Patent Application
20130058780
The present invention generally involves a turbine casing assembly mounting pin and method for utilizing the same. In particular embodiments, a mounting pin joins an inner casing with an outer casing in a manner that reduces distortion and eccentricity between the inner and outer casings while transferring torque and gravity loads.
Conventional turbine casings may include one or more outer turbine casings that surround one or more inner turbine casings. The outer turbine casing is often split into two hemispherical casings bolted together by flanges on a horizontal plane to facilitate maintenance and repair. The inner turbine casing is often supported through to the outer turbine casing by one or more axially spaced circumferential arrays of pins.
Generally, active clearance controls are employed to radially displace inner and outer turbine casings from one another during transient turbine operations. This has the effect of controlling tip clearance between buckets and shrouds, which can be beneficial since decreasing tip clearance improves turbine performance by reducing tip leakage as long as bucket tips are prevented from transiently contacting and thereby rubbing shrouds.
With both active and passive systems in many configurations relative movement occurs between the inner and outer turbine casings due to differential thermal growth of their respective components. The aforementioned pins which are used to join the outer turbine casing with the inner turbine casing tangentially can reduce eccentricity caused by the relative movement. However, such pins can affect outer casing bolt spacing if the primary vertical support pins are placed near a preferred center-line supported configuration and thus intersect the outer casing bolted flange. Wider bolt spacing at the pinned locations can lead to horizontal joint overboard leakage and thus performance degradation.
Thus, a need exists for pins that allow for mounting of an inner turbine casing with an outer turbine casing without impacting outer turbine casing bolt spacing. Methods relating to such pins would also be beneficial.
Aspects and advantages of the invention are set forth below in the following description, or may be obvious from the description, or may be learned through practice of the invention.
In certain embodiments of the present disclosure, a turbine casing assembly is described. The turbine casing assembly includes an inner casing and an outer casing surrounding the inner casing. The outer casing has a first outer casing section and a second outer casing section that join together along a flange. A bolt extends through the flange and joins together the first outer casing section and the second outer casing section. The turbine casing assembly further includes a pin. The pin has a segment defining an opening therethrough. The pin extends through the inner casing and the outer casing and supports the inner casing relative to the outer casing. The bolt passes through the opening defined by the pin.
In other embodiments of the present disclosure, a turbine is described. The turbine includes an inner casing and an outer casing. The inner casing carries nozzles and shrouds, the shrouds surrounding tips of buckets carried by a turbine rotor within the inner casing. The outer casing has a first outer casing section and a second outer casing section that join together along a flange. A bolt extends through the flange and joins together the first outer casing section and the second outer casing section. The turbine casing assembly further includes a pin. The pin has a segment defining an opening therethrough. The pin extends through the inner casing and the outer casing and supports the inner casing relative to the outer casing. The bolt passes through the opening defined by the pin.
In still other embodiments of the present disclosure, a method for assembling a turbine casing is described. The method includes joining together an inner casing and an outer casing with a pin, the pin having a segment defining an opening therethrough. The pin extends through the inner casing and the outer casing and supports the inner casing relative to the outer casing. The method further includes joining together a first outer casing section and a second outer casing section with a bolt, the bolt passing through the opening defined by the pin. The inner casing is surrounded with the outer casing.
Those of ordinary skill in the art will better appreciate the features and aspects of such embodiments, and others, upon review of the specification.
A full and enabling disclosure of the present invention, including the best mode thereof to one skilled in the art, is set forth more particularly in the remainder of the specification, including reference to the accompanying figures, in which:
Reference will now be made in detail to present embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the invention.
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 modifications and variations can be made in the present invention without departing from the scope or spirit thereof For instance, features illustrated or described as part of one embodiment may be used on 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.
Referring to
Referring again to
The outer casing 14 generally surrounds the one or more inner casings 12 and together form the turbine 10. In this manner, the inner casings 12 generally conform to the outer perimeter of the rotating component, and the outer casing 14 provides an enclosure around the rotating component.
Referring again to
To connect support the inner casing relative to the and outer casings casing to one another, one or more pin assemblies 54 pass through the outer casing 12 for connection with the inner casing 14. For instance, the pin assemblies can pass through flange 52 of outer casing 12. One or more pin assemblies 54 can be spaced along each flange 52 that extends across a section of the horizontal midline on either side of the turbine 10.
Referring to
Outer pin portion 58 includes an enlarged head 71 having a bolt circle 72 with one or more circumferentially defined bolt openings 74. Bolt circle further defines an opening 80 that outermost end 67 of inner pin portion 56 can extend through. The bolt openings can be configured to receive one or more bolts 76 that react out pin rotation through friction which can set alignment of inner and outer turbine casings. Alignment portion 78 extends from bolt circle 72 and defines an opening (not shown) in communication with bolt circle opening 80 which can receive inner pin portion and also allow for outer pin rotations after assembly within the alignment requirements of the unit. Alignment portion includes contact pads 84 that allow deterministic loading with the inner and outer turbine casings and which are generally aligned with contact pads 70 of inner pin portion. Alignment portion includes one or more alignment scallops 82 which permit pin assembly 54 to be located around a bolt as will be further described herein. Alignment scallops 82 are defined, in part, by ridge portions 85 that define openings that are greater than the diameter of opening 66 of bolt section 64 to allow for outer pin rotations and subsequent inner pin eccentricity after assembly during unit alignment. In this manner, alignment portion 78 does not obstruct the bolt that passes through opening 66 and secures the upper and lower outer casing casings.
When assembled, inner pin portion 56 can interface with an inner casing section and be joined to outer pin portion 58 which contacts outer casing through the outer casing flange. Inner nut 68 can secure inner pin portion 56 to outer pin portion 58 and can be covered by a bore cap 86 which is secured to bolt circle 72.
As illustrated in
One of ordinary skill in the art will readily appreciate that the structure previously described with respect to
Empirical testing and computer-generated models indicate that various embodiments of the present disclosure can one or more benefits over existing turbine casing assembly mechanisms and methods. The pin assemblies described herein can provide a convenient and reliable structure for ensuring the inner casings 12 are concentrically attached to the outer casing 14 during assembly without impacting casing bolt spacing and/or leakage.
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 and 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.
