector apparatus and method for combusting a fuel for a gas powered turbine

Abstract

A combustor for a gas powered turbine which employs a hypergolic or high energy air stream and an injector design to mix fuel with the high energy hypergolic air stream faster than the combustion rate of the fuel. A heat exchanger and a catalyst combusts a first portion of fuel in air without the production of undesired chemical species. A gas powered turbine requires expanding gases to power the turbine fans or blades. Fuel is generally combusted to produce the required gases. A catalyst is employed to lower the combustion temperature of the fuel. The catalyst is placed on a set of tubes in a heat exchanger such that a portion of the thermal energy may be transferred to the air before it engages the catalyst. After encountering the catalyst, the fuel that was combusted increases the temperature of the air to an auto-ignition temperature so that no other ignition source is needed to combust additional fuel added later. Therefore, as the air exits the heat exchanger, it enters a main combustion chamber and is mixed with a second portion of fuel at a rate that is greater than the combustion reaction rate of the fuel.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to gas turbine power plants, and more particularly relates to main combustion injectors for catalytic drive, substantially no noxious oxide emission power plants.

BACKGROUND OF THE INVENTION

[0002] 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. The oxygen is generally provided from atmospheric sources which also contains nitrogen and other compounds. These combustion systems often 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 and more preferably to a point where emissions are virtually eliminated. Emissions of NOX are generally accepted to be non-existent if they are equal to or less than about one part per million volume of dry weight emissions.

[0003] In a combustion chamber, fuel, such as methane, is combusted in atmospheric air where temperatures generally exceed about 1420° C. (about 2600° F.). This is especially true if flame holding zones or high temperature pilot flames are used to stabilize the combustion process. When temperatures are generally above about 1420° C., 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 various metals, to produce NOX compounds such as NO2 and NO.

[0004] Attempts have been made to reduce production of NOX compounds by initially heating the air before it enters the combustion chambers to an auto-ignition temperature. If the air enters the combustion chamber at or above an auto-ignition temperature, then pilot flames or recirculation flame holding zones are not necessary to combust the fuel. Auto-ignition temperatures are usually lower than pilot flame temperatures or the temperatures inside recirculation flame holding zones. One such method for heating air to the auto-ignition temperature is to mix the fuel in the air before it reaches the combustion chamber. This vitiated air, that is air which includes the fuel, is then ignited in a pre-burner where at least a portion of the entrained fuel is combusted. This raises the temperature of the air before it reaches the main combustion chamber. This decreases NOX production and emissions substantially. Nevertheless, NOX emissions still exist due to the initial pre-burning.

[0005] In view of the foregoing, it will be appreciated that it is desirable to decrease or eliminate pre-burning, thereby substantially eliminating all NOX emissions. Although the air is heated before entering the main combustion chamber, it may still need to be ignited in the combustion chamber to combust the remaining fuel. Therefore, an additional flame or arc is used to combust remaining fuel in the main combustion chamber. This reduces the temperature that the igniter must be at but still increases the temperature of the combustion chamber. In addition, no fuel is added to the air as it enters the combustion chamber. Rather all the fuel has already been entrained in the air before it enters the combustion chamber to be combusted. This greatly reduces control over where combustion occurs and the temperature in the combustion chamber.

[0006] Other attempts to lower NOX emissions include placing catalysts in catalytic converters on the emission side of the turbines. This converts the NOX compounds into more desirable compounds such as dinitrogen and dioxygen. These emission side converters, however, are not one hundred percent efficient thereby still allowing NOX emissions to enter the atmosphere. The emission converters also use ammonia NH3, gas to cause the reduction of NOX to N2. Undesirably, some of this ammonia is discharged into the atmosphere. Also, these converters are expensive and increase the complexity of the turbine and power production systems. Therefore, it is also desirable to eliminate the need for emission side catalytic converters.

SUMMARY OF THE INVENTION

[0007] The present invention is directed to a combustor and a combustion chamber for a gas powered turbine. A heat exchanger and a catalyst combust a first portion of fuel intermixed with air without the production of undesired chemical species. The gas powered turbine requires expanding gases to power the turbine fans or blades. Fuel is generally combusted to produce the required gases. A catalyst is employed to lower the combustion temperature of the fuel. The catalyst is placed on a set of tubes in a heat exchanger such that a portion of the thermal energy may be transferred to the air before it engages the catalyst. After encountering the catalyst, the fuel that was combusted increases the temperature of the air to an auto-ignition temperature so that no other ignition source is needed to combust additional fuel added later. Therefore, as the air exits the heat exchanger, it enters a main combustion chamber, is mixed with a second portion of fuel where it is auto-ignited and burned.

[0008] One preferred embodiment of the present invention includes a combustion system for use in a gas powered turbine which combusts a fuel in the presence of air while substantially eliminating nitrous oxide emissions. The system includes a pre-heater to heat compressed air to form a hypergolic air. An injector plate injects a fuel into the hypergolic air. An injector port, defined by the injector plate, provides the fuel to the hypergolic air before a substantial portion of the fuel combusts. Substantially all the fuel provided through the injector port reaches its hypergolic temperature at substantially the same time.

[0009] A second preferred embodiment of the present invention provides a gas powered turbine. The gas powered turbine includes a compressor that produces compressed atmospheric air to provide an oxidizer for the gas powered turbine. A combustion system mixes and combusts a fuel injected into the compressed atmospheric air to produce an expanding gas. A turbine fan is powered by the expanding gases.

[0010] The combustion system of the second preferred embodiment includes a pre-heat area, a first fuel line, a second fuel line, and an injector system. The first fuel line supplies a first portion of fuel to the compressed atmospheric air which is combusted in the pre-heat area to heat the compressed atmospheric air to a hypergolic temperature so as to produce hypergolic air. The second fuel line supplies a second portion of fuel to the hypergolic air. The injector system provides the second portion of fuel to the hypergolic air before any substantial portion of the second portion of fuel combusts. In addition, substantially all of the second portion of fuel combusts at substantially the same time such that the turbine emits substantially no nitrous oxide compounds.

[0011] The present invention provides for a new and unique method of combusting a fuel for a gas powered turbine in the presence of atmospheric air while substantially eliminating the emission of nitrous oxide compounds. The method includes providing a pre-heater. A first fuel-air mixture is formed by mixing a first portion of the fuel and the air. An auto-ignition air stream is produced by combusting the first fuel-air mixture. A second portion of the fuel is then added to the auto-ignition air stream. The second portion of fuel is then mixed with the auto-ignition air stream before substantially any of the second portion of fuel combusts.

[0012] Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

[0014] FIG. 1 is a perspective view of a gas powered turbine including a combustor in accordance with the present invention;

[0015] FIG. 2 is a partial cross-sectional perspective view of a single combustor;

[0016] FIG. 3 is a detailed, partial cross-sectional, perspective view of a portion of the heat exchanger; and

[0017] FIG. 4 is a detailed, cross-sectional view of a portion of the main injectors according to the present invention;

[0018] FIG. 5a is a detailed, elevational view of the downstream side of the main injector plate according to a first embodiment of the present invention;

[0019] FIG. 5b is a detailed cross-sectional view of the main injector plate taken along line 5b in FIG. 5a;

[0020] FIG. 6a is a detailed elevational view of a downstream side of the main injector plate according to a second embodiment of the present invention;

[0021] FIG. 6b is a detailed cross-sectional view of the injector plate taken along line 6b in FIG. 6a; and

[0022] FIG. 7 is a detailed, partial cross-sectional, perspective view of a portion of the heat exchanger according to the second embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] 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.

[0024] Referring to FIG. 1, a gas powered turbine in accordance with a preferred embodiment of the present invention is shown. The gas powered turbine 10 may use several different gaseous fuels, such as hydrocarbons (including methane and propane) and hydrogen, that are combusted and that expand to move portions of the gas powered turbine 10 to produce power. An important component of the 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. Generally, a plurality of turbine fans 16 are incorporated, however, the actual number depends upon the power the gas powered turbine 10 is intended to produce. Only a single turbine fan is illustrated for clarity.

[0025] 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 by 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 spins the turbine fans 16, which are in turn affixed to a shaft (not shown). Generally, at least two turbine fans 16 are incorporated. 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. After the gases have expanded through the turbine fans 16, they are expelled out through an exhaust port 18. It will be understood that gas powered turbines are used for many different applications such as engines for vehicles and aircraft or for power production in terrestrially based gas powered turbine power system.

[0026] The gases which are exhausted from the 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 pure oxygen but rather includes a majority 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 are exhausted from 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. It will be understood that although atmospheric air in a hydrocarbon fuel may be preferred for economic reasons other oxidizers and fuels may be provided. The air simply provides an oxidizer for the fuel to be combusted in. Therefore, other oxidizing materials such as pure oxygen may be used in the gas powered turbine 10. In addition, other fuels may be combusted which are not necessarily simply hydrocarbons. Regardless, the present invention may be used with any oxidizer or fuel which is used to power the gas powered turbine 10.

[0027] It will be understood that the gas powered turbine 10 may include more than one combustion chamber 14. A reference to only one combustion chamber 14, herein, is merely for simplifying the following discussion. With reference to FIG. 2, an exemplary combustion chamber 14 is illustrated. The combustion chamber may comprise any appropriate combustion chamber such as the one described in U.S. patent application Ser. No. 10/120,268 filed Apr. 10, 2002 entitled, “A Catalytic Combustor For Substantially Eliminating Nitrous Oxide Emissions,” incorporated herein by reference. The combustion chamber 14 includes a premix section or area 30, a heat exchange or pre-heat section 32, generally enclosed in a heat exchange chamber 33, and a main combustion section 34. A first or premix fuel line 36 provides fuel to the premix area 30 through a fuel manifold 37 while a second or main fuel line 38 provides fuel to the main combustion section 34 through a main injector 52. Positioned in the premix area 30 is a premix injector 40 that injects fuel from the first fuel line 36 into a premix chamber 42. Air from the compressor 12 enters the premix area 30 through a cooling tube 44 of a heat exchanger or pre-heater 45 (detailed in FIG. 3). The premix chamber 42 encompasses a volume between the premix injector 40 and the exit of the cooling tubes 44.

[0028] With further reference to FIG. 2, a plurality of catalytic heat exchange or catalyst tubes 48 extend into the heat exchange area 32. The heat exchange tubes 48 are spaced laterally apart. The heat exchange tubes 48, however, are not spaced vertically apart. This configuration creates a plurality of columns 49 of heat exchange tubes 48. Each heat exchange tube 48, and the column 49 as a whole, define a catalyst pathway. The columns 49, in turn, define a plurality of channels 50 therebetween. Extending inwardly from the walls of the heat exchange chamber 33 are directing fins (not particularly shown). The directing fins direct the flow of air to the top and the bottom of the heat exchange chamber 33 so that air is directed to flow vertically through the channels 50 defined by the heat exchange tubes 48.

[0029] Near the ends of the heat exchange tubes 48, where the heat exchange tubes 48 meet the main combustion section 34, is a main injector 52. The second fuel line 38 provides fuel to the main injector 52 so that fuel may be injected at the end of each heat exchange tube 48. Spaced away from the main injector plate 52, towards the premix area 30, is an intra-propellant plate 54. The intra-propellant plate 54 separates the air that is traveling through the channels 50 and the fuel that is being fed to the fuel manifold region 56 between the main injector face 52 and intra-propellant plate 54. It will be understood that the intra-propellant plate 54 is effectively a solid plate, though not literally so in this embodiment. Because the heat exchange tubes 48 are spaced apart the intra-propellant plate 54 is segmented wherein one portion of the intrapropellant plate 54 is placed in each channel 50 between two columns 49.

[0030] Air that exits out the heat exchange tubes 48 is entrained with fuel injected from an injector port 60 (illustrated more clearly herein) in the main injector plate 52 and this fuel then combusts in the main combustion section 34. The main combustion section 34 directs the expanding gases of the combusted fuel to engage the turbine fans 16 so that the expanded gases may power the turbine 10.

[0031] Turning to FIG. 3, an enlarged portion of the heat exchanger 45 including a catalyst is shown. Although the heat exchanger 45 includes a large plurality of tubes, as generally shown in FIG. 2, only a few of the heat exchange tubes 48 and cooling tubes 44 are illustrated for greater clarity. The heat exchanger 45 includes a plurality of cooling tubes 44 disposed parallel to and closely adjacent the heat exchange tubes 48. Each of the cooling tubes 44 and the heat exchange tubes 48 have a generally rectangular cross section and can be made of any generally good thermally conductive material. Preferably, the heat exchange tubes 48 and the cooling tubes 44 are formed out of stainless steel. It will be appreciated that while the cooling tubes 44 and the heat exchange tubes 48 are shown as being substantially square, the cross-sectional shape of the components could comprise a variety of shapes other than squares. It is believed, however, that the generally square shape will provide the best thermal transfer between the tubes 44 and 48.

[0032] The cooling tubes 44 extend parallel to the heat exchange tubes 48 for a portion of the length of the heat exchange tubes 48. The cooling tubes 44 extend between the columns 49 of the heat exchanger tubes 48. The cooling tubes 44 and the heat exchange tubes 48 form the heat exchanger 45 which can provide a surface-to-surface exchange of heat. It will be understood, however, that air traveling in the channels 50 between the heat exchange tubes 48 will also become heated due to the heat transferred from the heat exchange tubes 48 to the air in the channels 50.

[0033] Referring further to FIG. 3, fuel injector ports 60 are formed in the main injector 52. The injector ports 60 may be provided in any appropriate number, however, preferably there is at least one injector port 60 for each heat exchange tube 48, and more preferably at least two injector ports 60 for each heat exchange tube 48. The fuel is provided to the manifold region 56 which is bound by the inter-propellant plate 54, the main injector plate 52, and a manifold plate 61. The manifold plate 61 may underlay, overlay, or both the manifold region 56. This provides fuel to each of the injector ports 60 without requiring an individual fuel line to each injector port 60. Therefore, as air exits the heat exchange tube 48, fuel is injected from the injector port 60 to the stream of air emitted from each heat exchange tube 48. In this way, the fuel can be very efficiently and quickly distributed throughout the air flowing out of the heat exchanger 45, as discussed further herein.

[0034] On the interior walls of each heat exchange tube 48 is disposed a coating of a catalyst. The catalyst may be any appropriate catalyst that is able to combust a hydrocarbon fuel, but preferably includes a mixture of platinum and palladium. The catalyst is able to combust a hydrocarbon fuel, such as methane, without the presence of a flame or any other ignition source. The catalyst is also able to combust the fuel without generally involving any side reactions. Therefore, the combustion of fuel does not produce undesired products. It will be understood that if the fuel is not a hydrocarbon then a different, appropriate catalyst is used. The catalyst allows combustion of the fuel without an additional heat source.

[0035] After the air enters the premix chamber 42, it then flows out through the pathway formed by the heat exchange tubes 48. In the heat exchange tubes 48, the fuel in the air combusts as it engages the catalyst which has been coated on the inside walls of the heat exchange tubes 48. As the fuel combusts, the temperature of the air rises to between about 768° C. and 930° C. (between about 1400° F. and about 1700° F.). As the temperature of the air rises, it becomes highly energetic to form high energy air, wherein high energy air exits the heat exchange tubes 48. The temperature the high energy air reaches in the heat exchange tubes 48 is at least the hypergolic or auto-ignition temperature of the fuel being used in the gas powered turbine 10. Therefore, the high energy air that exits the heat exchange tubes 48 is, and may also be referred to as, hypergolic or auto ignition air. The auto-ignition temperature of the air is the temperature that the air may be at or above so that when more fuel is injected into the hypergolic air the fuel ignites automatically without any other catalyst or ignition source.

[0036] Additional fuel is injected through the main injector 52 as the air exits the heat exchange tubes 48 and enters the main combustion section 34. The fuel injected from the main injector 52 is injected through the individual injector ports 60. As described above, the ratio of heat exchange tubes 48 to fuel injector ports 60 is preferably about one to one. It will be understood, however, that a different ratio of heat exchange tubes 48 to fuel injector ports 60 may be used to suit a specific application. Therefore, all of the air exiting the heat exchanger 45 is thoroughly mixed with fuel. Any additional fuel to power the gas powered turbine 10 is injected at this point, such that fuel is only added to the air at the premix chamber 42 and from the injector parts 60.

[0037] The gas powered turbine 10 operates as generally described below. Air is forced from the compressor 12 into the heat exchange chamber 33. The air then travels through the channels 50 and through the cooling tubes 44 into the premix chamber 42. At this point a first or premix portion of fuel is intermixed with the air. The air then travels downstream through the heat exchange tubes 48 until the air is expelled from the heat exchange tubes 48 past the main injector 52 and to the combustion area 34 as hypergolic air.

[0038] As the air travels through the heat exchange tubes 48, the fuel that was entrained in the air in the premix chamber 42 is combusted by the catalyst. This raises the temperature of the air from the temperature that it enters the heat exchange chamber 33. In particular, the temperature of the air is raised to preferably between about 700° C. and 880° C. (between about 1300° F. and about 1600° F.). This temperature is generally the hypergolic temperature so that the fuel combusts spontaneously when added through the injector port 60. It will be understood that different fuels have different hypergolic temperatures. Therefore, the amount of fuel added in the premix section 42 may be altered to determine the temperature of the air exiting the heat exchange tubes 48.

[0039] With reference to FIG. 4, the heat exchange tubes 48 extend from an upstream side 70 through the intra-propellant plate 54 and terminate into the main injector 52. A face of the injector 52a is downstream of the heat exchange tubes 48. Fuel is provided through the main fuel line 38 to the manifold region 56 which is the area between the intra-propellant plate 54 and the main injector 52. Although only one main fuel line 38 is illustrated, it will be understood that more than one main fuel line may be provided. Formed in the main injector plate 52 are oxidizer passages or pathways 72 which are extensions of the heat exchange tubes 48 formed in the main injector plate 52. The hypergolic air from the heat exchange tubes 48 passes through the oxidizer pathways 72 and exits into the main combustion area 34.

[0040] Extending back from the injector port 60 is a fuel injection path 74. Each fuel injector port 60 includes at least one fuel pathway 74. The fuel pathway 74 is preferably a bore formed in the main injector plate 52 to allow access between the fuel manifold region 56 so that the fuel which is provided to the fuel manifold region 56 from the main fuel line 38 can reach the combustion area 34. Generally, the fuel pathways 74 are formed in the main injector plate 52 and the spaces or lands between the oxidizer pathways 72 which extend from the heat exchange tubes 48.

[0041] The fuel exits the injector ports 60 as a fuel stream 76 in line with the fuel pathway 74 provided in the main injector plate 52. Preferably, the fuel stream 76 has a half angle of between about 40° and about 50° and preferably of about 45°. Therefore as two of the fuel streams 76 intersect, in an area of the combustion chamber 34, which is downstream of the face 52a of the injector plate 52, the streams intersect at about an 80° to 100° angle. It will be understood, however, that the fuel streams 76 may intersect at a slightly different angle. For example, the fuel streams may intersect at angles ranging between about 20° and about 150°.

[0042] With reference to FIGS. 5a and 5b, a first embodiment of the fuel injector port 60 is illustrated. The hypergolic air, which acts as an oxidizer, exits from the oxidizer pathways 72. As this is happening, fuel exits from the injector ports 60 and is transmitted along fuel streams 76. Because the two fuel streams 76 are angled, they intersect at a point downstream of the oxidizer pathways 72 and between the oxidizer pathways 72 in a land region 77. As discussed above, preferably two fuel streams 76 intersect at an angle of about 90°. When this intersection occurs, the two fuel streams interrupt each other and produce a fuel plume 80 which spreads into the appropriate oxidizer pathways 72. The fuel plume 80 is a substantially and finely atomized from the fuel streams 76 that are spreading out extremely rapidly. This allows the fuel in the fuel streams 76 is to intermix very quickly with the hypergolic air as it exits the oxidizer pathways 72.

[0043] As discussed above, the air exits the oxidizer pathways 72 at approximately the auto-ignition or hypergolic temperature of the fuel in the fuel streams 76. Therefore, as soon as the fuel from the fuel streams 76 is raised to the temperature of the hypergolic air exiting the oxidizer pathways 72, the fuel will ignite. Therefore, if the fuel is able to mix substantially well with the air as it exits the oxidizer pathways 72, the entire amount of fuel injected with the fuel streams 76 will ignite at substantially the same time. When this occurs, the ignition of fuel from the fuel streams 76 across the face 52a of the injector plate 52 will be substantially constant and equal. Therefore, there are substantially no hot spots created, thus keeping the temperature of the combustion chamber 34 to one which allows substantially no nitrous oxide compounds to be produced. Because the fuel in the fuel plume 80 is spreading out so quickly into the high energy air exiting the oxidizer pathways 72, the fuel mixes with the hypergolic air and becomes heated to the hypergolic temperature faster than the ignition or combustion rate of the fuel. Therefore, substantially all of the fuel that is injected from the injector port 60 reaches the hypergolic temperature at the same time. Therefore, substantially all the fuel combusts at substantially the same time, not allowing the creation of any discrete hot spots.

[0044] With references to FIGS. 6a and 6b, a fuel injector port 90 according to a second preferred embodiment of the present invention is illustrated. With this embodiment, heated air still exits the main injector 52 through the oxidizer pathways 72. Fuel streams 76 are also produced as fuel exits injector ports 90. The injector ports 90 are not circular but rather are generally rectangle in shape having a height of H which substantially greater than a width W. The height H of the injector port 90 extends substantially parallel to the height of the oxidizer pathways 72. Therefore, a fuel stream or fan 92 is produced by the fuel injectors 90 that is substantially spread out or flattened, as it exists the injector port 90, as opposed to the fuel stream 76 described previously herein.

[0045] Fuel may enter the fuel pathway 74 through any appropriately shaped port but as the pathway 74 nears the injector port 90, the pathway becomes substantially rectangular having a height H which is much greater than a width W. With particular reference to FIG. 6b, the upstream side of the main injector plate 52 includes an inlet port 94, that is substantially circular in shape. Nevertheless, the injector port 90 is substantially rectangular in shape. The fuel stream 92 this produces is already substantially spread out or thinned before it reaches an intersection point with another fuel stream 92. As two fuel streams 92 intersect, they produce a fuel plume 96 which allows the fuel provided through the injector ports 90 to be mixed with the hypergolic air exiting the oxidizer pathways 72 before the fuel, provided in the fuel streams 92, reaches its ignition temperature.

[0046] This allows a substantial intermixing of the fuel with the air exiting the oxidizer pathways 72 before the fuel combusts so that the combustion in the combustion chamber 34, across the face of 52a of the main injector plate 52, is substantially even. This does not generally allow hot spots in the combustion area 34 to form, thereby substantially eliminating the production of NOX chemicals. It will be appreciated that in this second embodiment, opposing fuel fans 92 are not necessary to provide an appropriate fuel plume 96. Because the injector port 90 produces a fuel fan 92 which is already substantially spread out and dispersed, the impingement of two fuel streams is not generally necessary.

[0047] As discussed above, the air that exits the heat exchanger 45 is at the auto-ignition or hypergolic temperature of the fuel used in the gas powered turbine 10. Therefore, as soon as the fuel reaches the temperature of the air, the fuel ignites. Since the fuel has been thoroughly mixed with the air, using the fuel injector ports 60 and 90, the combustion of the fuel is nearly instantaneous and will not produce any localized or discrete hot spots. Since the fuel is so well mixed with the air exiting the heat exchanger 45, there will be no one point or area which has more fuel than any other point, which could also create hot spots in the main combustion section 34. Therefore, the temperature of the air coming from the main injector 52 and into the main combustion section 34 is substantially uniform. During operation of the gas powered turbine 10, the fuel's characteristic mixing rate is shorter than the combustion rate of the fuel.

[0048] The temperature of the air, after the additional fuel has been combusted from the main injector 52, is between about 1315° C. and 1595° C. (about 2400° F. and about 2800° F.). Preferably, the temperature, however, is not more than about 1426° F. (about 12600° F.). Different fuel to air ratios may be used to control the temperature in the main combustion section 34. The main combustion section 34 directs the expanding gases into a transition tube (not shown) so that it will engage the turbine fans 16 in the turbine area 15 at an appropriate cross sectional flow shape.

[0049] The use of the heat exchanger 45 raises the temperature of the air to create hot or heated air. The hot air allows the catalyst to combust the fuel that has been entrained in the air in the premix chamber 42 without the need for any other ignition sources. The catalyst only interacts with the hydrocarbon fuel and the oxygen in the air to combust the fuel without reacting any other chemical species. Therefore, the products of the combustion in the heat exchange tubes 48 are substantially only carbon dioxide and water due to the catalyst placed therein. No significant amounts of other chemical species are produced because of the catalyst. Also, the use of the heat exchange tubes 48, with a catalyst coated therein, allows the temperature of the air to reach the auto-ignition temperature of the fuel so that no additional ignition sources are necessary in the main combustion section 34. Therefore, the temperature of the air does not reach a temperature where extraneous species may be easily produced, such as NOX chemicals. Due to this, the emissions of the gas powered turbine 10 of the present invention has virtually no NOX emissions. That is, that the NOX emissions of the gas powered turbine 10 according to the present invention are estimated to be generally below about 1 part per million volume dry weight.

[0050] Also, the use of the heat exchanger 45 eliminates the need for any other pre-burners to be used in the gas powered turbine 10. The heat exchanger 45 provides the thermal energy to the air so that the catalyst bed is at the proper temperature. Because of this, there are no other areas where extraneous or undesired chemical species may be produced. Additionally, the equivalence ratio of the premix area is generally between about 0.20 and 0.30, while the equivalence ratio of the main injector 52 is between about 0.50 and about 0.60. This means that the fuel combustion will occur as a lean mixture in both areas. Therefore, there is never an excessive amount of fuel that is not combusted. Also, the lean mixture helps to lower temperatures of the air to more easily control side reactions. It will be understood that different fuel ratios may be used to produce different temperatures. This may be necessary for different fuels.

[0051] With reference to FIG. 7, a detail portion, similar to the portion illustrated in FIG. 3, of an alternative preferred heat exchanger 145 is illustrated. A premix chamber 142 allows air from the compressor to be mixed with a first portion of fuel. Air comes from the compressor and travels through a cooling fin 144 rather than through a plurality of cooling tubes 44, as discussed above in relation to the first embodiment. The cooling fin 144 is defined by two substantially parallel plates 144a and 144b. It will be understood, however, that other portions, such as a top 144c and a bottom 144d will be included to enclose the cooling fin 144. Additionally, a heat exchange or catalyst fin 148 is provided rather than heat exchange tubes 48, as discussed above in the first embodiment. Again, the catalyst fin 148 is defined by a top, and a bottom, and walls wherein the walls define a column 149. Each catalyst column 149, however, is defined by a single catalyst fin 148 rather than a plurality of catalyst tubes 48, as discussed above. The cooling fin 144 may include a plurality of cooling fins 144. Each cooling fin 144, in the plurality, defines a cooling pathway. Similarly, the heat exchange fin 148 may include a plurality of heat exchange 148 fins. Each, or the plurality of, the heat exchange fins 148 defines a heat exchange or catalyst pathway.

[0052] Channels 150 are still provided between each of the catalyst fins 148 so that air may flow from the compressor through the cooling fins 144 into the premix chamber 142. Air is then premixed with a first portion of fuel and flows back through the catalyst fins 148 to the main injector plate 152. Injection ports 160 are provided on the main injector plate 152 to inject fuel as the air exits the catalyst fin 148. A suitable number of injection ports 160 are provided so that the appropriate amount of fuel is mixed with the air as it exits the catalyst fins 148. An intra-propellant plate 54 is also provided.

[0053] Injector ports 60 or 90 are still provided on the main injector plate 152 to provide fuel streams 76 or 92 as heated air exits the oxidizer paths (not particularly shown) from the catalyst fins 148. Either of the previously described injector ports 60 or 90 may be used with the second embodiment of the heat exchanger 145 to provide a substantial mixing of the fuel with the air as it exits the catalyst fins 148. This still allows a substantial mixture of the fuel with the air as it exits the catalyst fins 148 before the fuel is able to reach its ignition temperature. Therefore, the temperatures across the face of the main injector 152 and in the combustion chamber 34 are still substantially constant without any hot spots where NOX chemicals might be produced.

[0054] The present invention thus provides an apparatus and method that virtually or entirely eliminates the creation of NOX emissions. Advantageously, this is accomplished without significantly complicating the construction of the gas powered turbine 10 or the combustors 14.

[0055] The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.

Claims

1. A combustion system for use in a gas powered turbine which combusts a fuel in the presence of air while substantially eliminating nitrous oxide emissions, comprising:

a pre-heater to heat a volume of an oxidizer to form a volume of high energy;

an injector member to inject a fuel, including a high temperature, into said volume of high energy oxidizer;

an injector port, defined by said injector member, to provide the fuel to said volume of high energy oxidizer before a substantial portion of the fuel combusts; and

wherein substantially all the fuel provided through said injector port reaches its said high temperature at substantially the same time.

2. The combustion system of claim 1, wherein said pre-heater comprises:

a fuel supply system to provide a fuel to said volume of oxidizer:

a heat exchanger including:

a catalyst pathway extending along a first axis;

a cooling pathway extending along a second axis;

wherein said catalyst pathway is in thermal contact with said cooling pathway;

wherein the oxidizer is adapted to first flow through said cooling pathway and then through said catalyst pathway;

a catalyst, placed within said catalyst pathway, and adapted to combust the fuel with said volume of oxidizer; and

wherein said volume of oxidizer is adapted to first flow past said catalyst pathway and through said cooling pathway, thereby receiving thermal energy from said catalyst pathway.

3. The combustion system of claim 2,

wherein said catalyst pathway comprises a plurality of catalyst tube, that form a plurality of catalyst tube columns each spaced apart transversally to said first axis and which define a plurality of channels adapted for allowing the oxidizer to flow therethrough;

wherein said cooling pathway comprises a plurality of cooling tubes that form a plurality of cooling tube columns each spaced apart transversally to said second axis; and

wherein said cooling tubes extend substantially adjacent said catalyst tubes along said second axis for at least a portion of the length of said catalyst tubes.

4. The combustion system of claim 1, further comprising:

at least a first and a second of said injector ports;

a first fuel stream produced by said first injector port;

a second fuel stream produced by said second injector port;

wherein said first fuel stream and said second fuel stream impinge into one another to form a fuel plume prior to intersecting the high energy air.

5. The combustion system of claim 4, wherein said first fuel stream and said second fuel stream intersect at an angle between about 20° and about 150°.

6. The combustion system of claim 4, further comprising:

a fuel path formed in said injector member such that the first fuel stream and the second fuel stream provided by said first and second injector ports intersect to produce said fuel plume.

7. The combustion system of claim 1, wherein said injector port is substantially rectangular in shape such that a fuel stream is flattened as said fuel stream exits said injector port.

8. A gas powered turbine, comprising:

a compressor to produce compressed atmospheric air to provide an oxidizer for the gas powered turbine;

a combustion system for mixing and combusting a fuel injected into the compressed atmospheric air to produce an expanding gas;

a turbine fan which is powered by the expanding gases:

wherein said combustion system comprises:

a pre-heat area;

a first fuel line to supply a first portion of fuel to the compressed atmospheric air which is combusted in the pre-heat area to heat the compressed atmospheric air to a hypergolic temperature so as to produce hypergolic air;

a second fuel line to supply a second portion of fuel to the hypergolic air;

an injector system to provide said second portion of fuel to said hypergolic air before any substantial portion of said second portion of fuel combusts; and

wherein substantially all of said second portion of fuel combusts at substantially the same time such that the gas powered turbine emits substantially no nitrous oxide compounds.

9. The turbine of claim 8, wherein said pre-heat area includes a heat exchanger including:

a catalyst pathway extending along a first axis;

a cooling pathway extending along a second axis which is parallel to said first axis;

wherein said catalyst pathway forms a plurality of columns spaced transversally to said first axis and defining a plurality of channels; and

wherein said cooling pathway extends a distance along said catalyst pathway and generally perpendicular to said channels.

10. The turbine of claim 9, wherein said catalyst pathway includes a plurality of catalyst tubes and said cooling pathway includes a plurality of cooling tubes.

11. The turbine of claim 8, further comprising:

a pre-mix area for mixing the fuel from said first fuel supply with the air before the air enters the pre-heat area;

a main injector plate comprising at least a first and a second of said injectors; and

a combustion area wherein said second supply of fuel is combusted.

12. The turbine of claim 11, further comprising:

a first fuel stream produced by said first injector port;

a second fuel stream produced by said second injector port;

wherein said first fuel stream and said second fuel stream impinge into one another forming a fuel plume prior to intersecting the hypergolic air.

13. The turbine of claim 12, wherein said first fuel stream and said second fuel stream intersect at an angle between about 20° and about 150°.

14. The turbine of claim 12, further comprising

a fuel path formed in said main injector plate such that fuel provided by said first and second injector ports intersects to produce said fuel plume.

15. The turbine of claim 8, wherein said injector port is substantially rectangular in shape such that a fuel stream is flattened as said fuel stream exits said injector port.

16. A method of combusting a fuel for a gas powered turbine in the presence of atmospheric air while substantially eliminating the emission of nitrous oxide compounds, the method comprising:

producing an auto-ignition air stream wherein a fuel homogeneously combusts spontaneously upon reaching the temperature of said auto-ignition air stream;

providing a first portion of the fuel to said auto-ignition air stream;

mixing said first portion of fuel with said auto-ignition air stream before substantially any of said first portion of fuel combusts to thereby substantially eliminate emission of nitrous oxide compounds.

17. The method of claim 16, further comprising:

producing an expanding gas by combusting said first portion of fuel in said auto-ignition air-stream, said expanding gas occurring when said portion of fuel in said auto-ignition air-stream combusts upon reaching the temperature of the auto-ignition air stream.

18. The method of claim 17, further comprising powering a turbine with said expanding gas.

19. The method of claim 16, wherein said auto-ignition air stream has a temperature between about 1400° F. and 1600° F.

20. The method of claim 16, wherein mixing said first portion of fuel further comprises:

impinging a first fuel stream upon a second fuel stream to form a fuel plume prior to intersecting the auto-ignition air stream.

21. The method of claim 20, wherein impinging said first fuel stream upon said second fuel stream occurs at an angle between about 20° and about 150°.

22. The method of claim 21, further comprising:

forming said first fuel stream and said second fuel stream as substantially flat streams before allowing said streams to impinge one another.

23. The method of claim 16, wherein mixing said first portion of fuel further comprises providing a substantially flat fuel stream to said auto-ignition air stream.

24. The method of claim 16, wherein producing an auto-ignition airstream further comprises:

forming a fuel-air mixture by mixing a second portion of fuel with a volume of air; and

combusting said second portion of fuel in said volume of air, wherein combusting said second portion of fuel increases the temperature of said volume of air to an auto-ignition temperature.