Patent Application
20130115867
The system described herein relates generally to an enclosure system and a method for applying a coating. More specifically, the system relates to an enclosure and method that is used to apply a coating on a rotating shaft of a turbomachine.
Turbine efficiency improvement is an important consideration of any steam turbine value package. Providing the most efficient design while assuring the upgrade or conversion meets or exceeds all performance guarantees and operates reliably is a key objective. When viewing the source of efficiency losses in a steam turbine, about 33% of the total loss can be attributed to leakage. These leakage losses are divided into tip leakage at about 22%, shaft packing at about 7% and root leakage at about 4%. Clearly reducing efficiency loss due to seal leakage can have a significant impact on steam turbine performance.
Brush seals are often used on turbine rotors, and contact between the rotor and the brush leads to frictional heating. Any initial bow in the rotor will lead to a high spot and can lead to a rotor bow due to differential heating. Interstage brush seals and those installed in the shaft ends have an impact on rotor critical speeds. The interstage seals tend to impact the first bending critical whereas the shaft end seals tend to impact the second bending critical. The bristles of the brush seals can also cause undesired wear at any location where they make contact with the rotor. This wear causes increased leakage and reduces overall system efficiency.
In an aspect of the present invention, an enclosure system is provided having a shroud configured to cover at least a portion of a shaft. The shroud includes an input port and an output port. The input port is configured to accept at least one of a coating tool and an abrasive supplying tool. The output port is connected to a vacuum system.
In another aspect of the present invention, a method of providing an enclosure system includes the steps of providing a shroud having an input port and an output port, the shroud configured to cover at least a portion of a shaft, providing at least one of a coating tool and an abrasive supplying tool, placing at least one of the coating tool and the abrasive supplying tool at least partially within the input port, and connecting a vacuum system to the output port.
These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
One or more specific embodiments of the present invention will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.
When introducing elements of various embodiments of the present invention, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Any examples of operating parameters and/or environmental conditions are not exclusive of other parameters/conditions of the disclosed embodiments. Additionally, it should be understood that references to “one aspect”, “an aspect”, “one embodiment”, or “an embodiment” of the present invention are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.
Referring to the drawings,
In operation, steam 24 enters an inlet 26 of turbine 10 and is channeled through stationary vanes 22. Note, however, that the steam inlet configurations may vary. Vanes 22 direct steam 24 downstream against blades 20. Steam 24 passes through the remaining stages imparting a force on blades 20 causing shaft 14 to rotate. At least one end of turbine 10 may extend axially away from rotor 12 and may be attached to a load or machinery (not shown) such as, but not limited to, a generator, and/or another turbine.
In one embodiment of the present invention as shown in
The coating tool 230 may be a high velocity oxygen fuel (HVOF) tool, an air plasma spraying (APS) tool, a low pressure plasma spraying (LPPS) tool, a physical vapor deposition (PVD) tool, an electron beam physical deposition (EBPVD) tool or a cold spray deposition tool. As only one non-limiting example, the coating tool 230 is a high velocity oxygen fuel tool and the high velocity oxygen fuel tool is connected to a fuel supply 250 having control panel 252 and a coating supply 254. The fuel supply 250 could comprise a gas such as hydrogen, methane, propane, propylene, acetylene, natural gas or a liquid such as kerosene, or any other suitable fuel as desired in the specific application. The coating supply 254 could comprise a powder or particulate material comprising ceramics and/or metallic materials, such as but not limited to, WC-Co, chromium carbide, MCrAlY, nickel based alloys or any other suitable coating having the desired wear resistant properties as desired in the specific application.
The coating tool 230 could be used to apply a wear resistant coating to the shaft 220 in likely wear areas, such as near brush seals. The wear resistant coating could be a tungsten-carbide coating, a nickel chromium coating, a chromium carbide coating or any other suitable coating having the desired wear resistant properties as desired in the specific application. As one example only, the wear resistant coating could be applied in a thickness range of about 200-400 microns. Alternatively, a thicker coating of about 8 millimeters to about 12 millimeters may also be used, or any other thickness above or below this range as may be desired in the specific application. In addition, the coating tool 230 may be manipulated by the use of a robotic arm 260 which may be under manual control or controlled by a computer controlled program.
The vacuum system is connected to the output port 214 and removes abrasive within shroud 210 as well as depositing the abrasive back into abrasive supply 350. Suitable filters (not shown) can be attached to or connected with the vacuum system 340 for removing any undesired contaminants from abrasive supply 350. The abrasive supplying tool draws abrasive from the supply 350 and directs it onto the shaft 220 to increase surface roughness, remove contaminants or remove desired layers. For example, before coating the shaft 220 with a wear resistant layer, certain contaminants (e.g., rust, etc.) can be removed, and the surface roughness of the shaft can be increased (or decreased) to obtain a desirable surface for adherence of the wear resistant coating. As only one example, the surface roughness of portions of the shaft could be manipulated to be about 50 to about 60 microns.
A method of providing an enclosure system is also provided, according to an aspect of the present invention. The method includes the steps of providing a shroud having an input port and an output port, where the shroud is configured to cover at least a portion of a shaft. Another step provides at least one of a coating tool and an abrasive supplying tool. A placing step places at least one of the coating tool and the abrasive supplying tool at least partially within the input port, and a connecting step connects a vacuum system to the output port. A providing step provides a sealing member to seal a junction between the shroud and the shaft, and this step may include providing the sealing member with an elastomeric sealing member, providing the sealing member with a magnetic sealing member, and/or providing the sealing member with both an elastomeric sealing member and a magnetic sealing member. Another providing step provides the input port with an input sealing member.
The step of providing at least one of a coating tool and an abrasive supplying tool may include providing a coating tool that is at least one of a high velocity oxygen fuel (HVOF) tool, an air plasma spraying (APS) tool, a low pressure plasma spraying (LPPS) tool, a physical vapor deposition (PVD) tool and an electron beam physical deposition (EBPVD) tool. In addition, this step may also include providing the high velocity oxygen fuel tool and connecting the high velocity oxygen fuel tool to a fuel supply and a coating supply. Further, the step of providing at least one of a coating tool and an abrasive supplying tool may also include providing an abrasive supplying tool that is a grit blasting gun connected to an abrasive supply.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
