Micro-mixer fuel plenum and methods for fuel tube installation

The present application provides a fuel plenum for a micro-mixer combustor. The fuel plenum may include a first assembly plate with a first assembly plate aperture, a second assembly plate with a second assembly plate aperture, a fuel tube extending through the first assembly plate aperture of the first assembly plate and the second assembly plate aperture of the second assembly plate, and an installation insert positioned between the fuel tube and the first assembly plate aperture.

TECHNICAL FIELD

The present application and the resultant patent relate generally to gas turbine engines and more particularly relate to a fuel plenum for a micro-mixer combustor and methods for installing fuel tubes therein with relaxed tolerances and an improved lifetime.

BACKGROUND OF THE INVENTION

Operational efficiency and output of a gas turbine engine generally increases as the temperature of the hot combustion gas stream increases. High combustion gas stream temperatures, however, may produce higher levels of nitrogen oxides (NOx) and other types of regulated emissions. A balancing act thus exists between operating a gas turbine engine in an efficient temperature range while also ensuring that the output of nitrogen oxides and other types of regulated emissions remain below mandated levels. Lower emission levels of nitrogen oxides and the like may be promoted by providing for good mixing of the fuel stream and the air stream before combustion. Such premixing tends to reduce combustion temperatures and the output of nitrogen oxides. One method of providing such good mixing is through the use of a micro-mixer combustor where the fuel and the air are mixed in a number of micro-mixer tubes positioned within a fuel plenum.

Specifically, a micro-mixer combustor generally includes a fuel plenum with a number of fuel tubes extending through a number of support or assembly plates. Current methods for installing the fuel tubes require precise machining of a number of apertures through the assembly plates. The fuel tubes then may be brazed directly to the assembly plates. Requiring two assembly plates to be prepared and aligned, however, such that the fuel tubes may be brazed properly to both assembly plates may be a manufacturing challenge. This challenge may be further complicated when fuel tube tolerances are taken into account as well as the requirement that not one but multiple fuel tubes must be brazed to a single assembly plate. Such requirements may lead to increased manufacturing costs, stress on the components, and/or inefficient overall operation.

There is thus a desire for an improved micro-mixer fuel plenum and methods for installing fuel tubes therein. Such an improved micro-mixer fuel plenum design may provide fast and efficient fuel tube installation with relaxed overall tolerances.

SUMMARY OF THE INVENTION

The present application and the resultant patent thus provide a fuel plenum for a micro-mixer combustor. The fuel plenum may include a first assembly plate with a first assembly plate aperture, a second assembly plate with a second assembly plate aperture, a fuel tube extending through the first assembly plate aperture of the first assembly plate and the second assembly plate aperture of the second assembly plate, and an installation insert positioned between the fuel tube and the first assembly plate aperture.

The present application and the resultant patent further provide a method of installing a fuel tube into a fuel plenum. The method may include the steps of positioning a first aperture in a first assembly plate, positioning a second aperture in a second assembly plate, extending a fuel tube between the first aperture of the first assembly plate and the second aperture of the second assembly plate, inserting an installation insert between the first aperture of the first assembly plate and the fuel tube, and brazing the installation insert to the fuel tube and/or the first assembly plate.

The present application and the resultant patent further provide a fuel plenum. The fuel plenum may include a first assembly plate with a number of first assembly plate apertures, a second assembly plate with a number of second assembly plate apertures, a number of fuel tubes extending through the first assembly plate apertures of the first assembly plates and the second assembly plate apertures of the second assembly plates, and a number of installation inserts positioned between the fuel tubes and the first assembly plate apertures. The installation inserts may include a circular flange sized to cover one of the first assembly plate apertures.

These and other advantages and improvements of the present application and the resultant patent will become apparent to one of ordinary skill in the art upon review of the following detailed description when taken in conjunction with the several drawings and the appended claims.

DETAILED DESCRIPTION

Referring now to the drawings, in which like numerals refer to like elements throughout the several views,FIG. 1shows a schematic view of gas turbine engine10as may be used herein. The gas turbine engine10may include a compressor15. The compressor15compresses an incoming flow of air20. The compressor15delivers the compressed flow of air20to a combustor25. The combustor25mixes the compressed flow of air20with a pressurized flow of fuel30and ignites the mixture to create a flow of combustion gases35. Although only a single combustor25is shown, the gas turbine engine10may include any number of the combustors25. The flow of combustion gases35is in turn delivered to a turbine40. The flow of combustion gases35drives the turbine40so as to produce mechanical work. The mechanical work produced in the turbine40drives the compressor15via a shaft45and an external load50such as an electrical generator and the like.

The gas turbine engine10may use natural gas, liquid fuels, various types of syngas, and/or other types of fuels and blends thereof. The gas turbine engine10may be any one of a number of different gas turbine engines offered by General Electric Company of Schenectady, N.Y., including, but not limited to, those such as a7or a9series heavy duty gas turbine engine and the like. The gas turbine engine10may have different configurations and may use other types of components. Other types of gas turbine engines also may be used herein. Multiple gas turbine engines, other types of turbines, and other types of power generation equipment also may be used herein together.

FIG. 2shows a schematic diagram of an example of the combustor25as may be used with the gas turbine engine10described above. The combustor25may extend from an end cap52at a head end to a transition piece54at an aft end about the turbine40. A number of fuel nozzles56may be positioned about the end cap52. A liner58may extend from the fuel nozzles56towards the transition piece54and may define a combustion zone60therein. The liner58may be surrounded by a flow sleeve62. The liner58and the flow sleeve62may define a flow path64therebetween for the flow of air20from the compressor15or otherwise. The combustor25described herein is for the purpose of example only. Combustors with other components and other configurations may be used herein

FIGS. 3 and 4show an example of a known micro-mixer fuel plenum70. The micro-mixer fuel plenum70may be used about the fuel nozzles56or otherwise. The micro-mixer fuel plenum70may include a number of fuel tubes74therein. The fuel tubes74may extend from and through a first support or assembly plate76on a first end78thereof to and through a second support or assembly plate80on a second end82thereof. Any number of the fuel tubes74may be used herein in varying configurations. Specifically, the fuel tubes74and the assembly plates76,80may have any size, shape, or configuration.

As is shown inFIG. 4, current assembly methods require the fuel tubes74to be brazed directly to the assembly plates76,80. The assembly plates76,80thus include a number of apertures84surrounded by a raised braze surface86. A braze material88may be positioned between the fuel tube74and the braze surface86for the brazing process. The braze material88may be conventional. As described above, the process of brazing requires tight tolerances between the surfaces to be attached during the brazing process. Any gaps between the respective components may lead to a leakage therethrough and a reduction in overall efficiency. The micro-mixer fuel plenum70described herein is for the purpose of example only. Many other types of micro-mixer fuel plenum designs and components may be used in varying sizes, shapes, or configurations.

FIG. 5shows an example of a fuel plenum100as may be described herein. The fuel plenum100may be a micro-mixer fuel plenum110. Other types of fuel plenums may be used herein. The fuel plenum100may include a first support or assembly plate120on a first side130thereof and a second support or assembly plate140on a second side150thereof. Any number of the plates may be used herein. A number of fuel tubes160may extend through the first assembly plate120and the second assembly plate140of the fuel plenum100. Any number of the fuel tubes160may be used herein. The fuel tubes160may have any size, shape, or configuration. The fuel tubes160may extend through a number of first assembly plate apertures170in the first assembly plate120and a number of second assembly plate apertures180on the second assembly plate140. Although the assembly plate apertures170,180may be sized for the fuel tubes160to pass therethrough, the apertures170,180need not have the same tight tolerances as described above. Given such, the second assembly plate aperture180is shown in this example as being larger in diameter than the first assembly plate aperture170. Neither aperture170,180, however, need be as closely tolerance with respect to the fuel tube160as compared to the configuration shown inFIG. 4. The apertures170,180thus may have any suitable size, shape, or configuration.

The fuel plenum100also may include one or more installation inserts190. In this example, the installation inserts190may include a tube portion200and a surrounding circular flange210. The tube portion200and the circular flange210may have a substantial “top hat” like configuration. The tube portion200may be sized for the respective fuel tube160with reasonably corresponding tolerances. The circular flange210may extend laterally away from the fuel tube160and cover the apertures170,180. A braze material220may be positioned between the tube portion200of the installation insert190and the fuel tube160and/or between the circular flange210and the assembly plates120,140. The braze material220may secure the fuel tube160to the tube portion200and the assembly plates120,140to the circular flange210. The fuel tube160outside diameter will be held within the inside diameter of the tube portion200of the insulation insert190. The diameter of the assembly plate apertures170,180, however, may have the larger tolerances described above due to the ability of the insulation insert190to fill any misalignment. Moreover, the joint formed by the braze material220will be placed in compression during thermal growth of the fuel tube160so as to extend the expected life of the joint therebetween. Other components and other configurations may be used herein.

FIG. 6shows a further embodiment of a fuel plenum250as may be described herein. The fuel plenum250may have a first support or assembly plate260on a first side270and a second support or assembly plate280on a second side290thereof. Any number of the plates may be used herein. A number of fuel tubes300may extend through the assembly plates260,280. Specifically, the assembly plates260,280may have a first assembly plate aperture310and a second assembly plate aperture320. In this example, the first assembly plate260may include a braze surface330similar to that described inFIG. 4. An amount of a braze material340may be positioned between the braze surface330and the fuel tube300. The second aperture320of the second assembly plate280may not be as toleranced as the first aperture310about the braze surface330. In this example, the fuel tube300may include an installation insert345thereon. The installation insert345may include a circular flange350positioned about the second aperture320. The circular flange350may be brazed to the second assembly plate280with an amount of the brazed material340. The circular flange350thus may be used in case of occasional misalignments between the plates260,280or otherwise. Other components and other configurations may be used herein.

The methods and structures shown inFIGS. 5 and 6may be used independently and/or in combination with one another and/or with the assembly shown inFIG. 4. The fuel plenums thus may have relaxed manufacturing tolerances given the use of the installation inserts. For example, the installation insert may be machined independently of the assembly plates. The inner diameter of the tube portion200of the insulation insert190may suitably match the outer diameter of the fuel tube160so as to provide an optimal gap for brazing. Likewise, the circular flanges210,350also may be brazed to the assembly plates so as to reduce the diameter and the true position of the apertures and the fuel tubes therein. The fuel plenums described herein thus allow for a certain amount of misalignment between the assembly plates. Moreover, the steps described herein allow for a reliable and repeatable method in which the fuel tube brazes may be placed in compression so as to improve the expected life of the brazed joint and thus potentially increase the overall lifetime of the micro-mixer fuel plenum and related components.