Patent Application
20140318140
The present invention generally relates to a gas turbine combustor. More specifically, embodiments of the present invention relate to an apparatus and method for altering the natural frequencies of the dome plate assembly for a gas turbine combustor.
In a typical gas turbine engine, a compressor having alternating stages of rotating and stationary airfoils is coupled to a turbine through an axial shaft, with the turbine also having alternating stages of rotating and stationary airfoils. The compressor stages decrease in size in order to compress the air passing therethrough. The compressed air is then supplied to one or more combustors, which mixes the air with fuel. An ignition source proximate the one or more combustors ignite the mixture, forming hot combustion gases. The expansion of the hot combustion gases drives the stages of a turbine, which is coupled to the compressor through an axial shaft. The exhaust gases can then be used as a source of propulsion, to generate steam through a heat recovery steam generator, or in powerplant operations to turn a shaft coupled to a generator for producing electricity.
The combustion system of a gas turbine engine can take on a variety of configurations. A combustion system for a gas turbine engine can comprise a single combustion chamber, a plurality of individual combustion chambers spaced about the axis of the engine, a plenum-type combustion system, or a variety of other combustion systems. Depending on the engine geometry, performance requirements, and physical operating location, the exact combustor arrangement will vary.
A typical combustion system generally comprises at least a casing secured to the frame of the engine, a combustion liner secured within at least a part of the casing, and one or more fuel nozzles positioned within or adjacent to the combustion liner for injecting a fuel (gas, liquid, or both) into the combustion chamber. The combustion system is in fluid communication with the engine. More specifically, the casing and liner arrangement provides a way for air from the compressor to enter the combustion system, where it mixes with fuel from the one or more fuel nozzles. The fuel-air mixture is ignited by an ignition source, such as a spark igniter. Hot combustion gases travel through the combustion liner and often through one or more transition pieces and into the turbine. The transition piece is essentially a duct having a geometry that changes from the shape of the combustor to the inlet of the turbine.
The combustion liner is at the center of combustor operations. The combustion liner geometry is dictated by the operating parameters of the engine, performance requirements, or available geometry. While combustion liner geometries can vary, the combustion liner typically includes at least a portion for receiving fuel nozzles, for mixing fuel and air together and for containing the reaction when the fuel and air mixture is ignited.
Combustion liners of the prior art have met certain performance requirements, but have also exhibited various shortcomings. Combustion liners are subjected to various thermal conditions and as such must be able to withstand the high thermal and mechanical stresses of such operating conditions. By nature, the combustion liner has a series of natural operating frequencies. The gas turbine engine and combustion system also have a natural frequency, and orders of the natural frequency (i.e. 1E, 2E, 3E, etc.). When a component, such as the combustion liner, has a natural frequency or mode that coincides with, or approaches, an engine natural frequency or order thereof, the component can become dynamically excited. If care is not taken to avoid the crossings of these frequencies, operating at these frequencies, or minimizing the time for the crossing, the component may experience excessive wear or failure as a result of the vibratory stress that occurs when operating at or near the natural frequency of the gas turbine engine or combustion system.
In accordance with the present invention, there is provided a novel and improved component for a combustion liner of a gas turbine engine. The combustion liner is generally cylindrical in shape and has an inlet end and a discharge end, opposite the inlet end. The combustion liner of the present invention comprises a premixer assembly capable of receiving a plurality of fuel nozzles. The premixer assembly is designed so as to provide a way of altering its natural frequency.
In accordance with an embodiment of the present invention, there is provided a plate assembly for a gas turbine combustor, the plate assembly comprising a dome plate, a pilot mixer assembly, a plurality of extension tabs extending from an outer wall of the pilot mixer assembly, and a plurality of radially extending struts secured to both the extension tabs and the dome plate.
In accordance with another embodiment of the present invention, a system is provided for altering the natural frequency of a premixer assembly. The system comprises a generally circular dome plate, a pilot mixer having an outer wall portion, a plurality of extension tabs fixed at one end to the outer wall and extending through a pilot cone portion, and a plurality of struts extending between the extension tabs and the dome plate.
In accordance with yet another embodiment of the present invention, a method of altering the natural frequency of a premixer assembly is provided. The method comprises the steps of providing a dome plate, a pilot mixer assembly, a plurality of extension tabs, and a quantity of radially extending struts. The quantity of radially extending struts are secured to the plurality of extension tabs and dome plate. Then, additional radially extending struts are secured to the plurality of extension tabs and dome plate upon a determination to increase stiffness of the dome plate. Altering the stiffness of the dome plate in turn alters its natural frequency such that its natural frequency is outside of the dynamic frequencies generated by the combustion system.
Additional advantages and features of the present invention will be set forth in part in a description which follows, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned from practice of the invention. The instant invention will now be described with particular reference to the accompanying drawings.
The present invention is described in detail below with reference to the attached drawing figures, wherein:
The subject matter of the present invention is described with specificity herein to meet statutory requirements. However, the description itself is not intended to limit the scope of this patent. Rather, the inventors have contemplated that the claimed subject matter might also be embodied in other ways, to include different components, combinations of components, steps, or combinations of steps similar to the ones described in this document, in conjunction with other present or future technologies.
Referring initially to
The present invention is shown in detail in
The dome plate 334 further comprises a plurality of openings, or air holes, 374 extending through the thickness of the dome plate 334. For the embodiment depicted in FIGS. 9 and 12-14, the cooling holes 374 are oriented generally perpendicular to the dome plate 334. Alternatively, the cooling holes 374 could be oriented at a surface angle relative to the dome plate 334 as well as a compound angle. The dome plate 334 includes numerous cooling holes 374 for directing a flow of compressed air into the combustion zone of the combustion liner 300. The exact quantity, size, and shape of the cooling holes 374 can vary depending on the amount of compressed air to be directed through the dome plate 334 as well as to maintain a desired pressure drop into the combustion zone. For the dome plate depicted in
The swirler assemblies 332 are positioned so as to be in fluid communication with adjacent tubes 352, or hoovers, which pass the flow of fuel and air from the swirler assembly 332 to the mixing zone of the combustion liner 300. That is, the swirler assemblies 332 are positioned so as to be adjacent to or slightly engaged in the tubes 352.
The plate assembly 430 also comprises a pilot mixer assembly 440. The pilot mixer assembly 440, while shown in the plate assembly 430 in
The plate assembly 430 also comprises a plurality of extension tabs 450 extending from the outer wall of the pilot mixer assembly 440 and through the pilot cone 448. The plurality of extending tabs 450 are secured to the outer wall 442 of the pilot mixer assembly 440. The plurality of extending tabs can be secured to the outer wall 442 via a weld, braze or other acceptable joining process. Alternatively, the plurality of extending tabs 450 can be integrally formed with the outer wall 442 of the pilot mixer assembly 440, as would be produced via a casting process.
The plate assembly 430 also comprises a plurality of radially extending struts 452 secured to the plurality of extension tabs 450. The plurality of struts 452, or stiffeners, are used to provide increased rigidity and support to the dome plate 334, thereby increasing the stiffness of the plate assembly 430, resulting in an increase in its natural frequency. The struts 452 are oriented generally perpendicular to the dome plate 334 and are secured at one end to the plurality of extension tabs 450 and at an opposing end to the dome plate 334, as shown in
The radially extending struts 452 are secured to the dome plate 334 at multiple locations, as shown in
The radially extending strut and extension tab configuration described herein is merely one such embodiment of a configuration to adjust the natural frequency of the dome plate 334. The design described herein, where the extension tab 450 is secured to the radially extending strut 452, is one such embodiment that lends to ease of manufacturing, lower manufacturing costs, while providing a design that alters the natural frequency of the dome plate. It is conceivable that other configurations for the radially extending strut and extension tabs are possible.
The present invention also provides a system for altering the natural frequency of a premixer assembly, where the system comprises a generally circular dome plate 334 having a central opening 432, an upstream face 334A, an opposing downstream face 334B, and a plurality of cooling holes 374. A pilot mixer assembly 440 is located within the central opening 432 where the pilot mixer assembly 440 has an outer wall 442 and a pilot cone 448 that surrounds a portion of the outer wall 442, as shown in
As discussed above, and shown clearly in
Referring to
Referring now to
The present invention has been described in relation to particular embodiments, which are intended in all respects to be illustrative rather than restrictive. Alternative embodiments and required operations, such as machining of shroud faces other than the hardface surfaces and operation-induced wear of the hardfaces, will become apparent to those of ordinary skill in the art to which the present invention pertains without departing from its scope.
From the foregoing, it will be seen that this invention is one well adapted to attain all the ends and objects set forth above, together with other advantages which are obvious and inherent to the system and method. It will be understood that certain features and sub-combinations are of utility and may be employed without reference to other features and sub-combinations. This is contemplated by and within the scope of the claims.
This application claims priority to U.S. Provisional Patent Application Ser. No. 61/815,835, filed on Apr. 25, 2013. This application is related by subject matter to commonly-assigned U.S. Non-Provisional Patent Applications entitled REMOVABLE SWIRLER ASSEMBLY FOR A COMBUSTION LINER (Attorney Docket No. PSM-316/PSSF.199280) and PREMIXER ASSEMBLY FOR A GAS TURBINE COMBUSTOR (Attorney Docket No. PSM-317/PSSF.199281).
| Number | Date | Country | |
|---|---|---|---|
| 61815835 | Apr 2013 | US |
