Assembly for preventing fluid flow

According to one aspect of the invention, an assembly for preventing fluid flow between turbine components includes a shim and a first woven wire mesh layer that includes a first surface coupled to a first side of the shim and a second surface of the woven wire mesh layer opposite the first surface. The assembly also includes a first outer layer coupled to the second surface of the woven wire mesh layer, where the first outer layer includes a high temperature non-metallic material.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to gas turbines. More particularly, the subject matter relates to seals between components of gas turbines.

In a gas turbine, a combustor converts chemical energy of a fuel or an air-fuel mixture into thermal energy. The thermal energy is conveyed by a fluid, often compressed air from a compressor, to a turbine where the thermal energy is converted to mechanical energy. Leakage of the compressed air between turbine parts or components causes reduced power output and lower efficiency for the turbine. Leaks may be caused by thermal expansion of certain components and relative movement between components during operation of the gas turbine. Accordingly, reducing gas leaks between turbine components can improve efficiency and performance of the turbine.

BRIEF DESCRIPTION OF THE INVENTION

According to one aspect of the invention, an assembly for preventing fluid flow between turbine components includes a shim and a first woven wire mesh layer that includes a first surface coupled to a first side of the shim and a second surface opposite the first surface. The assembly also includes a first outer layer coupled to the second surface of the woven wire mesh layer opposite the first surface. The assembly also includes a first outer layer coupled to the second surface of the woven wire mesh layer, where the first outer layer includes a high temperature non-metallic material.

According to another aspect of the invention, a gas turbine includes a first turbine component, a second turbine component adjacent to the first turbine component and a cavity formed between the first and second turbine components. The gas turbine also includes a shim assembly placed within the cavity to prevent fluid flow between the first and second turbine components, the shim assembly comprising a high temperature non-metallic layer disposed on a metallic shim member

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1is a schematic diagram of an embodiment of a gas turbine system100. The system100includes a compressor102, a combustor104, a turbine106, a shaft108and a fuel nozzle110. In an embodiment, the system100may include a plurality of compressors102, combustors104, turbines106, shafts108and fuel nozzles110. The compressor102and turbine106are coupled by the shaft108. The shaft108may be a single shaft or a plurality of shaft segments coupled together to form shaft108.

In an aspect, the combustor104uses liquid and/or gas fuel, such as natural gas or a hydrogen rich synthetic gas, to run the engine. For example, fuel nozzles110are in fluid communication with an air supply and a fuel supply112. The fuel nozzles110create an air-fuel mixture, and discharge the air-fuel mixture into the combustor104, thereby causing a combustion that heats a pressurized gas. The combustor100directs the hot pressurized exhaust gas through a transition piece into a turbine nozzle (or “stage one nozzle”) and then a turbine bucket, causing turbine106rotation. The rotation of turbine106causes the shaft108to rotate, thereby compressing the air as it flows into the compressor102. The turbine components or parts are joined by seals or seal assemblies configured to allow for thermal expansion and relative movement of the parts while preventing leakage of the gas. Specifically, reducing leakage of compressed gas flow between turbine components increases hot gas flow along the desired path, enabling work to be extracted from more of the hot gas, leading to improved turbine efficiency. Seals and seal assemblies for placement between turbine parts are discussed in detail below with reference toFIGS. 2-4.

FIG. 2is a side view of an embodiment of a portion of a gas turbine200, showing components along a hot gas202path or flow. The gas turbine200includes a nozzle204, bucket206(also called a “blade” or “vane”), nozzle208and shroud210, wherein the hot gas202flows through the vane or airfoil-shaped nozzles and buckets to cause rotation of rotors about an axis212. As depicted, the bucket206and shroud210are part of a rotor assembly between two stators, wherein the stator assemblies include nozzles204and208. The nozzle204and bucket206are described as stage one components, while nozzle208is a stage two component of the turbine200. The nozzle208is positioned on a diaphragm214of the stator assembly. A seal assembly216is at least partially positioned in the diaphragm214to prevent leakage of hot gas202from the path that includes buckets206and nozzles204and208. The seal assembly216is positioned between adjacent diaphragm components that are circumferentially positioned about axis212. The gas turbine200may include a plurality of seal assemblies216located between adjacent components to prevent leakage of hot gas202from the desired flow path. Exemplary turbine components include stator components, rotor components and transition piece components.

FIG. 3is a side sectional view of the seal assembly216positioned between adjacent turbine components or parts214and300. The seal assembly216is positioned in a cavity302formed between the turbine components214and300. The seal assembly216includes a shim304, first layer306, second layer308and outer layer310. In an embodiment, the shim304is member formed from a high temperature material, such as a metal alloy, stainless steel, or nickel-based alloy. The shim304member includes a middle portion with two surfaces and raised longitudinal edges, wherein recesses are formed by the raised longitudinal edges for placement of the layers306and308. The first layer306and second layer308each comprise a metallic woven wire mesh or cloth metallic material. As depicted, the first layer306and second layer308are positioned on each surface or side of the shim304. The first layer306and second layer308are coupled to one another and the shim304via high temperature couplings, such as welds, brazes or high temperature adhesives. The outer layer310comprises a high temperature non-metallic material that is configured to improved sealing of the seal assembly216. In one embodiment, the outer layer310comprises a mica-based or graphite-based material.

In aspects, the seal assembly216includes the first layer306, second layer308and outer layer310positioned on one surface of the shim304. Further, another embodiment of seal assembly includes the first layer306and outer layer310positioned on one or both surfaces of the shim304, wherein the second layer308is not included. In yet another embodiment, the outer layer310is disposed on the shim304, without first layer306or second layer310. The outer layer310is coupled to the components of seal assembly216by any suitable high temperature-resistant mechanism, such as high temperature adhesives or high strength durable fasteners. Alternatively, one or more portions of the shim304can be wrapped to substantially surround or constrain the outer layer310. In an embodiment, as hot gas flows through gas turbine200(FIG. 2), the gas flow pressures the seal assembly216to move in a direction312into contact with turbine components214and300. Further, when contacting the components214and300, the high temperature non-metallic material of outer layer310provides and reduction of gas flow through the seal assembly216by reducing the effective gap between the seal assembly216and the components214and300.

FIG. 4is a side sectional view of an exemplary seal assembly400positioned between adjacent turbine components or parts408and410. The seal assembly400is positioned in a cavity402formed between the turbine components408and410. The seal assembly400includes outer layer404disposed on base layer406. The outer layer404comprises a high temperature non-metallic material that is configured to improved sealing of the seal assembly400. In one embodiment, the outer layer404comprises a mica-based or graphite-based material. The base layer406comprises a high temperature material, such as a metal alloy, stainless steel, or nickel-based alloy. The outer layer404is coupled to the base layer406via any suitable high temperature-resistant mechanism, such as high temperature adhesives or high strength fasteners. In an embodiment, as hot gas flows through gas turbine200(FIG. 2), the gas flow pressures the seal assembly400to move in a direction412into contact with turbine components408and410. When contacting the components408and410, the high temperature non-metallic material of outer layer404provides a reduced effective gap between components and reduces gas flow through the seal assembly400. In an embodiment, the outer layer404comprises a mica-based or graphite-based material. An exemplary outer layer404is a non-metallic material configured to provide a seal between turbine components at high temperatures, such as greater than about 700 degrees Fahrenheit.

As depicted inFIGS. 3 and 4, the high temperature non-metallic material of outer layer310and404reduces fluid flow through the seal assemblies216and400. The high temperature non-metallic material layer is disposed on one or more sides of any type of static-static seal, such as those including the shim304and mesh layers306,308as well as base layer406. Fluid flow, including hot gas flowing through the turbine200(FIG. 2), is reduced due to improved contact and sealing provided by outer layer310and404when contacting the turbine components (214,300,408,410). In addition, exemplary embodiments of the shim304and base layer406may be referred to as a substantially rigid metallic body wherein the outer layers310and404are disposed on the shim304and base layer406, respectively. As depicted inFIG. 3, the outer layer310is disposed on one or more layers, such as first layer306and second layer308. As shown inFIGS. 3 and 4, the seal assemblies216and400are configured to sealingly engage one or more turbine parts (214,300,408,410) to prevent fluid flow through cavities302and402. For example, the seal assembly216may contact an inner wall314of the turbine parts214and300to prevent or reduce fluid flow. In embodiments, the high temperature non-metallic material is substantially impermeable, even at elevated temperatures, thereby providing improved contact area with the turbine components and a resulting improved seal. The increased sealing effectiveness of the seal assembly216results from a decreased effective leakage area provided by the non-metallic material. The decreased effective leakage area is a result of a larger contact area and small amount of deformation of the layer high temperature non-metallic material.