Fuel distribution manifold for a combustor of a gas turbine

A fuel distribution manifold for a combustor of a gas turbine includes an annular flange having an outer surface that extends circumferentially around the flange. A primary fuel plenum extends circumferentially within the flange. A first orifice and a second orifice extend radially through the outer surface of the flange to provide for fluid communication into the primary fuel plenum. The first orifice includes an inlet that is adjacent to the outer surface. The second orifice includes an inlet that is adjacent to the outer surface. A fuel distribution cap extends partially across the outer surface of the flange. The fuel distribution cap includes an inlet port. A fuel distribution plenum is at least partially defined within the fuel distribution cap. The fuel distribution plenum is in fluid communication with the inlet port and with the first orifice inlet and the second orifice inlet.

FIELD OF THE INVENTION

The present invention generally involves a combustor for a gas turbine. More specifically, the invention relates to a fuel distribution manifold of the combustor.

BACKGROUND OF THE INVENTION

A combustion section of a gas turbine generally includes a plurality of combustors that are arranged in an annular array around an outer casing such as a compressor discharge casing. Pressurized air flows from a compressor to the compressor discharge casing and is routed to each combustor. Fuel from a fuel nozzle is mixed with the pressurized air in each combustor to form a combustible mixture within a primary combustion zone of the combustor. The combustible mixture is burned to produce hot combustion gases having a high pressure and high velocity. The combustion gases are routed towards an inlet of a turbine of the gas turbine through a hot gas path that is at least partially defined by an annular combustion liner and an annular transition duct that extends downstream from the combustion liner and terminates at the inlet to the turbine. Thermal and kinetic energy are transferred from the combustion gases to the turbine to cause the turbine to rotate, thereby producing mechanical work. For example, the turbine may be coupled to a shaft that drives a generator to produce electricity.

In particular combustors, a combustion module is utilized to inject a generally lean fuel-air mixture into the hot gas path downstream from the primary combustion zone. The combustion module generally includes an annular fuel distribution manifold and a fuel injection assembly that extends between the fuel distribution manifold and the inlet to the turbine. The fuel injection assembly generally includes an annular combustion liner that defines the hot gas path within the combustor. The fuel injection assembly further includes a plurality of radially extending fuel injectors, also known as late lean fuel injectors that are fluidly coupled to the fuel distribution manifold. The fuel injectors inject the lean fuel-air mixture into the hot gas path downstream from the primary combustion zone. As a result, the combustion gas temperature is increased and the thermodynamic efficiency of the combustor is improved without producing a corresponding increase in the production of undesirable emissions such as oxides of nitrogen (NOx).

The fuel distribution manifold includes an annular flange that extends radially outward and circumferentially around the fuel distribution manifold. The flange includes a plurality of axially extending bolt holes arranged circumferentially around the flange and a fuel plenum that is defined within the flange. The flange is bolted to an outer casing that surrounds the combustor to form a seal therebetween. Fuel is delivered to the fuel plenum through an inlet port that extends outward from the flange.

Current fuel distribution manifold designs use a singular inlet orifice that provides for fluid communication between the inlet port and the fuel plenum. At least one of the bolt holes is skipped in order to provide a sufficient inlet area of the inlet orifice to meet the required fuel flow rate to the fuel plenum during late lean fuel injection operation of the combustor. By skipping the one or more bolt hole(s) an uneven preload between the outer casing and the flange results, thereby potentially resulting in leakage of the compressed working fluid around the flange.

A second issue with having a single inlet orifice is that the flow velocity of the fuel through the inlet orifice is undesirably high. In addition, when cold fuel flows into the inlet port and through the inlet orifice, various thermal issues result at an intersection joint formed between the inlet port and the inlet orifice which may impact the overall durability of the fuel distribution manifold. Therefore, an improved fuel distribution manifold, in particular an improved inlet configuration for routing the fuel into the fuel plenum of the fuel distribution manifold would be useful.

BRIEF DESCRIPTION OF THE INVENTION

One embodiment of the present invention is a fuel distribution manifold for delivering fuel to a combustor of a gas turbine. The fuel distribution manifold includes an annular flange having an outer surface that extends circumferentially around the flange. A primary fuel plenum extends circumferentially within the flange. A first orifice and a second orifice extend radially through the outer surface of the flange to provide for fluid communication into the primary fuel plenum. The first orifice includes an inlet that is adjacent to the outer surface. The second orifice includes an inlet that is adjacent to the outer surface. A fuel distribution cap extends partially across the outer surface of the flange. The fuel distribution cap includes an inlet port. A fuel distribution plenum is at least partially defined within the fuel distribution cap. The fuel distribution plenum is in fluid communication with the inlet port and with the first orifice inlet and the second orifice inlet.

Another embodiment of the present invention is a combustion module for a combustor of a gas turbine. The combustion module includes a fuel injection assembly that terminates at an aft end of the combustion module. The fuel injection assembly includes an annular combustion liner that defines a combustion chamber within the combustion module and a fuel injector that provides for fluid communication through the combustion liner and into the combustion chamber. The combustion module further includes a fuel distribution manifold for delivering fuel to the fuel injection assembly. The fuel distribution manifold includes an annular flange having an outer surface that extends circumferentially around the flange. The flange at least partially defines a primary fuel plenum that extends circumferentially within the flange. A first orifice and a second orifice extend radially through the outer surface of the flange to provide for fluid communication into the primary fuel plenum. The first orifice includes an inlet that is adjacent to the outer surface of the flange, and the second orifice includes an inlet adjacent that is adjacent to the outer surface of the flange. The fuel distribution manifold further includes a fuel distribution cap that extends partially across the outer surface of the flange and that has an inlet port. A fuel distribution plenum is at least partially defined within the fuel distribution cap and is in fluid communication with the inlet port. The fuel distribution plenum is in fluid communication with the first orifice inlet and the second orifice inlet.

The present invention may also include a gas turbine. The gas turbine generally includes a compressor, a combustor disposed downstream from the compressor and a turbine disposed downstream from the combustor. The combustor is at least partially surrounded by an outer casing and includes a fuel distribution manifold for delivering fuel to the combustor. The fuel distribution manifold includes an annular flange having an outer surface that extends circumferentially around the flange. The flange is connected to the outer casing. A primary fuel plenum extends circumferentially within the flange. A first orifice and a second orifice extend radially through the outer surface of the flange to provide for fluid communication into the primary fuel plenum. The first orifice has an inlet that is adjacent to the outer surface of the flange, and the second orifice has an inlet that is adjacent to the outer surface of the flange. A fuel distribution cap extends partially across the outer surface of the flange. The fuel distribution cap includes an inlet port. A fuel distribution plenum is at least partially defined within the fuel distribution cap and is in fluid communication with the inlet port. The fuel distribution plenum is in fluid communication with the first orifice inlet and the second orifice inlet.

DETAILED DESCRIPTION OF THE INVENTION

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. As used herein, the terms “first”, “second”, and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. The terms “upstream” and “downstream” refer to the relative direction with respect to fluid flow in a fluid pathway. For example, “upstream” refers to the direction from which the fluid flows, and “downstream” refers to the direction to which the fluid flows. The term “radially” refers to the relative direction that is substantially perpendicular to an axial centerline of a particular component, and the term “axially” refers to the relative direction that is substantially parallel to an axial centerline of a particular component.

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. 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 incorporated into any turbomachine and is not limited to a gas turbine combustor unless specifically recited in the claims.

Referring now to the drawings, wherein identical numerals indicate the same elements throughout the figures,FIG. 1provides a functional block diagram of an exemplary gas turbine10that may incorporate various embodiments of the present invention. As shown, the gas turbine10generally includes an inlet section12that may include a series of filters, cooling coils, moisture separators, and/or other devices to purify and otherwise condition a working fluid (e.g., air)14entering the gas turbine10. The working fluid14flows to a compressor section where a compressor16progressively imparts kinetic energy to the working fluid14to produce a compressed working fluid18at a highly energized state.

The compressed working fluid18is mixed with a fuel20from a fuel supply22to form a combustible mixture within one or more combustors24. The combustible mixture is burned to produce combustion gases26having a high temperature and pressure. The combustion gases26flow through a turbine28of a turbine section to produce work. For example, the turbine28may be connected to a shaft30so that rotation of the turbine28drives the compressor16to produce the compressed working fluid18. Alternately or in addition, the shaft30may connect the turbine28to a generator32for producing electricity. Exhaust gases34from the turbine28flow through an exhaust section36that connects the turbine28to an exhaust stack38downstream from the turbine28. The exhaust section36may include, for example, a heat recovery steam generator (not shown) for cleaning and extracting additional heat from the exhaust gases34prior to release to the environment.

FIG. 2provides a cross sectional side view of a portion of an exemplary gas turbine10including an exemplary combustor50that may encompass various embodiments of the present disclosure. As shown, the combustor50is at least partially surrounded by an outer casing52such as a compressor discharge casing and/or an outer turbine casing. The outer casing52is in fluid communication with the compressor16and at least partially defines a high pressure plenum54that surrounds at least a portion of the combustor50. An end cover56is coupled to the outer casing52at one end of the combustor50.

As shown inFIG. 2, the combustor50generally includes at least one axially extending fuel nozzle58that extends downstream from the end cover56, an annular cap assembly60that extends radially and axially within the outer casing52downstream from the end cover56, an annular hot gas path duct or combustion liner62that extends downstream from the cap assembly60and an annular flow sleeve64that surrounds at least a portion of the combustion liner62. The combustion liner62defines a combustion chamber66within the combustor50and a hot gas path68for routing the combustion gases26through the combustor50. The end cover56and the cap assembly60at least partially define a head end70of the combustor50. The fuel nozzle(s)58extend at least partially through the cap assembly60to provide a first combustible mixture72that consists primarily of the fuel20(FIG. 1) and a portion of the compressed working fluid18from the compressor16to a primary combustion zone74that is defined within the combustion chamber66downstream from the fuel nozzle(s)58.

In particular embodiments, the combustor50includes one or more radially extending fuel injectors76also known as late-lean fuel injectors that extend through the flow sleeve64and the combustion liner62at a point that is downstream from the primary combustion zone74. The combustion liner62may further define a secondary combustion zone78that is proximate to the fuel injector(s)76and downstream from the primary combustion zone74.

As shown inFIG. 2, the combustor50may include an annular fuel distribution manifold100for providing fuel to the combustor50. In particular embodiments, the fuel distribution manifold100provides fuel to the fuel injector(s)76. However, the fuel distribution manifold100may be modified to provide fuel to any part of the combustor50such as to the axially extending fuel nozzle(s)56. As shown, the fuel distribution manifold100may at least partially surround the cap assembly60.

FIG. 3provides a perspective view of the fuel distribution manifold100according to at least one embodiment of the present invention,FIG. 4provides a cross section side view of the fuel distribution manifold100as shown inFIG. 3, andFIG. 5provides a cross section downstream view of the fuel distribution manifold100as shown inFIG. 3. In particular embodiments, as shown inFIG. 3, an annular flange102is disposed at an upstream end104of the fuel distribution manifold and a fuel distribution cap106extends outward from an outer surface108of the flange102. The outer surface108extends circumferentially around the flange102. One or more annular support sleeve(s)110may extend generally downstream from the flange102towards a downstream end112of the fuel distribution manifold100.

In particular embodiments, as shown inFIG. 3, the fuel distribution cap106extends partially across the outer surface108of the flange102. For example, the fuel distribution cap106generally extends axially and circumferentially across at least a portion of the outer surface108of the flange102and radially outward from the outer surface108of the flange102. The fuel distribution cap106may be connected to the flange by welding, brazing or by any other mechanical means known in the art suitable for the operating environment of the fuel distribution manifold100.

As shown inFIG. 4, the fuel distribution manifold100defines an axial direction114that corresponds to an axial centerline116of the flange102and a radial direction118that is defined along a line120that extends perpendicular to the axial centerline116. As shown inFIG. 5, a circumferential direction122is defined with the respect to the axial centerline116of the fuel distribution manifold100.

In particular embodiments, as show inFIGS. 4 and 5, a primary fuel plenum124extends circumferentially within the flange102. The primary fuel plenum124may extend partially or entirely around the flange102. The primary fuel plenum124may be cast into the flange102and/or may be machined into the flange102. As shown inFIG. 4, the primary fuel plenum124may be sealed using an outer band126that extends circumferentially around the flange102. The outer band126may be joined to the flange102in any manner known in the art that is suitable to seal the primary fuel plenum. For example, the outer band126may be brazed or welded to the flange102.

In particular embodiments, as shown inFIG. 5, a plurality of bolt holes128extend axially through the flange102. The bolt holes128are generally evenly spaced circumferentially around the flange102to provide for an even pre-load around the circumference of the flange102when installed into the combustor50(FIG. 2).

FIG. 6provides an enlarged view of a portion of the fuel distribution manifold100as shown inFIG. 5, according to one embodiment of the present invention. As shown inFIG. 6, a plurality of radially extending orifices130extend through the outer surface108of the flange102to provide for fluid communication into the primary fuel plenum124. By having a plurality of the orifices130, additional fuel inlet area may provided when compared to a single orifice without offsetting the spacing between the bolt holes128. As a result fuel velocity may be lowered as the fuel enters the primary fuel plenum124. Each orifice130includes an inlet132generally adjacent to the outer surface108of the flange, an outlet134that is generally adjacent and in fluid communication with the primary fuel plenum124and an inner surface136that extends between the inlet132and the outlet134. In addition, each orifice130may include a step feature138that is disposed generally adjacent to the inlet132.

In one embodiment, the plurality of orifices130include a first orifice140and a second orifice142that extend radially through the outer surface108of the flange102to provide for fluid communication into the primary fuel plenum124. In other embodiments, the plurality of orifices130may include a third orifice144a fourth orifice146, or any number of the orifices130that extend radially through the outer surface108of the flange102to provide fluid communication into the primary fuel plenum124.

As shown inFIG. 6, the orifices130extend between two adjacent bolt holes128without interrupting a common circumferential spacing between each of the plurality of bolt holes128. This allows for an even pre-load at each bolt hole128location around the flange102, thereby providing for an even seal between the outer casing52(FIG. 2) and the flange102. In addition, by having a plurality of the orifices130rather than one large orifice, the wall thickness between each orifice130and a corresponding bolt hole128is optimized, thereby enhancing the durability of the flange102and allowing for a thinner flange102which decreases weight and cost. In one embodiment, the first orifice140is circumferentially separated from the second orifice142by at least one of the plurality of bolt holes128.

FIG. 7provides an enlarged view of a portion of the fuel distribution manifold100as shown inFIG. 6, according to one embodiment of the present invention. In particular embodiments, as shown inFIG. 7, the fuel distribution manifold100includes a plurality of orifice inserts144. Each orifice insert144is received in a corresponding orifice130so as to extend generally radially through the orifice130. Each orifice insert144may be coaxially or concentrically aligned within each corresponding orifice130. Each or some of the orifice inserts144may be sized and/or shaped the same or differently so as to achieve a desired flow rate of fuel flowing through the orifice inserts144into the primary fuel plenum124.

As shown inFIG. 7, the orifice inserts144have a generally cylindrical shape. However, it should be obvious to one of ordinary skill in the art that the orifice inserts144may have any cross section shape which allows fuel to flow through the orifice130into the primary fuel plenum124. For example, the orifice inserts144may have a circular, oval, rectangular, square cross sectional shape or any combination thereof. The orifice inserts144include an inlet146that is disposed at the inlet132of a corresponding orifice130and an outlet148that is disposed generally adjacent to the outlet134of the corresponding orifice130and that is in fluid communication with the primary fuel plenum124.

In one embodiment, as shown inFIG. 7, each orifice insert144includes a rib150or other separation feature that extends outward from an outer surface152of the orifice inserts144. The rib150positions the orifice inserts144concentrically and/or coaxially into the orifice130. The rib150also provides for an insulation gap154between the outer surface152of the orifice insert144and the inner surface136of the orifice130, thereby reducing conductive cooling of the flange102caused by the fuel flowing through the orifice inserts144into the primary fuel plenum124. As a result, thermal stress associated with the thermal gradients between the orifice insert144and the flange102may be reduced which enhances the overall durability of the fuel distribution manifold100.

In one embodiment the plurality of orifice inserts144includes at least a first orifice insert156that is disposed within the first orifice140and a second orifice insert158that is disposed within the second orifice142. A first insulation gap160is defined between the first orifice insert156and the first orifice140and a second insulation gap162is defined between the second orifice insert158and the second orifice142.

In particular embodiments, as shown inFIGS. 6 and 7, a fuel distribution plenum164is at least partially defined within the fuel distribution cap106. The fuel distribution plenum164is in fluid communication with the inlet132of each orifice130(FIG. 6) and/or the inlet146of each of the orifice insert144(FIG. 7). In one embodiment, as shown inFIG. 7, the fuel distribution cap106includes an inlet port166that is in fluid communication with the fuel distribution plenum164. The fuel inlet port166may be coupled to an external fuel supply22(FIG. 1) so as to provide a flow of fuel168into the fuel distribution plenum164.

The fuel distribution cap106is configured to evenly distribute fuel168between the fuel distribution plenum164and each inlet132of each orifice130(FIG. 6) and/or the inlet146of each orifice insert144(FIG. 7). For example, in one embodiment as shown inFIG. 6, the fuel distribution cap106is flared outward between the inlet port166and the outer surface108of the flange102, thereby at least partially stabilizing pressure head of the fuel before it is fed into each inlet132of each orifice130(FIG. 6) and/or the inlet146of each orifice insert144(FIG. 7). As a result, the flow velocity of the fuel168may be regulated so as to evenly distribute the fuel168between each orifice130as the fuel flows into the primary fuel plenum124, thereby enhancing the overall performance of the fuel distribution manifold100.

FIG. 8provides a cross section perspective view of the fuel distribution cap106according to one embodiment of the present invention as shown in part inFIG. 7. As shown inFIG. 8, the fuel distribution cap106comprises a floor or bottom portion170that partially defines the fuel distribution plenum164. A plurality of outlets172extend through the floor portion170. As shown inFIG. 7, each outlet172is substantially coaxially and/or concentrically aligned with a corresponding inlet132(FIG. 6) of a corresponding orifice130(FIG. 6) and/or with the inlet146of a corresponding orifice insert146(FIG. 9). In one embodiment, as shown inFIG. 7, the plurality of outlets172includes a first outlet174that is coaxially aligned with the first orifice140and/or the first orifice insert156and a second outlet176that is coaxially aligned with the second orifice142and/or the second orifice insert158.

In at least one embodiment, as shown inFIG. 7, a generally radial gap178is defined between the floor portion170of the fuel distribution cap106and the outer surface108of the flange102. In operation, the flange102is generally much hotter than the fuel168flowing into and through the fuel distribution plenum164. The gap178provides an insulation boundary between the fuel168flowing through the fuel distribution plenum144and the outer surface108of the flange102, thereby reducing thermal stresses around the fuel distribution cap106and along the flange102outer surface108. As a result, the overall durability of the fuel distribution manifold100may be enhanced.

FIG. 9provides a perspective view of an assembled combustion module200that may incorporate various embodiments of the present invention, andFIG. 10provides an exploded view of the combustion module200as shown inFIG. 9. As shown inFIG. 9, the combustion module200generally includes the fuel distribution module100disposed at a forward or upstream end202and a fuel injection assembly204that extends generally downstream from the fuel distribution manifold100and that terminates at an aft or downstream end206of the combustion module200.

As shown inFIG. 10, the fuel injection assembly204may include some or all of the combustion liner62, the flow sleeve64and the fuel injector(s)76. When assembled, as shown inFIG. 9, a forward portion208(FIG. 10) of the flow sleeve64is concentrically aligned within one of the support sleeves110of the fuel distribution manifold100. A compression or spring seal210extends generally radially between the forward portion208of the flow sleeve and the support sleeve110to provide structural support and/or to allow for axial movement between the fuel injection assembly204and the fuel distribution manifold100during operation of the combustor50(FIG. 2).

As shown inFIG. 9, each fuel injector76may be fluidly coupled to the fuel distribution manifold100through a fluid conduit212that extends between the fuel injector76and the flange102of the fuel distribution manifold100. As shown inFIG. 2, the flange102of the fuel distribution manifold100may be coupled or connected to the outer casing52thereby providing mounting support for the combustion module200within the combustor50. The fluid conduit generally provides for fluid communication between the primary fuel plenum124(FIG. 5) and the fuel injector(s)76during late-lean operation of the combustor50. (FIG. 2).