The present subject matter relates generally to turbine systems and, more particularly, to variable vane assemblies for turbine systems and methods for removing and assembling variable vane assemblies in turbine systems.
Turbine systems are widely utilized in fields such as power generation. For example, a conventional gas turbine system includes a compressor section, a combustor section, and at least one turbine section. The compressor section is configured to compress air as the air flows through the compressor section. The air is then flowed from the compressor section to the combustor section, where it is mixed with fuel and combusted, generating a hot gas flow. The hot gas flow is provided to the turbine section, which utilizes the hot gas flow by extracting energy from it to power the compressor, an electrical generator, and other various loads.
A typical compressor for a gas turbine may be configured as a multi-stage axial compressor and may include both rotating and stationary components. A shaft drives a central rotor drum or wheel, which has a number of annular rotors. Rotor stages of the compressor rotate between a similar number of stationary stator stages, with each rotor stage including a plurality of rotor blades secured to the rotor wheel and each stator stage including a plurality of stator vanes secured to an outer casing of the compressor. During operation, airflow passes through the compressor stages and is sequentially compressed, with each succeeding downstream stage increasing the pressure until the air is discharged from the compressor outlet at a maximum pressure.
In order to improve the performance of a compressor, one or more of the stator stages may include variable stator vanes, or variable vanes, configured to be rotated about their longitudinal or radial axes. Such variable stator vanes generally permit compressor efficiency and operability to be enhanced by controlling the amount of air flowing into and through the compressor by rotating the angle at which the stator vanes are oriented relative to the flow of air. Rotation of the variable stator vanes is generally accomplished by attaching, for example, a lever arm or gear assembly to each stator vane. The lever arms or gear assemblies may be rotated, thereby causing each stator vane to rotate about its radial or longitudinal axis.
During the life of a turbine system, a variable vane may require repair or replacement. Thus, it may be necessary to remove the variable vane from the compressor. Variable vanes are disposed in the compressor between an outer casing and the rotor, to which the rotor stages are attached. To remove a variable vane, an upper outer casing may be separated from a lower outer casing. Presently known designs of compressors then require that the rotor be removed from the lower outer casing before a variable vane can be removed, because presently known variable vane designs require that the vane be moved radially inward from the outer casing to separate the variable vane from the outer casing for removal. Removal of the rotor from the outer casing is a burdensome, time-consuming, and expensive process which may require, for example, operation of a crane to pick up and move the rotor. In many cases, such as during in-field repair or replacement, removal of the rotor may thus be extremely difficult or impossible.
Accordingly, improved variable vane assemblies for turbine systems and improved methods for removing and assembling variable vane assemblies in turbine systems are desired. For example, variable vane assemblies and methods that allow for removal and assembly of the variable vanes while the rotor remains within the lower outer casing would be advantageous.
Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.
In one embodiment, the present disclosure is directed to a variable vane assembly for a turbine system. The variable vane assembly includes a variable stator vane comprising a radially inner end, a radially outer end, and a body therebetween, and an outer casing proximate the radially outer end, the outer casing comprising an inner wall, and outer wall, and a body therebetween. A generally annular ring channel is defined in the outer casing, the ring channel extending from the inner wall into the casing. The variable vane assembly further includes a ring segment disposed in the ring channel, and a stem extending from the radially outer end of the variable stator vane at least partially through the ring segment.
In another embodiment, the present disclosure is directed to a variable vane assembly for a turbine system. The variable vane assembly includes a variable stator vane comprising a radially inner end, a radially outer end, and a body therebetween, and a ring segment. The variable vane assembly further includes a stem extending from the radially outer end of the variable stator vane and configured to extend at least partially through the ring segment, and a stem extension configured to couple with the stem and protrude from the ring segment.
In another embodiment, the present disclosure is directed to a method for removing a variable stator vane in a turbine system. The method includes separating an upper outer casing from a lower outer casing, and sliding a ring segment in a ring channel defined in one of the upper outer casing or lower outer casing towards an edge surface of one of the upper outer casing or lower outer casing. The variable stator vane is coupled to the ring segment.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:
Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.
In one embodiment, the compressor section 12 may comprise a multi-stage axial compressor having a plurality of corresponding rotor and stator stages. In such an embodiment, one or more of the stator stages may include a plurality of variable stator vanes. For example, the compressor section 12 may include a plurality of fixed stator vanes in its downstream stages, with the variable stator vanes being disposed in the upstream stages thereof. Alternatively, all of the stator stages of a compressor section 12 may include variable stator vanes.
During operation of the gas turbine 10, the compressor section 12 supplies compressed air to the combustor section 14. Air and fuel are mixed and burned within combustors of the combustor section 14, and hot gases of combustion flow in a hot gas path from the combustor section 14 to the turbine section 16, wherein energy is extracted from the combustion gases to produce work.
As shown in
The outer casing 50 in exemplary embodiments further includes a lower outer casing 62 and an upper outer casing 63. The lower outer casing 62 and upper outer casing 63 may include edge surfaces defining the outer boundaries of the casings, and some of which may mate together to form outer casing 50. For example, edge surfaces 64 at respective horizontal joints 66 of the lower outer casing 62 and upper outer casing 63 may mate together to form the outer casing 50. Mechanical fasteners, such as nut-bolt combinations or other suitable mechanical fasteners, may be utilized to fasten the lower outer casing 62 and upper outer casing 63 together at the horizontal joints 66.
As further shown in
One or more ring segments 72 may be provided, each of which may be configured to fit within the ring channel 70 and move through the ring channel 70, such as towards an edge surface. Thus, when assembled, a ring segment 72 may be disposed within the ring channel 70. Each ring segment 72 may be sized and shaped to fit within the ring channel 70. Further, ring segments 72 may be sized such that the ring channel 70 can accommodate one or more ring segments 72. For example, the portion of the ring channel 70 defined in the lower outer casing 62 may accommodate one ring segment 72 that extends through the entire ring channel 70, or more than one ring segment 72 that together extend through the entire ring channel 70. When fully assembled, the ring segments 72 disposed in the ring channel 70 may extend through the entire ring channel 70 or any portion thereof.
In exemplary embodiments, the ring channel 70 may include a dovetail slot 74 or other suitable female coupling portion. This slot 74 or portion may in exemplary embodiments as shown be the portion of the ring channel 70 furthest from the inner wall 52. Alternatively, the slot 74 or portion may be any suitable portion of the ring channel 70. The ring segments 72 may include dovetails 76 or other suitable male coupling portions configured to couple with the dovetail slot 74 or other suitable female coupling portion, thus coupling the ring segments 72 to the ring channel 70 such that the ring segments 72 are movably retained within the ring channel 70. When movably retained, a ring segment 72 can move, such as slide, within the ring channel 70 such as in the circumferential direction, but are generally retained in and thus generally cannot move in, for example, the radial direction.
As shown in
In some embodiments, the stem 80 may extend in the generally radial direction entirely through the ring segment 72. In other embodiments, the stem 80 may extend in the generally radial direction partially through the ring segment 72. Further, a variable vane assembly 20 according to the present disclosure may include a stem extension 82 configured for coupling with the stem 80. When assembled, the stem extension 82 may extend radially inward through the casing 50, such as through the body 56 thereof, from the outer wall 54 towards the inner wall 52. Further, in embodiments wherein the stem 80 extends only partially through the ring segment 72, the stem extension 82 may extend partially through the ring segment 72 to couple with the stem 80. In exemplary embodiments as shown, the stem extension 82 protrudes from the outer wall 54 of the casing 50. In other embodiments, a radially outer end of the stem extension 82 may be flush with the outer wall 54 or within the body 56.
When assembled, the stem 80 and stem extension 82 are coupled together. For example, one of the stem 80 or stem extension 82 may include a male coupling feature 84, and the other of the stem 80 or stem extension 82 may include a mating female coupling feature 86. In exemplary embodiments as shown, the stem 80 includes the male coupling feature 84 and the stem extension 82 includes the mating female coupling feature 86. The coupling features 84, 86 may be sized and shaped such that, when assembled, the male coupling feature 84 generally fits within the female feature 86, coupling the stem 80 and stem extension 82 together.
In some embodiments, as shown in
As discussed, the variable stator vanes 22 may each rotate about a generally radial axis extending through the body 32 of each vane 22. In some embodiments, a variable vane assembly 20 may thus include a vane arm 90. The vane arm 90 may be rotatably coupled to the vane 22, such as through rotational coupling to the stem extension 82. Rotation of the vane arm 90 may rotate the stem extension 82, thereby causing rotation of the stem 80 and thus the vane 22. Alternatively, a gear assembly or any other suitable rotational apparatus may be coupled to the vane 22, such as to the stem extension 82.
Variable vane assemblies 20 according to the present disclosure facilitate efficient and cost-effective removal and assembly of variable stator vanes 22. Further, such variable vane assemblies 20 allow for removal and assembly of vanes 22 while the rotor 24 of the turbine system 10 remains within the outer casing 50, such as within the lower outer casing 62. For example, the upper outer casing 63 may be separated from the lower outer casing 62 to provide access to the vanes 22. However, the vanes 22 can then be removed from the lower outer casing 62 (as well as from the upper outer casing 63) without requiring removal of the rotor 24 from the lower outer casing 62. Such advantageous removal and assembly of the vanes 22 is facilitated by the inclusion in the variable vane assemblies 20 of ring segments 72, which the vanes 22 are coupled to. The ring segments 72 move, such as slide, within ring channels 70. Such movement in exemplary embodiments is generally annular or circumferential about the casing 50, such as towards an edge surface 64. The rings segments 72 can thus be removed from or placed into the ring channels 70 by moving them through the ring channels 70. Accordingly, vanes 22 coupled to a ring segment 72 can be removed with the ring segment 72 due to movement of the ring segment 72. Movement of the vanes 22 in the radial direction for removal or installation, which thus requires removal of the rotor 24, is thus no longer required.
The present disclosure is thus further directed to methods for removing variable stator vanes 22 in a turbine system 10. A method may include, for example, separating an upper outer casing 63 from a lower outer casing 62. Such separating may be facilitated by, for example, unfastening mechanical fasteners that fasten the upper outer casing 63 and lower outer casing 62 together, such as at the horizontal joints 66, and lifting the upper outer casing 63 form the lower outer casing 62.
The method may further include, for example, sliding a ring segment 72 in a ring channel 70 defined in the lower outer casing 62 or upper outer casing 63 towards an edge surface 64. One or more variable stator vanes 22 may be coupled to the ring segment 72. In exemplary embodiments as shown, the edge surface 64 is at the horizontal joint 66. Further, in exemplary embodiments as shown, the ring channel 70 is generally annular, and may thus extend circumferentially about the casing 50. A ring segment 72, and thus the variable stator vanes 22 coupled to the ring segment 72, may be removed from the casing 50 by sliding the ring segment 72 in the ring channel 70 past the edge surface 64.
In some embodiments, a stem 80 may extend from the variable stator vane 22 at least partially through the ring segment 72, as discussed above. The stem 80 may couple the vane 22 and ring segment 72 together. Further, in some embodiments, a stem extension 82 may be coupled to the stem 80. The stem extension 82 may extend through the body 56 of the casing 50. Thus, in some embodiments, a method according to the present disclosure may further include uncoupling a stem extension 82 from the stem 80, and removing the stem extension 82 from the ring segment 72. Such uncoupling may require, for example, removing a male coupling 84 from a female coupling feature 86.
Further, in some embodiments, the method may include removing a mechanical fastener 88 fastening the stem 80 and stem extension 82 together. Still further, in some embodiments, the method may include uncoupling a vane arm 90 from the stem extension 82.
It should further be understood that the various steps disclosed herein may be reversed to assembly variable stator vanes 22 in a turbine system 10. Such as method for assembling such vanes 22 may include, for example, sliding a ring segment 72 in a ring channel 70 defined in a lower outer casing 62 or upper outer casing 63 away from an edge surface 64; coupling a stem extension 82 and stem 80 together; fastening the stem extension 82 and stem 80 together such as with a mechanical fastener 88; coupling a vane arm 90 and a stem extension 82 together; and engaging an upper outer casing 63 and a lower outer casing 62
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 include 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.