BACKGROUND [0001] 1. Field

[00Θ2] Disclosed embodiments are generally related to combustion turbine engines, such as gas turbine engines, and, more particularly, to a dual stage, multi-fuel nozzle including a flow-separating wall with a slip-fit joint.

[00Θ3] 2. Description of the Related Art

In gas turbine engines, fuel is delivered from a fuel source to a combustion section where the fuel is mixed with air and ignited to generate hot combustion products that define working gases. The working gases are directed to a turbine section where they effect rotation of a turbine rotor. Fuel nozzles are employed to introduce the fuel into the combustion section. Thermal gradients typically

encountered in fuel nozzles are relatively high, which can result in the formation of exceedingly high stresses that need to be appropriately alleviated.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004] FIG. 1 is a cut away, side view of a disclosed multi-fuel nozzle embodying aspects of the present invention.

[00Θ5] FIG. 2 is a zoomed-in view of a portion of FIG. 1 for illustrating non- limiting structural features involving slip-fit joints that may be used in a multi-fuel nozzle embodying aspects of the present invention.

[0006] FIG. 3 illustrates an alternative non-limiting embodiment of a slip-fit joint that may be used in a multi-fuel nozzle embodying aspects of the present invention.

[0007] FIG. 4 is a fragmentary cut away, side view of a further disclosed multi- fuel nozzle embodying aspects of the present invention. DETAILED DESCRIPTION

[00Θ8] The inventors of the present invention have recognized certain issues that can arise in nozzles that may involve a dual stage design, such as may be used in combustion turbine engines capable of multi-fuel operation. For example, internal wal l structures of the nozzle may be subject to varying thermal stresses due to varying temperatures across the nozzle. Certain prior art nozzles involve bellows or piston rings to accommodate variable thermal expansion of the wall structures. However, the present inventors have cleverly recognized that the use of such bellows or piston rings can impose substantial cross-sectional constraints in the flow passages that in certain applications could impede appropriate fuel flow through such passages. In view of such a recognition, the present inventors propose an improved multi-fuel nozzle including slip-fit joints not subject to the above-discussed cross-sectional constraints and that can accommodate thermally- induced movement (e.g., axial

expansion/contraction) of such wall structures in the varying thermal environment of the combustion turbine engine while providing a cost-effective and reliable seal to fluids passing by the joints.

[00Θ9] In the following detailed description, various specific details are set forth in order to provide a thorough understanding of such embodiments. However, those skilled in the art will understand that embodiments of the present invention may be practiced without these specific details, that the present invention is not limited to the depicted embodiments, and that the present invention may be practiced in a variety of alternative embodiments. In other instances, methods, procedures, and components, which would be well-understood by one skilled in the art have not been described in detail to avoid unnecessary and burdensome explanation.

[0010] Furthermore, various operations may be described as multiple discrete steps performed in a manner that is helpful for understanding embodimen ts of the present invention. However, the order of description should not be construed as to imply that these operations need be performed in the order they are presented, nor that they are even order dependent, unless otherwise indicated . Moreover, repeated usage of the phrase "in one embodiment" does not necessarily refer to the same embodiment, although it may. It is noted that disclosed embodiments need not be construed as mutually exclusive embodiments, since aspects of such disclosed embodiments may be appropriately combined by one skil led in the art depending on the needs of a given application,

[0011] The terms "comprising", "including", "having", and the like, as used in the present application, are intended to be synonymous unless otlienvise indicated. Lastly, as used herein, the phrases "configured to" or "arranged to" embrace the concept that the feature preceding the phrases "configured to" or "arranged to" is intentionally and specifical ly designed or made to act or function in a specific way and should not be construed to mean that the feature just has a capability or suitability to act or function in the specified way, unless so indicated.

[0012] FIG, 1 is a cut away, side view of a disclosed multi-fuel nozzle 10, as may be used in a combustion turbine engine, such as a gas turbine engine that in one non- limiting application may be part of an Integrated Gasification Combined Cycle (IGCC) power plant. In one non-limiting embodiment, multi-fuel nozzle 10 includes a support flange 12 that may be disposed between an upstream end of the nozzle and a downstream end the nozzle to be mounted onto a respective combustor (not shown). Multi-fuel nozzle 10 includes a first fuel-injecting stage 14 defining a first conduit extending along a longitudinal axis 15 of the nozzle to convey a first fluid, to a downstream end of the nozzle, in one non-limiting application, the first fluid may be a gaseous fuel having a relatively higher heating value (HHV), such as natural gas,

[0013] Multi-fuel nozzle 10 further includes a second fuel-injecting stage 16 defining a second conduit annularly disposed about the first fuel-injecting stage to convey a second fluid to the downstream end of the nozzle. In one non-limiting application, second fuel-injecting stage 16 may comprise a relatively larger size stage compared to first fuel-injecting stage 14 and the second fluid may be a gaseous fuel having a relatively lower heating value (LHV), such as syngas/hydrogen fuel .

[0014] In one non-limiting embodiment, a centrally disposed lance 17 may be used to convey a liquid fuel (e.g., oil) to the downstream end of the nozzle. It will be appreciated that during a syngas/hydrogen mode of operation of the combustion turbine engine, each of stages 14, 16 may convey syngas/hydrogen fuel while during a natural gas mode of operation of the combustion turbine engine, one of stages 14, 16 may convey the natural gas while the other stage may convey a suitable diluent, such as nitrogen (N2) or steam.

[0015] First and second fuel-injecting stages 14, 16 mutually share a flow- separating wall 18 between one another. Flow-separating wall 18 extends along the longitudinal axis of the nozzle. In one non-limiting embodiment, as may be appreciated in FIG. 1, flow-separating wall 18 may be a longitudinally bifurcated (i.e., split) flow-separating wall, such as may include a first wall section 19 extending from a downstream side of support flange 12 towards the downstream end of the nozzle, and a second wall section 21 extending from an upstream side of side support flange 12 towards the upstream end of the nozzle. Slip-fit joints 20 may be disposed to mechanically couple flow-separating wall. 18 to support flange 12. Slip-fit joints 20 are configured with a relatively small cross-sectional radial profile to accommodate thermally-induced movement (e.g., axial expansion/contraction) of the flow- separating wall in the varying thermal env ironment of the turbine engine while providing a cost-effective and reliable seal to fluids passing by the joints.

[0016] FIG. 2 provides a zoomed-in view of the section of multi-fuel nozzle 10 within oval line 25 ( FIG. 1 ), for illustrating non-limiting structural features in connection with slip-fit joints that may be used in a multi-fuel nozzle embodying aspects of the present invention. In one non- limiting embodiment, support flange 12 includes a slot 30 to receive a corresponding end of flow-separating wall 18. As may be further appreciated in FIG. 2, support flange 12 may further include a guide member 32 located to guide insertion into the slot of the corresponding end of the flow-separating wall.

[0017] In one non-limiting embodiment, flow-separating wall 18 may be a cylindrical w ^r all and slip-fit joint 20 may be a knife edge seal, as illustrated in FIG. 2. Slip fit joints 20 may be configured so that the respective wall sections 19, 21 of flow- separating wall 18 engage sufficiently tightly into corresponding slots 30 in support flange 12. As the respective wail sections of flow-separating wall 18 expand and contract over the operation range, the respective wall sections of flow-separating wall 18 would slide within respective slots 30. Slot depth may be configured so that it is sufficiently deep to accept the respective ends of flow-separating wall 18 without interference during periods of maximum expansion. Conversely, the travel engagement between the respective ends of flow-separating wall. 18 and slots 30 may be configured so that it is sufficiently long to ensure that the respective ends of flow- separating wall 18 remain seated within slots 30 during periods of maximum contraction. In alternative embodiments, the slip-fit joint could be implemented by way of a trombone-seal 34, as schematically illustrated in FIG. 3.

[0018] In accordance with yet further aspects of the present invention, slip-fit joints 20 may facilitate performing servicing and repair operations in connection with multi-fuel nozzle 10, such as servicing and repair of a nozzle cap 40 of multi-fuel nozzle 10. In one non-limiting embodiment, nozzle cap 40 may be attached to first wall section 19 of flow-separating wall 18. A cutting operation may, for example, be performed across points 42 (labeled with the letter x) on an outer wall. 44 of multi-fuel nozzle 10 to gain access to inner structures of the nozzle. One may then perform straightforward and user-friendly slidable removal by way of slip-fit joint 20 of first wal l section 19 of flow-separating wal l 18 together with nozzle cap 40 of multi-fuel nozzle 10. This would then allow repair and/or replacement of cap 40, without having to deal with burdensome and time-consuming actions that otherwise would be encountered if flow-separating wall 18 involved bellows in lieu of the disclosed slip- fit.

[00.1.9] FIG. 4 is a fragmentary cut away, side view of a further disclosed multi- fuel nozzle embodying aspects of the present invention. In this embodiment, further slip-fit joints 20' may be arranged in an inwardly flow-separating wall 52, such as may separate the respective flows through the conduit defined by the centrally disposed lance 17 and the conduit defined by first fuel-injecting stage 14. For the sake of visual simplicity, FIG. 4 illustrates just the slip-fit joints 20' disposed at the downstream end of flange 12. It will be appreciated, however, that the upstream end of flange 12 can be similarly arranged to provide a slip-fit connection to the upstream section of inwardly flow-separating wall 52. It will be appreciated that this embodiment allows elimination of the bellows 54 illustrated in FIG. 1 and thus, based on the reduced radial profile of slip-fit joint 20' compared to bellow structures, the cross-sectional area of the first conduit can also be unimpeded by the incremental radial profile that otherwise would be taken by such bellows. [0020] In operation, disclosed embodiments are expected to provide a versatile dual stage, multi-fuel nozzle 10 that can accommodate thermally-induced axial expansion'' contraction of flow-separating wall 18 and/or inwardly flow-separating wall 52 in the varying thermal environment of the combustion turbine engine while providing a cost-effective and reliable seal to fluids passing by the joints. Additionally, based on a reduced radial profile of slip-fit joint 20 compared to bellow structures, in one non-limiting application the cross-sectional area of the second conduit can establish a sufficient flow of the second fluid, particularly when the second fluid comprises a gaseous fuel having a relatively lower heating value (LHV). Lastly, disclosed embodiments are expected to provide user-friendly accessibility and removability of certain nozzle components, such as the nozzle cap.

[0021] While embodiments of the present disclosure have been disclosed in exemplary forms, it will be apparent to those skilled in the art that many

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