Patent Application
20130111918
The subject matter disclosed herein relates to the art of turbomachines and, more particularly, to a combustor assembly for a gas turbomachine.
In general, gas turbomachines combust a fuel/air mixture that releases heat energy to form a high temperature gas stream. The high temperature gas stream is channeled to a turbine portion via a hot gas path. The turbine portion converts thermal energy from the high temperature gas stream to mechanical energy that rotates a turbine shaft. The turbine portion may be used in a variety of applications, such as for providing power to a pump or an electrical generator.
Turbomachine efficiency increases as combustion gas stream temperatures increase. Unfortunately, higher gas stream temperatures produce higher levels of nitrogen oxide (NOx), an emission that is subject to both federal and state regulation. Therefore, there exists a careful balancing act between operating gas turbomachines in an efficient range, while also ensuring that the output of NOx remains below federal and state mandated levels. One method of achieving low NOx levels is to ensure good mixing of fuel and air prior to combustion, and providing an environment that leads to more complete combustion of the fuel/air mixture.
According to one aspect of the exemplary embodiment, a turbomachine combustor assembly includes a combustor housing, a first combustion zone arranged in the combustor housing, a second combustion zone arranged downstream from the first combustion zone, and one or more injector assemblies positioned downstream from the first combustion zone and upstream from the second combustion zone. The one or more injector assemblies includes a first injector member having a first centerline axis and a second injector member having a second centerline axis. The second injector member extends though the first injector member with the second centerline axis being off-set from the first centerline axis.
According to another aspect of the exemplary embodiment, a turbomachine includes a compressor portion, a turbine portion operatively connected to the compressor portion, and a combustor assembly fluidly linking the compressor portion and the turbine portion. The combustor assembly includes a combustor housing, a first combustion zone arranged in the combustor housing, a second combustion zone arranged downstream from the first combustion zone, and one or more injector assemblies positioned downstream from the first combustion zone and upstream from the second combustion zone. The one or more injector assemblies includes a first injector member having a first centerline axis and a second injector member having a second centerline axis. The second injector member extends though the first injector member with the second centerline axis being off-set from the first centerline axis.
According to yet another aspect of the exemplary embodiment, a method of combusting a fluid in a turbomachine combustor assembly includes combusting a first combustible mixture in a first combustion zone arranged in the combustor assembly, introducing a first portion of a second combustible mixture downstream from the first combustion zone through a first injector member of an injector assembly, introducing a second portion of the second combustible mixture upstream from a substantial portion of the first portion of the combustible mixture through a second injector member of the injector assembly. The second injector member extends through and is axially off-set relative to the first injector member.
These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.
The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.
With reference to
As further shown in
As best shown in
Injector member 50 also includes a second injector member 94 that extends through central passage 80 off-set relative to centerline axis 86. Second injector member 94 includes a body 98 having an outer surface 100 and an inner surface 102 that defines a central conduit 105 having a centerline axis 108. Central conduit 105 includes an outlet portion 111 that, in the exemplary embodiment shown, is substantially coplanar with outlet section 89 of first injector member 83. Of course it should be understood that the relative positioning of outlet portion 111 and outlet section 89 could vary. As discussed above, second injector member 94 is off-set relative to centerline axis 86 of first injector member 83. In the exemplary embodiment shown, second injector member 94 is arranged at leading edge 68. With this arrangement, a second fluid, such as a fuel, is introduced slightly upstream from a majority of the first fluid. The particular introduction point of the second fluid relative to the first fluid produces more complete mixing of the fluids which, in turn, leads to more complete combustion. In addition, the particular positioning of second injector member 94 relative to first injector member 83 reduces localized metal temperature gradients and pressure drops of the combustion gases.
At this point it should be understood that the exemplary embodiments provide a system for combusting combustible mixtures in a turbomachine. More specifically, the exemplary embodiments disclose an injector assembly having an airfoil shaped profile that establishes a first injector member and provides space for a second, upstream injector member. The particular geometry of the injector members allows for more complete mixing of the combustible mixture to reduce certain combustion byproducts such as NOx. Reducing certain combustion byproducts provides enhanced turndown capacity for the turbomachine. In addition, the relative positioning of the first and second injector members leads to reduced thermal gradients so as to improve component life. Also, while shown arranged in combustor housing 12, it should be understood that injector assembly 50 could also be arranged in transition piece 20 such as shown in
While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
