A multi-burner cluster for turbomachines, a combustor including the multi-burner cluster, and a turbomachine including the combustor

Abstract

A multi-burner cluster (15) for turbomachines comprising a holder (31) having a cylindrical body (31.1), which houses a plurality of burners (33). Each burner has at least a first fuel inlet duct (37). The multi-burner cluster further comprises a first peripheral fuel distribution line (35) which extends peripherally around the cylindrical body and at least partially surrounds the burners (33). The first peripheral fuel distribution line (35) is fluidly coupled with a first fuel inlet port (17) formed in the holder (33), and with the first fuel inlet ducts (37) of at least some of said burners (33).

Description

A multi-bumer cluster for turbomachines, a combustor including the multi-burner cluster, and a turbomachine including the combustorDESCRIPTIONTECHNICAL FIELD

[0001] The present disclosure pertains to the field of gas turbines. Embodiments disclosed herein particularly concern gas turbine burners.BACKGROUND ART

[0002] Designing and manufacturing burners for gas turbine engines is complex and challenging.

[0003] Modem burners are often arranged in a multi-bumer cluster inside the combustion chamber of the gas turbine engine. In various configurations, each burner is supplied by multiple different fuel supply ducts. These ducts are utilized to modulate fuel delivery based on the operating conditions of the gas turbine engine, with the aim of reducing fuel consumption, enhancing the efficiency of the gas turbine engine, and mitigating noxious emissions.

[0004] Currently, multiple burners are needed based on the heat rate required for gas turbine performance. To assemble multiple burners using mechanical arrangements and flow lines for each burner is highly complicated. The design becomes even more difficult, if each burner requires to be fed by more than one fuel line.

[0005] It would be therefore beneficial to provide a novel design for multi-burner clusters, which makes construction easier, by inter alia reducing the number and extension of the fuel flow lines.

[0006] Another challenging issue in multi-bumer cluster design relates to the need to provide precisely manufactured fuel delivery lines, such that the same fuel flowrate is delivered to all burners in a given operating condition and all burners operate correctly. To this end, each burner of a multi-burner cluster shall be carefully manufactured, such that all burners operate under the same conditions, in particular regarding fuel supply. The fuel flow conditions can be influenced largely by the geometry of thefuel feeding ducts. Manufacturing tolerances may result in unbalanced operating conditions of the various burners of the same cluster, meaning that the burners of the same cluster are not supplied with the same fuel flow rate, for instance, or fuel is supplied at different pressure conditions to the different clusters.

[0007] An unbalanced operating condition may occur, for instance, if an uneven fuel flow is supplied to individual burners, resulting in imbalance in the operation of the different burners within the same multi-burner cluster Such unbalanced operating conditions shall be avoided.

[0008] If a test phase reveals that the multi-burner cluster operates in an unbalanced manner due to production defects, lack of precision in manufacturing, excessively wide processing tolerances, or other reasons, the cluster must be rejected, and a new production run must be initiated.

[0009] Embodiments disclosed herein are directed towards mitigating or eliminating one or more of the aforementioned drawbacks.SUMMARY

[0010] According to embodiments disclosed herein, a multi-burner cluster assembly comprises a holder having a cylindrical body, which houses a plurality of burners. Each burner has at least a first fuel inlet duct. The multi-burner cluster further comprises a first fuel distribution line which at least partially surrounds the burners. The first fuel distribution line is fluidly coupled with a first fuel inlet port formed in the holder, and with the first fuel inlet ducts of at least some of the burners which are partially or entirely surrounded by the fuel distribution line.

[0011] The resulting layout is compact and easy to manufacture and assembled.

[0012] In some embodiments, the first fuel distribution line is fluidly coupled with all the burners, such that fuel from the first fuel inlet port can be delivered to each burner.

[0013] In some embodiments, each burner comprises more than just one fuel inlet duct. Preferably, each burner comprises the same number of fuel inlet ducts. Theholder may comprise one fuel distribution line for each fuel inlet duct of the burners. For instance, if the burners include each three fuel inlet ducts, the holder can be provided with three fuel distribution lines. At least one fuel distribution line can be split into two distribution lines, each of which feeds a respective sub-group of burners, as will be described here below for the third one of a set of three fuel distribution lines.

[0014] Each fuel distribution line can extend around a main body of the holder, for instance a main body of cylindrical shape, such that the burners are all placed inside the peripherally extending fuel distribution lines. In some embodiments, however, additional burners can be positioned outside the fuel distribution lines. For instance, the (one or more) fuel distribution lines can surround central part of the holder, where a first set of burners are positioned, and additional burners can be arranged outward of the (one or more) fuel distribution lines.

[0015] In embodiments described in more detail below, reference being made to the attached drawings, all the burners are positioned inside the fuel distribution lines, which are therefore arranged as peripheral fuel distribution lines around the burner cluster.

[0016] Each fuel distribution line can entirely or partly surround the burners.

[0017] The holder, wherein the burners are housed, or which is manufactured mon- olithically (e.g., by additive manufacturing) with the burners, can have a main body which houses the burners, and a peripheral sleeve surrounding the main body. The main body can be cylindrical, with a circular or non-circular cross-section. The sleeve can be cylindrical and may have a circular cross-section. The sleeve may encircle the main body of the holder.

[0018] The fuel distribution lines can extend peripherally around the main body, for instance a cylindrical body, of the holder. The fuel inlet ports can be manufactured in a central portion of the main body surrounded by the peripheral fuel distribution lines.

[0019] The fuel distribution lines can be positioned between the main body of the holder and the sleeve. For instance, the fuel distribution lines can be in the form of peripheral channels in a peripheral surface of the main body of the holder, which peripheral surface is surrounded by the sleeve. The sleeve closes radially outwardly thechannels, thus forming peripheral fuel distribution lines.

[0020] In some embodiments, additional burners can be positioned outside the sleeve. The sleeve may be apertured, to provide a flow coupling between the fuel distribution lines formed in the main body of the holder, and burners positioned around the sleeve, for instance manufactured in a ring which surrounds the sleeve.

[0021] In some embodiments, the holder and the burners are manufactured mono- lithically by additive manufacturing. In other embodiments, the holder is manufactured separately from the burners, which are assembled into seats of the holder. The holder and / or the burners can be manufactured entirely or partially by additive manufacturing, by casting, machining, or combinations thereof, for instance. Each burner may in turn be manufactured starting from two or more burner segments, which are assembled by welding, for instance. Each burner segment can be manufactured by additive manufacturing, by casting, by machining or by combinations of these technologies.

[0022] Further features and embodiments of the multi-burner cluster of the present disclosure are outlined in the enclosed claims and will be described with reference to the attached drawings.

[0023] Disclosed herein are also a combustor including a multi-burner cluster as outlined above, and a gas turbine including such a combustor.BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Reference is now made briefly to the accompanying drawings, in which:Fig. l illustrates a sectional view of a combustion chamber of a gas turbine engine, including a multi-burner cluster according to the present disclosure;Fig. l A illustrates an enlargement of a detail of Fig. l, showing the multiburner cluster and relevant end cover assembly;Fig.2 illustrates a front view of the multi-burner cluster according to line Illi of Fig.l,Fig. 3 illustrates a cross-sectional view of the multi-burner cluster and end cover assembly according to III-III of Fig.2Fig.3A illustrates an enlargement of detail A of Fig.3;Figs 4 and 5 illustrate axonometric views of the multi-burner cluster and end cover assembly according to two angles of view;Fig.6 illustrates a side view of the multi-burner cluster and end cover assembly;Fig.7 illustrates a side view of the multi-cluster assembly in isolation;Figs. 8, 9 and 10 and illustrate sectional views according to lines VIII- VIII, IX-IX and X-X of Fig.7;Fig.11 illustrates a sectional view according to line XI-XI in Fig.10;Fig.12 illustrates a sectional view according to line XII-XII in Fig.11 ;Figs. 13, and 14 illustrate front views according to lines XIII-XIII and XIV- XIV of Fig.7; andFigs. 15 and 16 illustrate axonometric views of the multi -burner cluster in two different orientations.DETAILED DESCRIPTION

[0025] Fig. l illustrates a portion of a gas turbine engine 1 comprising a combustion chamber 3 shown in a sectional view. The combustion chamber 3 comprises a forward casing 5 and an aft casing 7 connected to one another. The aft casing 7 and the forward casing 5 house a liner 8 which is fluidly coupled to a transition piece 9. The transition piece 9 extends inside a gas turbine casing 11 towards the stationary nozzles 12 and the rotary blades 14 of the first turbine stage. The combustion chamber 3 further comprises an end cover assembly 13, attached to the forward casing 5. A multi-burner cluster 15 is attached on the side of the end cover assembly 13 facing the interior of the liner 8. The multi-burner cluster 15 will be described in more detail below.

[0026] The end cover assembly 13 comprises a plurality of components, which are shown in detail in Figs.1 A and 3. In this embodiment, the end cover assembly 13 comprises a plurality of fuel pipes 13.1. In other embodiments, the end cover assembly can include a single fuel pipe. In the example shown four fuel pipes 13.1 are provided, but in other exemplary embodiments a different number of fuel pipes can be provided, for instance two or three, or even more than four fuel pipes 13.1 can be foreseen.

[0027] Each fuel pipe 13.1 is fluidly coupled to a respective fuel inlet port of a holderof the multi -burner cluster 15, which will be described in greater detail below.

[0028] Each fuel pipe 13.1 is coupled through a respective flange to a cover plate 13.2. The cover plate 13.2 is in turn coupled to an end cover 13.3, whereto the multiburner cluster 15 is mechanically and fluidly coupled. Each fuel pipe 13.1 extends through a fuel pipe line 13.5 which ends in a respective fuel port 17 (Fig.lA) formed in the holder of the multi -burner cluster 15. In the embodiment shown in the attached drawings, the multi -burner cluster 15 comprises four fuel ports, to which a controlled fuel flowrate can be delivered as a function of the operating conditions of the gas turbine engine 1. As will be described in greater detail below, each fuel port can be fluidly coupled to all burners of the multi -burner cluster 15, or to a sub-group of burners.

[0029] The end plate assembly 13 further includes a water duct 19, which delivers cooling water into a cavity 21 formed in the end cover 13.3. The cavity 21 is closed by the cover plate 13.2 and is fluidly coupled to a plurality of water lines, not shown, extending from the side of the end cover 13.3 opposite to the cover plate 13.2. Each water line is fluidly coupled to one of the burners of the multi -burner cluster 15, to deliver cooling water thereto.

[0030] The multi -burner cluster 15 is shown in detail in Figs. 3 A to 16. In this embodiment, the multi -burner cluster 15 comprises a holder 31, which supports a plurality of burners 33. In the embodiment of Figs. 1 to 18 the multi-burner cluster 15 comprises twelve burners 33. In this embodiment a first set of eight burners 33 is arranged along a first circle surrounding an axis of symmetry A-A of the multi -burner cluster 15. A second set of four burners 33 is arranged along a second circle surrounding the axis A- A of the multi -burner cluster 15. The two circles are co-axial.

[0031] The holder 31 comprises a main body, which is substantially cylindrical and develops around axis of symmetry A-A. The main body is labeled 31.1 and is referred to herein as the “cylindrical body”. It shall be understood that the term “cylindrical” shall not be construed in a strict geometrical sense, but shall rather indicate that the central body has a roughly cylindrical shape with an axis A-A. Moreover, the cylindrical body is shown as having a circular cross-section. This can be beneficial for instance if the multi-burner cluster assembly faces the interior of a liner which has a circular inner combustion chamber. However, in other embodiments, the main bodymay have a non-circular cross-section, for example an elliptical cross-section or a polygonal cross-section.

[0032] The cylindrical body 31.1 is surrounded by an outer sleeve 31.2 for the purpose which will become clear from the description below. The shape of the sleeve can be cylindrica, for instance circular, as shown, but may be different and depends upon the shape of the peripheral surface of the main body 31.1.

[0033] The holder 31 can feature seats for the burners 33, i.e. the cylindrical body 31.1 of the holder 31 can be manufactured as a mechanical component, for instance by additive manufacturing, or by chip removal, or by casting and chip removal combination, or by other techniques. The cylindrical body 31.1 can feature a plurality of seats, in the example twelve seats, one for each burner 33. The burners can be manufactured separately from the cylindrical body 31.1 and introduced in the seats thereof. Each burner 33 can be manufactured by machining, additive manufacturing, casting or combinations thereof. Each burner can in turn be manufactured as a single monolithic piece, e.g. by additive manufacturing. In other embodiments, each burner 33 can be manufactured by two or more components or sections, which are subsequently assembled to one another. Each component or section into which the burner 33 is divided can be manufactured by additive manufacturing, by casting, by machining (chip removal), or combinations thereof.

[0034] In other embodiments, as shown in the drawings, the cylindrical body 31.1 and the burners 33 are manufactured as a monolithic component, for instance by additive manufacturing. In other words, the burners 33 and the cylindrical body 31.1 of the holder 31 are generated by additive manufacturing as a single piece.

[0035] The central body, or main body 31.1 of the holder 31 comprises one or more peripheral fuel distribution lines. In some embodiments, if the multi -burner cluster 15 comprises a single fuel port 17 and a single fuel pipe 13.1, a single peripheral fuel distribution line can be foreseen in the cylindrical body 31.1.

[0036] In the embodiment shown in the attached drawings, the multi-burner cluster 15 comprises four fuel ports, which are labeled 17A, 17B, 17C, 17D for clarity, see e.g. Fig.16. Herein, reference number 17 refers to a generic fuel port. Each fuel port17 is fluidly coupled with a respective one of the four fuel pipes 13.1. Each fuel port 17 is fluidly coupled, through a respective peripheral fuel distribution line, to a plurality of burners 33. As will be described in detail below, one or some of the peripheral fuel distribution lines can extend around the entire cylindrical body 31.1 and can be fluidly coupled to each burner 33. One or some of the peripheral fuel distribution lines can extend around a portion of the cylindrical body 31.1 and can be fluidly coupled to only a sub-group of burners 33. In this case the peripheral fuel distribution line does not extend around the entire central cylindrical body 31.1, but will rather extend around a portion of a circumference.

[0037] More specifically, the cylindrical body 31.1 comprises a first peripheral fuel distribution line 35 which is fluidly coupled to the first fuel port 17A, as shown in Fig. 8 . The first peripheral fuel distribution line 35 is fluidly coupled to each burner 33 through an inwardly oriented first fuel inlet duct 37 for each burner 33. The term “inwardly oriented” as understood herein means that the fuel inlet ducts 37 extend from the periphery of the cylindrical body 31.1 towards the central area of the cylindrical body 31.1. As shown in detail in the sectional views of Figs.3 A and 11, each first fuel inlet duct 37 has two portions of different diameter, namely a larger portion 37.1 and narrower portion 37.2. The larger portion 37.1 has an inlet end fluidly coupled to the first peripheral fuel distribution line 35 and an outlet end fluidly coupled to an inlet end of the narrower portion 37.2. This latter has in turn an outlet end fluidly coupled to the respective burner 33. In some embodiments, each first fuel inlet duct 37 houses a first flow adjusting element 39, which forms a first orifice 41, as best shown in Fig.3A. The orifice 41 can have a circular section and can be characterized by a diameter and a length, in the direction of flow, i.e. in the direction of the respective first fuel inlet duct 37. In Fig. I l a modified embodiment is shown, where no flow adjusting element 39 is foreseen.

[0038] In use, when fuel flows through first fuel inlet duct 37, each first flow adjusting element 39 generates a concentrated head loss. The head loss is determined by the cross-sectional area and the length of the orifice 41. By modifying the geometrical features of the orifice, such as in particular the length in the flow direction and / or the cross-sectional area of the orifice 41, the concentrated head loss can be modified. Specifically, if the orifice has a circular cross-section, the concentrated head loss can bemodified by varying one or both diameter and length in the flow direction of the orifice 41.

[0039] Each first flow adjusting element 39 is interchangeable. By replacing one flow adjusting element 39 with another flow adjusting element having an orifice with a different diameter and / or a different length, the concentrated head loss can be modified.

[0040] Each first flow adjusting element 39 with the respective orifice 41 can be designed such that, in use, each burner 33 receives the same fuel flow rate.

[0041] As the path from the first fuel inlet port 17A to the burner 33 varies between burners, the pressure drop along this path is not constant for all burners. To achieve uniform fuel flowrate, it is therefore possible to use orifices 41 with different geometric characteristics.

[0042] Machining of the burners 33 and the holder 31, along with their respective fuel flow passages, is complex and can lead to errors in shape and size. Even small errors can result in significant imbalances in fuel flows to individual burners 33, i.e., different fuel flow rates to different burners 33. Once the multi-burner cluster 15 is assembled, it can be tested to verify that each burner 33 receives the correct fuel flow through port 17A. If this is not the case, for example, if a burner receives a lower fuel flow rate than designed, this defect can be corrected by replacing the respective flow adjusting element 39 with another flow adjusting element 39 having an orifice 41 with different geometric characteristics, such as a different diameter and / or length. Specifically, if the flow rate to a burner 33 is lower than it should be, the respective flow adjusting element 39 can be replaced with another flow adjusting element having an orifice 41 with a larger diameter orifice and / or shorter length.

[0043] In the illustrated embodiment, the cylindrical body 31.1 comprises a second peripheral fuel distribution line 45, which is fluidly coupled to the second fuel port 17B, as shown in Figs. 3 A, 9 and 11. The second peripheral fuel distribution line 45 is fluidly coupled to each burner 33 through an inwardly oriented second fuel inlet duct 47 for each burner 33. As shown in detail in the sectional views of Figs. 3A and 11, each second fuel inlet duct 47 has two portions of different diameter, namely a largerportion 47.1 and narrower portion 47.2. The larger portion 47.1 has an inlet end fluidly coupled to the second peripheral fuel distribution line 45 and an outlet end fluidly coupled to an inlet end of the narrower portion 47.2. This latter has in turn an outlet end fluidly coupled to the respective burner 33. Each second fuel inlet duct 47 houses a second flow adjusting element 49, which forms a second orifice 51 (Fig. 3 A). Similarly to the orifices 41, each orifice 51 can have a circular section and can be characterized by a diameter and a length, in the direction of flow, i.e. in the direction of the respective second fuel inlet duct 47. The modified embodiment of Fig.11 shows a configuration where no flow adjusting element is included in the ducts 47.

[0044] Similarly to what has been disclosed above, in connection with the first flow adjusting element 39, in use, when fuel flows through second fuel inlet duct 47, each second flow adjusting element 49 generates a concentrated head loss. The head loss is determined by the cross-sectional area and the length of the orifice 51. By modifying the geometrical features of the orifice, such as in particular the length in the flow direction and / or the cross-sectional area of the orifice 41, the concentrated head loss can be modified. Each second flow adjusting element 49 is interchangeable, such that by replacing one flow adjusting element 49 with another flow adjusting element having an orifice with a different diameter and / or a different length, the concentrated head loss can be modified.

[0045] Similarly to what was described regarding orifices 41, by replacing the flow adjusting elements 49, it is possible to correct manufacturing defects and eliminate imbalances in fuel flow rates to individual burners 33 with regard to the fuel delivered through the second fuel inlet port 17B.

[0046] Each one of the first and second fuel ports 17 A, 17B are separately connected to each burner 33 through the respective peripheral fuel distribution lines 35 and 45, such that different fuel flows can be delivered to the burners, for instance depending upon the operating conditions of the turbine.

[0047] In the illustrated embodiment, the multi -burner cluster 15 further includes two additional fuel ports 17C, 17D, each of which is fluidly coupled to a sub-group of burners 33 through respective peripheral fuel distribution lines. In other embodiments, only one fuel port 17C can be foreseen, with a single peripheral fuel distribution linefluidly coupled to each burner 33.

[0048] As best shown in Figs. 3 A, 10 and 11, in the illustrated embodiment, the cylindrical body 31.1 comprises a third peripheral fuel distribution line 55, which is fluidly coupled to the third fuel port 17C. The third peripheral fuel distribution line 55 is fluidly coupled to half of the burners 33 through respective inwardly oriented third fuel inlet ducts 57. The cylindrical body 31.1 further comprises a fourth peripheral fuel distribution line 65, which is fluidly coupled to the fourth fuel port 17D. The fourth peripheral fuel distribution line 65 is fluidly coupled to half of the burners 33 through respective inwardly oriented fourth fuel inlet ducts 67. Each third and fourth peripheral fuel distribution line 55, 65 extend around approximately 160-170°. Two barriers 60 separate the third peripheral fuel distribution line 55 from the fourth peripheral distribution line 65, such that one half of the burners 33 are fed with fuel from the third fuel port 17C through the third peripheral fuel distribution line 55, and the other half of the burners 33 are fed with fuel from the fourth fuel port 17D through the fourth peripheral fuel distribution line 65.

[0049] As shown in Figs 3 A and 11, each third fuel inlet duct 57 has two portions of different diameter, namely a larger portion 57.1 and narrower portion 57.2. The larger portion 57.1 has an inlet end fluidly coupled to the second peripheral fuel distribution line 55 and an outlet end fluidly coupled to an inlet end of the narrower portion 57.2. This latter has in turn an outlet end fluidly coupled to the respective burner 33. Each third fuel inlet duct 57 houses a third flow adjusting element 59, which forms a third orifice 61 (Fig. 3 A). Similarly to the orifices 41 and 51, each third orifice 61 can have a circular section and can be characterized by a diameter and a length, in the direction of flow, i.e. in the direction of the respective third fuel inlet duct 57. In the modified embodiment of Fig.11 the third flow adjusting elements 59 are omitted.

[0050] The same arrangement is foreseen along the fourth fuel inlet ducts 67, which include a larger portion 67.1 and narrower portion 67.2 (see Fig.11). The larger portion 67.1 has an inlet end fluidly coupled to the second peripheral fuel distribution line 65 and an outlet end fluidly coupled to an inlet end of the narrower portion 67.2. This latter has in turn an outlet end fluidly coupled to the respective burner 33. Each fourth fuel inlet duct 67 can house a fourth flow adjusting element (not shown and not presentin the embodiment of Fig.11), which forms a fourth orifice. Each fourth orifice can have a circular section and can be characterized by a diameter and a length, in the direction of flow, i.e. in the direction of the respective third fuel inlet duct 57.

[0051] Similarly to what was described above, in connection with the first flow adjusting elements 39 and the second flow adjusting elements 49, in use, when fuel flows through third fuel inlet duct 57 and fourth fuel inlet duct 67, each third flow adjusting element 59 and fourth flow adjusting element generates a concentrated head loss. The head loss is determined by the cross-sectional area and the length of the respective orifices. By modifying the geometrical features of the orifices, such as in particular the length in the flow direction and / or the cross-sectional area of the orifice, the concentrated head loss can be modified.

[0052] Similarly to what was described regarding orifices 41 and 51, by replacing the flow adjusting elements in the third fuel inlet duct 57 and fourth fuel inlet duct 67, it is possible to correct manufacturing defects and eliminate imbalances in fuel flow rates to individual burners 33 regarding the fuel delivered through the third and fourth fuel inlet ports 17C and 17D.

[0053] In the illustrated embodiments, the first and second peripheral fuel distribution lines 35 and 45 are manufactured in form of annular channels in the outer surface of the cylindrical body 31.1 of the holder 31 and are closed radially outwardly by the cylindrical sleeve 31.2. For instance, the channels can be generated through additive manufacturing on the outer cylindrical surface of the cylindrical body 31.1 and the cylindrical sleeve 31.2 can be assembled once the flow adjusting elements 39 and 49 have been mounted in their respective fuel inlet ducts 37, 47. The first and second peripheral fuel distribution lines 35, 45 are offset with respect to one another in an axial direction, i.e., parallel to the axis A-A.

[0054] The third and fourth peripheral fuel distribution lines 55 and 65 are similarly manufactured as semi-annular channels extending around the cylindrical outer surface of the cylindrical body 31.1. The third and fourth peripheral fuel distribution lines 55, 65 can be substantially coplanar to one another and can be axially offset with respect to the second peripheral fuel distribution line 65. The cylindrical sleeve 31.2 closes the semi-annular channels 55, 65, as well as the first and second peripheral fueldistribution lines 35 and 45, once the flow adjusting elements 39, 49, 59 have been mounted in the respective fuel inlet ducts 57, 67.

[0055] With the above-described arrangement of flow adjusting elements 39, 49, 59, each fuel flow path to each burner 33 of the multi-burner cluster 15 can be adjusted until a correctly balanced fuel flow from the fuel inlet ports 17 A, 17B, 17C, 17D to each burner 33 is achieved, despite possible manufacturing defects or inaccuracies. In case of unbalanced flowrate, individual flow adjusting elements can be replaced by other flow adjusting elements, the orifices whereof have different geometric features, to modify the local head loss concentrated in the orifice, thus adjusting the total pressure loss along each individual fuel flow path from the fuel inlet port 17 to the respective burner 33.

[0056] It shall be understood that the concept described above, of using replaceable flow adjusting elements featuring respective orifices can be used also in multi-burner clusters having a different burner arrangement, interchangeable orifices can be advantageously used in all situations where it may be useful or necessary to compensate for manufacturing defects or inaccuracies, without the need to discard the entire multiburner cluster and rebuild it from scratch.

[0057] Moreover, the special arrangement of the holder, the fuel distribution lines and the burners as described above can be configured also without replaceable orifices and interchangeable flow adjusting elements.

[0058] While in the above description reference is made to the use of interchangeable flow adjusting elements featuring respective orifices to adapt the head loss in fuel flow paths of a generic multi-burner cluster, another aspect of the present disclosure relates to the novel structure of the multi -burner cluster irrespective of the use of interchangeable flow adjusting elements. Specifically, disclosed herein is a multi-burner cluster defined by the following clauses.Clause 1. A multi-burner cluster assembly comprising a plurality of burners; wherein each burner comprises a first fuel inlet duct; wherein each first fuel inlet duct contains a first removable and replaceable flow adjusting element forming a first orifice; wherein the first orifice has at least one geometric feature that impactsfuel flow conditions through the first fuel inlet duct towards the respective burner; such that by replacing the first orifice with a substitute first orifice having a different geometric feature, the fuel flow conditions through the first fuel inlet duct towards the respective burner are modified.Clause 2. The multi-burner cluster assembly of clause 1, wherein each burner comprises a second fuel inlet duct; wherein each second fuel inlet duct contains a second removable and replaceable flow adjusting element forming a second orifice; wherein the second orifice has at least one geometric feature that impacts fuel flow conditions through the second fuel inlet duct towards the respective burner; so that by replacing the second orifice with a substitute second orifice having a different geometric feature, the fuel flow conditions through the second fuel inlet duct towards the respective burner are modified.Clause 3. The multi -burner cluster assembly of clause 2, wherein each burner comprises a third fuel inlet duct; wherein each third fuel inlet duct contains a third removable and replaceable flow adjusting element forming a third orifice; wherein the third orifice has at least one geometric feature that impacts fuel flow conditions through the third fuel inlet duct towards the respective burner; such that by replacing the third orifice with a substitute third orifice having a different geometric feature, the fuel flow conditions through the third fuel inlet duct towards the respective burner are modified.Clause 4. The multi-burner cluster assembly of any one of the preceding clauses, comprising a holder in which the burners are supported; and wherein the fuel inlet ducts of the burners are formed in the holder.Clause 5. The multi -burner cluster assembly of clause 4, wherein the holder and the burners are manufactured monolithically by additive manufacturing.Clause 6. The multi-burner cluster assembly of clause 4, wherein the holder comprises a plurality of seats, and wherein each seat contains one of said burners.Clause 7. The multi-burner cluster assembly of any one of clauses 4 to 6, wherein the holder comprises a first fuel distribution line formed in the holder; wherein the first fuel distribution line is fluidly coupled with a first fuel inlet port and with at least some of said first fuel inlet ducts.Clause 8. The multi -burner cluster assembly of clause 7, wherein the first peripheral fuel distribution line is fluidly coupled with each of said first fuel inlet ducts.Clause 9. The multi-burner cluster assembly of clause 9, comprising a supplemental fuel distribution line, formed in the holder; wherein the supplemental fuel distribution line is fluidly coupled with a supplemental fuel inlet port; wherein the first fuel distribution line is fluidly coupled with some of the first fuel inlet ducts; and wherein the supplemental fuel distribution line is fluidly coupled with the others of said first fuel inlet ducts.Clause 10. The multi -burner cluster assembly of clause 7 or 8 or 9, when depending at least on clause 2, wherein a second fuel distribution line is formed in the holder; wherein the second fuel distribution line is fluidly coupled with a second fuel inlet port and with at least some of said second fuel inlet ducts.Clause 11. The multi -burner cluster assembly of clause 10, wherein the second fuel distribution line is fluidly coupled with each of said second fuel inlet ducts.Clause 12. The multi-burner cluster assembly of clause 10 or 11, wherein the first fuel distribution line and the second distribution line are offset in an axial direction, parallel to an axial extension of the burners.Clause 13. The multi -burner cluster assembly of any one of clauses 10 to 12, when depending at least on clause 3, wherein a third fuel distribution line is formed in the holder; wherein the third fuel distribution line is fluidly coupled with a third fuel inlet port and with at least some of said third fuel inlet ducts.Clause 14. The multi-burner cluster assembly of clause 13, wherein thethird fuel distribution line is fluidly coupled with each of said third fuel inlet ducts.Clause 15. The multi -burner cluster assembly of clause 13 or 14, wherein the first fuel distribution line, the second distribution line and the third distribution line are offset in an axial direction, parallel to an axial extension of the burners.Clause 16. The multi -burner cluster assembly of any one of clauses 7 to 15, wherein the holder has a cylindrical body; and wherein each of said fuel distribution lines is a peripheral fuel distribution line extending peripherally around said cylindrical body and around the burners.Clause 17. The multi -burner cluster assembly of clause 16, wherein the holder comprises an outer cylindrical sleeve surrounding the cylindrical body; wherein each peripheral fuel distribution line extends along a peripheral surface of the cylindrical body and is closed radially outwardly by the outer cylindrical sleeve.Clause 18. The multi -burner cluster assembly of any one of the preceding clauses, wherein the burners are arranged according to a plurality of concentric circles around a central axis of the multi-burner cluster.Clause 19. The multi -burner cluster assembly of any one of clauses 1 to 17, wherein the burners are arranged according to a linear burner array, and wherein each of said fuel distribution lines extends peripherally around each burner and sequentially from one burner to the other along the linear burner array.Clause 20. A gas turbine combustor comprising a combustor chamber and at least one multi-burner cluster according to any one of the preceding clauses housed in the combustor chamber.

Claims

CLAIMS1. A multi-bumer cluster assembly comprising:- a holder;- a plurality of burners housed in the holder, each burner having at least a first fuel inlet duct;- a first fuel distribution line which at least partially surrounds said burners; wherein the first fuel distribution line is fluidly coupled with a first fuel inlet port formed in the holder, and with the first fuel inlet ducts of at least some of said burners; wherein each first fuel inlet duct contains a removable and replaceable flow adjusting element forming an orifice; wherein the orifice has at least one geometric feature that impacts on fuel flow conditions through the respective fuel inlet duct towards the respective burner; such that by replacing the flow adjusting element with a substitute flow adjusting element having a different geometric feature, the fuel flow conditions through the respective fuel inlet duct towards the respective burner are modified.

2. The multi-bumer cluster assembly of claim 1, wherein the first fuel distribution line entirely surrounds said burners and is fluidly coupled with the first fuel inlet ducts of each of said burners.

3. The multi-bumer cluster assembly of claim 1 or 2, wherein each burner comprises a second fuel inlet duct; and wherein the holder comprises at least a second fuel distribution line which at least partially surrounds said burners; wherein the second fuel distribution line is fluidly coupled with a second fuel inlet port formed in the holder, and with the second fuel inlet ducts of at least some of said burners.

4. The multi-bumer cluster assembly of claim 3, wherein each second fuel inlet duct contains a removable and replaceable flow adjusting element forming an orifice; wherein the orifice has at least one geometric feature that impacts on fuel flow conditions through the respective fuel inlet duct towards the respective burner; such that by replacing the flow adjusting element with a substitute flow adjusting element having a different geometric feature, the fuel flow conditions through the respective fuel inlet duct towards the respective burner are modified.

5. The multi -burner cluster assembly of claim 3 or 4, wherein the second fuel distribution line entirely surrounds said burners and is fluidly coupled with the second fuel inlet ducts of each of said burners.

6. The multi-burner cluster assembly of any one of the preceding claims, wherein each burner comprises a third fuel inlet duct; and wherein the holder comprises at least a third fuel distribution line which at least partially surrounds said burners; wherein the third fuel distribution line is fluidly coupled with a third fuel inlet port formed in the holder, and with the third fuel inlet ducts of at least some of said burners.

7. The multi-burner cluster of claim 6, wherein each third fuel inlet duct contains a removable and replaceable flow adjusting element forming an orifice; wherein the orifice has at least one geometric feature that impacts on fuel flow conditions through the respective fuel inlet duct towards the respective burner; such that by replacing the flow adjusting element with a substitute flow adjusting element having a different geometric feature, the fuel flow conditions through the respective fuel inlet duct towards the respective burner are modified8. The multi-burner cluster assembly of claim 6 or 7, the third fuel distribution line entirely surrounds said burners and is fluidly coupled with the third fuel inlet ducts of each of said burners.

9. The multi-burner cluster assembly of claim 6 or 7, wherein the holder comprises a fourth fuel distribution line which at least partially surrounds said burners; wherein the fourth fuel distribution line is fluidly coupled with a fourth fuel inlet port formed in the holder; and wherein: the third fuel distribution line is fluidly coupled with the third fuel inlet ducts of a first sub-group of said burners, and the fourth fuel distribution line is fluidly coupled with the third inlet ducts of a second sub-group of said burners.

10. The multi -burner cluster assembly of any one of the preceding claims, wherein each distribution line is arranged peripherally around the holder, and entirely or partly encircles the burners arranged in the holder.

11. The multi -burner cluster assembly of any one of the precedingclaims, wherein the holder and the burners are manufactured monolithically by additive manufacturing.

12. The multi-burner cluster assembly of claim 11, wherein the holder comprises a plurality of seats, and wherein each seat contains one of said burners.

13. The multi-burner cluster assembly of claim 12, wherein the holder is formed by additive manufacturing.

14. The multi-burner cluster assembly of claim 12 or 13, wherein each burner is formed by a plurality of burner sections, each burner section being manufactured by additive manufacturing separately from the other burner sections, and said burner sections are connected to one another to form the burner.

15. The multi -burner cluster assembly of any one of the preceding claims, wherein the fuel distribution lines are offset in an axial direction, parallel to an axial extension of the burners.

16. The multi -burner cluster assembly of any one of the preceding claims, wherein the holder comprises a main body, and wherein the fuel distribution lines extend around the main body.

17. The multi -burner cluster assembly of claim 16, wherein the main holder comprises outer sleeve surrounding the main body; wherein each fuel distribution line extends along a surface of the main body and is closed radially outwardly by the outer sleeve.

18. The multi -burner cluster assembly of any one of the preceding claims, wherein said burners are arranged according to a plurality of concentric circles around a central axis of the multi-burner cluster.

19. A gas turbine combustor comprising a combustor chamber and at least one multi-burner cluster assembly according to any one of the preceding claims housed in the combustor chamber.

20. A gas turbine comprising a gas turbine combustor according to claim

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