WO2025259263A1

WO2025259263A1 - Combustor having an axial fuel staging subsystem in a gas turbine engine

Info

Publication number: WO2025259263A1
Application number: PCT/US2024/033328
Authority: WO
Inventors: Nishant Govindbhai Parsania
Original assignee: Siemens Energy Global GmbH and Co KG; Siemens Energy Inc
Current assignee: Siemens Energy Global GmbH and Co KG; Siemens Energy Inc
Priority date: 2024-06-11
Filing date: 2024-06-11
Publication date: 2025-12-18
Anticipated expiration: 2026-12-11

Abstract

A combustion system having an axial fuel staging subsystem is provided. A ring seal (18) is arranged between a liner (14) and a transition duct (16). A plurality of injectors (20) is circumferentially distributed in a wall defined by ring seal (18) to convey combustion reactants into a secondary combustion zone. At least some of the respective injectors include a respective through hole (30) having an inlet disposed at a radially-outward outer surface of a wall of the ring seal to receive air. Through hole (30) further receives fuel so that combustion reactants fuel and air are conveyed to the secondary combustion zone. In certain embodiments, a respective air curtain circuit (60) is arranged to form a respective air curtain (62) to dilute the combustion reactants conveyed by through hole (30). This dilution is effective to delay ignition of flamelets at locations slightly spaced apart from the axial stage injectors and surrounding structures.

Description

COMBUSTOR HAVING AN AXIAL FUEL STAGING SUBSYSTEM

IN A GAS TURBINE ENGINE

BACKGROUND

[0001] Disclosed embodiments relate generally to the field of combustion, and, more specifically, to a combustor having an axial fuel staging subsystem in a gas turbine engine.

[0002] Certain known combustion systems involve a plurality of combustion cans, where each combustion can uses a fuel system including a first arrangement of injectors at a main combustion zone and a second arrangement of injectors at a secondary combustion zone downstream from the main combustion zone. In applications involving high reactivity fuels like hydrogen, undesirable flashback can occur. This in turn may necessitate use of flashback sensing instrumentation to detect flashback and control logic in a control system configured to implement appropriate control actions to avoid or inhibit effects of the flashback on components of the engine. Accordingly, there is a need to inhibit occurrence of flashback without increasing emissions while eliminating a need of deploying flashback sensing instrumentation and the concomitant control logic.

BRIEF SUMMARY

[0003] In one aspect, a combustion system has an axial fuel staging subsystem including a liner, a transition duct, and a ring seal arranged between the liner and the transition duct to seal a circumferential gap between the liner and the transition duct. A plurality of respective injectors is circumferentially distributed about a longitudinal axis of the combustion system to convey combustion reactants into a secondary combustion zone downstream from a main combustion zone of the combustion system. At least some of the respective injectors include a respective through hole having an inlet disposed at a radially-outward outer surface of a wall of the ring seal to receive air. The at least some of the respective injectors further include a respective conduit having an outlet to convey fuel into a respective injector of the at least some of the respective injectors. The at least some of the respective injectors have a respective outlet fluidly coupled to the secondary combustion zone to convey the combustion reactants. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0004] FIG. 1 illustrates in part a fragmentary, half cross-sectional view of one disclosed embodiment.

[0005] FIG. 2 illustrates an aspect of the subject matter in accordance with the embodiment of FIG. 1.

[0006] FIG. 3 illustrates a fragmentary isometric view focusing on certain features of another disclosed embodiment.

[0007] FIG. 4 illustrates a sectional view of an air delivery component involved in the embodiment of FIG. 1.

[0008] FIG. 5 illustrates a fragmentary isometric view focusing on certain features of the embodiment of FIG. 1.

[0009] FIG. 6 illustrates is a fragmentary isometric view of still another disclosed embodiment involving a backward facing step.

[0010] FIG. 7 is a fragmentary isometric view of yet another disclosed embodiment.

DETAILED DESCRIPTION

[0011] A variety of industries, such as including power generation and various other industrial processes involving combustion, seek to reduce their carbon footprint and are turning to hydrogen, as our world focuses on transitioning to clean or cleaner forms of energy. For example, in addition to being an alternative to fossil fuels, combustion of hydrogen releases no carbon dioxide and other undesirable emissions.

[0012] As will be appreciated by one skilled in the art, hydrogen’s flame speed, which is about five to about ten times faster than the flame speed of natural gas, is a basic consideration when evaluating any design involving combustion of hydrogen fuel. For example, known burner designs that utilize lean premixed flame combustion, generally have been somewhat lacking for appropriately handling a fuel stream comprising a relatively high composition of hydrogen. As the composition of hydrogen increases in the fuel stream, these burners can become more susceptible to flashback. Flashback occurs when the fuel and air mixture velocity exiting an outlet of the burner is slower than the flame speed. Damage to the burner components can result when flashback occurs. [0013] In operation, disclosed embodiments are believed to offer various advantages, such as without limitation; i. Effectively inhibiting flashback since the injection technique used practically eliminates premixing passages and instead relies on a direct injection technique in combination with a dilution technique by way of air injection; ii. Diffusion typically tends to increase local temperature/s and thus could lead to higher NOx levels, however, this is mitigated by way of circumferentially arranging a relatively higher number of injectors, which in turn results in a substantially even circumferential distribution of heat release; iii. Disclosed embodiments effectively reduce NOx by way of diluting air, and in turn this dilution sufficiently delays ignition of flamelets at locations slightly spaced apart from the axial stage injectors and surrounding structures. Additionally, our arrangement effectively manages the amount of air involved to reach a given NOx reduction through dilution; iv. Offer an scalable design, such as by way of arranging multiple rows of injectors and/or tailoring the size of fuel holes and/or air holes; v. Cost-effective adaptation of a sealing component (e.g., ring seal) typically interposed between a transition duct and a liner so that the adapted component effectively becomes a dual-functionality component, e.g., providing axial stage fuel injecting functionality plus sealing functionality; and vi. Manufacturability by way of three-dimensional (3D) printing, and, optionally, the fuel and air holes can be drilled by way of conventional drilling techniques for applications that may involve tighter tolerances.

[0014] Before disclosed embodiments are explained in detail, it is to be understood that disclosed embodiments are not limited in their application to the details of construction and the arrangement of components set forth in this description or illustrated in the following drawings. Disclosed embodiments are capable of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

[0015] Various technologies that pertain to disclosed embodiments will now be described with reference to the drawings, where like reference numerals represent like elements throughout. The drawings discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged apparatus. It is to be understood that functionality that is described as being carried out by certain system elements may be performed by multiple elements. Similarly, for instance, an element may be configured to perform functionality that is described as being carried out by multiple elements. The numerous innovative teachings of the present application will be described with reference to exemplary non-limiting embodiments.

[0016] It should be understood that the words or phrases used herein should be construed broadly, unless expressly limited in some examples. For example, the terms “including,” “having,” and “comprising,” as well as derivatives thereof, mean inclusion without limitation. The singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Further, the term “and/or” as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. The term “or” is inclusive, meaning and/or, unless the context clearly indicates otherwise. The phrases “associated with” and “associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like. Furthermore, while multiple embodiments or constructions may be described herein, any features, methods, steps, components, etc. described with regard to one embodiment are equally applicable to other embodiments absent a specific statement to the contrary.

[0017] Also, although the terms “first”, “second”, “third” and so forth may be used herein to refer to various elements, information, functions, or acts, these elements, information, functions, or acts should not be limited by these terms. Rather these numeral adjectives are used to distinguish different elements, information, functions or acts from each other. For example, a first element, information, function, or act could be termed a second element, information, function, or act, and, similarly, a second element, information, function, or act could be termed a first element, information, function, or act, without departing from the scope of the present disclosure.

[0018] In addition, the term “adjacent to” may mean that an element is relatively near to but not in contact with a further element or that the element is in contact with the further portion, unless the context clearly indicates otherwise. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise. Terms “about” or “substantially” or like terms are intended to cover variations in a value that are within normal industry manufacturing tolerances for that dimension. If no industry standard is available, a variation of twenty percent would fall within the meaning of these terms unless otherwise stated.

[0019] Those of ordinary skill in the art will appreciate that hardware and/or software depicted in connection with disclosed embodiments may vary for particular implementations. The depicted examples are provided for the purpose of explanation only and are not meant to imply architectural limitations with respect to the present disclosure. Also, those skilled in the art will recognize that, for simplicity and clarity, the full structure and operation of all data processing systems suitable for use with the present disclosure is not being depicted or described herein. Instead, only so much of a data processing system as is unique to the present disclosure or necessary for an understanding of the present disclosure is depicted and described. The remainder of the construction and operation of the data processing system may conform to any of the various current implementations and practices known in the art.

[0020] FIG. 1 illustrates in part a fragmentary, half cross-sectional view of one disclosed embodiment of a combustion system 10 having an axial fuel staging subsystem 12, as may be used in a gas turbine engine. As shown in FIG. 1, a ring seal 18 is arranged between a liner 14 and a transition duct 16 to seal a circumferential gap between the liner 14 and the transition duct 16. A plurality of respective injectors 20 is circumferentially distributed about a longitudinal axis 22 of combustion system 10 to convey combustion products into a secondary combustion zone 26 downstream from a main combustion zone or stage 28 of combustion system 10.

[0021] In certain embodiments, at least some of the respective injectors 20 include a respective through hole 30 (see also FIG. 2) having an inlet 32 disposed at a radially-outward outer surface 34 of a wall 36 of ring seal 18 to receive air. That is, the respective through hole 30 extends all the way through the wall 36. The at least some of the respective injectors further include a respective conduit 40 having an outlet 42 (e.g., a fuel entry point for the respective injector) to convey fuel into a respective injector of the at least some of the respective injectors. The at least some of the respective injectors have a respective outlet 38 fluidly coupled to secondary combustion zone 26 to convey the combustion reactants. [0022] A fuel manifold 50 may be constructed in the wall 36 defined by ring seal 18. Fuel manifold 50 is fluidly coupled to convey the fuel to at least some of the respective injectors 20 by way of conduit 40.

[0023] Certain embodiments include an air curtain circuit 60 (FIG. 2) to form a respective air curtain (schematically indicated by arrow 62 in FIG. 2) arranged to dilute the combustion reactants (air and fuel) conveyed by the respective through hole 30. Angles 0i and O2 indicate one example of an angular range for a constituent jet of the air curtain. 0i represents an example angle of -10 degrees or so relative to a radial direction indicated by axis 63, and 02 represents an example angle of 30 degrees or so relative to the radial direction.

[0024] In certain embodiments, the respective outlet 42 of conduit 40 where fuel is conveyed into the respective injector is at a point disposed adjacent to outlet 38 of through hole 30. In one example embodiment, the respective outlet 42 (fuel entry point for the respective injector) of conduit 40 to convey the fuel is disposed just upstream relative to the outlet of through hole 30, as shown in FIG. 1. In another example embodiment, the respective outlet 42 of conduit 40 to convey the fuel is disposed just downstream relative to the outlet 38 of the through hole, as shown in FIG. 5. Surfaces in the figures shown with a dotted stippling are indicative of surfaces having a thermal barrier coating to enhance thermal protection to components involved, such as surfaces of ring seal 18 that may be subject to elevated temperatures or surfaces that may be desirable to keep relative at relatively cooler temperatures. For example, radially-inner surface 74 of wall 36 of ring seal 18 that faces secondary combustion zone 26 is one example of such a surface.

[0025] FIG. 2 illustrates a fragmentary isometric view focusing on certain features of the embodiment of FIG. 1. In one example embodiment, air curtain circuit 60 comprises a non- through hole 64 (see FIG. 1 and also FIG. 4) in the wall 36 defined by ring seal 18. In one example embodiment, non-through hole 64 has an inlet 66 at the radially-outward outer surface 34 of the wall 36 of ring seal 18 to receive air. That is, opposite to through holes 30, non- through holes 64 do not extend all the way through the wall 36.

[0026] As can be appreciated in FIG. 4 non-through hole 64 has respective air conduits 68 to convey the received air to respective neighboring injectors of the at least some of the respective injectors to form respective air curtains 60 as in Fig 1. Arrows 65 in FIG. 1 schematically represent air flow communication through air conduits 68 from non-through hole 64 to the neighboring through holes 30. In one example embodiment, as can be further appreciated in FIG. 1 respective non-through holes 64 and respective through holes 30 form an alternating sequence of non-through holes 64 and through holes 30 so that each respective non-through hole 64 feeds the received air to the respective neighboring through holes 30 by way of the respective air conduits 68. In general, through holes 30 convey either a mixture of fuel and air or just air while non-through holes 64 convey just air.

[0027] In one example embodiment, air curtain circuit 60 has an outlet 70 arranged to surround at least a portion of the outlet 38 of through hole 30 to deliver a jet of air from air curtain circuit 60 into the combustion reactants conveyed by way of outlet 38 of through hole 30 and thus dilute by way of the conveyed air such combustion reactants. As should be now appreciated, air curtain circuit 60 is arranged to inhibit or delay auto ignition of fuel and air. This ignition delay is conducive to reduction of undesirable hot spots near exposed surfaces of wall 36. In one example embodiment, the outlet 38 of through hole 30 defines a conic section and the outlet 70 of air curtain circuit 60 has an outlet 70 that defines a conic section concentric with and partially surrounding the outlet 38 of through hole 30. In one example embodiment, the conic section of the outlet 38 of through hole defines a circular section and the conic section of the outlet 70 of air curtain circuit 60 defines a partial circular section.

[0028] In one example embodiment, the through holes 30 are circumferentially spaced apart from one another by respective arcs 76 (FIG. 1) ranging, for example, from 5 degrees or so to 10 degrees or so in the wall 36 defined by ring seal 18.

[0029] FIG. 3 illustrates a fragmentary isometric view focusing on certain features of another disclosed embodiment. As described above, through holes 30 convey combustion reactants (e.g., air and fuel, schematically represented by arrow 39) into the secondary combustion zone. However, in lieu of an air curtain circuit involving non-through holes 64, this embodiment alternatively involves neighboring through holes 31 arranged to convey respective jets of air 37 to dilute the air and fuel (schematically represented by arrow 39) conveyed by through hole 30. In one example embodiment, a longitudinal axis of through holes 31 may be tilted towards neighboring through holes 30. In one example embodiment, an example angular range of respective jets of air 37 may be up to 45 degrees or so from a radial direction.

[0030] FIG. 6 illustrates a fragmentary isometric view of yet another disclosed embodiment involving an upstream facing step 78 (conceptually analogous to a ridge) circumferentially interposed between a plurality of respective injectors 630 and 631. Essentially, upstream facing step 78 (e.g., a backward facing step) faces the flow of combustion products (schematically represented by arrow 79) passing from the main combustion stage and is arranged to form a flame holding location by creating some recirculation upon a portion of the flow of combustion products from the main combustion stage striking or otherwise impinging on the upstream facing step 78. Upstream facing step 78 is conducive to strategically concentrate heat release locations such that released heat can be diluted further downstream, and this is effective to realize a relatively more uniform distribution of circumferential temperatures. The uniformity of combustion products passing by way of transition duct 16 and entering the turbine section of the engine is effective to reduce hotspots and increase turbine first stage nozzle life.

[0031] In this embodiment, injectors 630 convey combustion reactants (e.g., air and fuel, schematically represented by arrow 640) into the secondary combustion zone. Outlet 42 of conduit 40 (not shown in FIG. 6) serves to convey fuel into a respective injector 630. That is, injectors 630 may be viewed as conceptually analogous to through holes 30, as described above in the context of FIG. 3. In this embodiment, injectors 631 convey respective jets of air 37 to dilute the air and fuel conveyed by injectors 630. That is, injectors 631 may be viewed as conceptually analogous to through holes 31, as described above in the context of FIG. 3. Thus, in this embodiment, injectors 631 convey the respective jets of air 37 to dilute the air and fuel conveyed by a neighboring injector 630.

[0032] As may be appreciated in FIG. 6, in one example embodiment, the length-to-diameter (1/d) ratio of a respective injector 630 can be arranged to vary between its inlet 32 and its outlet 38. More specifically, the 1/d ratio between inlet 32 and the fuel entry point for the respective injector (outlet 42) is relatively higher compared to the 1/d ratio between the fuel entry point for the respective injector (outlet 42) and outlet 38. The exit opening allows some additional air to be delivered into the recirculation zone, thus further reducing hot spot. This arrangement contributes to diluting hot combustion products with relatively cooler air and inhibits formation of hot spots in the recirculation zone.

[0033] FIG. 7 is a fragmentary isometric view of yet another disclosed embodiment. In this embodiment, the respective conduit 40 that conveys the fuel into a respective injector is arranged to turn from an initial axial direction to a radial direction so that the flow of fuel (schematically represented by arrow 702) delivered by outlet 42 (e.g., the fuel entry point) is surrounded by a flow of air (schematically represented by arrows 704). It will be appreciated that this embodiment is one example alternative to an embodiment involving air curtain circuits, as the fuel flow (schematically represented by arrow 702) is co-axially surrounded by air. The delayed ignition allows temperature increase slightly downstream without flashback and eliminating need for flashback monitoring devices.

Claims

CLAIMS What is claimed is:

1. A combustion system (10) having an axial fuel staging subsystem (12) comprising: a liner (14); a transition duct (16); a ring seal (18) arranged between the liner and the transition duct to seal a circumferential gap between the liner and the transition duct; a plurality of respective injectors (20) circumferentially distributed about a longitudinal axis (22) of the combustion system to convey combustion reactants into a secondary combustion zone (26) downstream from a main combustion zone (28) of the combustor, at least some of the respective injectors comprising a respective through hole (30) having an inlet (32) disposed at a radially-outward outer surface (34) of a wall (36) of the ring seal to receive air, the at least some of the respective injectors having a respective outlet (38) fluidly coupled to the secondary combustion zone to convey the combustion reactants, the at least some of the respective injectors further comprising a respective conduit (40) having an outlet (42) to convey fuel into a respective injector of the at least some of the respective injectors.

2. The combustion system of claim 1, wherein the respective outlet of the conduit where fuel is conveyed into the respective injector is at a point disposed adjacent to the outlet (38) of the through hole.

3. The combustion system of claim 2, wherein the point to convey the fuel is disposed upstream relative to the outlet of the through hole.

4. The combustion system of claim 2, wherein the point to convey the fuel is disposed downstream relative to the outlet of the through hole

5. The combustion system of any one of claims 1 to 4, further comprising a fuel manifold (50) in the wall (36) defined by the ring seal, the fuel manifold fluidly coupled to convey the fuel to the respective injector.

6. The combustion system of claim 5, further comprising a respective air curtain circuit (60) to form a respective air curtain arranged to dilute the combustion reactants conveyed by the respective injector.

7. The combustion system of claim 6, wherein the respective air curtain circuit comprises a non-through hole (64) in the wall defined by the ring seal, the non-through hole having an inlet (66) at the radially-outward outer surface of the wall of the ring seal to receive air, the non- through hole having respective air conduits (68) to convey the received air to respective neighboring injectors of the at least some of the respective injectors to form respective air curtains.

8. The combustion system of claim 7, wherein the outlet (38) of the through hole defines a conic section and the air curtain circuit (60) has an outlet (70) that defines a conic section concentric with and partially surrounding the outlet (38) of the through hole.

9. The combustion system of claim 8, wherein the conic section of the outlet (38) of the through hole defines a circular section and the conic section of the outlet (70) of the air curtain circuit defines a partial circular section.

10. The combustion system of claim 7, wherein the outlet (70) of the air curtain circuit is disposed upstream relative to the outlet of the through hole.

11. The combustion system of claim 7, wherein respective non-through holes (64) and respective through holes (30) form an alternating sequence of non-through holes and through holes so that each respective non-through hole feeds the received air to the respective neighboring injectors by way of the respective air conduits.

12. The combustion system of claim 1, further comprising a respective thermal barrier coating (72) disposed at a radially-inner surface (74) of the wall of the ring seal facing the secondary combustion zone.

13. The combustion system of claim 1, wherein respective neighboring injectors of the at least some of the respective injectors comprising through holes are circumferentially spaced apart from one another by respective arcs (76) ranging from 5 degrees to 10 degrees in the wall defined by the ring seal.

14. The combustion system of claim 1, further comprising an upstream facing step (78) circumferentially interposed between the plurality of respective injectors.

15. The combustion system of claim 14, wherein the respective outlet (42) of the conduit where fuel is conveyed into the respective injector is at a point disposed between the inlet and outlet of the through hole.

16. The combustion system of claim 15, wherein the plurality of respective injectors forms an alternating sequence of holes configured to inject fuel and air and holes configured to inject just air, wherein air from the holes configured to inject just air is directed to dilute the fuel from the holes configured to inject fuel and air.

17. The combustion system of claim 1, a gas turbine engine including the axial fuel staging subsystem of claim 1.

18. A ring seal in an axial fuel staging subsystem of a gas turbine engine, the ring seal comprising: a plurality of respective injectors (20) circumferentially distributed about a longitudinal axis (22) of the combustion system to convey combustion reactants into a secondary combustion zone (26) downstream from a main combustion zone (28) of the combustion system; at least some of the respective injectors comprising a respective through hole (30) having an inlet (32) disposed at a radially-outward outer surface (34) of a wall (36) of the ring seal to receive air, the at least some of the respective injectors having a respective outlet (38) fluidly coupled to the secondary combustion zone to convey the combustion reactants, the at least some of the respective injectors further comprising a respective conduit (40) having an outlet (42) to convey fuel into a respective injector of the at least some of the respective injectors, wherein the respective outlet of the conduit where fuel is conveyed into the respective injector is at a point disposed adjacent to the outlet (38) of the through hole; a fuel manifold (50) in the wall (36) defined by the ring seal, the fuel manifold fluidly coupled to convey the fuel to the respective injector; a respective air curtain circuit (60) to form a respective air curtain arranged to dilute the combustion reactants conveyed by the respective injector, wherein the respective air curtain circuit comprises a non-through hole (64) in the wall defined by the ring seal, the non-through hole having an inlet (66) at the radially-outward outer surface of the wall of the ring seal to receive air, the non-through hole having respective air conduits (68) to convey the received air to respective neighboring injectors of the at least some of the respective injectors to form respective air curtains, wherein respective non-through holes (64) and respective through holes (30) form an alternating sequence of non-through holes and through holes so that each respective non- through hole feeds the received air to the respective neighboring injectors by way of the respective air conduits.

19. The ring seal of claim 18, wherein respective non-through holes (64) and respective through holes (30) form an alternating sequence of non-through holes and through holes so that each respective non-through hole feeds the received air to the respective neighboring injectors by way of the respective air conduits.

20. The ring seal of claim 19, wherein respective neighboring injectors of the at least some of the respective injectors comprising through holes are circumferentially spaced apart from one another by respective arcs (76) ranging from 5 degrees to 10 degrees in the wall defined by the ring seal.