Methods and apparatus for providing a sacrificial shield for a fuel injector

Embodiments of methods and apparatus for providing a sacrificial shield for a fuel injector are provided. According to one example embodiment, a method for shielding a fuel injector associated with a combustion device is provided. The method can include providing at least one shield support device operable to mount to a tip of a fuel injector. The method can also include mounting a plurality of shields to the at least one support device, wherein each of the plurality of shields is spaced apart from each respective adjacent shield by at least one segmentation, and wherein each of the plurality of shields is operable to reduce heat exposure to the tip of the fuel injector.

FIELD OF THE INVENTION

The invention relates to combustion equipment, and more specifically relates to methods and apparatus for providing a sacrificial shield for a fuel injector.

BACKGROUND OF THE INVENTION

Generally, fuel is introduced into a combustion chamber for a gas turbine by one or more fuel injectors. Various fuels can include natural gas, coal slurry, and other fossil fuel-based, carbon-based or hydrogen-based fuels. Fuel injectors typically have a limited life span due to their constant exposure to high temperatures. High temperatures are caused by radiant heat from the partial combustion of fuel and oxygen within the combustion chamber. When a fuel injector begins to show heat damage or otherwise fails due to overheating, the associated gas turbine must be shut down to permit repairs or replacement of the damaged fuel injector.

At least one conventional fuel injector uses water circulation to cool particular portions of the fuel injector. In such a fuel injector, cooling can be achieved by circulating water in one or more cavities in the tip of the fuel injector and/or within a jacket surrounding some or all of the body of the fuel injector. However, conventional fuel injectors using water cooling require operating and maintaining associated water circulation systems, which increase the cost to operate the gas turbine.

Accordingly, there is need for methods and apparatus for increasing the life of a fuel injector. There is a further need for providing a sacrificial shield for a fuel injector. There is a further need for providing shielding to a fuel injector associated with a combustion device.

BRIEF DESCRIPTION OF THE INVENTION

Embodiments of the invention can address some or all of the needs described above. According to one embodiment of the invention, there is disclosed a method for providing a sacrificial shield for a fuel injector. The method can include providing at least one shield support device operable to mount to a tip of a fuel injector. The method can also include mounting a plurality of shields to the at least one support device, wherein each of the plurality of shields is spaced apart from each respective adjacent shield by at least one segmentation, and wherein each of the plurality of shields is operable to reduce heat exposure to the tip of the fuel injector.

According to another embodiment of the invention, there is disclosed an apparatus for providing shielding to a fuel injector associated with a combustion device. The apparatus may include at least one shield support device operable to mount to a tip of a fuel injector. The apparatus can also include a plurality of shields to the at least one support device, wherein each of the plurality of shields is spaced apart from each respective adjacent shield by at least one segmentation, and wherein each of the plurality of shields is operable to reduce heat exposure to the tip of the fuel injector.

According to yet another embodiment of the invention, there is disclosed a fuel injector for a combustion system. The fuel injector can include a tip end. The fuel injector can also include at least one shield support device operable to mount to adjacent to the tip end. Furthermore, the fuel injector can include a plurality of shields to the at least one support device, wherein each of the plurality of shields is spaced apart from each respective adjacent shield by at least one segmentation, and wherein each of the plurality of shields is operable to reduce heat exposure to the tip of the fuel injector.

Other embodiments, aspects, and features of the invention will become apparent to those skilled in the art from the following detailed description, the accompanying drawings, and the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

Disclosed are methods and methods and apparatus for providing a sacrificial shield for a fuel injector.FIG. 1illustrates a perspective view of an example fuel injector100and apparatus102in accordance with an embodiment of the invention.FIGS. 2-9illustrate various views of either or both the example fuel injector100and apparatus102shown inFIG. 1.FIG. 1shows certain components of an example fuel injector100, which includes a body104and a tip106adjacent to one end of the body104. In the embodiment shown inFIGS. 1-4and7, the body104can generally be, for example a cylindrical tube-shaped portion connected to, for example, a generally tapering and open-ended portion forming the tip106. The apparatus102shown inFIG. 1can include at least one shield support device108, a plurality of layers110,112,114of shields116, and at least one retaining device118. As shown by way of example inFIGS. 1,5, and7, a shield support device108can be a ring-shaped device with one or more slots120,122,124operable to receive a corresponding plurality of shields, such as116. As shown inFIGS. 4 and 7, the shield support device108can generally mount adjacent the tip106of a fuel injector, such as100.

Each of the plurality of shields116, for example, shields116A,116B, . . .116N, can also be known as a “leaf” or collectively as “leaves”. Collectively, the leaves or plurality of shields116can be arranged generally circumferentially around a portion of a tip of a fuel injector, such as106. In one embodiment, each of the plurality of shields can be made from materials including, but not limited to, a ceramic, a sintered ceramic, a ceramic composite, a ceramic coated metal, mechanically alloyed oxide dispersion strengthened metals such as PM 2000, stainless steel, superalloys, nickel-chromium-aluminum-iron alloys such as Haynes 214 alloy nickel-chromium-tungsten-molybdenum alloys such as Haynes 230 alloy, an oxidizing material, a reducing material, or any combination thereof. In the example shown, each of the plurality of shields116can be shaped to generally conform with the outer surface contour of the body104and/or tip106of the fuel injector100. In the embodiment shown inFIGS. 3 and 7, the inner layer110of plurality of shields116can, for example, have a first portion126generally conforming with the outer surface contour of the body104, and a second portion128generally conforming with the outer surface contour of the tip106to form an open-tipped cone-shape. When each of the inner layer110of plurality of shields116is mounted to the innermost slot120, the outer surface of the tip106portion of the fuel injector100can generally be shielded from direct exposure to radiant and/or convective heat when the fuel injector100and mounted apparatus102are inserted into a combustion chamber associated with a gas turbine. Each of the slots120,122,124shown inFIGS. 5 and 7are machined or otherwise molded circumferentially around the outer periphery of the shield support device108. As shown inFIGS. 3,5, and7, other layers112,114of shields116can overlap the initial or inner layer110of plurality of shields116. For example, an intermediate layer112and outer layer114of shields116can respectively mount to an intermediate slot122and/or outer slot124, which provide concentric positioning of each successive layer112,114of shields116to the initial or inner layer110of shields116.

Depending on the type of materials used for the shield support device108and the shields116, a variety of mounting devices and/or techniques can be used including, but not limited to, welding, spot welding, tack welding, stitch welding, brazing, bolting, pressure fitting, swage fitting, anti-rotation pins, and any combination thereof. Furthermore, depending on the position, shape and/or length of the slots120,122,124in the at least one shield supporting device108, any number of shields116in the respective layers110,112,114can be designed or otherwise shaped to provide radiant heat protection to either or both the tip106of the fuel injector100and any underlying layers of shields116.

As shown inFIGS. 3 and 5, each of the plurality of shields110can be spaced apart from each respective adjacent shield of the same layer by at least one segmentation130. Generally, a segmentation130can permit adjacent shields116of the same layer, such as110,112,114, to thermally expand and/or vibrate during operation of the fuel injector100and/or use of the apparatus102. In the example shown inFIGS. 3 and 5, the segmentation130is relatively narrow and consistent open space or gap between adjacent shields116. In other embodiments, a segmentation can include, but is not limited to, a fault line, a perforation, a weakened portion, an etched line, or an etched pattern. In any instance, the segmentation130can facilitate the “shedding of” or loss of an adjacent shield when the adjacent shield becomes overheated or otherwise damaged, and any remaining shields mounted to the shield support device108can maintain protection of adjacent portions of the tip106.

With each successive layer112,114of shields116, the length of successive layers112,114of shields116may generally become relatively greater in length to provide heat protection to the inner layer110of shields116. In one embodiment, each successive layer of shields116may cover a substantial portion of an adjacent inner shield, with a relatively small concentric-shaped portion of each inner shield exposed when axially viewed from the tip of the fuel injector100. Each shield116within each layer110,112,114may generally have a similar width and shape. However, in certain embodiments each successive layer112,114of shields116may have fewer or greater numbers of respective shields than the initial or inner layer110of shields116, and each layer112,114of shields116may have a dissimilar width, length, and shape than each shield of the initial or inner layer110of shields116. As shown inFIGS. 1,6,8and9, the collective layers110,112,114of shields116can protect the tip106of a fuel injector100from radiant and convective heat, with each successive layer112,114of shields116protecting a respective underlying layer110,112of shields116. Thus, in the embodiment shown, three layers110,112,114of shields116can be utilized to protect a tip106of a fuel injector100. In other embodiments, fewer or greater numbers of layers of shields can utilized.

In the embodiment shown inFIGS. 1,5,7, and8, at least one retaining device118can facilitate the mounting the at least one shield supporting device108to the tip106of the fuel injector100. In this embodiment, the at least one retaining device is ring-shaped to generally conform with a cavity132machined in the exterior surface of the at least one shield supporting device108. When the at least one shield supporting device108is mounted to the exterior surface of the tip106of the fuel injector100, the at least one retaining device118can be mounted into the corresponding cavity132of the at least one shield supporting device108to provide additional gripping force by the at least one shield supporting device on the exterior surface of the tip106of the fuel injector100.

As shown inFIGS. 5 and 9, a series of notches134in an edge of at least one shield supporting device108can facilitate mounting and/or positioning the shield supporting device108with respect to the tip106. Any number of a corresponding guides can be present on the exterior surface of the body104of the fuel injector100, and when the series of notches134of the shield supporting device108are aligned with the guides, the notches134can facilitate mounting the shield supporting device108adjacent to the tip106. Thus, in the embodiment shown, a combination of corresponding guides and notches134can be used to mount the shield supporting device108with respect to the tip106. In other embodiments, a variety of other devices and/or techniques can be used.

In one embodiment, one or more shields116can be brazed into corresponding slots in a shield support device such as108. A portion of the shield support device108could then be swaged to maintain the positions of the shields116with respect to the shield support device108. In another embodiment, a shield support device such as108could be made from a plurality of segments, which together could form a relatively thick circular-shaped ring. In this configuration, a relatively thin and smaller first ring-shaped segment with a first layer of shields mounted to the first ring-shaped segment could be fillet welded to the body104and/or tip106of the fuel injector100. An intermediate and larger second ring-shaped segment with a second layer of shields mounted to the second ring-shaped segment could be fillet welded to the body104and/or tip106of the fuel injector100. Then, an outer third ring-shaped segment with a third layer of shields mounted to the third ring-shaped segment could be fillet welded to the body104and/or tip106of the fuel injector100.

Other configurations for an apparatus can exist in accordance with other embodiments of the invention depending on the shape and size of the fuel injector associated with a combustion device. The apparatus102shown inFIGS. 1-9is shown by way of example only, and other embodiments of the apparatus can provide sacrificial shielding of a body and/or tip of a fuel injector.

FIG. 10is a flowchart illustrating an example method1000for shielding a fuel injector associated with a combustion device. In the embodiment shown, the example method1000can be implemented to shield a fuel injector associated with a combustion device, such as a fuel injector100and apparatus102shown inFIGS. 1-9.

The example method begins at block1002. At block1002, at least one shield support device operable to mount to a tip of a fuel injector is provided, as is described with reference toFIGS. 1-9.

In one aspect of an embodiment of the invention, providing at least one shield support device operable to mount to a tip of a fuel injector can include providing a ring-shaped shield support device comprising a plurality of slots operable to receive a corresponding plurality of shields.

In another aspect of an embodiment of the invention, the plurality of shields can include at least one of: a ceramic, a sintered ceramic, a ceramic composite, a ceramic coated metal, mechanically alloyed oxide dispersion strengthened metals such as PM 2000, stainless steel, superalloys, nickel-chromium-aluminum-iron alloys such as Haynes 214 alloy, nickel-chromium-tungsten-molybdenum alloys such as Haynes 230 alloy, an oxidizing material, a reducing material, or any combination thereof.

Following block1002is block1004, in which a plurality of shields is mounted to the at least one support device, wherein each of the plurality of shields is spaced apart from each respective adjacent shield by at least one segmentation, and wherein each of the plurality of shields is operable to reduce heat exposure to the tip of the fuel injector.

In one aspect of an embodiment of the invention, mounting a plurality of shields to the at least one support device can include inserting the plurality of shields into respective slots provided in the at least one support device.

In another aspect of an embodiment of the invention, the at least one segmentation can include at least one of: a gap between adjacent shields, a fault line, a perforation, a weakened portion, an etched line, or an etched pattern.

In an embodiment of the invention, the method1000can include mounting a plurality of layers of the plurality of shields to the at least one shield support device, wherein each of the plurality of layers of the plurality of shields is operable to reduce heat exposure to the tip of the fuel injector.

In an embodiment of the invention, the method1000can include mounting the at least one shield support device to the tip of the fuel injector.

In an embodiment of the invention, the method1000can include mounting a retaining device operable to maintain at least one position of the at least one shield support device with respect to the tip of the fuel injector.

The method1000ends after block1004

The example elements ofFIG. 10are shown by way of example, and other process embodiments can have fewer or greater numbers of elements, and such elements can be arranged in alternative configurations in accordance with other embodiments of the invention.