Patent Application
20130189632
The present application and the resultant patent relate generally to a gas turbine engine and more particularly relate to a fuel nozzle with a nozzle collar having a number of purge holes therein for improved fuel-air mixing, flame holding resistance, and overall performance.
Generally described, a gas turbine engine may employ one or more fuel nozzles to facilitate fuel-air mixing in a combustor. Each fuel nozzle may direct a flow of fuel, a flow of air, and optional flows of other fluids into the combustor for combustion therein. In certain conditions, a combustion flame may flash back and/or hold to a surface of the fuel nozzle. Flame holding may cause significant damage to the fuel nozzles and/or reduce the performance of the fuel nozzles and the overall gas turbine engine.
Specifically, flame holding may occur if a flammable fuel-air mixture resides in a low velocity region in close proximity to a combustion source. In fuel nozzles used in diffusion based combustion systems, low velocity regions generally may be found near the interior walls of the fuel nozzles due to the aerodynamics therein. Such a flammable mixture potentially may result in flame holding inside the fuel nozzles. Flame holding inside fuel nozzles may result in the fuel nozzles burning out, i.e., experiencing flame damage therein.
There is thus a desire for an improved fuel nozzle design. Preferably such an improved fuel nozzle design may limit or reduce flammable fuel/air mixtures in low velocity regions about the fuel nozzles so as to limit flame holding and the like. Limiting flame holding should improve the overall performance and durability of the fuel nozzles and the gas turbine engine.
The present application and the resultant patent thus provide an example of a fuel nozzle for mixing a flow of fuel and a flow of air. The fuel nozzle may include a downstream face, a number of fuel passages positioned about the downstream face for the flow of fuel, and a nozzle collar position about the downstream face. The nozzle collar may include a number of air vanes for the flow of air and one or more purge holes therethrough.
The present application and the resultant patent further provide an example of a method of limiting flame holding about a fuel nozzle. The method may include the steps of providing a flow of fuel through a downstream face of the fuel nozzle, providing a flow of air through a number of air vanes of a nozzle collar of the fuel nozzle, mixing the flow of fuel and the flow of air downstream of the fuel nozzle, providing a flow of purge air through a number of purge holes in the air vanes, and limiting the creation of one or more recirculation zones downstream of the fuel nozzle with the flow of purge air.
The present application and the resultant patent further provide an example of a combustor for use with a gas turbine engine. The combustor may include a combustion chamber and a number of fuel nozzles positioned about the combustion chamber. Each of the fuel nozzles may include a nozzle collar thereon. The nozzle collar may include one or more air vanes with one or more purge holes for a flow of purge air therethrough.
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 air 20 and 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 100 also may include a nozzle collar 160 positioned about the downstream end of the outer tube 110. The nozzle collar 160 may surround the downstream face 120 and the fuel nozzle tip 130. The nozzle collar 160 may include a number of air vanes 170. The air vanes 170 may be angled so as to direct the flow of air 20 therethrough and/or to impart swirl therein. The air vanes 170 may have size, shape, or configuration. Any number of the air vanes 170 may be used. The air vanes 170 may direct the flow of air 20 about the fuel passages 140 and the tip outlets 150. The air vanes 170 may support a downstream ring 180 at the end thereof. Other components and other configurations also may be used herein.
As described above, a number of recirculation zones 190 may be formed as a result of the interaction between the flows of air 20 and fuel 30. These recirculation zones 190 may lead to flame holding about the fuel nozzle 100 via a region of low velocity. As a result, a number of purge holes 200 may be positioned through the air vanes 170. The purge holes 200 may have any size, shape, or configuration. Any number of the purge hole 200 may be used herein. The purge holes 200 may be angled and/or multiple angles may be used herein. Additional purge holes 200 also may extend through the downstream ring 180 and/or elsewhere. Other components and other configurations may be used herein.
The purge holes 200 thus provide for a flow of purge air 210 therethrough as part of the overall flow of air 20. The flow of purge air 210 through the purge holes 200 may disrupt the recirculation zones 190 downstream of the fuel nozzles 100 caused by the regions of low velocity or otherwise. The purge holes 200 may be angled such that the purge air 210 disrupts the creation of the recirculation zones 190 in a substantially circumferential direction. Elimination or reduction of these recirculation zones 190 along the circumferential direction should reduce flame holding thereon. As such, the reduction in flame holding should provide the fuel nozzle 100 with improved durability and lifetime. Moreover, the overall gas turbine engine 100 may have improved emissions and overall improved performance. The use of the purge holes 200 with the flow of purge air 210 therethrough may be original equipment or added as part of a retrofit.
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.
