Burner for gas turbine engine and method for inhibiting effects of flashback on the burner

Abstract

Burner (100) and method for inhibiting effects of flashback on the burner are disclosed. The burner includes a combustor can (102) and plurality of premixing tubes (104) circumferentially arranged about a longitudinal axis (106) of the combustor can. Each respective premixing tube extends to an outlet (108) of the respective premixing tube, where each premixing tube defines a respective gap (110) relative to an adjacent premixing tube, and where each premixing tube is arranged to form a jet flame in a combustion zone (114) disposed downstream from the outlet. A fluidic injection arrangement (120) is configured to form a fluidic barrier to inhibit ingestion of jet flames through the respective gaps and thereby inhibit effects of flashback on the burner.

Description

BURNER FOR GAS TURBINE ENGINE AND METHOD FOR INHIBITINGEFFECTS OF FLASHBACK ON THE BURNERBACKGROUND

[0001] Disclosed embodiments relate generally to the field of combustion, and, more specifically, to a burner for a gas turbine engine and / or method for inhibiting effects of flashback on the burner.

[0002] Hydrogen is expected to play an important role in the future supply and storage of energy as the need to reduce greenhouse gas emissions further increases. This has sparked the interest in operating gas turbines on fuel mixtures involving substantial amounts of hydrogen. Achieving a stable combustion process while still maintaining the required low emissions levels (e.g., in terms of NOx) is challenging, particularly when a hydrogen-based burner is desired to be implemented.

[0003] State-of-the-art gas turbines have utilized various approaches, including lean premixed flame combustion. One technical challenge that remains is adapting lean premixed flame combustion to permit utilization of fuel mixtures comprising up to 100% hydrogen while inhibiting flame flashback into components of the burner.BRIEF SUMMARY

[0004] In one aspect, a burner is disclosed. The burner includes a combustor can and plurality of premixing tubes circumferentially arranged about a longitudinal axis of the combustor can. Each respective premixing tube of the plurality of premixing tubes extends to an outlet of the respective premixing tube, where each respective premixing tube defines a respective gap relative to an adjacent premixing tube of the respective premixing tube, and where each respective premixing tube is arranged to form a respective jet flame in a combustion zone disposed downstream from the outlet. A fluidic injection arrangement configured to form a fluidic barrier to inhibit ingestion of jet flames from the combustion zone through the respective gap and thereby inhibit effects of a flashback condition on the burner.

[0005] In another aspect, a method for inhibiting effects of a flashback condition on a burner of gas turbine engine is disclosed. The method includes circumferentially arranging a plurality of premixing tubes about a longitudinal axis of a combustor can, where eachrespective premixing tube of the plurality of premixing tubes extends to an outlet of the respective premixing tube, wherein each respective premixing tube defines a respective gap relative to an adjacent premixing tube of the respective premixing tube, wherein each respective premixing tube is arranged to form a respective jet flame in a combustion zone disposed downstream from the outlet. The method further includes configuring a fluidic injection arrangement to form a fluidic barrier to inhibit ingestion of jet flames from the combustion zone through the respective gap and thereby inhibit effects of a flashback condition on the burner.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] FIG. 1 is a simplified sectional view of one non-limiting example of a disclosed burner.

[0007] FIG. 2 is an isometric view showing one non-limiting example of a fluidic injection arrangement featured in a disclosed burner, where the fluidic injection arrangement is configured to form a fluidic barrier to inhibit effects of flashback on the burner.

[0008] FIG. 3 is a computational fluid dynamics (CFD) simulation that shows a sectional view indicative of an example temperature distribution in a burner equipped with the fluidic injection arrangement of FIG. 2.

[0009] FIG. 4 is a CFD simulation that shows a front view of the example temperature distribution in the burner equipped with the fluidic injection arrangement of FIG. 2.

[0010] FIG. 5 is an isometric view showing another non-limiting example of a fluidic injection arrangement featured in a disclosed burner.

[0011] FIG. 6 is a CFD simulation that shows a sectional view of an example temperature distribution in a burner equipped with the fluidic injection arrangement of FIG. 5.

[0012] FIG. 7 is a CFD simulation that shows a front view of the example temperature distribution in the burner equipped with the fluidic injection arrangement of FIG. 5.

[0013] FIG. 8 is a CFD simulation that for comparative purposes shows a sectional view of an example temperature distribution in a burner not equipped with any fluidic injection arrangement.

[0014] FIG. 9 is a CFD simulation that for comparative purposes shows a front view of the example temperature distribution in the burner not equipped with the fluidic injection arrangement as noted in connection with FIG. 8.DETAILED DESCRIPTION

[0015] 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.

[0016] As will be appreciated by one skilled in the art, hydrogen’s flame speed, which is nearly five times than the flame speed of natural gas, is a basic consideration when evaluating any design of a hydrogen-based burner. 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 gas velocity exiting an outlet of the burner is slower than the flame speed in a premixed application. Damage to the burner components can result when flashback occurs.

[0017] As would be appreciated by one skilled in the art, burners involving lean premixed flame combustion include premixing tubes for premixing fuel and air during operation of the burner. The present inventor has recognized that burner designs having, for example, open- ended premixing tubes can be susceptible to ingesting hot gases through open spaces (e.g., gaps) between the premixing tubes and in turn such hot gases can become sources for flame flashback. At least in view of the foregoing considerations, disclosed embodiments, include features arranged to inhibit such hot gas ingestion and hence effective for inhibiting sources of flame flashback.

[0018] In operation, disclosed embodiments are believed to offer various advantages, such as without limitation: inhibiting ingestion of hot gases through the open spaces (e.g., gaps) between the premixing tubes; extending a margin for flame flashback, such as due to hot wall temperatures on a wall boundary layer; a relatively more uniform mixing profile at the outlet of the premixing tubes; lowering metal temperatures of the premixing tubes, and other burnercomponents, such as the respective bodies of a pilot injector and ignitor; avoiding damage to such components and achieving longer burner durability, particularly when the gas turbine engine is operated with a fuel mixture having a relatively large content of hydrogen.

[0019] Disclosed embodiments propose features to inject a fluid at high velocity to inhibit the ingestion of hot gases through the open spaces between the premixing tubes. More specifically, disclosed embodiments feature a “fluid curtain”, such as comprising air or liquid nitrogen, to form a shield with fluid (e.g., air or liquid nitrogen) injected between the premixing tubes to form a barrier inhibiting the hot gases from entering through such gaps.

[0020] By way of example, in certain embodiments using compressed air from a compressor section of the gas turbine engine, the air curtain can be formed with a relatively small amount of the total air received from the compressor section. For example, it is estimated that a range from approximately 0.1% to approximately 0.5% of the total air received from the compressor section can be sufficient to form the air curtain.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] FIG. 1 is a simplified sectional view of one example embodiment of a disclosed burner 100. Without limitation, it is contemplated that burner 100 can be implemented as a burner of a type colloquially referred to in the art as a DOC (Depleted Oxygen Combustion) burner involving premixed flame combustion. Burner 100 includes a combustor can 102, a plurality of premixing tubes 104 circumferentially arranged (e.g., circumferentially staggered over a full 360°) about a longitudinal axis 106 of burner 100 and a centrally disposed pilot burner 109 that in operation forms a pilot flame 111.

[0028] As would be appreciated by one skilled in the art, each premixing tube 104 premixes fuel and air during operation of the burner and comprises an open-ended tube. More specifically, burner 100 comprises a hydrogen-based burner, where, for example, a concentration of hydrogen in fuel supplied to the burner is in a range from 60% to 90%; or, in another example, the range of the concentration of hydrogen in fuel supplied to the burner is from 70% to 100%. Each respective premixing tube 104 extends to or otherwise defines a respective outlet 108. In one example embodiment, each respective premixing tube 104 defines a respective gap 110 or spatial separation (see Fig. 2 and FIG. 5) with respect to an adjacent premixing tube of the respective premixing tube.

[0029] In one example embodiment, each respective premixing tube 104 is arranged to form a respective main jet flame 112 in a combustion zone 114 disposed downstream from outlet 108 of each respective premixing tube 104. As elaborated in greater detail below, a fluidic injection arrangement 120 is configured to form a fluidic barrier (e.g., made up of air, liquid nitrogen,etc.) to inhibit ingestion of jet flames from combustion zone 114 through the respective gaps 110 and thereby inhibit effects of a flashback condition on the burner.

[0030] In one example embodiment, as may be better appreciated in FIG. 2, fluidic injection arrangement 120 comprises a plurality of sets of fluidic injection openings 122. Each respective set fluidic injection opening 122 disposed along a respective arc segment 124 spanning (e.g., widthwise) the respective gap 110. In one example embodiment, arc segment 124 is located axially upstream at a distance (e.g., schematically represented by twin arrowhead labeled DI) relative to outlet 108 of the respective premixing tube 104. In one example embodiment, each respective fluidic injection opening 122 in a respective set, during operation, delivers a respective jet of the fluid through a liner 126 of the burner, where the respective jet contributes to form the fluidic barrier (schematically indicated in FIG. 3 and FIG. 4 by single arrowhead labeled 132). Each respective jet delivered by way of its respective fluidic injection opening 122 is a jet of air in a direction that forms a crossflow pattern relative to the mixture of reactants that flows in the respective premixing tube 104.

[0031] In another example embodiment, as may be better appreciated in FIG. 5, fluidic injection arrangement 120 comprises a plurality of respective fluid reservoirs 128 fluidly coupled to a plurality of respective sets of fluidic injection openings 122 disposed along arc segment 124 over the respective gaps 110. As noted above, arc segment 124 is located axially upstream at a distance (e.g., schematically represented by twin arrowhead labeled D2) relative to outlet 108 of the respective premixing tube 104.

[0032] In this example embodiment, each respective fluidic injection opening 122, during operation, delivers a respective jet of the fluid through a radially inward surface 130 of fluid reservoir 128 facing the respective gap, where the respective jet contributes to form the fluidic barrier (schematically indicated in FIG. 6 and FIG. 7 by single arrowhead labeled 132’). That is, in this embodiment, the respective sets of fluidic injection openings 122 are disposed in or otherwise extend through the respective radially inward surfaces 130 of fluid reservoirs 128. As noted above, each respective jet delivered by way of its respective fluidic injection opening 122 is a jet of air in a direction that forms a crossflow pattern relative to a mixture of reactants that flows in the respective premixing tube 104.

[0033] It will be appreciated that the configuration of the fluidic injection openings 122 and / or the number of fluidic injection openings 122 per set can be optimized based on the needsof a given application, such as the scalability of the burner. For example, the number of fluidic injection openings 122 in certain example applications can range from 3 openings to 10 openings per set. In certain alternative applications the number of fluidic injection openings 122 can range from 4 openings to 8 openings per set.

[0034] In certain example applications, the diameter of the injection openings 122 can range from approximately 1.5mm to approximately 3.0mm. One desired target of such configurations is reaching an appropriate velocity for the respective jets from the fluidic injection openings 122. In one example application, this velocity is in a range between approximately 50 m / s and approximately 100 m / s. It will be appreciated that various cross-sectional configurations can be used for the fluidic injection openings 122, such as circular, oval, tear dropped or rectangular. Additionally, at least some of the fluidic injection openings 122 can have a predefined inclination angle defined between the longitudinal axis of the respective injection opening and a normal line, such as in a range from about 0 degrees to about 45 degrees. The normal line is a line perpendicular to a plane defined by the liner surface or by the radially inward surface of the respective fluid reservoir and where the fluidic injection opening is located. Lastly, distances DI and D2 (the respective example distances that define the location of arc segment 124 relative to outlet 108 of the respective premixing tube 104) can be appropriately optimized based on the needs of a given application. 3. In certain embodiments, an igniter 140 is disposed proximate to or in a respective gap 110, where the fluidic barrier 132 inhibits effects of the flashback condition on the igniter 140, as can be appreciated, for example, in FIG 4 and FIG. 7.

[0035] FIG. 8 and FIG. 9 are CFD simulations that, for comparative purposes, show respective views of example temperature distributions in a burner 800 not equipped with any fluidic injection arrangement. That is, not equipped with any fluidic injection arrangement that permits forming a fluidic barrier to inhibit effects of flashback on the burner, as discussed in the preceding disclosure.

[0036] In operation, disclosed embodiments are believed to offer various advantages, such as without limitation: inhibiting ingestion of hot gases through the open spaces (e.g., gaps) between the premixing tubes; extending a margin for flame flashback, such as due to hot wall temperatures on a wall boundary layer; a relatively more uniform mixing profile at the outlet of the premixing tubes; lowering metal temperatures of the premixing tubes, and other burner components, such as the respective bodies of a pilot injector and ignitor; avoiding damage tosuch components and achieving longer burner durability, particularly when the gas turbine engine is operated with a fuel mixture having a relatively large content of hydrogen.

[0037] Although exemplary embodiments of the present disclosure have been described in detail, those skilled in the art will understand that various changes, substitutions, variations, and improvements disclosed herein may be made without departing from the spirit and scope of the disclosure in its broadest form. None of the description in the present application should be read as implying that any particular element, step, act, or function is an essential element, which must be included in the claim scope. The scope of patented subject matter is defined by the allowed claims. Moreover, none of these claims are intended to invoke a means plus function claim construction unless the exact words "means for" are followed by a participle.

Claims

CLAIMSWhat is claimed is:

1. A burner comprising: a combustor can; a plurality of premixing tubes circumferentially arranged about a longitudinal axis of the combustor can, wherein each respective premixing tube of the plurality of premixing tubes extends to an outlet of the respective premixing tube, wherein each respective premixing tube defines a respective gap relative to an adjacent premixing tube of the respective premixing tube, wherein each respective premixing tube is arranged to form a respective jet flame in a combustion zone disposed downstream from the outlet; and a fluidic injection arrangement configured to form a fluidic barrier to inhibit ingestion of jet flames from the combustion zone through the respective gap and thereby inhibit effects of a flashback condition on the burner, wherein the fluidic injection arrangement comprises a plurality of sets of fluidic injection openings disposed along an arc segment over the respective gap, wherein the arc segment is located axially upstream relative to the outlet of the respective premixing tube, wherein each respective fluidic injection opening of the plurality of the sets of fluidic injection openings during operation delivers a respective jet of a fluid through a liner of the burner, the respective jet contributing to form the fluidic barrier, wherein the respective jet delivered by way of the fluidic injection opening is a jet of air in a direction that forms a crossflow pattern relative to a mixture of reactants that flows in the respective premixing tube.

2. The burner of claim 1, further comprising a fluid reservoir fluidly coupled to the plurality of sets of fluidic injection openings.

3. The burner of claim 1, wherein the burner comprises a depleted oxygen combustion (DOC) burner.

4. The burner of claim 1, wherein the burner comprises a hydrogen-based burner.

5. The burner of claim 3, wherein a concentration of hydrogen in fuel supplied to the burner is in a range from 60% to 90%.

6. The burner of claim 5, wherein the range of the concentration of hydrogen in fuel supplied to the burner is from 70% to 100%.

7. The burner of any of the preceding claims, wherein the plurality of premixing tubes comprises open-ended tubes.

8. The burner of any of the preceding claims, wherein each respective premixing tube constitutes a respective main burner.

9. The burner of any of the preceding claims, further comprising a centrally disposed pilot burner.

10. The burner of claim 1, further comprising an igniter disposed proximate to or in the respective gap, wherein the fluidic barrier inhibits effects of the flashback condition on the igniter.

11. A gas turbine engine comprising a burner in accordance with any of the preceding claims.

12. A method for inhibiting effects of a flashback condition on a burner of gas turbine engine, the method comprising: circumferentially arranging a plurality of premixing tubes about a longitudinal axis of a combustor can, wherein each respective premixing tube of the plurality of premixing tubes extends to an outlet of the respective premixing tube, wherein each respective premixing tube defines a respective gap relative to an adjacent premixing tube of the respective premixing tube, wherein each respective premixing tube is arranged to form a respective jet flame in a combustion zone disposed downstream from the outlet;configuring a fluidic injection arrangement to form a fluidic barrier to inhibit ingestion of jet flames from the combustion zone through the respective gap and thereby inhibit effects of a flashback condition on the burner, wherein the configuring of the fluidic injection arrangement comprises disposing a plurality of sets of fluidic injection openings along an arc segment over the respective gap, and locating the arc segment axially upstream relative to the outlet of the respective premixing tube, wherein each respective fluidic injection opening during operation delivering a respective jet of the fluid through a liner of the burner, the respective jet contributing to form the fluidic barrier, locating the arc segment axially upstream relative to the outlet of the respective premixing tube, wherein each respective fluidic injection opening during operation delivers a respective jet of a fluid through a radially-inward surface of the fluid reservoir facing the respective gap, wherein the respective jet contributes to form the fluidic barrier, wherein the respective jet delivered by way of the fluidic injection opening is a jet of air, and arranging the jet of air in a direction to define a crossflow pattern relative to a mixture of reactants that flows in the respective premixing tube.

13. The method of claim 12, wherein the burner comprises a hydrogen-based burner, and a concentration of hydrogen in fuel supplied to the burner is in a range from 60% to 90%.

14. The method of claim 13, wherein the range of the concentration of hydrogen in fuel supplied to the burner is from 70% to 100%.

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