WO2016160010A1

WO2016160010A1 - Pre-mixing based fuel nozzle for use in a combustion turbine engine

Info

Publication number: WO2016160010A1
Application number: PCT/US2015/023849
Authority: WO
Inventors: Joseph Meadows; Chunyang Wu
Original assignee: Siemens Energy Inc
Current assignee: Siemens Energy Inc
Priority date: 2015-04-01
Filing date: 2015-04-01
Publication date: 2016-10-06
Anticipated expiration: 2017-10-01
Also published as: US20180051883A1; EP3278030A1

Abstract

A pre-mixing type of fuel nozzle (10) for use in a combustion turbine engine is provided. The nozzle includes an array of pre-mixing conduits (20) that extends between an inlet end (14) and an outlet end (16) of a body (12) of the nozzle. The nozzle may further include an array of air flow conduits (22) disposed radially inwardly relative to the array of pre-mixing conduits. The nozzle may include an inter-conduit passageway 24 arranged to aerodynamically reduce flow recirculation in the array of pre-mixing conduits. A fuel-directing structure (26) may include non-swirl elements (28) to direct fuel flow along a radial direction, each non-swirl element including at least one orifice (32) to inject the fuel flow directed along the radial direction into a respective pre-mixing conduit to pre-mix air and fuel.

Description

PRE-MIXI G BASED FUEL NOZZLE

FOR USE IN A COMBUSTION TURBINE ENGINE

STATEMENT REGARDING FEDERALLY SPONSORED DEVELOPMENT [0001] Development for this invention was supported in part by Contract No. DE- FC26-05NT 42644, awarded by the United States Department of Energy.

Accordingly, the United States Government may have certain rights in this invention.

BACKGROUND [0002] 1. Field

[0003] Disclosed embodiments are generally related to a fuel nozzle for use in a combustion turbine engine, such as a gas turbine engine and, more particularly, to a pre-mixing type of fuel nozzle that in one non-limiting application may be used in a distributed combustion system (DCS) injection system. [0004] 2. Description of the Related Art

[0005] In gas turbine engines, fuel is delivered from a fuel source to a combustion section where the fuel is mixed with air and ignited to generate hot combustion products defining working gases. The working gases are directed to a turbine section. The combustion section may comprise one or more stages, each stage supplying fuel to be ignited. See US patent Nos. 8,281594 and 8,752,386 in connection with fuel nozzles involving pre-mixing of air and fuel.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] FIG. 1 is an isometric view that may be helpful for visualizing an upstream end of one non-limiting embodiment of a fuel nozzle embodying aspects of the invention that may be used in a combustor of a combustion turbine engine.

[0007] FIG. 2 is a top view of the upstream end of the fuel nozzle shown in FIG. 1. [0008] FIG. 3 is a bottom view of a downstream end of the fuel nozzle shown in FIG. 1.

[0009] FIG. 4 is a cross-sectional view illustrating a non-limiting schematic representation of respective pre-mixing conduits and air flow conduits constructed in the body of the fuel nozzle.

[0010] FIG. 5 is a cross-sectional view illustrating a non-limiting schematic representation of fuel flow in a fuel-directing structure constructed in the body of the fuel nozzle.

[0011] FIG. 6 is a top view illustrating a non-limiting schematic representation of fuel- injecting locations in a given pre-mixing conduit.

[0012] FIG. 7 is a simplified schematic of one non- limiting embodiment of a combustion turbine engine, such as a gas turbine engine, that can benefit from disclosed embodiments of the present invention.

DETAILED DESCRIPTION

[0013] The inventors of the present invention have recognized certain issues that can arise in the context of certain prior art fuel nozzles involving pre-mixing of air and fuel, also referred in the art as micro-mixing. These prior art fuel nozzles generally involve a large number of point injection arrays having a relatively small diameter, and the fabrication of such injection arrays may involve costly fabrication techniques. In view of such a recognition, the present inventors propose an improved fuel nozzle that can benefit from more economical fabrication techniques while providing appropriate levels of NO_x emissions and enabling practically a flashback- free operation, even on applications involving a relatively high-content of hydrogen fuel.

[0014] In the following detailed description, various specific details are set forth in order to provide a thorough understanding of such embodiments. However, those skilled in the art will understand that embodiments of the present invention may be practiced without these specific details, that the present invention is not limited to the depicted embodiments, and that the present invention may be practiced in a variety of alternative embodiments. In other instances, methods, procedures, and components, which would be well-understood by one skilled in the art have not been described in detail to avoid unnecessary and burdensome explanation.

[0015] Furthermore, various operations may be described as multiple discrete steps performed in a manner that is helpful for understanding embodiments of the present invention. However, the order of description should not be construed as to imply that these operations need be performed in the order they are presented, nor that they are even order dependent, unless otherwise indicated. Moreover, repeated usage of the phrase "in one embodiment" does not necessarily refer to the same embodiment, although it may. It is noted that disclosed embodiments need not be construed as mutually exclusive embodiments, since aspects of such disclosed embodiments may be appropriately combined by one skilled in the art depending on the needs of a given application.

[0016] The terms "comprising", "including", "having", and the like, as used in the present application, are intended to be synonymous unless otherwise indicated. Lastly, as used herein, the phrases "configured to" or "arranged to" embrace the concept that the feature preceding the phrases "configured to" or "arranged to" is intentionally and specifically designed or made to act or function in a specific way and should not be construed to mean that the feature just has a capability or suitability to act or function in the specified way, unless so indicated.

[0017] FIG. 1 is an isometric view of one non- limiting embodiment of a fuel nozzle 10 embodying aspects of the invention that in one non-limiting application may be used in a combustor of a combustion turbine engine, such as a gas turbine engine. Fuel nozzle 10 includes a body 12 having an inlet end 14 and an outlet end 16 and defines a central axis 18 that extends between inlet end 14 and outlet end 16 along an axial direction of the fuel nozzle.

[0018] As may be appreciated in FIG.1, an array of pre-mixing conduits 20 extends between inlet end 14 and outlet end 16 of body 12. The array of pre-mixing conduits 20 is circumferentially disposed about central axis 18. Each pre-mixing conduit 20 is fluidly coupled to receive air at a respective inlet. [0019] In one non- limiting embodiment, fuel nozzle 10 further includes an array of air flow conduits 22 disposed radially inwardly relative to the array of pre-mixing conduits 20. In one non-limiting embodiment, fuel nozzle 10 may include means to aerodynamically reduce flow recirculation (flow separation) in the array of pre- mixing conduits 20. It will be appreciated that the reduction of flow recirculation need not be limited to within the array of pre-mixing conduits 20, since zones beyond outlet end 16 can also benefit from such flow recirculation reduction. As may be appreciated in FIG. 4, in one non-limiting embodiment, the means to aerodynamically reduce the flow recirculation in a respective pre-mixing conduit 20 may comprise an inter-conduit passageway 24 arranged to provide fluid communication between the respective pre-mixing conduit 20 and a corresponding air flow conduit 22. It will be appreciated that the geometry of pre-mixing conduits 20 may be optionally configured to reduce flow recirculation in combination or in lieu of inter-conduit passageways 24.

[0020] As may be appreciated in FIG. 5, fuel nozzle 10 further includes a fuel- directing structure 26 that in one-non-limiting embodiment includes a plurality of non-swirl elements 28. Each non-swirl element includes a radially-extending passageway to direct fuel flow along a radial direction (schematically represented by arrows 30). Each non-swirl element 28 includes at least one orifice 32 arranged to inject the fuel that flows along the radial direction into a respective air/ fuel pre- mixing conduit. Without limitation, orifices 32 may be located in regions of relatively high axial flow velocity, thus increasing the static pressure drop across orifices 32. See FIG. 6 that illustrates a non-limiting example of fuel-injecting locations

(schematically represented by arrows 34) in a given pre-mixing conduit 20. Fuel- directing structure 26 further includes a central passageway 36 (FIG. 5) arranged to direct fuel flow along the axial direction (schematically represented by arrows 38) towards a central outlet 39.

[0021] In one non-limiting embodiment, the array of pre-mixing conduits 20 each comprises at least a respective pre-mixing conduit segment (schematically represented by line 40 (FIG. 4)) having a cross-sectional area that increases as the respective pre- mixing conduit segment extends from a location between inlet end 14 and outlet end 16 towards a respective outlet 41 of the respective pre-mixing conduit. This may be effective so that flow velocity is increased without substantially increasing the overall pressure drop. In one non-limiting embodiment, pre-mixing conduit segment 40 includes at least one surface 42 tilted radially inwardly relative to central axis 18 as the segment extends towards the respective outlet 41 of the respective pre-mixing conduit 20. [0022] In one non- limiting embodiment, the array of air flow conduits 22 each comprises at least a respective air flow conduit segment (schematically represented by line 44 (FIG. 4) having a cross-sectional area that decreases as the respective air flow conduit segment 44 extends from a respective inlet 45 of the respective air flow conduit 22 towards a location between inlet end 14 and outlet end 16. In one non- limiting embodiment, the array of air flow conduits 22 each comprises an outlet 46 arranged radially inwardly relative to central axis 18. In one non-limiting embodiment, central outlet 39 of central passageway 36 in combination with the respective outlets 46 of the array of air flow conduits 22 forms a jet-assisted mixing stage. It will be appreciated that the respective starting/end points and/or respective geometries of the conduit segments schematically represented by lines 40 and 44 should be construed in a non-limiting sense since other starting/end points and/or geometries may be arranged depending on the needs of a given application.

[0023] FIG. 7 is a simplified schematic of one non- limiting embodiment of a combustion turbine engine 50, such as gas turbine engine, that can benefit from disclosed embodiments of the present invention. Combustion turbine engine 50 may comprise a compressor 52, a combustor 54, a combustion chamber 56, and a turbine 58. During operation, compressor 52 takes in ambient air and provides compressed air to a diffuser 60, which passes the compressed air to a plenum 62 through which the compressed air passes to combustor 54, which mixes the compressed air with fuel, and provides combusted, hot working gas via a transition 64 to turbine 58, which can drive power-generating equipment (not shown) to generate electricity. A shaft 66 is shown connecting turbine 58 to drive compressor 52. Disclosed embodiments of a fuel nozzle embodying aspects of the present invention may be incorporated in combustor 54 of the combustion turbine engine to achieve superior pre-mixing of fuel and air.

[0024] In operation and without limitation, disclosed embodiments are expected to provide a cost-effective fuel nozzle including arrays of fluid flow conduits that produce a substantially homogenous mixture of fuel and air at the outlet end of the nozzle and thus effective to produce appropriate pre-mixing of fuel and air conducive to ultra-low levels of NO_x emissions. Additionally, disclosed embodiments need not involve swirler elements, and thus flashback resistance is substantially high, even for fuel blends comprising a high hydrogen content (e.g., at least 50% hydrogen content by volume).

[0025] Without limitation, practical embodiments of the disclosed fuel nozzle may comprise fluid flow conduits having a minimum diameter in a range from about 0.75 mm to about 1 mm and thus capable of benefitting from relatively low-cost manufacturing technologies, such as, without limitation, three-dimensional (3D) printing, direct metal laser sintering (DLMS), etc., in lieu of presently costlier manufacturing technologies.

[0026] While embodiments of the present disclosure have been disclosed in exemplary forms, it will be apparent to those skilled in the art that many

modifications, additions, and deletions can be made therein without departing from the spirit and scope of the invention and its equivalents, as set forth in the following claims.

Claims

What is claimed is:

1. A fuel nozzle comprising:

a body having an inlet end and an outlet end and defining a central axis that extends between the inlet end and the outlet end along an axial direction of the fuel nozzle;

an array of pre-mixing conduits extending between the inlet end and the outlet end of the body, the array of pre-mixing conduits circumferentially disposed about the central axis of the body, each pre-mixing conduit fluidly coupled to receive air at a respective inlet;

an array of air flow conduits disposed radially inwardly relative to the array of pre-mixing conduits ;

means to aerodynamically reduce flow recirculation in the array of air/fuel pre-mixing conduits; and

a fuel-directing structure in the body comprising a plurality of non-swirl elements, each non-swirl element including a radially-extending passageway to direct fuel flow along a radial direction, each non-swirl element including at least one orifice to inject the fuel flow directed along the radial direction into a respective pre-mixing conduit.

2. The fuel nozzle of claim 1, wherein the means to aerodynamically reduce the flow recirculation in a respective pre-mixing conduit comprises an inter-conduit passageway arranged to provide fluid communication between the respective pre- mixing conduit and a corresponding air flow conduit.

3. The fuel nozzle of claim 1, wherein the array of pre-mixing conduits each comprises at least a respective pre-mixing conduit segment having a cross-sectional area that increases as the respective pre-mixing conduit segment extends from a location between the inlet end and the outlet end towards a respective outlet of the respective pre-mixing conduit.

4. The fuel nozzle of claim 3, wherein the respective pre-mixing conduit segment includes at least one surface tilted radially inwardly relative to the central axis as the segment extends towards the respective outlet of the respective pre-mixing conduit.

5. The fuel nozzle of claim 1, wherein the array of air flow conduits each comprises at least a respective air flow conduit segment having a cross-sectional area that decreases as the respective air flow conduit segment extends from a respective inlet towards a location between the inlet end and the outlet end.

6. The fuel nozzle of claim 1, wherein the array of air flow conduits each comprises an outlet arranged radially inwardly relative to the central axis.

7. The fuel nozzle of claim 6, wherein the fuel-directing structure further comprises a central passageway arranged to direct fuel along the axial direction.

8. The fuel nozzle of claim 7, wherein the fuel-directing structure comprises a central outlet that in combination with the respective outlets of the array of air flow conduits forms a jet-assisted mixing stage.

9. A combustor in a combustion turbine engine comprising the fuel nozzle of any of the preceding claims.

10. A fuel nozzle comprising:

an array of pre-mixing conduits circumferentially disposed about the central axis of the body, each pre-mixing conduit fluidly coupled to receive air at a respective inlet, wherein the array of pre-mixing conduits each comprises at least a respective pre-mixing conduit segment having a cross-sectional area that increases as the respective pre-mixing conduit segment extends from a location between the inlet end and the outlet end towards a respective outlet of the respective pre-mixing conduit; and

a fuel-directing structure in the body, the fuel-directing structure comprising a plurality of non-swirl elements each including a radially-extending passageway to direct fuel flow along a radial direction, each non-swirl element including at least one orifice to inject the fuel flow directed along the radial direction into a respective pre- mixing conduit.

11. The fuel nozzle of claim 10, further comprising an array of air flow conduits disposed radially inwardly relative to the array of pre-mixing conduits.

12. The fuel nozzle of claim 11, further comprising means to aerodynamically reduce flow recirculation in the array of pre-mixing conduits.

13. The fuel nozzle of claim 12, wherein the means to aerodynamically reduce the flow recirculation in a respective pre-mixing conduit comprises an inter-conduit passageway arranged to provide fluid communication between the respective pre- mixing conduit and a corresponding air flow channel.

14. The fuel nozzle of claim 10, wherein the respective pre-mixing conduit segment includes at least one surface tilted radially inwardly relative to the central axis, as the segment extends towards the respective outlet of the respective pre-mixing conduit.

15. The fuel nozzle of claim 11, wherein the array of air flow conduits each comprises at least a respective air flow conduit segment having a cross-sectional area that decreases as the respective air flow conduit segment extends from a respective inlet towards a location between the inlet end and the outlet end.

16. The fuel nozzle of claim 11 , wherein the array of air flow conduits each comprises an outlet arranged radially inwardly relative to the central axis.

17. The fuel nozzle of claim 16, wherein the fuel-directing structure further comprises a central passageway arranged to direct fuel along the axial direction.

18. The fuel nozzle of claim 17, wherein the fuel-directing structure comprises a central outlet that in combination with the respective outlets of the array of air flow conduits forms a jet-assisted mixing stage.

19. A combustor in a combustion turbine engine comprising the fuel nozzle of any of claims 10 through 18 inclusive.

20. A fuel nozzle comprising:

an array of pre-mixing conduits extending between the inlet end and the outlet end of the body, the array of pre-mixing conduits circumferentially disposed about the central axis of the body, each pre-mixing conduit fluidly coupled to receive air at a respective inlet, wherein the array of pre-mixing conduits each comprises at least a respective pre-mixing conduit segment having a cross-sectional area that increases as the respective pre-mixing conduit segment extends from a location between the inlet end and the outlet end towards a respective outlet of the respective pre-mixing conduit;

an array of air flow conduits disposed radially inwardly relative to the array of pre-mixing conduits;

an inter-conduit passageway arranged to provide fluid communication between a respective pre-mixing conduit and a corresponding air flow conduit;

and