Patent Application
20130232977
The present invention generally involves a fuel nozzle and a combustor for a gas turbine.
Gas turbines generally include a combustor with one or more fuel nozzles positioned about an end cover in various configurations. For example, some combustors may include a six fuel nozzle configuration which includes a center fuel nozzle surrounded by five outer fuel nozzles. In particular combustor designs, the fuel nozzle(s) extend downstream from the end cover and at least partially through one or more annular passage(s) of a cap assembly. Typically, the annular passage(s) includes an annular impingement sleeve disposed concentrically within the annular passage and/or a floating collar coupled to the impingement sleeve and/or the cap assembly. During assembly of the combustor, the fuel nozzle(s) are generally positioned so that a radial gap exists between the fuel nozzle and the floating collar.
In operation, a fuel and/or a working fluid flow through the fuel nozzle(s) and into the floating collar before exiting the cap assembly for combustion in a combustion zone within the combustor. However, during operation the floating collar may shift radially and/or axially due to combustor dynamics, thermal growth and/or compressor discharge pressures within the combustor, thereby contacting the fuel nozzle(s) and potentially reducing the mechanical life of the fuel nozzle(s) and/or the cap assembly.
Improved floating collar designs, however, may result in increased manufacturing, maintenance, and repair costs. For example, improved floating collar designs typically incorporate costly wear resistant materials. However, these materials do not prevent the collar from contacting the fuel nozzle. Therefore, an improved fuel nozzle design that eliminates the floating collar from the cap assembly would be useful.
Aspects and advantages of the invention are set forth below in the following description, or may be obvious from the description, or may be learned through practice of the invention.
One embodiment of the present invention is a fuel nozzle for a gas turbine. The fuel nozzle includes an annular passage configured to flow a fuel and includes a first end axially separated from a second end. A disk concentric with the annular passage is disposed at the second end and extends radially outward from the second end. A plurality of passages extend through the disk from an upstream surface of the disk to a downstream surface of the disk and are configured to impart swirl to a fluid flowing through the passages. A shroud circumferentially surrounds the disk and includes an upstream end axially separated from a downstream end, wherein the shroud is coupled to the disk.
Another embodiment is a fuel nozzle for a gas turbine that includes an annular passage configured to flow a fuel and includes a first end axially separated from a diverging second end. A disk concentric with the annular passage is disposed at the diverging second end and extends radially outward from the diverging second end. A plurality of passages extends through the disk from an upstream surface of the disk to a downstream surface of the disk. A shroud, including an upstream end axially separated from a downstream end, circumferentially surrounds and extends axially downstream from the disk and is coupled to the disk. The fuel nozzle further includes a spring at least partially surrounding the shroud.
Embodiments of the present invention may also include a combustor. The combustor generally includes an end cover. An annular passage extends from the end cover and is configured to flow a fuel. The annular passage includes a first end axially separated from a diverging second end. A disk concentric with the annular passage is disposed at the diverging second end and extends radially outward from the diverging second end. A plurality of passages extend through the disk from an upstream surface of the disk to a downstream surface of the disk. The passages are configured to impart swirl to a fluid flowing through the passages. A shroud at least partially circumferentially surrounds the disk and extends axially downstream from the disk. The combustor further includes a spring at least partially surrounding the shroud.
Those of ordinary skill in the art will better appreciate the features and aspects of such embodiments, and others, upon review of the specification.
A full and enabling disclosure of the present invention, including the best mode thereof to one skilled in the art, is set forth more particularly in the remainder of the specification, including reference to the accompanying figures, in which:
Reference will now be made in detail to present embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the invention.
Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope or spirit thereof. For instance, features illustrated or described as part of one embodiment may be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.
Various embodiments of the present invention provide a combustor and a fuel nozzle for a gas turbine. The combustor generally includes an end cover, a casing, a fuel nozzle and a cap assembly. In particular embodiments, the fuel nozzle may include an annular passage configured to connect to the end cover and to flow a fuel and/or a diluent. The fuel nozzle may further include a disk disposed at one end of the annular passage. In particular embodiments, a plurality of passages may extend from an upstream surface of the disk through a downstream surface of the disk and may be configured to impart swirl to the fuel and/or a working fluid passing through the passages. The fuel nozzle may further include a shroud generally surrounding and extending downstream form the disk. In certain embodiments, the fuel nozzle may also include a spring and an annular plate at least partially surrounding the shroud. The cap assembly may include an annular passage and an annular impingement sleeve disposed within the annular passage and configured to receive the fuel nozzle. In this manner, the various embodiments within the scope of the present invention may increase the mechanical life of the fuel nozzle and the cap assembly without compromising cooling flow within the combustor, reduce manufacturing costs of the combustor and provide a retrofit option for existing gas turbines. Although exemplary embodiments of the present invention will be described generally in the context of a combustor incorporated into a gas turbine for purposes of illustration, one of ordinary skill in the art will readily appreciate that embodiments of the present invention may be applied to any combustor and are not limited to a gas turbine combustor unless specifically recited in the claims.
As shown in
The disk 32 may be disposed at the second end 40 of the annular passage 30. The disk 32 may be mechanically coupled; for example, welded or brazed, or the disk may be cast and/or machined as part of the annular passage 30. The disk 32 may be constructed from steel or steel alloys capable of withstanding the expected temperatures found within the combustor 14, and may be constructed of similar or dissimilar materials from that of the annular passage 30 and/or the shroud 34. The disk 32 generally extends radially outward and axially downstream and/or upstream from the second end 40. The disk 32 also includes an upstream surface 44 axially separated from a downstream surface 46 and a circumferential outer surface 48 extending axially from the upstream surface 44 to the downstream surface 46. The disk 32 may include a plurality of passages 50 extending through the disk 32 from the upstream surface 44 to the downstream surface 46. In particular embodiments, the passages 50 may be configured to impart swirl to the fuel and/or the working fluid flowing through the passages 50. The passages 50 may be configured to impart clockwise and/or counterclockwise swirl. In this manner, the fuel and/or working fluid may premix prior to combustion, thereby resulting in a more efficient burn of the fuel and/or the working fluid and decreased NOx emissions.
The shroud 34 generally circumferentially surrounds and may be coupled to the disk 32. In alternate embodiments, the shroud 34 may be coupled to the annular passage 30. The shroud 34 may be coupled by any mechanical means, such as welding or brazing, or the shroud may be cast and/or machined as part of the annular passage 30 and/or the disk 32. The shroud 34 includes an upstream end 52 axially separated from a downstream end 54 and forms an axial flow path for the fuel and/or the working fluid. The shroud 34 may be constructed from steel or steel alloys capable of withstanding the expected temperatures found within the combustor 14, and may be constructed of similar or dissimilar materials from that of the annular passage 30 and/or the disk 32. In particular embodiments, the shroud 34 may further include a flange 56 extending radially outward from the shroud 34. The flange 56 may at least partially circumferentially surround the shroud 34 and may be disposed at any point axially along the shroud 34. In particular embodiments, the flange 56 may be coupled to the shroud 34 at or near the upstream end 52. The flange 56 may be coupled by any mechanical means, such as welding or brazing, or the flange 56 may be cast and/or machined as part of the shroud 34. The flange 56 may be constructed from steel or steel alloys capable of withstanding the expected temperatures and may be annularly or conically shaped to reduce the flow resistance as the compressed working fluid flows around the flange 56.
The spring 36 extends axially downstream from the upstream end 52 of the shroud 34 and includes a first surface 58 axially separated from a second surface 60. The first surface 58 and/or the second surface 60 may be filed or otherwise formed to provide a generally flat surface. In particular embodiments, the spring 36 may be coupled to the shroud 34. For example, the first surface 58 of the spring may be coupled to the upstream end of the shroud 34 and/or to the flange 56. The spring 36 may be coupled to the shroud 34 or to the flange 56 by any mechanical means, such as welding or brazing. In particular embodiments, as shown, the spring 36 may include a bellows spring 36. In this manner, the bellows spring 36 may provide a compressive force to seal the fuel nozzle(s) 24 with the cap assembly 26. As a result, the bellows spring 36 may form a plenum wherein the working fluid may flow to cool the fuel nozzle(s) 24. In addition, the bellows spring 36 may decrease the likelihood of misalignment in both the axial and/or radial directions between the fuel nozzle(s) 24 and the cap assembly 26 during assembly and/or operation of the combustor. In alternate embodiments, the spring 36 may include any spring 36 designed to resist compression loads. For example, the spring 36 may include a coil spring, a conical spring, a helical spring, a wave spring or a Belleville washer. The spring 36 may be constructed from steel or steel alloys or any material capable of withstanding the expected temperatures and compressive loads.
In particular embodiments, the fuel nozzle(s) 24 may include an at least partially annular plate 62 disposed on the second surface of the spring 60. As shown in
As shown in
During assembly of the combustor, the fuel nozzle(s) may be inserted generally axially through the impingement sleeve. The annular plate first mating surface may seal against the impingement sleeve second mating surface due to a compressive force provided by the spring. The compressive force may also provide for proper axial and radial alignment between the fuel nozzle(s) and the cap assembly. Particularly, in the case where the cap assembly may be misaligned. During operation of the combustor, the spring may allow for thermal growth variations between the fuel nozzle(s) and the cap assembly without compromising the seal. As a result, leakage of the working fluid and/or the fuel may be significantly reduced.
The technical effect of the present matter is improved performance and/or operation of a gas turbine. In particular, by adding the shroud and and/or the spring to the fuel nozzle(s), wear between the cap assembly and the fuel nozzle(s) may be significantly reduced and the need for expensive wear coatings may be eliminated. As a result, the mechanical life of the combustor may be extended and the design simplified, thereby resulting in decreased operating costs. In addition, the design may be retrofitted to existing gas turbine combustors to increase the life of the fuel nozzle(s) and the cap assembly.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
