DIFFUSION COMBUSTOR FUEL NOZZLE FOR LIMITING NOx EMISSIONS

Abstract

The present application and the resultant patent provide a diffusion combustor fuel nozzle for a gas turbine engine. The fuel nozzle may include one or more gas fuel passages for one or more flows of gas fuel, a swirler surrounding the one or more gas fuel passages and positioned about a downstream face of the fuel nozzle, a number of swirler gas fuel ports defined in the swirler, and a number of downstream face gas fuel ports defined in the downstream face of the fuel nozzle. The swirler may include a number of swirl vanes and a number of air chambers defined between adjacent swirl vanes. The present application and the resultant patent further provide a method of operating a diffusion combustor fuel nozzle of a gas turbine engine.

Description

TECHNICAL FIELD

The present application and the resultant patent relate generally to gas turbine engines and more particularly relate to a diffusion combustor fuel nozzle including fuel ports configured to limit emissions such as nitrogen oxides and the like while maintaining efficient performance of the gas turbine engine.

BACKGROUND OF THE INVENTION

Operational efficiency in a gas turbine engine generally increases as the temperature of the combustion stream increases. Higher combustion stream temperatures, however, may result in the production of high levels of nitrogen oxides (NO_X) and other types of undesirable emissions. Such emissions may be subject to both federal and state regulations in the United States and also may be subject to similar regulations abroad. A balancing act thus exists between operating the gas turbine engine within an efficient temperature range while also ensuring that the output of nitrogen oxides and other types of regulated emissions remain well below mandated levels. Many other types of operational parameters also may be varied in providing such an optimized balance.

In a gas turbine engine that includes a diffusion-type combustor, i.e., non-premixed, fuel is injected into an air swirler of a fuel nozzle. Air flows through the air swirler so as to mix with the fuel for downstream combustion. In certain air swirler configurations, the mixing of the air and the fuel may produce high combustion stream temperatures, which may result in the production of high levels of NO_X. Additionally, in certain air swirler configurations, the fuel and the resultant hot combustion gases may become entrained in a recirculation zone downstream of the air swirler. As a result, the liner surrounding the fuel nozzles and the combustion chamber may experience relatively high head-end temperatures. Moreover, the relatively high head-end temperatures may be increased even further when the combustor burns certain types of liquid fuels. Such high temperatures may have an impact on the integrity and the lifetime of the liner and other components.

There is thus a desire for an improved fuel nozzle for use in a combustor, particularly a diffusion type combustor in a gas turbine engine. Such a fuel nozzle for a diffusion type combustor may limit recirculation of the fuel and the hot combustion gases downstream of the fuel nozzle. Additionally, such a fuel nozzle for a diffusion combustor may efficiently combust the fuel and the air streams therein with limited emissions while also limiting liner temperatures for increased component lifetime.

SUMMARY OF THE INVENTION

The present application and the resultant patent thus provide a diffusion combustor fuel nozzle for a gas turbine engine. The fuel nozzle may include one or more gas fuel passages for one or more flows of gas fuel, a swirler surrounding the one or more gas fuel passages and positioned about a downstream face of the fuel nozzle, a number of swirler gas fuel ports defined in the swirler, and a number of downstream face gas fuel ports defined in the downstream face of the fuel nozzle. The swirler may include a number of swirl vanes and a number of air chambers defined between adjacent swirl vanes.

The present application and the resultant patent further provide a method of operating a diffusion combustor fuel nozzle of a gas turbine engine. The method may include the steps of providing one or more flows of gas fuel through the nozzle, passing a first portion of the one or more flows of gas fuel through a number of swirler gas fuel ports defined in a swirler positioned about a downstream face of the fuel nozzle, and passing a second portion of the one or more flows of gas fuel through a number of downstream face gas fuel ports defined in the downstream face of the fuel nozzle.

The present application and the resultant patent further provide a diffusion combustor fuel nozzle for a gas turbine engine. The fuel nozzle may include one or more gas fuel passages for one or more flows of gas fuel, a swirler surrounding the one or more gas fuel passages and positioned about a downstream face of the fuel nozzle, a number of swirler gas fuel ports defined in the swirler, and a number of downstream face gas fuel ports defined in the downstream face of the fuel nozzle. The one or more gas fuel passages may extend towards the downstream face of the fuel nozzle. The swirler may include a number of swirl vanes and a number of air chambers defined between adjacent swirl vanes. The number of swirler gas fuel ports each may be defined in the swirler between adjacent swirl vanes.

These and other features and improvements of the present application and the resultant patent will become apparent to one of ordinary skill in the art upon review of the following detailed description when taken in conjunction with the several drawings and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a gas turbine engine including a compressor, a combustor, and a turbine.

FIG. 2 is a side view of an example of a combustor such as that shown in FIG. 1.

FIG. 3 is a side cross-sectional view of a fuel nozzle that may be used in the combustor of FIG. 2.

FIG. 4 is a front plan view of the fuel nozzle of FIG. 3.

FIG. 5 is a side cross-sectional view of a fuel nozzle as may be described herein.

FIG. 6 is a front plan view of the fuel nozzle of FIG. 5.

FIG. 7 is a side cross-sectional view of a fuel nozzle as may be described herein.

DETAILED DESCRIPTION

Referring now to the drawings, in which like numerals refer to like elements throughout the several views, FIG. 1 shows a schematic view of a gas turbine engine 10 as may be used herein. The gas turbine engine 10 may include a compressor 15. The compressor 15 compresses an incoming flow of air 20. The compressor 15 delivers the compressed flow of air 20 to a combustor 25. The combustor 25 mixes the compressed flow of air 20 with a pressurized flow of fuel 30 and ignites the mixture to create a flow of combustion gases 35. Although only a single combustor 25 is shown, the gas turbine engine 10 may include any number of combustors 25. The flow of combustion gases 35 is in turn delivered to a turbine 40. The flow of combustion gases 35 drives the turbine 40 so as to produce mechanical work. The mechanical work produced in the turbine 40 drives the compressor 15 via a shaft 45 and an external load 50 such as an electrical generator and the like. Other configurations and other components may be used herein.

The gas turbine engine 10 may use natural gas, various types of syngas, and/or other types of fuels. The gas turbine engine 10 may be any one of a number of different gas turbine engines offered by General Electric Company of Schenectady, N.Y., including, but not limited to, those such as a 7 or a 9 series heavy duty gas turbine engine and the like. The gas turbine engine 10 may have different configurations and may use other types of components. Other types of gas turbine engines also may be used herein. Multiple gas turbine engines, other types of turbines, and other types of power generation equipment also may be used herein together.

FIG. 2 shows an example of the combustor 25 that may be used with the gas turbine engine 10 and the like. The combustor 25 may include a number of fuel nozzles 55 therein. Each of the fuel nozzles 55 may direct the flow of air 20, the flow of fuel 30, and optional flows of other fluids for combustion therein. Any number of the fuel nozzles 55 may be used in any configuration. The fuel nozzles 55 may be attached to an end cover 60 near a head-end 65 of the combustor 25. The flows of the air 20 and the fuel 30 may be directed through the end cover 60 and the head-end 65 into each of the fuel nozzles 55 so as to distribute a fuel-air mixture downstream thereof.

The combustor 25 also may include a combustion chamber 70 therein. The combustion chamber 70 may be defined by a combustion casing 75, a combustion liner 80, a flow sleeve 85, and the like. The liner 80 and the flow sleeve 85 may be coaxially positioned with respect to one another so as to define an air pathway 90 for the flow of air 20 therethrough. The combustion chamber 70 may lead to a downstream transition piece 95. The flows of the air 20 and the fuel 30 may mix downstream of the fuel nozzles 55 for combustion within the combustion chamber 70. The flow of combustion gases 35 then may be directed via the transition piece 95 towards the turbine 40 so as to produce useful work therein. Other components and other configuration also may be used herein.

FIGS. 3 and 4 show an example of the fuel nozzle 55 that may be used with the combustor 25 and the like. The fuel nozzle 55 may be a diffusion fuel nozzle 100. More specifically, the fuel nozzle 55 may be a dual fuel nozzle 105. Given such, the flow of fuel 30 may include one or more flows of a gas fuel 110 such as natural gas and one or more flows of a liquid fuel 115 such as a syngas and the like. Other types of fuel flows and other types of combinations of fuel flows may be used herein.

The fuel nozzle 55 may include an outer tube 120. The outer tube 120 may lead to a downstream face 125 with a fuel nozzle tip 130. The outer tube 120 may include a number of fuel, air, and water passages therein. Specifically, a number of gas fuel passages 135 may extend through the outer tube 120 and may be axially positioned about the downstream face 125. The gas fuel passages 135 may be in communication with the flow of gas fuel 110. A number of tip outlets 140 also may extend through the outer tube 120 and may be positioned about the fuel nozzle tip 130. The tip outlets 140 may include a liquid fuel outlet 145 in communication with the flow of liquid fuel 115. The tip outlets 140 also may include an atomizing air outlet 150 in communication with a flow of atomizing air as well as a water outlet 155 in communication with a flow of water. Other components and other configurations may be used herein.

A swirler 160 may be positioned about the downstream face 125 of the fuel nozzle 55. The swirler 160 may include a number of swirl vanes 165. The swirl vanes 165 may define a number of air chambers 170. The air chambers 170 may be in fluid communication with the flow of air 20 from the end cover 60. A number of gas fuel ports 175 may extend from the gas fuel passages 135 to the air chambers 170 for guiding and delivering at least a portion of the flow of gas fuel 110. The flow of air 20 and the flow of gas fuel 110 thus may begin to mix about the swirler 160 for combustion within the downstream combustion chamber 70. Generally described, all of the flow of air 20 thus passes through the air chambers 170 of the swirler 160 as a swirler flow 180. A collar 185 may surround the swirler 160. A cone (not shown) may extend from the fuel nozzle 55 to the liner 80. Other types of fuel nozzles 55 and other types of combustors 25 may be used herein with differing types of fuel. Likewise, other components and other configurations may be used herein.

FIG. 5 and FIG. 6 show a fuel nozzle 200 as may be described herein. The fuel nozzle 200 may be a diffusion nozzle with little to no upstream fuel-air premixing. The fuel nozzle 200 also may be a dual fuel nozzle 205 for use with both a flow of gas fuel 210 and a flow of the liquid fuel 215. Other types of flows may be used herein. In a manner similar to that described above, the fuel nozzle 200 includes a downstream face 225, a fuel nozzle tip 230, and one or more gas fuel passages 235 extending through the fuel nozzle 200. The gas fuel passages 235 may extend towards the downstream face 225. The fuel nozzle 200 also may include a number of tip outlets 240. The tip outlets 240 may be positioned about the fuel nozzle tip 230 about the downstream face 225. The fuel nozzle 200 also may include one or more liquid fuel passages 242, and the tip outlets 240 may include one or more liquid fuel outlets 245 corresponding to the one or more liquid fuel passages 242. The tip outlets 240 also may include outlets for atomizing air, water, and the like. Other components and other configurations also may be used herein.

The fuel nozzle 200 also may include a swirler 260 positioned about the downstream face 225 thereof. The swirler 260 surrounds the fuel nozzle tip 230. The swirler 260 may include a number of swirl vanes 265 that define a number of air chambers 270 extending therethrough. The swirl vanes 265 and the air chambers 270 may have any size, shape, or configuration. Any number of the swirl vanes 265 and the air chambers 270 may be used herein. A number of swirler gas fuel ports 275 may be defined in the swirler 260. The swirler gas fuel ports 275 may extend from one of the gas fuel passages 235 to the air chambers 270 for guiding and delivering at least a portion of the flow of gas fuel 210 therethrough. Each of the swirler gas fuel ports 275 may be defined in the swirler 260 between adjacent swirl vanes 265 and upstream of the downstream face 225 of the nozzle 200. An air inlet 277 may be defined on the upstream end of the swirler 260 in communication with the flow of air 20 from the end cover 60. In a manner similar to that described above, the flow of air 20 thus enters the air inlet 277 and passes through the air chambers 270 as a swirler flow 280. The air inlet 277 may have any size, shape, or configuration. Additionally, a collar 285 may surround the swirler 260, and a cone (not shown) may extend from the fuel nozzle 200 to the liner 80. The nozzle 200 also may include a number of downstream face gas fuel ports 290 defined in the downstream face 225 of the nozzle 200. The downstream face gas fuel ports 290 may extend from one of the gas fuel passages 235 to the downstream face 225 of the nozzle 200 for guiding and delivering at least a portion of the flow of gas fuel 210 therethrough. The downstream face gas fuel ports 290 may be parallel to an axis of the fuel nozzle 200. Alternatively, the downstream face gas fuel ports 290 may be angled relative to the axis of the fuel nozzle 200. Other components and other configurations also may be used herein.

In use, at least a first portion of the flow of gas fuel 210 passes through one of the gas fuel passages 235, through the swirler gas fuel ports 275, and into the air chambers 270 of the swirler 260. At least a second portion of the flow of gas fuel 210 passes through one of the gas fuel passages 235, through the downstream face gas fuel ports 290, and out of the nozzle 200 into the combustion chamber 70. Likewise, the flow of liquid fuel 215, the atomizing airflow, and the water flow pass through the tip outlets 240 and out of the nozzle 200 into the combustion chamber 70. The flow of air 20 passes through the air inlet 277 of the swirler 260 and into the air chambers 270 as the swirler flow 280. The first portion of the flow of gas fuel 210 and the swirler flow 280 begin to mix within the air chambers 270 of the swirler 260 to create a mixed fuel-air flow passing into the combustion chamber 70. Accordingly, the combustion chamber 70 receives the mixed fuel-air flow from the swirler 260 and the second portion of the flow of gas fuel 210 from the downstream face gas fuel ports 290 for combustion within the combustion chamber 70.

As shown in FIG. 5, the swirler gas fuel ports 275 and the downstream face gas fuel ports 290 may be in fluid communication with the same gas fuel passage 235. Accordingly, the same type of gas fuel would pass through the swirler gas fuel ports 275 and the downstream face gas fuel ports 290, forming the mixed fuel-air flow from the swirler 260 and the second portion of the flow of gas fuel 210 from the downstream face gas fuel ports 290. In this manner, the gas fuel passage 235 may deliver gas fuel from a common fuel source to the swirler gas fuel ports 275 and the downstream face gas fuel ports 290. As discussed above, the nozzle 200 also may include a liquid fuel passage 242 and a liquid fuel outlet 245 for passing a flow of liquid fuel 215, such that the nozzle 200 operates as a dual fuel nozzle.

Alternatively, as shown in FIG. 7, the swirler gas fuel ports 275 and the downstream face gas fuel ports 290 may be in fluid communication with different gas fuel passages 235. For example, the swirler gas fuel ports 275 may be in fluid communication with a first gas fuel passage 292, and the downstream face gas fuel ports 290 may be in fluid communication with a second gas fuel passage 294. As shown, the first gas fuel passage 292 is separate from, and thus is not in fluid communication with, the second gas fuel passage 294. In this manner, a first type of gas fuel may be delivered from a first fuel source, through the first gas fuel passage 292, and through the swirler gas fuel ports 275, while a second type of gas fuel may be delivered from a second fuel source, through the second gas fuel passage 294, and through the downstream face gas fuel ports 290, such that the nozzle 200 operates as a dual fuel nozzle. Additionally, the nozzle 200 also may include a flow of liquid fuel 215, such that the nozzle 200 operates as a tri fuel nozzle.

In use, the different flows of fuel through the nozzle 200 may be varied according to the operational mode of the gas turbine engine 10. For example, the dual fuel nozzle 200, as shown in FIG. 5, may be operated at startup or low load conditions by passing the flow of liquid fuel 215 through the liquid fuel outlet 245 and into the combustion chamber 70, while no gas fuel is passed through the swirler gas fuel ports 275 or the downstream face gas fuel ports 290. In contrast, the dual fuel nozzle 200 may be operated at base load conditions by passing the flow of gas fuel 210 through the swirler gas fuel ports 275 and the downstream face gas fuel ports 290. The ratio of the area of the swirler gas fuel ports 275 and the area of the downstream face gas fuel ports 290 may be selected to achieve optimum emissions, lean blowout (LBO) margining, dynamics, exit profile, and metal temperatures.

As another example, the tri fuel nozzle 200, as shown in FIG. 7, may be operated at startup or low load conditions by passing the flow of liquid fuel 215 through the liquid fuel outlet 245 and into the combustion chamber 70, while no gas fuel is passed through the swirler gas fuel ports 275 or the downstream face gas fuel ports 290. Alternatively, the tri fuel nozzle 200 may be operated at startup or low load conditions by passing the first gas fuel through the swirler gas fuel ports 275, while no fuel is passed through the downstream face gas fuel ports 290 or the liquid fuel outlet 245. In contrast, the tri fuel nozzle 200 may be operated at base load conditions by passing the first portion of the flow of gas fuel 210 through the swirler gas fuel ports 275 and the second portion of the flow of gas fuel 210 through the downstream face gas fuel ports 290, while no fuel is passed through the liquid fuel outlet 245. The ratio of the area of the swirler gas fuel ports 275 and the area of the downstream face gas fuel ports 290 may be selected to achieve optimum emissions, LBO margining, dynamics, exit profile, and metal temperatures.

Passing a flow of gas fuel 210 through both the swirler gas fuel ports 275 and the downstream face gas fuel ports 290 prevents the mixed fuel-air flow and/or the flow of combustion gases 35 from being entrained in a recirculation zone about the fuel nozzle 200. The configuration of the fuel ports 275, 290 thus limits NO_x emissions and the like. Accordingly, the fuel nozzle 200 produces an unexpected result with respect to emissions because generally accepted wisdom in the art teaches that a reduction in fuel-air premixing will result in increased emissions. In other words, by passing a portion of the flow of gas fuel 210 through the downstream face gas fuel ports 290, and thus not premixing that portion with the flow of air 20, the NO_x emissions of the fuel nozzle 200 are unexpectedly reduced even though the degree of premixing carried out in the fuel nozzle 200 is reduced. Furthermore, the reduction in premixing may reduce combustion stream temperatures and thus extend the useful lifetime of the liner 80 and other components in the hot gas path. The water to fuel ratio also may be reduced as a result of the configuration of the fuel ports 275, 290.

The fuel nozzle 200 described herein thus limits natural gas emissions while providing wide fuel flexibility. Compared to the traditional approach of increasing fuel-air premixing, the fuel nozzle 200 described herein actually lowers premixing so as to improve overall NO_x emissions. This non-intuitive approach of lowering fuel-air premixing is distinct from such traditional fuel nozzle designs and operational theories. The use of the swirler gas fuel ports 275 and the downstream face gas fuel ports 290 described herein thus improves emissions and overall component lifetime.

It should be apparent that the foregoing relates only to certain embodiments of the present application and the resultant patent. Numerous changes and modifications may be made herein by one of ordinary skill in the art without departing from the general spirit and scope of the invention as defined by the following claims and the equivalents thereof.

Claims

1. A diffusion combustor fuel nozzle for a gas turbine engine, the fuel nozzle comprising:

one or more gas fuel passages for one or more flows of gas fuel;

a swirler surrounding the one or more gas fuel passages and positioned about a downstream face of the fuel nozzle, the swirler comprising a plurality of swirl vanes and a plurality of air chambers each defined between adjacent swirl vanes;

a plurality of swirler gas fuel ports defined in the swirler; and

a plurality of downstream face gas fuel ports defined in the downstream face of the fuel nozzle.

2. The diffusion combustor fuel nozzle of claim 1, wherein each of the swirler gas fuel ports is defined in the swirler between adjacent swirl vanes.

3. The diffusion combustor fuel nozzle of claim 1, wherein each of the swirler gas fuel ports is defined in the swirler upstream of the downstream face of the fuel nozzle.

4. The diffusion combustor fuel nozzle of claim 1, wherein each of the swirler gas fuel ports extends from one of the gas fuel passages to one of the air chambers.

5. The diffusion combustor fuel nozzle of claim 1, wherein each of the swirler gas fuel ports extends towards the downstream face of the fuel nozzle.

6. The diffusion combustor fuel nozzle of claim 1, wherein each of the downstream face gas fuel ports extends from one of the gas fuel passages to the downstream face of the fuel nozzle.

7. The diffusion combustor fuel nozzle of claim 1, wherein each of the downstream face gas fuel ports is parallel to an axis of the fuel nozzle.

8. The diffusion combustor fuel nozzle of claim 1, wherein each of the downstream face gas fuel ports is angled relative to an axis of the fuel nozzle.

9. The diffusion combustor fuel nozzle of claim 1, wherein the one or more gas fuel passages extend towards the downstream face of the fuel nozzle.

10. The diffusion combustor fuel nozzle of claim 1, wherein each of the swirler gas fuel ports extends from a first gas fuel passage to one of the air chambers, and each of the downstream face gas fuel ports extends from the first gas fuel passage to the downstream face of the fuel nozzle.

11. The diffusion combustor fuel nozzle of claim 1, wherein each of the swirler gas fuel ports extends from a first gas fuel passage to one of the air chambers, and wherein each of the downstream face gas fuel ports extends from a second gas fuel passage to the downstream face of the fuel nozzle.

12. The diffusion combustor fuel nozzle of claim 1, wherein each of the swirler gas fuel ports is in fluid communication with a first gas fuel source, and wherein each of the downstream face gas fuel ports is in fluid communication with the first gas fuel source.

13. The diffusion combustor fuel nozzle of claim 1, wherein each of the swirler gas fuel ports is in fluid communication with a first gas fuel source, and wherein each of the downstream face gas fuel ports is in fluid communication with a second gas fuel source.

14. The diffusion combustor fuel nozzle of claim 1, further comprising a liquid fuel passage and a liquid fuel outlet for a flow of liquid fuel, wherein the liquid fuel passage extends towards the downstream face of the fuel nozzle, and wherein the liquid fuel outlet is positioned about the downstream face of the fuel nozzle.

15. A method of operating a diffusion combustor fuel nozzle of a gas turbine engine, the method comprising:

providing one or more flows of gas fuel through the fuel nozzle;

passing a first portion of the one or more flows of gas fuel through a plurality of swirler gas fuel ports defined in a swirler positioned about a downstream face of the fuel nozzle; and

passing a second portion of the one or more flows of gas fuel through a plurality of downstream face gas fuel ports defined in the downstream face of the fuel nozzle.

16. The method of claim 15, further comprising mixing the first portion of the one or more flows of fuel with a flow of air within air chambers of the swirler, and passing the mixed fuel-air flow into a combustion chamber of the diffusion combustor.

17. A diffusion combustor fuel nozzle for a gas turbine engine, the fuel nozzle comprising:

one or more gas fuel passages for one or more flows of gas fuel, the one or more gas fuel passages extending towards a downstream face of the fuel nozzle;

a swirler surrounding the one or more gas fuel passages and positioned about the downstream face of the fuel nozzle, the swirler comprising a plurality of swirl vanes and a plurality of air chambers each defined between adjacent swirl vanes;

a plurality of swirler gas fuel ports each defined in the swirler between adjacent swirl vanes; and

a plurality of downstream face gas fuel ports defined in the downstream face of the fuel nozzle.

18. The diffusion combustor fuel nozzle of claim 17, wherein each of the swirler gas fuel ports extends from a first gas fuel passage to one of the air chambers, and each of the downstream face gas fuel ports extends from the first gas fuel passage to the downstream face of the fuel nozzle.

19. The diffusion combustor fuel nozzle of claim 17, wherein each of the swirler gas fuel ports extends from a first gas fuel passage to one of the air chambers, and wherein each of the downstream face gas fuel ports extends from a second gas fuel passage to the downstream face of the fuel nozzle.

20. The diffusion combustor fuel nozzle of claim 17, further comprising a liquid fuel passage and a liquid fuel outlet for a flow of liquid fuel, wherein the liquid fuel passage extends towards the downstream face of the fuel nozzle, and wherein the liquid fuel outlet is positioned about the downstream face of the fuel nozzle.