System and method for preventing liberation and damage to airfoil in gas turbine
Patent Information
- Application Number
- JP2024101004
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-07-25
- Filing Date
- 2024-06-24
- Publication Date
- 2025-02-14
Smart Images
Figure 2025022757000001_ABST
Abstract
Description
[Technical field]
[0001] The present disclosure relates generally to gas turbine engines, and more particularly to systems and methods for preventing and limiting the disassociation and damaging effects of gas turbine airfoils. [Background technology]
[0002] A gas turbine is conventionally made up of two sections, a compressor section and a turbine section. The compressor section takes in air or other suitable gas and compresses its volume. The turbine section mixes the flow of compressed air from the compressor section of the gas turbine with a flow of fuel to generate hot combustion gases. The turbine in the turbine section receives the flow of hot combustion gases from the combustor and extracts energy from the gas to drive a compressor and output power to an external load, such as a generator. The compressor section has a number of airfoils connected around a central shaft, the rotation of which enables the airfoils to compress the ambient air drawn into the compressor. For example, there may be about 19 stages of compressor airfoil sections in the compressor section.
[0003] When gas turbine engines are idling or not constantly running, water may condense on the surfaces of the airfoils, casings, and other components of the compressor section. Such condensed water typically contains corrosive elements, and the water acts as an electrolyte to promote corrosion. Thus, the accumulation and constant contact of water and corrosive elements on the compressor components initiates corrosion of the components, and more specifically, the airfoils. This corrosion manifests itself in the form of pits or "pitting" that can dramatically affect the overall airflow characteristics of the compressor. These corrosion pits can often be up to about 20 mm deep, creating fracture surfaces or lines that can increase the likelihood of dismemberment (i.e., failure of the airfoil by detachment of all or part of it). Dismemberment of one airfoil often causes the fracture of one or more other airfoils, which can be ejected from the gas turbine and cause injury to nearby personnel. Vibrations within the gas turbine when the turbine is in use or not idling often act as a crack propagation agent, thus exacerbating the problems caused by the pits. Given the severity of airfoil detachment, these airfoils often must be replaced in their entirety to prevent further catastrophic problems.
[0004] Previous attempts to reduce or eliminate pitting caused by condensation and / or corrosive elements have focused on the upstream intake air. These solutions generally involved air filtration to remove impurities from the air so that the condensation on the airfoil is closer to pure water. However, these air filters are expensive and have a short lifespan.
[0005] Another existing method to minimize corrosion pitting is galvanic protection of the airfoils. This galvanic protection layer helps protect the substrate from the corrosive environment and helps ensure a conductive path between the galvanic protection layer and the steel substrate. Such galvanic protection layers can be made of sacrificial materials such as aluminum or other conductive materials. Traditionally, this galvanic protection layer has been applied as a coating to the entire surface of each individual airfoil. However, the galvanic protection layer coating can degrade the surface finish over time and reduce the overall efficiency of the compressor because the surface finish itself can form pits or gaps in the coating, roughening the surface of the airfoil. Furthermore, repairing this coating is costly and time consuming as it requires inspection of every part of each airfoil to determine the magnitude and location of damage to the galvanic protection layer coating.
[0006] Therefore, there is a need for improved corrosion inhibitors to reduce or eliminate the occurrence of pitting on the surfaces of gas turbine airfoils to address one or more of the above-mentioned technical problems. Summary of the Invention
[0007] Mitigation of degradation due to galvanic protective coatings can be achieved by using replaceable anodes made of sacrificial materials. These anodes can be of various shapes and can be placed in specific locations on the turbine components to improve corrosion resistance without compromising compressor efficiency and substrate finish. Additionally, individual airfoils and stages of airfoils as a whole can be modified in shape, orientation and design to properly direct condensate to the anodes to create an efficient corrosion protection system. The galvanic protective layer improves the turbine components' resistance to pitting and other damaging effects due to corrosion, and the anodes prevent degradation of the surface finish due to the galvanic protective layer, allowing airfoils and other turbine components to function safely for an extended period of time before maintenance or replacement.
[0008] These and other features and improvements of the present application and the resulting patent will become apparent to those skilled in the art from the following detailed description taken in conjunction with the drawings and claims. [Brief description of the drawings]
[0009] The detailed description will now be described with reference to the accompanying drawings. Note that the same reference numerals may refer to the same or similar items. Various embodiments may utilize components and / or parts other than those shown in the drawings, and some components and / or parts may not be present in various embodiments. Components and / or parts in the drawings are not necessarily drawn to scale. Throughout this disclosure, singular and plural terms may be used interchangeably, depending on the context. [Figure 1] 1 is a schematic diagram of a gas turbine engine including a compressor, combustor, turbine, and an external load. [Diagram 2] FIG. 2 is a schematic diagram of a compressor that may be used in the gas turbine engine of FIG. 1; [Diagram 3] 3 is a perspective view of an airfoil that may be used in the turbine of the gas turbine engine of FIG. 1 and / or the compressor of FIG. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0010] The present disclosure generally relates to gas turbines and turbine protection systems for reducing erosion and turbine damaging effects. In some examples, the turbine protection system includes one or more airfoils that engage the compressor. As used herein, an "airfoil" is an aerodynamic body configured to generate lift when air passes over the surface of the airfoil. The compressor of a gas turbine typically includes dozens of compressor blades in the form of both "rotor blades" and "stator vanes," which are typically separated into an "airfoil" portion for compressing the air and a "base" portion for coupling the airfoil to the compressor shaft. However, for simplicity, the term "airfoil" is used herein to refer to the entire compressor airfoil, either the rotor or the stator. The rotor blades and stator vanes may vary in shape depending on the desired airflow characteristics through the compressor, but the protection system described herein may be implemented on rotors or stators of any shape.
[0011] In some embodiments, one or more airfoils include a blade, a platform, a dovetail, and a base. The "blade" of an airfoil is the characteristic airfoil portion that compresses air when the airfoil is operating as part of a compressor. The "base" or root of an airfoil is typically characterized by a curved joint and represents the portion of the airfoil where the blade joins to the platform. The "platform" of an airfoil generally defines the radially inner boundary of the airflow path across the airfoil face. When multiple airfoils are placed together on a compressor disk, the platform of each airfoil approaches a smooth cylindrical surface. The "dovetail" of an airfoil is configured to join the airfoil to the compressor disk, and the eponymous dovetail shape is configured to secure the airfoil to the compressor disk, where the dovetail is subjected to high pressures for a tight fit as the compressor rotates.
[0012] In some embodiments, the turbine protection system includes one or more anodes attached to the airfoil. The anodes may be attached to any suitable portion of the airfoil, including the platform, base, dovetail, or blade, depending on the corrosion protection needs of the particular turbine and / or airfoil. In some embodiments, the one or more anodes include a sacrificial material configured to provide galvanic protection against corrosion. The sacrificial material may be disposed between the anode and the airfoil. In some embodiments, the anodes are formed from aluminum, zinc, magnesium, lithium, or combinations thereof.
[0013] In some embodiments, the sacrificial material is formed from aluminum, zinc, magnesium, or combinations thereof. Without being bound to a particular theory, it is believed that the inclusion of a sacrificial material, such as aluminum, zinc, or magnesium, promotes corrosion of the sacrificial material rather than the airfoil itself. The unexpected finding was that the inclusion of an anode material allows for a significant reduction in size of the sacrificial material without compromising the corrosion inhibition properties. For example, a conventional corrosion prevention technique is to coat the entire airfoil with a sacrificial material. The inclusion of an anode may further promote corrosion to occur selectively on the sacrificial material rather than on the airfoil, without affecting the aerodynamic surface of the airfoil. In embodiments where the anode is incorporated within the surface of the airfoil (i.e., in place of the airfoil material), the anode has the same mass as the portion of the airfoil, platform, dovetail, or other compressor component in which the anode is embedded.
[0014] In some embodiments, the turbine protection system further includes a conductive material coated on the sacrificial material between the sacrificial material and the anode. In some embodiments, the conductive material includes bronze, iron, brass, or alloys thereof. Without being bound to a particular theory, it is believed that the inclusion of the conductive material in the sacrificial material enhances the ability of the anode to promote corrosion of the sacrificial material.
[0015] In some embodiments, the conductive material is attached through the use of mechanical fastening means such as adhesives, screws or bolts, or is fabricated as part of the anode with the sacrificial material. This conductive material may be the same or different thickness and / or shape as the sacrificial material. Without being bound to a particular theory, it is believed that having the conductive material in a different shape or thickness than the sacrificial material may be more effective in directing water to the sacrificial material. In some embodiments, the conductive material is attached on top of the sacrificial layer and shaped to have channels, grooves, gaps or holes. In other embodiments, the conductive material is attached under the sacrificial material. Including a conductive material under the sacrificial layer may increase the duration of the corrosion protection effect because the conductive material can supplement the anodic attraction of the corrosive elements in the condensed water when the sacrificial layer begins to corrode.
[0016] In some embodiments, the anodes are releasably attached to the airfoil. By forming a turbine protection system with one or more releasably attachable anodes, it has been unexpectedly discovered that one or more anodes can be added to any particular location on the airfoil to reduce or substantially eliminate erosion of the airfoil. Furthermore, the anodes can be removed whenever convenient, such as during a scheduled downtime period, without the need to completely erode the sacrificial material, ensuring that the anodes retain an optimal degree of corrosion protection at all times.
[0017] In some embodiments, the anode is attached using an adhesive. In some embodiments, the adhesive may include an epoxy, polyurethane, cyanoacrylate, anaerobic adhesive, silicone, or acrylic adhesive. For example, a portion of the anode may be coated with epoxy and then fitted into a platform such that the top surface of the anode sits flush with the surface of the platform. Additionally, in some embodiments, it may be preferred to first apply the adhesive to the surface of the compressor part. In some other embodiments, a portion of the anode is designed with grooves or channels configured to guide the application of the adhesive. In other embodiments, the adhesive is an industrial tape. For example, the adhesive may include polyimide tape or self-adhesive silicone tape.
[0018] In some embodiments, the anode is attached to the airfoil or other compressor part via a notched protrusion that connects to a groove or channel. For example, the anode may have a small protrusion with a rectangular shape, and the airfoil may have an opening in a cavity with a shape complementary to the protrusion on the anode, and the protrusion may be inserted into the opening and moved, rotated or translated to a secondary position in the cavity where a secure connection can be made. In other embodiments, the protrusion is rectangular, square, angled or trapezoidal. In some embodiments, there are multiple protrusions on the anode and multiple openings and cavities on the airfoil, so that all the protrusions are aligned with the openings. In some embodiments, the various openings and protrusions have the same shape so that the anode can be placed in the corresponding opening. In other embodiments, each anode has a unique protrusion configured to be inserted into exactly one corresponding opening, such as when the anode is shaped and / or sized to provide a corrosion protection effect at a specific location on the airfoil.
[0019] In some embodiments, the anode is attached to the airfoil or other compressor part via a threaded part. In some embodiments, the anode includes male or female threads, parallel threads, tapered threads or multi-start threads, and the airfoil or other compressor part includes a complementary portion of the thread system. By including a threaded system on the anode and compressor part, the system can provide an easier way to attach and remove the anode. In some embodiments, different anodes may have different thread types or thread sizes, and the threads are specific to the attachment of the anode at a particular location on the airfoil or other compressor part. In some embodiments, the threaded part is a vibration resistant thread. In some embodiments, the threaded part is combined with a thread locking agent, such as an adhesive, that is applied to the threads of either the compressor part or the anode. In some embodiments, some anodes have a protrusion / opening means for fastening to the airfoil, while some anodes are attached using a threaded means.
[0020] In some embodiments, the anode is attached to the airfoil or other compressor part using a magnetic connection. In some embodiments, the magnetic connection includes two or more permanent magnets, which may include neodymium iron boron, samarium cobalt, alnico, or ceramic / ferrite magnets. In some embodiments, the magnetic connection includes one or more temporary magnets. For example, a temporary magnet, such as a soft iron device, may be attached to the anode and may engage another temporary, permanent, or electromagnetic magnet attached to the airfoil or other compressor part. In some embodiments, the magnetic connection includes an electromagnet. In some embodiments, a solenoid contained within the airfoil or other compressor part may be used to attach the anode, including the magnetic component.
[0021] In some embodiments, the anode is machined to be part of the airfoil, platform, dovetail, or other compressor component. By incorporating the formation and attachment of the anode into the manufacturing process of the airfoil or other compressor component, installation of the anode can be greatly simplified.
[0022] In some embodiments, the anode is comprised of multiple layers of different materials. For example, the anode may include a base layer of a non-sacrificial material and a top layer that includes a sacrificial material. By including the base layer, the anode may be more easily attached to an airfoil or other compressor component. For example, the base layer may be machined to have notches that engage within the airfoil or platform to allow the anode to be easily attached for easy removal. The base layer may include an adhesive component, an internally threaded port, an externally threaded port, a carbon plate, or another suitable attachment method. In some embodiments, there are multiple layers of different sacrificial materials in the anode. Without being bound to a particular theory, it is believed that an anode having two or more layers of different sacrificial materials may be able to slow the corrosion rate. For example, the top layer may include aluminum and the bottom layer may include magnesium. In some embodiments, the layers may be of the same or different thicknesses and / or shapes. In some embodiments, a layer of conductive material may be added to the anode to increase the effectiveness of the anode. For example, a conductive layer may be disposed between the top layer and the bottom layer. In another example, a conductive layer may be disposed on both the top and bottom layers. In another example, a conductive layer may be disposed only on the top layer. This conductive layer may be of the same or different thickness and / or shape as the sacrificial material layer.
[0023] In some embodiments, the airfoils, casing, platform, turbine, or other parts of the compressor section of the gas turbine may include features shaped or configured to direct water to the anode. By shaping the compressor section parts to direct water to the anode, the turbine may more effectively direct water away from the airfoils and non-anode parts, further reducing the risk of these parts corroding. For example, parts such as airfoils may have channels cut into them that do not affect the overall performance and effectiveness of the compressor, but that facilitate directing condensed water to one or more anodes. These channels may be added after the airfoil is manufactured by a secondary process, or the channels may be machined into the airfoil during the manufacturing process. In some embodiments, these channels or other configurations that direct water from the parts may be specifically designed for different anode arrangements. For example, there may be different channels that each direct water to a different anode. In some embodiments, different airfoils within an airfoil stage of the compressor have different channels. By directing the water in different directions for different airfoils within an airfoil stage, the channels can better use gravity to direct the water to the anode. As mentioned above, when the turbine is idle and not running, i.e., when the airfoils are not rotating, water can condense and cause corrosion. Thus, when the turbine is not running, airfoils that are angled horizontally away from the central shaft may use channels that direct the water diagonally toward the anode on the platform, while airfoils that are angled downward from the central shaft may use channels that direct the water downward toward the anode at the tip of the airfoil.
[0024] In some embodiments, the anode may be sized and shaped to fit into a particular portion of an airfoil, dovetail, platform, or other compressor part. For example, the anode may have a top surface that is circular, rectangular, trapezoidal, square, triangular, diamond, or the like. Making the anode different shapes and sizes allows the anode to be more effectively attached to different compressor parts because each part has a different shape, angle, position, and size. In some embodiments, the anode has multiple levels of elevation to match the curvature of the platform. In some embodiments, the anode has grooves, channels, or other surface designs. By including texture on the surface of the anode, the anode may be more effective in some embodiments because the sacrificial material erodes more easily and in a more precise pattern.
[0025] In some embodiments, the anode is attached to the tip of the airfoil. By including an anode at the tip of the airfoil, the airfoil can use the influence of gravity to direct water to the anode. During idle or shutdown, some airfoils point downward from the central shaft, therefore, in some embodiments, it is preferred to have the anode at the tip of the airfoil.
[0026] In some embodiments, there are multiple anodes attached at different locations on the airfoil, platform, dovetail, or other compressor part. By including multiple anode locations, the anodes can more effectively direct water on the airfoil or part to the sacrificial material. Additionally, in some cases, when the gas turbine is idling or stopped, the airfoil may point in different directions away from the central shaft at different times. Therefore, it may be preferable to have anodes at different locations along the airfoil or other compressor part so that water is directed to a more preferred anode based on proximity and direction.
[0027] In some embodiments, the anode is mounted inside the compressor casing. Some compressors include airfoils that are in constant contact with the casing, or the spacing between the airfoil and the casing is small enough that water contacts the anode from the tips of the blades. Without wishing to be bound by theory, it is believed that mounting the anode inside the compressor casing allows for more efficient corrosion protection in cases where condensed water accumulates on the tips of the airfoils or migrates from the tips of the airfoils into the compressor casing.
[0028] Reference is now made to the drawings, in which like elements are numbered like throughout. FIG. 1 illustrates a schematic diagram of a gas turbine engine 100 that may be used with the present invention. The gas turbine engine 100 includes a compressor 102. The compressor 102 compresses an incoming flow of air 104. The compressor 102 channels the flow of compressed air 104 to a number of combustor cans 106. The combustor cans 106 mix the compressed flow of air 104 with a pressurized flow of fuel 108 and ignite the mixture to generate a flow of hot combustion gases 110. Although only one combustor can 106 is shown, the gas turbine engine 100 may include any number of combustor cans 106 arranged, such as in a circumferential array. Alternatively, the combustor 106 may be an annular combustor. The flow of combustion gases 110 is then channeled to a turbine 112. The flow of combustion gases 110 drives the turbine 112 to generate mechanical work. The mechanical work generated by the turbine 112 drives the compressor 102 via a rotor shaft 114 and an external load 116, such as an electrical generator.
[0029] The gas turbine engine 100 may use natural gas, various synthetic gases, liquid fuels, and / or other types of fuels and blends thereof. The gas turbine engine 100 may be any of a wide variety of gas turbine engines offered by General Electric (Schenectady, NY, USA), such as, but not limited to, a 7 Series or 9 Series heavy duty gas turbine engine, and may be part of a simple cycle or combined cycle power generation system. The gas turbine engine 100 may be of different configurations and may use other types of components. Other types of gas turbine engines may also be used with the present invention. Multiple gas turbine engines, other types of turbines, and other types of power generation equipment may also be used with the present invention.
[0030] 2 illustrates an example of a compressor 200. Compressor 200 includes multiple compressor stages, also referred to as rotor / stator stages, and is passed through an axial compressor flowpath 202. The exact number of rotor and stator stages is a matter of engineering design choice and may be more or less than the number shown in the figure. Any number of rotor and stator stages may be provided.
[0031] Each stage of compressor 200 may include a number of circumferentially spaced rotor blades 204 attached to a rotor wheel 206 and a number of circumferentially spaced stator vanes 208 attached to a stationary compressor case 210. Each of rotor wheels 206 may be attached to an aft drive shaft 212, which may connect to a turbine section of the engine. The rotor blades and stator vanes may reside in a flowpath 202 of compressor 200. The direction of airflow through compressor flowpath 202 is generally from left to right in FIG. 2. Other components and configurations may be used herein.
[0032] The compressor rotor blades 204 impart kinetic energy to the airflow to produce the desired pressure rise. Directly behind the rotor blades 204 may be a stage of compressor stator vanes 208. However, in some designs, the stator vanes may precede the rotor blades. Both the rotor blades and the stator vanes rotate the airflow, slowing the airflow velocity (in the reference frame of the respective airfoil) and raising the static pressure of the airflow. Typically, multiple rotor / stator stages are arranged in an axial compressor to achieve a desired discharge to inlet pressure ratio. Each rotor blade and stator vane includes an airfoil as described herein, which may be secured to a rotor wheel or stator case by a suitable mounting arrangement, often known as a "root", "base" or "dovetail". In addition, the compressor 200 may also include inlet guide vanes (IGVs) 214, variable stator vanes (VSVs) 216, and outlet or exhaust guide vanes (EGVs) 218. All of these blades and vanes have airfoils that act on a medium (e.g., air) passing through the compressor flowpath 202. As such, all of the airfoils of the blades and vanes depicted in Figure 2 may be susceptible to pitting as a result of moisture and corrosion. Other parts and configurations may be used herein.
[0033] FIG. 3 illustrates an exemplary rotor blade or airfoil 300 that may be incorporated into the compressor of FIG. 2 in one or more of a rotor blade, a stator vane, a variable stator vane, and / or an exit or exhaust guide vane. The airfoil 300 extends from an axially forward leading edge 302 to an axially aft trailing edge 304 and from a radially inner base or root 306 to a radially outer tip 308. The airfoil 300 includes a platform 310 that defines a radially inner boundary of the gaspath. The airfoil 300 also includes a dovetail 312. The illustrated airfoil 300 also includes an anode 314 located on the platform 310, as well as an anode 314 on the dovetail 312.
[0034] Variations and modifications of the methods and apparatus described herein will be apparent to those skilled in the art from the foregoing detailed description. Such variations and modifications are intended to fall within the scope of the appended claims. The above relates only to specific embodiments of the present application, and it is apparent that numerous changes and modifications may be made herein by those skilled in the art without departing from the general spirit and scope of the present disclosure.
[0035] Although specific embodiments of the present disclosure have been described, many other variations and alternative embodiments are within the scope of the present disclosure. For example, any of the functionality described with respect to a particular device or component may be performed by another device or component. Moreover, while a particular device characteristic is described, the disclosed embodiments may relate to numerous other device characteristics. Moreover, while the embodiments are described in language specific to structural features and / or methodological acts, it should be understood that the disclosure is not necessarily limited to the particular features or acts described. Rather, the particular features and acts are disclosed as exemplary forms of implementing the embodiments. In particular, conditional language such as "can," "could," "may," or "may" is generally intended to convey that a particular embodiment may include a particular feature, element, and / or step, but that other embodiments may not, unless specifically stated otherwise or understood otherwise within the context in which it is used. Thus, such conditional language is generally not intended to imply that a feature, element, and / or step is in any way required for one or more embodiments. [Explanation of symbols]
[0036] 100 Gas Turbine Engine 102 Compressor 104 Air 106 Combustor 108 Fuel 110 Combustion Gas 112 Turbine 114 rotor shaft 116 External Load 300 Airfoil 302 Leading Edge 304 Trailing edge 306 Base 308 Tip 310 Platform 312 Dovetail 314 Anode
Claims
1. 1. A turbine protection system for reducing corrosion and turbine action in a turbine, the turbine protection system comprising: at least one airfoil for engaging the compressor, the at least one airfoil including a blade, a platform, a dovetail, and a base; one or more anodes attached to the airfoil; wherein at least one of the one or more anodes comprises: A sacrificial material disposed between the anode and the airfoil configured to provide galvanic protection against corrosion. A turbine protection system including:
2. The turbine protection system of claim 1 , wherein the one or more anodes comprise aluminum, zinc, magnesium, lithium, or combinations thereof.
3. The turbine protection system of claim 1 , further comprising a conductive material coated on the sacrificial material.
4. The turbine protection system of claim 3 , wherein the electrically conductive material comprises bronze, iron, brass, or alloys thereof.
5. The turbine protection system of claim 1 , wherein the one or more anodes are releasably attached to the one or more airfoils.
6. The turbine protection system of claim 1 , wherein the anode is mounted to a platform.
7. The turbine protection system of claim 1 , wherein the anode is mounted to a base.
8. The turbine protection system of claim 1 , wherein the sacrificial material comprises aluminum, zinc, magnesium, or a combination thereof.
9. 1. A method for reducing erosion of a gas turbine airfoil, the method comprising: attaching a sacrificial material to a surface of the compressor airfoil; Attaching the anode to the sacrificial material The method includes: