Patent Application
20140260302
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.
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 (NOX) 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 NOX. 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.
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.
Referring now to the drawings, in which like numerals refer to like elements throughout the several views,
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.
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.
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.
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
Alternatively, as shown in
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
As another example, the tri fuel nozzle 200, as shown in
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 NOx 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 NOx 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 NOx 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.
