Counterflow injection mechanism having coaxial fuel-air passages
In accordance with certain embodiments, a system includes a fuel-air injection mechanism having coaxial fuel and air passages leading to fuel and air injection openings. The fuel and air injection openings are configured to reside at an off-axis position of a gas turbine combustor, and the fuel and air injection openings are configured to orient in an injection direction not aligned with a flow direction through the gas turbine combustor to a turbine.
This section is intended to introduce the reader to various aspects of art that may be related to aspects of the present invention, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
Combustion engines, such as gas turbine engines, produce a variety of pollutant emissions. For example, pollutant emissions generally include carbon oxides (COx), nitrogen oxides (NOx), sulfur oxides (SOx), and particulate matter (PM). These pollutant emissions are highly regulated in the United States and elsewhere. NOx emissions from a gas turbine engine can be reduced by premixing fuel and air. Unfortunately, premixing can result in unstable flames that are difficult to anchor, and the best premixed systems today cannot reach the NOx emission targets. Another approach is selective catalytic reduction (SCR) of NOx through ammonia injection. Unfortunately, the SCR approach is relatively expensive.
Accordingly, an improved technique is needed to reduce pollutant emissions, such as NOx emissions, from a gas turbine combustor.
BRIEF DESCRIPTIONCertain aspects commensurate in scope with the originally claimed invention are set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of certain forms the invention might take and that these aspects are not intended to limit the scope of the invention. Indeed, the invention may encompass a variety of aspects that may not be set forth below.
In accordance with certain embodiments, a system includes a fuel-air injection mechanism having coaxial fuel and air passages leading to fuel and air injection openings. The fuel and air injection openings are configured to reside at an off-axis position of a gas turbine combustor, and the fuel and air injection openings are configured to orient in an injection direction not aligned with a flow direction through the gas turbine combustor to a turbine.
In accordance with other embodiments, a system includes a gas turbine combustor having a combustion liner with a generally lengthwise flow axis extending from a stagnation zone to a turbine nozzle. The gas turbine combustor also includes a counterflow fuel-air injector disposed in the combustion liner at one or more intermediate positions between the stagnation zone and the turbine nozzle. The counterflow fuel-air injector includes coaxial fuel and air passages extending to fuel and air injection openings not aligned with a flow direction from the stagnation zone to the turbine nozzle.
In accordance with further embodiments, a method includes coaxially flowing fuel and air to a counterflow fuel-air injector oriented in a generally counterflow direction relative to a generally lengthwise flow axis from a stagnation zone to a turbine nozzle of a gas turbine combustor.
Various refinements of the features noted above exist in relation to the various aspects of the present invention. Further features may also be incorporated in these various aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to one or more of the illustrated embodiments may be incorporated into any of the above-described aspects of the present invention alone or in any combination. Again, the brief summary presented above is intended only to familiarize the reader with certain aspects and contexts of the present invention without limitation to the claimed subject matter.
DRAWINGSThese and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
One or more specific embodiments of the present invention will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliant with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.
As indicated by the arrows, air flows through the intake section 16 and into the compressor 18, which compresses the air prior to entry into the combustor section 20. The illustrated combustor section 20 includes a combustor housing 28 disposed concentrically or annularly about the shaft 26 between the compressor 18 and the turbine 22. Inside the combustor housing 28, the combustor section 20 includes a plurality of combustors 30 disposed at multiple radial positions in a circular or annular configuration about the shaft 26. As discussed in further detail below, the compressed air from the compressor 18 enters each of the combustors 30, and then mixes and combusts with fuel within the respective combustors 30 to drive the turbine 22.
In certain embodiments, the combustors 30 may be configured as multi-stage combustors, wherein fuel injectors are positioned at different stages along the length of respective combustors 30. Alternatively, the combustors 30 may be configured as single stage combustors, wherein fuel injectors are arranged for a single stage or zone of combustion. In the following discussion, the combustors 30 are described as single stage combustors, yet the disclosed embodiments may be utilized with either single stage or multi-stage combustors within the scope of the present techniques.
The disclosed embodiments of the combustor 30 include a variety of counterflow fuel-air injection mechanisms, which direct the air and fuel in one or more directions generally against the flow through the combustors 30. For example, the counterflow fuel-air injection mechanisms may include a plurality of lengthwise-directed fuel-air injectors, crosswise-directed fuel-air injectors, or angled fuel-air injectors having both lengthwise and crosswise directional portions. The lengthwise-directed fuel-air injectors may be generally aligned in lengthwise directions along the combustors 30, whereas the crosswise-directed fuel-air injectors may be generally aligned in crosswise, transverse, or radial directions relative to a lengthwise flow or axis along the combustors 30. The angled fuel-air injectors may be oriented in an acutely angled direction relative to a lengthwise flow axis or inner surface of the combustor 30. The acutely angled direction generally includes or can be broken down into lengthwise and crosswise directional portions. Each of these lengthwise directions, crosswise directions, and acutely angled directions may be defined as counterflow directions.
As discussed in further detail below, the counterflow fuel-air injection mechanisms inject the fuel and air away from the turbine 22 in these counterflow directions toward an opposite end of the combustor 30, such that the fuel and air mixes and combusts in a stagnation zone. The stagnation zone at the opposite end of the combustor 30 generally increases stability and anchoring of flames within the combustor 30. The hot products of combustion then travels back toward the turbine 22 past the counterflow fuel-air injection mechanisms. Again, the counterflow fuel-air injection mechanisms facilitate mixing of the fuel and air with the hot products of combustion. The hot products of combustion then pass through nozzles 32 leading to the turbine 22. These hot products of combustion drive the turbine 22, thereby driving the compressor 18 and a load 34 of the application 14 via the shaft 26. The hot products of combustion then exhaust through the exhaust section 24.
The illustrated counterflow injection mechanism 50 includes a fuel injection assembly 64 disposed adjacent an air injection assembly 66. In certain embodiments, the fuel and air injections assemblies 64 and 66 are arranged in close proximity to one another. The fuel injection assembly 64 includes a plurality of fuel injectors 68 having an elongated injector tip 70. The air injection assembly 66 includes a plurality of acutely angled air passages 72 disposed at various radial positions about the inner circumference of the solid inner casing 56. In certain embodiments, the elongated injector tip 70 may be disposed in close proximity to the air passage 72. For example, in the illustrated embodiment of
In the illustrated embodiment of
In operation, the combustor 30 as illustrated in
At the fuel-air injection lobes 52, the elongated injector tips 70 inject fuel flows 96 that accompany air flows 98 from the air passages 72. In the illustrated embodiment, the fuel and air flows 96 and 98 are coaxial or concentric relative to one another. Specifically, the air flows 98 are disposed concentrically about the fuel flows 96 as a result of the concentric or coaxial configuration of the elongated injector tips 70 within the air passages 72. Again, the elongated injector tips 70 and air passages 72 are disposed at respective angles 82 and 84, thereby causing the fuel and air flows 96 and 98 to travel at least initially at the angles 82 and 84 in a converging manner toward the axis 62 and the stagnation zone 86. Thus, the coaxial or concentric configuration of the fuel-air injection lobes 52 and resultant flows 96 and 98 facilitate fuel-air mixing in the combustor 30 rather than premixing. In addition, the converging relationship of the fuel-air injection lobes 52 facilitates mixing of the fuel and air in the stagnation zone 86, as indicated by flow/mixing arrows 100. As illustrated, the flow 100 includes U-shaped flows inwardly toward the axis 62 and outwardly toward the walls of the solid inner casing 56. In other words, as the flows 100 move in the counterflow direction from the fuel-air injection lobes 52 toward the closed rear portion 88, the flows 100 generally reverse in a U-shaped manner both toward the axis 62 and the walls of the solid inner casing 56. A similar flow pattern occurs with the other embodiments discussed below. The fuel-air mixture 100 combusts in the stagnation zone 86 in the vicinity of the closed rear portion 88, which advantageously holds or anchors the flame to improve flame stability within the combustor 30.
Subsequently, the hot products of combustion travel from the stagnation zone 86 lengthwise along the combustor 30 toward the nozzle 32 as indicated by arrows 102. Thus, the hot products of combustion 102 flow in the same general direction 80 of flow through the gas turbine engine 12, whereas the fuel and air flows 96 and 98 injected from the fuel-air injection lobes 52 are generally counterflow. Again, the counterflow may be directed in a lengthwise direction toward the stagnation zone 86, or a crosswise direction relative to the axis 62 or solid inner casing 56, or an acutely angled direction having lengthwise and crosswise directional portions, or combinations thereof. In this manner, the counterflow injection mechanism 50 improves the mixture of fuel and air along with the hot products of combustion within the combustor 30, thereby improving the combustion and reducing pollutant emissions (e.g., NOx emissions) from the combustor 30. Also, the lobe structures 74 slightly offset the elongated injector tips 70 and the air passages 72 relative to the inner circumference of the solid inner casing 56, thereby positioning the injection of the fuel and air flows 96 and 98 slightly away from the inner circumference to improve the mixing of fuel, air, and hot products of combustion.
In other embodiments, the fuel-air injection lobes 52 may be oriented toward the stagnation zone 86 in a converging manner toward the axis 62, while being at least slightly off-center relative to the axis 62 as indicated by dashed arrow 126. As a result of this off-center converging direction of the fuel-air injection lobe 52, the fuel and air flows 96 and 98 may create a swirling flow as indicated by dashed arrow 128. In either configuration, the converging relationship between the fuel-air injection lobes 52 facilitates fuel and air mixing within the stagnation zone 86 (and also mixing with the hot products of combustion). However, the addition of swirling flow 128 within the stagnation zone 86 may further improve the fuel-air mixing and combustion within the combustor 30. In some embodiments, the fuel-air injection lobes 52 all may be oriented to create a clockwise swirling flow or a counter clockwise swirling flow. Alternatively, the fuel-air injection lobes 52 may be staggered to produce both clockwise and counter clockwise swirling flows. For example, the odd fuel-air injection lobes 52 (e.g., at radial positions 110, 114, 118, and 122) may be oriented to produce a clockwise swirling flow, while the even fuel-air injection lobes 52 (e.g., at radial positions 112, 116, 120, and 124) may be configured to produce a counter clockwise swirling flow. Again, certain embodiments of the illustrated combustor 30 may include the annular array of fuel-air injection lobes 52 as illustrated in
The illustrated fuel-air injection members 152 have a co-flow body 154 with coaxial fuel-air ports 156 and 157 disposed along an edge 158 facing the stagnation zone 86. In the illustrated embodiment, the coaxial fuel-air ports 156 include three ports 156 that are generally parallel with the axis 62, while the coaxial fuel air port 157 includes a single port 157 that is angled inwardly toward (or converging upon) the axis 62 in the counterflow direction toward the stagnation zone 86. In alternative embodiments, the fuel-air ports 156 and 157 may include any other number or arrangement of ports disposed in a desired spacing along the co-flow body 156. The coaxial fuel-airports 156 are coupled to fuel pumps or injectors 160 and air passages 162 extending to the space between the solid inner casing 56 and the perforated outer casing 58 of the combustion liner 54.
Accordingly, the fuel-air injection members 152 receive both fuel and air through the co-flow body 154, which then injects co-flows of fuel and air from the coaxial fuel-air ports 156 and 157 into the combustor 30 in generally lengthwise directions toward the stagnation zone 86, as indicated by arrows 164 and 165. In the illustrated embodiment, the lengthwise flows 164 of fuel and air are generally parallel with the axis 62 of the combustor 40, while the flows 165 are generally converging toward the axis 62. However, in other embodiments, the coaxial fuel-air ports 156 may be oriented in a generally converging or diverging angle relative to the axis 62. Moreover, the coaxial fuel-air ports 156 and 157 may be directed in a generally clockwise or counter clockwise angle about the axis 62, such that swirling flow may be created within the combustor 30 as discussed above with reference to
In operation, similar to the embodiment of
In the illustrated embodiment, the fuel-air injection members 152 are disposed at multiple radial positions about the inner circumference or periphery of the solid inner casing 56, as indicated by dashed lines 166, 168, 170, 172, 174, 176, 178, and 180. In addition, the fuel-air injection members 152 are generally aligned or centered with the axis 62. However, an inner or free end of the inwardly cantilevered fuel-air injection members 152 is generally offset or off-center from the axis 62 as indicated by arrow 182. In certain embodiments, the fuel-air injection members 152 may be angled relative to the axis 62, thereby creating a counter clockwise or clockwise swirling flow downstream in the stagnation zone 86. For example, the fuel-air injection members 152 may be acutely angled relative to the inner surface of the solid inner casing 56 rather than being substantially perpendicular. In the illustrated embodiment, the counterflow injection mechanism 150 includes eight fuel-air injection members 152 in the peripheral-radial configuration as illustrated in
In contrast, the coaxial fuel-air ports 210 are directed crosswise at a distance relative to the axis 62. In other words, the coaxial fuel-air ports 210 are oriented to produce flows generally perpendicular to the view of
As illustrated in
In addition to the features of the embodiment of
In certain embodiments, the rotating or swirling fuel and air flows 336 and 340 have a common rotational direction, such as either clockwise or counter clockwise. However, in other embodiments, the rotational or swirling fuel and air flows 336 and 340 may have opposite rotational directions, such as clockwise and counter clockwise, or vice versa. Moreover, some embodiments of the swirling injection mechanism 320 may include only the air swirling mechanism 332 without the fuel swirling mechanism 328, or only the fuel swirling mechanism 328 without the air swirling mechanism 332. Other embodiments may include additional fuel or air swirling mechanisms 328 and 332 disposed in series or in parallel with one another. Again, these swirling mechanisms 328 and 332 facilitates fuel and air mixing within the swirling injection mechanism 320. In addition, the coaxial fuel-air swirling injection mechanism 320 facilitates fuel-air mixing within the combustor 30 rather than premixing the fuel and air.
While the invention may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. However, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims.
Claims
1. A system, comprising:
- a fuel-air injection mechanism comprising coaxial fuel and air passages leading to fuel and air injection openings, wherein the fuel and air injection openings are configured to reside at an off-axis position of a gas turbine combustor, and the fuel and air injection openings are configured to orient in an injection direction not aligned with a flow direction through the gas turbine combustor to a turbine.
2. The system of claim 1, wherein the fuel and air injection openings are generally coaxial with one another.
3. The system of claim 1, wherein the fuel and air injection openings are offset from one another along a common axis of the coaxial fuel and air passages.
4. The system of claim 1, wherein the fuel and air injection openings are oriented crosswise relative to one another.
5. The system of claim 4, wherein the fuel injection opening is disposed in a circumferential wall of an air passage of the coaxial fuel and air passages.
6. The system of claim 4, wherein the fuel injection opening is disposed in a circumferential wall of a fuel passage of the coaxial fuel and air passages.
7. The system of claim 1, wherein the coaxial fuel and air passages comprise a fuel swirling mechanism, or an air swirling mechanism, or counter swirling mechanisms, or a combination thereof.
8. The system of claim 1, comprising a plurality of fuel-air injection mechanisms, including the fuel-air injection mechanism, disposed at multiple radial positions in a circumferential arrangement.
9. The system of claim 8, wherein the plurality of fuel-air injection mechanisms is oriented in a generally converging relationship.
10. The system of claim 1, comprising the gas turbine combustor.
11. The system of claim 10, wherein the gas turbine combustor comprises a combustion liner having an inner casing and an outer casing, an air flow path between and along the inner and outer casings, and the air flow path extends to the fuel-air injection mechanism.
12. The system of claim 10, comprising a gas turbine engine having the turbine and a compressor coupled to the gas turbine combustor.
13. The system of claim 12, comprising a power generator, or a propulsion system, or a vehicle, or a combinations thereof coupled to the gas turbine engine.
14. A system, comprising:
- a gas turbine combustor, comprising: a combustion liner having a generally lengthwise flow axis extending from a stagnation zone to a turbine nozzle; and a counterflow fuel-air injector disposed in the combustion liner at one or more intermediate positions between the stagnation zone and the turbine nozzle, wherein the counterflow fuel-air injector comprises coaxial fuel and air passages extending to fuel and air injection openings not aligned with a flow direction from the stagnation zone to the turbine nozzle.
15. The system of claim 14, wherein the fuel and air injection openings are generally coaxial with one another.
16. The system of claim 14, wherein the fuel and air injection openings are oriented crosswise relative to one another.
17. The system of claim 16, wherein the fuel injection opening is disposed in a circumferential wall of an air passage of the coaxial fuel and air passages, or the fuel injection opening is disposed in another circumferential wall of a fuel passage of the coaxial fuel and air passages, or a combination thereof.
18. The system of claim 14, wherein the coaxial fuel and air passages comprise a fuel swirling mechanism, or an air swirling mechanism, or counter swirling mechanisms, or a combination thereof.
19. The system of claim 14, wherein the combustion liner comprises a hollow annular wall having a perforated outer casing disposed about a substantially solid inner casing, and an air circulation path extends throughout the hollow annular wall to air passages of the coaxial fuel and air passages.
20. The system of claim 14, comprising a gas turbine engine including a turbine and a compressor coupled to the gas turbine combustor.
21. The system of claim 14, wherein the fuel and air injection openings are oriented in a generally converging relationship toward the stagnation zone.
22. The system of claim 14, wherein the counterflow fuel-air injector is disposed in a generally off-axis configuration relative to the generally lengthwise flow axis.
23. A method, comprising:
- coaxially flowing fuel and air to a counterflow fuel-air injector oriented in a generally counterflow direction relative to a generally lengthwise flow axis from a stagnation zone to a turbine nozzle of a gas turbine combustor.
24. The method of claim 23, wherein coaxially flowing fuel and air comprises coaxially injecting fuel and air through coaxial fuel-air openings in the counterflow fuel-air injector.
25. The method of claim 23, wherein coaxially flowing fuel and air comprises radially injecting fuel from a fuel port into an air passage.
26. The method of claim 23, wherein coaxially flowing fuel and air comprises swirling the air, or swirling the fuel, or swirling the fuel and air in a common rotational direction, or counterswirling the fuel and air in opposite rotational directions.
27. The method of claim 23, wherein coaxially flowing fuel and air comprises injecting fuel and air from a plurality of counterflow fuel-air injectors oriented to converge toward the stagnation zone.
28. The method of claim 23, wherein coaxially flowing fuel and air comprises circulating air through a hollow annular combustion liner and injecting the air into the gas turbine combustor along with fuel.
Type: Application
Filed: Jan 3, 2006
Publication Date: Jul 5, 2007
Inventor: Joel Haynes (Schenectady, NY)
Application Number: 11/325,643
International Classification: F23R 3/02 (20060101);