Patent Application
20130232788
The subject matter disclosed herein relates generally to methods and devices to facilitate the installation of turbine casing segments, and more particularly, to a drive assembly that engages the horizontal joint flange counter bores of the turbine casing segments.
Gas turbines include a rotor and rotating disks that are attached to the rotor, and airfoils that are positioned at the outer diameter of the disks. These components are surrounded by a turbine casing. Typically, a turbine casing is made in two segments, an upper turbine casing segment and a lower turbine casing segment, split on a horizontal centerline to facilitate assembly and provide access to the rotor and internal stationary portions of the turbine. The segments are normally connected through a bolted flange at their horizontal joint and act to contain the working fluid while maintaining the working fluid in intimate contact with the blade elements. The upper turbine casing segment may be installed between a compressor discharge casing (CDC) and exhaust casing vertical joints during gas turbine maintenance. The fit for the casing is tight and the structure is hung as it is installed. There are occasions, including in the manufacturing phase and during maintenance when the upper casing segment will require lifting. To facilitate lifting, the upper casing segment is fitted with lifting lugs to allow the component to be raised and moved.
The level continuous installation of the upper casing segment is a difficult task. The installation is usually carried out without specialized tools and generally requires significant manpower. The improper installation of the upper casing segment may cause quality issues such as galling and damage to the flange, distortion to the casing and bolting, as well as improper crane loading.
In accordance with one exemplary non-limiting embodiment, the invention relates to an apparatus for installing a turbine casing having a first drive subassembly and a member coupled to the first drive subassembly configured for engaging a first segment of the turbine casing. The apparatus also includes a second member coupled to a second drive subassembly configured for engaging the first segment of the turbine casing. The apparatus is provided with a first retainer connected to the first member and configured for engaging a second segment of the turbine casing, and a second retainer connected to the second member and configured for engaging the second segment of the turbine casing.
In another embodiment a method for aligning a first casing segment with a second casing segment includes disposing a first pair of members through a first pair of bore holes in a flange on a first side of the first casing segment. The method includes disposing a second pair of members through a second pair of bore holes in a flange on a second side of the first casing segment, and connecting the first pair of rods and the second pair of rods to the second casing segment. The method also provides for displacing the first casing segment by displacing the first pair of members and the second pair of members.
Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.
Illustrated in
In one embodiment, the casing installation apparatus 11 may include a right drive assembly 25 having two subassemblies, including a first drive arm 27 and a second drive arm 29. The first drive arm 27 may be coupled to a first right connecting member 31, such as a beam or rod, and the second drive arm 29 may be coupled to a second right connecting member 33. A left drive assembly 26 may be similarly coupled to a first left connecting member 35 and a second left connecting member 37. In one embodiment the first right connecting member 31, the second right connecting member 33, the first left connecting member 35 and the second left connecting member 37 may be threaded rods. Although the preceding embodiment describes a right drive assembly 25 and a left drive assembly 26 each with two subassemblies, in another embodiment a single arm may be used.
Illustrated in
Illustrated in
In another mode of operation, the Thomson shaft 45 may be lifted thereby disengaging upper spur gear 57 and lower spur gear 59. Torque may be applied to the first drive nut 47 to raise or lower the first right connecting member 31 independently from the second right connecting member 33. The ability to independently rotate or displace a rod (e.g. first right connecting member 31) allows a single operator to level the upper casing segment 13 during installation thereby reducing the manpower needed to perform the operation, and improving quality. The use of the casing installation apparatus 11 may also result in maintenance labor cost reduction and the reduction of the time that a turbine is down for maintenance.
Although in the embodiment described above the right drive assembly 25 and the left drive assembly 27 are described as having spur gears (spur gear 59, 63, etc.) sprockets (e.g. sprocket 69) and a chain belt 71 it would be apparent to one of ordinary skill in the art to substitute other mechanical components or means for displacing the connecting members to accomplish the same result. For example, in one embodiment a rack and pinion mechanism may be substituted for spur gears and threaded rod. Other types of gears such as helical, internal ring, helical rack, face, worm, bevel, spiral and screw gears, among others may be used to displace the connecting members (first right connecting member 31, second right connecting member 33, first left connecting member 35, and second left connecting member 37). Alternately an internal electric motor, magnetic linear system or hydraulic mechanism may be used to displace the connecting members.
An embodiment of a method of installing an upper casing segment 13 to a lower casing segment 15 may include disposing the right drive assembly 25 and attached first right connecting member 31 and second right connecting member 33 through the right upper casing counter bores 19. The first right connecting member 31 and second right connecting member 33 may then be inserted through the corresponding lower casing counter bore(s) 23, and secured to the right lower casing flange 21 with the casting nut 42 and the doweled retainer 43. The corresponding procedure may then be used to secure left drive assembly 26 and associated first left connecting member 35 and second left connecting member 37 to the left lower casing flange 22. The operator may then bring the upper casing segment 13 together with the lower casing segment 15 by using a ratchet or electric drill to apply torque to the Thomson shaft drive nut 46. The operator may also level the upper casing segment 13 by first displacing the Thomson shaft thereby disengaging the upper spur gear 57 and lower spur gear 59. The operator may then use a ratchet or electric drill to rotate one of the connecting members (first right connecting member 31, second right connecting member 33, first left connecting member 35 or second left connecting member 37). Position indicator 67 may be used to define and compare the relative position of the right upper casing flange 17 and left upper casing flange 18 to the horizontal.
As one of ordinary skill in the art will appreciate, the many varying features and configurations described above in relation to the several exemplary embodiments may be further selectively applied to form the other possible embodiments of the present invention. For the sake of brevity and taking into account the abilities of one of ordinary skill in the art, all of the possible iterations is not provided or discussed in detail, though all combinations and possible embodiments embraced by the several claims below or otherwise are intended to be part of the instant application. In addition, from the above description of several exemplary embodiments of the invention, those skilled in the art will perceive improvements, changes and modifications. Such improvements, changes and modifications within the skill of the art are also intended to be covered by the appended claims. Further, it should be apparent that the foregoing relates only to the described embodiments of the present application and that numerous changes and modifications may be made herein without departing from the spirit and scope of the application as defined by the following claims and the equivalents thereof.
