Patent Application
20120180494
The subject matter disclosed herein relates to turbines and, more particularly, fuel nozzles for gas turbines.
In a gas turbine, a combustor converts chemical energy of a fuel or an air-fuel mixture into thermal energy. The thermal energy is conveyed by a fluid, often compressed air from a compressor, to a turbine where the thermal energy is converted to mechanical energy. The fuel and/or air are directed into the combustor via one or more fuel nozzles. In an aspect, the fuel nozzle is an assembly that includes a plurality of components that are made of different materials. A temperature differential between flowing fuel and air within the fuel nozzle assembly can cause thermal expansion and corresponding movement of the nozzle components, causing wear and tear on the components and joints between the components. Reducing stress caused by relative movement of fuel nozzle components will improve durability and reliability of the fuel nozzle and turbine.
According to one aspect of the invention, a fuel nozzle assembly for a turbine includes an inner conduit and a flange coupled to the inner conduit thereby forming a chamber for flow of a gas fuel. In addition, the flange includes a diaphragm member coupled to the inner conduit, the diaphragm member being configured to flex in response to relative movement between the inner conduit and the flange.
According to another aspect of the invention, a method for flowing fuel in a turbine includes directing air within an inner conduit and directing a fuel into a cavity between the inner conduit and a flange, wherein the inner conduit and flange are coupled by a coupling. The method further includes flexing a diaphragm member in the flange to compensate for a movement of the inner conduit, wherein the flexing of the diaphragm member reduces stress on the coupling between the inner conduit and flange.
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.
In an aspect, the combustor 104 uses liquid and/or gas fuel, such as natural gas or a hydrogen rich synthetic gas, to run the engine. For example, fuel nozzles 110 are in fluid communication with an air supply and a fuel supply 112. The fuel nozzles 110 create an air-fuel mixture, and discharge the air-fuel mixture into the combustor 104, thereby causing a combustion that creates a hot pressurized exhaust gas. The combustor 100 directs the hot pressurized exhaust gas through a transition piece into a turbine nozzle (or “stage one nozzle”), causing turbine 106 rotation. The rotation of turbine 106 causes the shaft 108 to rotate, thereby compressing the air as it flows into the compressor 102. In an embodiment, each of the fuel nozzles 110 includes a diaphragm member configured to allow relative movement of fuel nozzle 110 components. The fuel nozzle 110 components may experience relative movement due to thermal differentials and differing material expansion rates of fuel nozzle 110 components. Exemplary embodiments of the fuel nozzle 110 assemblies are discussed in detail below with reference to
The diaphragm member 214 comprises a durable material configured to withstand the heat and pressure of the hot and pressurized fluid flow within fuel nozzle assembly 200. Exemplary materials may include composites and metallic or steel alloys, such as a stainless steel. Further, the diaphragm member 214 material is configured to elastically deform in response to expansion of fuel nozzle assembly 200 components, such as inner conduit 204 and flange 202. The flange comprises any suitable durable strong material, including a metallic material, a composite material or a steel alloy. In an exemplary embodiment, the flange 202 and diaphragm member 214 are formed together and comprise the same material, such as stainless steel. In other embodiments, the flange 202 and diaphragm member 214 are separate components, which may or may not be formed from the same material. In an embodiment, the fuel flow 220 is about 20 degrees Celsius as it enters the chamber 221 and the compressed air flow 226 is about 430 degrees Celsius, wherein the relatively cool fuel flow 220 causes a contraction or shrinking of the inner conduit 204 relative to the flange 202 heated by the compressed air flow 226. Thus, axial contraction, expansion and/or overall movement of the inner conduit 204 relative to flange 202 is compensated by flexing or elastic deformation of the diaphragm member 214. The elastic deformation of diaphragm member 214 is reversible. The expansion due to thermal and/or material differences between components, such as inner conduit 204 and flange 202, creates forces causing the elastic deformation of diaphragm member 214. Once the forces are no longer applied, such as when the turbine engine is cooled and not running, the diaphragm member 214 returns to its original shape.
Still referring to
The bellows 328 and diaphragm member 314 are each configured to allow expansion and movement of inner conduit 304 relative to flange 302, caused by differing material properties of the components. The material properties may include a coefficient of thermal expansion or any characteristic that affects rigidity, stiffness, shape and/or volume in response to an energy, such as temperature or pressure change. For example, the fuel flow 320 is approximately about 350 to about 450 degrees Celsius cooler than the compressed air flow 326, thereby causing the flange 302 to expand axially relative to the inner conduit 304. Accordingly, the diaphragm member 314 comprises the wall thickness 316 with a selected relationship to a thickness 330 of inner conduit 304. An embodiment of thickness 316 is about one to about five times as thick as thickness 330. Another embodiment of diaphragm member 314 has a thickness 316 about one to about three times as thick as thickness 330. Yet another embodiment of diaphragm member 314 has a thickness 316 about two to about three times as thick as thickness 330. Accordingly, the diaphragm 314 and bellows 328 are configured to elastically deform or flex to reduce wear and improve the reliability of fuel nozzle assembly 300. Accordingly, the exemplary fuel nozzle assembly 300, including diaphragm member 314 and bellows 328 are configured to compensate for movement of turbine components over time, thereby reducing stresses on the fuel nozzle assembly 300.
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.
