Patent Application
20080069691
The foregoing and other features and advantages of the present invention should be more fully understood from the following detailed description of illustrative embodiments taken in conjunction with the accompanying Figures in which like elements are numbered alike in the several Figures:
Referring to
The system 10 also includes at least one key structure 28. As will be discussed further along in the description, the key structure 28, and the manner in which it functions in conjunction with the surfaces (particularly the tapered surface 26) of the groove 16, is a critical component to formation of a seal between the inner shell assembly 12 and outer shell assembly 20. The key structure 28 is disposable in the groove 16 between the sealing surface 21 of the tongue 18 and at least one of (depending on which part of the key structure 28 is being referred to) the alignment slot 22, the association surface 24, and the tapered surface 26. In an exemplary embodiment, the groove 16 defined by each inner shell segment 14a-b will include the key structure 28.
The key structure 28 includes an alignment segment 30 and a seal segment 32. The alignment segment 30 is disposed in the alignment slots 22 of the groove 16, and aids in key structure 28 alignment, as will be discussed further along in the disclosure. In an exemplary embodiment, the seal segment 32 includes a tapered portion 33 that is associable and mateable with the tapered surface 26 of the groove 16. The seal segment 32 may be referred to as having two sections; a sealing section 32a and an associating section 32b. The sealing section 32a may extend 360 degrees around the entire groove 16, and may include a sealing arrangement 34, such as a pliant flex-rope 35 disposed in a rope groove 36 (the rope groove 36 being defined by the seal segment 32), a C seal, an M seal or a configuration of radial teeth. The association section 32b (which may or may not extend 360 degrees around the groove 16) associates the key structure 28 with the inner shell segments 14a-b at the association surface 24 of the groove 16. In an exemplary embodiment, the association section 32b defines at least one axial slot 38 and the association surface 24 defines at least one threaded cavity 40, wherein at least one threaded instrument 42 is threaded through the axial slot 38 and the threaded cavity 40 to associate the key structure 28 with the inner shell segment 14a or 14b. It should be appreciated that the axial slot(s) 38 are configured to allow axial movement of the key structure 28 relative to the threaded instrument 42, which will be in fixed association with the association surface 40. Allowance of this movement is demonstrated by clearance gaps 44a-b between the threaded instrument and axial slot 38, as shown in
In an exemplary embodiment, the system 10 may also include at least one actuator 46. The actuator 46 is disposed in the groove 16, and may be any device capable of actuating the seal portion 32 of the key structure 28 towards the tapered surface 26. By way of example, the actuator 46 may be a compression spring disposed between the seal portion 32 and a wall 48 of the groove 16.
With the components of the system 10 described above, the manner in which the system 10 aligns and seals will now be discussed. Referring to alignment, the inner shell assembly 12 is axially aligned with the outer shell assembly 20 via a 360 degree tongue 18 and groove 16 fit. This fit entails metal-to-metal contact between the inner shell segments 14a-b and outer shell segments (of which the turbine outer shell assembly 20 is comprised), and maintains a correct axial position of the inner shell assembly 12. In an exemplary embodiment, the groove 16 will include a width 70 that is large enough to accommodate distortion in side walls 72a-b of the tongue 18. The key structure 28 is also aligned with the inner shell segments 14a-b (one key structure 28 for each inner shell segment in an exemplary embodiment) via disposal of the alignment segment 30 in the alignment slots 22 found in the groove 16. In an exemplary embodiment, the alignment slots 22 are disposed at a relative center of each inner shell segment 14a or 14b, with the threaded instruments 42 associating the seal segment 32 (particularly association section 32b) with the association surface 24 at each relative side of the alignment slot 22 of the particular inner shell segment 14a or 14b.
In systems that do not include the components of the system 10, the tongue 18 and groove 16 fit would also be primarily responsible for creating a pressure seal that divides a high-pressure exhaust region 50 from a hot reheat region 52. While this fit is partly responsible for the pressure seal created by the system 10, the key structure 28 increases the effectiveness of the seal, helping to eliminate the need to field machine the side wall surfaces 72a-b of the tongue 18 during retrofitting.
Referring to creation of seals in the system 10, the key structure 28 creates a pressure seal against the segments of both the inner shell assembly 12 and outer shell assembly 20. Referring to the inner shell assembly 12, an inner pressure seal 54 is creatable at contact between the tapered surface 26 of the groove 16 and the tapered portion 33 of the seal segment 32. The tapered portion 33 is configured to align with tapered surface 26 by virtue of running at substantially the same angle as the tapered surface 26. Due to pressurized fluid flowing into and creating the high pressure exhaust region 50, and/or applied force from the actuator 46, the tapered portion 33 is forced into contact with the tapered surface 26. In an exemplary embodiment, this contact creates the inner pressure seal 54. In addition, the pressure drop and/or force from the actuator 46 causes the seal segment 32 (along with the rest of the key structure 28) to move/slide along the tapered surface 26, towards contact with the sealing surface 21 of the tongue 18. Guidance via the angle of both the tapered surface 26 and tapered portion 33 at contact, along with the force(s) supplied, creates this resultant movement towards the sealing surface 21.
Although an exemplary embodiment includes the tapered portion 33 of the key structure 28, it should be appreciated that any portion of the key structure 28 may be designed to contact, align, and/or seal with the tapered surface 26. This optional portion of the key structure 28 may not be tapered like the tapered portion 33, instead aligning/mating with the tapered surface 26 via any other means of association, such as a tongue-groove fit, wherein the key structure would include a tongue and the tapered surface 26 would include a groove. In addition, while an exemplary embodiment also includes a key structure 28 that forms the inner pressure seal 54, the key structure 28 (tapered portion 33 or otherwise) may also be merely associable with the tapered surface 26, acting as a guide, but not forming the inner pressure seal 54.
Referring now to creation of a seal with the outer shell assembly 20, the key structure 28 moves towards the sealing surface 21 of the tongue 18 until the sealing arrangement 34 of the seal section 32 contacts the sealing surface 21, and creates an outer pressure seal 56. This is the pressure seal against the outer shell assembly 20 referred to above. Once both the outer pressure seal 56 been established via the initial pressure drop (between the hot reheat region 52 and high pressure exhaust region 50) and/or actuator 46, pressure differential between the high-pressure exhaust region 50 and the hot reheat region 52 builds, further strengthening the seal 56. The outer pressure seal 56 created by the system 10 eliminates the need to field machine creep and distortion (cause by high temperature and pressure conditions over time and usage) out of the sealing surface 21 of the tongue 18 during retrofit with the groove 16 of a new inner shell segment. This outer pressure seal 56 can be achieved without machining the side wall surfaces 72a-b to include(or regain) a surface that is perpendicular with respect to a turbine centerline. This is because the sealing arrangements 34 (such as the pliant flex-rope 35 disposed in the rope groove 36, or the configuration of radial teeth) will be pushed into contact and seal with the sealing surface 21, and this contact will create a seal. Thus, machining of the tongue 18 for retrofit, and the costs associated with this machining, are eliminated.
Referring particularly now to
Referring to
Referring to
The method 100 additionally includes moving at least a portion of the at least one key structure 28 towards a tapered surface 26 of the groove 16, and guiding at least a portion of the at least one key structure 28 into contact with said tongue 18 via contact between at least a portion of the at least one key structure 28 and the tapered surface 26 of the groove 16, as shown in operational block 106. In an exemplary embodiment, the portion of the key structure 28 that would contact the tapered surface 26 would be a tapered portion 33, and this contact would allow creation of an inner pressure seal 54 between the tapered portion 33 and the tapered surface 26. Further included in the method 100 is creating an outer pressure seal 56 between at least a portion of the at least one key structure 28 and the tongue 18 via the moving and the guiding, as shown in operational block 108. Both the inner and outer pressure seals 54 and 56 may seal with the first shell assembly 12 and tongue 18 respectively at 360 degrees around the groove 16. Also, the inner and outer pressure seals 54 and 56 may be actuating the key structure 28 into a position that forms the inner and outer pressure seals 54 and 56 via at least one of an actuator 46 and a pressure differential between a high-pressure exhaust region 50 and a hot reheat region 54 of the groove 16.
While the invention has been described with reference to an exemplary embodiment, it should be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or substance to the teachings of the invention without departing from the scope thereof. Therefore, it is important that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the apportioned claims. Moreover, unless specifically stated any use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another.
