Patent Application
20170080530
The field of the invention relates to electron beam (“EB”) welding.
Gas turbines include numerous components. These components may include a combustor for mixing air and fuel for ignition, a turbine blade and rotor assembly for producing power, and a fuel nozzle assembly for providing fuel to the combustor for operation of the gas turbine. Fuel nozzle assemblies in gas turbines often include a fuel nozzle end cover with at least one fuel nozzle insert that is brazed into the fuel nozzle end cover.
Gas turbine components, including fuel nozzle assemblies, are frequently located near the combustor and typically must withstand high temperatures for extended periods of time. As a result, durability limits of these components are often reached or exceeded, requiring replacement, repair, and/or reconditioning/refurbishing of the components for continued operation of the gas turbine.
Replacing, repairing, and/or reconditioning gas turbine components, including fuel nozzle inserts, is often challenging, due to the limitations of traditional brazing and EB welding. EB welding is useful in gas turbine assemblies because EB welded joints have increased ability to handle tension from thermal strain, compared to brazed joints. EB welded joints also have the ability to yield and distribute loads. However, traditional EB welding may require a geometric structure, such as a backing shelf or other geometric configuration, to work effectively. Additionally, there is a requisite loss of wall thickness and weakening of wall integrity required to form a backing shelf, a limited containment of excess weld material escaping the weld joints, and also a limited number of repairs that can be performed, due to loss of wall thickness. As a result, a new and improved method of EB welding is needed that addresses these problems, among others.
This summary presents a high-level overview of various aspects of the invention and a selection of concepts that are further described below in the detailed description section. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in isolation to determine the scope of the claimed subject matter. The scope of the invention is defined by the claims.
In brief, and at a high level, this disclosure describes, among other things, an improved method of EB welding that reduces leakage of excess weld material, improves integrity of welded surfaces, and allows for greater versatility of EB welding, due to reduced geometric requirements. The method may include forming a collection pocket in at least one of a first and a second surface that are to be EB welded together, coupling the first and second surfaces together at an EB welding location, and EB welding the first and second surfaces together at the EB welding location. The collection pocket may be located at least partially between the first and second surfaces at the EB welding location to collect and retain excess weld material. The method may be used in tight-tolerance or thin-walled applications where EB welding with a backing shelf, which provides alignment and a barrier, may be difficult or impossible due to geometric constraints. The method, in one exemplary application, allows for improved replacement and reconditioning of a fuel nozzle insert in a fuel nozzle assembly of a gas turbine.
In a first embodiment, an electron beam (EB) welded turbine component is provided. The component comprises an insert, or a component thereof, and a receiving component comprising a base material that forms a cavity corresponding to a shape of at least a portion of the insert or the component thereof. The outer surface of the insert or the component thereof is EB welded to an inner surface of the cavity at a first location, and, at the first location, at least one of the outer surface of the insert or the component thereof and the inner surface of the cavity includes a collection pocket.
In a second embodiment, a method of reconditioning a turbine component with electron beam (EB) welding is provided. The method comprises providing a receiving component comprising a base material that forms a cavity having an inner surface, providing an insert or a component thereof having an outer surface, forming a collection pocket on at least one of the inner surface and the outer surface, coupling the inner surface to the outer surface at a first location, and EB welding the inner surface and the outer surface together at the first location.
In a third embodiment, a method of EB welding gas turbine components is provided. The method comprises providing a first component having a first surface, providing a second component having a second surface, forming a collection pocket in at least one of the first surface and the second surface, and EB welding the first surface to the second surface.
Although the EB welding methods, devices, and systems described in this disclosure are described in the context of gas turbine components, assemblies, and systems, the methods described herein may be used for joining any two surfaces where effective EB welding is desired, and should not be limited merely to components, assemblies, and systems of gas turbines.
Illustrative embodiments of the present invention are described in detail below with reference to the attached drawing figures, wherein:
The subject matter of the various embodiments of the present invention is described with specificity in this disclosure to meet statutory requirements. However, the description is not intended to limit the scope of invention. Rather, the claimed subject matter may be embodied in various other ways to include different features, components, elements, combinations, and steps, similar to the ones described in this document, and in conjunction with other present and future technologies. Terms should not be interpreted as implying any particular order among or between various steps unless the stated order of steps is explicitly required. Many different arrangements of the various components depicted, as well as use of components not shown, are possible without departing from the scope of the claims.
At a high level, the present invention generally relates to an improved method of EB welding that incorporates a collection pocket. The collection pocket may be formed in one or more surfaces that are to be EB welded together, to reduce the deposit of excess weld material around the EB weld, and also to reduce an amount of wall thickness required to form a secure EB weld connection, due to the reduced requirement for specific wall geometry (e.g., a backing shelf). For example, the method may be applied to replacement of an insert, such as a fuel nozzle insert in an assembly of a gas turbine. In such an example, a pre-installed insert, such as a fuel nozzle insert, may be removed from a receiving component, such as a fuel nozzle end cover, leaving a cavity, an outer surface of a fuel nozzle insert component may be coupled to an inner surface of the cavity at an EB welding location, and the outer surface may be EB welded to the inner surface at the EB welding location. Additionally, prior to EB welding the surfaces, a collection pocket may be formed on at least one of the inner surface and the outer surface, such that the collection pocket is at least partially between the inner and outer surfaces at the EB welding location. In this regard, in any application where two surfaces are being EB welded together, the collection pocket may be formed on one or both of the surfaces that are EB welded, such that in either scenario, the collection pocket is at least partially between the surfaces that are EB welded.
Having described some general aspects of the invention, reference is now made to
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The first location 134 may be described as a portion of the inner surface 110 of the cavity 106 and a portion of the outer surface 132 of the first component 120 that are in contact with each other, and between or in which the collection pocket 118 is disposed, or located. The first component 120, once coupled against the inner surface 110 of the cavity 106, may be EB welded from first and/or second ends 136, 138 of the first location 134, joining the material of the inner surface 110 and the outer surface 132 at the first location 134. As the EB welding is performed, even without a backing shelf or other geometric feature built into the surfaces 110, 132, the collection pocket 118 may help to receive, retain, collect, and store excess weld material (e.g., weld blow, weld spatter, weld leakage, etc.) escaping the first location 134. In gas turbine assemblies, excess weld material outside of EB welded joints may interfere with operation of the gas turbine, or cause detrimental effects to the gas turbine, and as a result, it is desirable to avoid such excess material buildup. Reducing excess weld material and maintaining maximum wall thickness by EB welding with a collection pocket may allow for repeated reconditioning processes, as well as protection of internal components, which may extend the life of the end cover 102 or another gas turbine component which is EB welded.
Furthermore, the inner surface 110 of the cavity 106 and the outer surface 144 of the third component 124 are coupled at a fourth location 152 that is separate from the first, second, and third locations 134, 142, 148. A collection pocket 118 is disposed, or located, between the inner surface 110 of the cavity 106 and the outer surface 144 of the third component 124 at the fourth location 152. The fourth location 152 may be described as a portion of the inner surface 110 of the cavity 106 and a portion of the outer surface 144 of the third component 124 that are in contact with each other, so that EB welding of the surfaces 110, 144 can occur, and between or against which the collection pocket 118 is located. EB welding may occur from first or second ends 136, 138 of the fourth location 152, to join the outer surface 144 of the third component 124 and the inner surface 110 of the cavity 106.
In the assembly process illustrated in
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The EB welding location 606 may be described as the length between the first end 136 and the second end 138 along which the first and second surfaces 602, 604 are coupled and EB welded. The EB welding may be performed from either end 136, 138 of the EB welding location 606, including both ends, depending on the geometric arrangement of components and structures to which the first and second surfaces 602, 604 are joined (i.e., the accessibility of each end 136, 138 for performing EB welding).
The collection pocket 118 may be formed or constructed to include different shapes, sizes, and/or orientations. For example, the collection pocket 118 may have straight portions, curved portions, or be defined by shapes formed in adjacent surfaces joined together for EB welding. Additionally, the collection pocket 118 may be circular, ovular, elliptical, square, rectangular, and/or symmetrical or asymmetrical. Additionally, the collection pocket 118 may be positioned on the inner surface 110 of the cavity 106 and may be oriented towards an interior 111 of the cavity 106, or the collection pocket 118 may be positioned on an outer surface (e.g., outer surface 132) of an insert component (e.g., component 120) and may be oriented away from the interior 111 of the cavity 106, as exemplified in
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A system for reconditioning a turbine component with EB welding is also provided, in accordance with an embodiment of the present invention. The system may comprise a fuel nozzle end cover comprising a base material that forms a cavity having an inner surface, and a fuel nozzle insert or a plurality of components thereof, wherein the fuel nozzle insert or the plurality of components thereof include a respective outer surface that is EB welded to the inner surface of the cavity at a separate location. Additionally, at each separate location, one of the inner surface of the cavity and the outer surface of the fuel nozzle or respective component thereof includes a collection pocket.
Removal of pre-installed fuel nozzle inserts in the end cover, and installation of a replacement fuel nozzle insert, may be performed in multiple steps. For example, for an existing brazed insert, or otherwise installed insert, a horizontal boring mill, or other device, may be used to remove the pre-installed insert and leave a semi-finished cavity. Next, a vertical boring machine, or other device, may be used to provide a machined finish to the cavity. Then, the inner surface of the resulting cavity may be further prepared as needed for proper EB welding (e.g., polishing, finishing, stress relief, heat treating, etc.), and installing of the components may be commenced. After completing the EB welding process, additional pressure testing, heat treating, or polishing may occur to provide a fully finished, reconditioned fuel nozzle insert.
A further exemplary process of replacing or reconditioning a fuel nozzle insert may include rough machining a pre-installed fuel nozzle insert to remove at least a portion of the material forming the pre-installed insert, final machining the cavity in which the pre-installed insert was located, cleaning the cavity, EB welding new components into the cavity to form the replacement fuel nozzle insert in the cavity, heat treating the new fuel nozzle insert and end cover, and final machining the fuel nozzle insert and end cover. Additionally, pressure testing, visual inspection, and other testing may be performed. After completion of the replacement, final assembly and final inspection of the fuel nozzle assembly may be performed, as well as flow testing and flow adjustments.
In addition to combustion end covers and fuel nozzle inserts, the methods described herein may be utilized for EB welding other turbine components and assemblies, in addition to other non-gas turbine related surfaces and components. Such additional components and assemblies of gas turbines may include fuel nozzles, transition duct picture frames, blade squealer tips, or any other turbine component assembly or component that may be welded or brazed.
The collection pocket described herein may be incorporated into a variety of welding applications. One such welding application is the construction of a fuel nozzle assembly in a gas turbine, as described above. Additionally, EB welding utilizing a collection pocket may be used to improve traditional EB welding with a backing shelf. Non-limiting examples of EB welding with a collection pocket include joining airfoils and shrouds, fuel manifold construction, fuel nozzle tip attachment, connection of tubing, and/or any other scenario in which one turbine component is inserted in, and/or coupled to, another turbine component in order to EB weld the turbine components together.
Embodiments of the technology have been described herein to be illustrative rather than restrictive. Alternative embodiments will become apparent to readers of this disclosure. Further, alternative means of implementing the aforementioned elements and steps can be used without departing from the scope of the claims, as would be understood by one having ordinary skill in the art. Certain features and sub-combinations are of utility and may be employed without reference to other features and sub-combinations, and are contemplated as within the scope of the claims.
