Connector tube for a turbine rotor cooling circuit

#This invention relates generally to land based gas turbine power plants, and specifically to a tubular connector used to radially connect axially extending cooling tubes in a gas turbine rotor cooling circuit.

#A steam cooling circuit for a gas turbine rotor is disclosed in commonly owned U.S. Pat. No. 5,593,274. Briefly, cooling steam is supplied via a tube concentric to the rotor and then via radial passages to axially extending tubes (parallel to but radially outwardly of the rotor axis) which supply cooling steam to the buckets of one or more of the turbine stages. A similar return path is employed to remove the steam. Because of the rotating environment of the turbine rotor assembly and the centrifugal forces generated thereby, and because of thermal expansion of the various components, any radially oriented coolant tubes must be designed to accommodate relative axial and radial shifting movements where the radial tubes interface at opposite ends with the axial tube fittings.

#This invention relates to a tube having coupling profiles at opposite ends which are particularly advantageous in the context of radial connecting tubes in a rotating environment. Specifically, the tubes to be coupled are substantially parallel but radially offset relative to the rotor axis The fittings which mate with the tube of this invention, however, are in axial alignment with the radial tube. For purposes of this discussion, and unless otherwise explained, references to radial vs. axial or to radially “outer” or radially “inner,” take into account the orientation of the tube as installed in a turbine rotor assembly. References to the “upper” or “lower” ends of the tube correspond to radially outer and inner ends of the tube, respectively, relative to the rotor axis. Reference to a “radial flange” on the tube, however, is made with respect to the longitudinal center axis of the tube itself.

#FIG. 1 is a partial side section of a gas turbine rotor assembly incorporating the connector tube of this invention; and

#FIG. 2 is a side section of the connector tube in accordance with an exemplary embodiment of the invention.

#FIG. 1 is a partial side section of a gas turbine rotor assembly incorporating the connector tube of this invention;

#Referring now to the drawings, there is illustrated a portion of a turbine, including a turbine rotor assembly, generally designated 10, comprised of axially stacked components, for example, rotor wheels 12, 14, 16 and 18 which form portions of a four-stage exemplary turbine rotor with spacers 20, 22 and 24 alternating between the wheels. The wheel and spacer elements are held together on the rotor by a plurality of elongated, circumferentially extending bolts. only one of which is illustrated at 26. The wheels 12, 14, 16 and 18 mount a plurality of circumferentially spaced turbine buckets 12a, 14a, 16a and 18a, respectively. The combination of nozzles 30, 32, 34 and 36 and respective wheels 12, 14, 16 and 18 comprise the stages of the turbine. An aft shaft wheel 42 forms part of the rotor 10 and is bolted to the stacked wheels and spacers.

#In an advanced gas turbine designed by the assignee hereof. the aft shaft 44 houses a bore tube assembly described and illustrated in detail in co-pending U.S. patent application Ser. No. 09/216363. Briefly, the bore tube assembly includes axially extending outer and inner tubes 48 and 50, respectively, defining an annular steam-cooling supply passage 52 and a spent steam-cooling return passage 54. The passages 52 and 54 communicate steam to and from the outer rim of the rotor through sets of radially extending conduits or tubes 56 and 58, respectively, which in turn communicate with corresponding sets of axially extending tubes spaced circumferentially about the rim of the rotor. The steam supplied through the steam supply passage 52 and radial tubes 56 supply cooling steam to buckets 12a and 14a of the first and second stages, respectively, via axially extending tubes (not shown), while axial tubes (one shown at 57) and radial tubes 58 and return passage 54 receive the spent cooling steam from the buckets for return to a stationary or static pipe (not shown). It will be appreciated that the bore tubes 48 and 50 as well as axial tubes 57 are part of and rotate with the rotor assembly 10.

#With reference also to FIG. 2, the radial connector tubes 56, 58 in accordance with an exemplary embodiment of the invention are identical and only tube 58 will be described in detail. Connector tube 58 includes a tubular body with a conventional “B-nut” 60 at its radially outer end, and a “half-spoolie” connector 62 at its opposite, radially inner end. The “B-nut” 60 at the radially outer end includes a radial flange 64 and a spherically-shaped or tapered surface 66. The latter is designed to engage a flat, annular tapered surface 68 of, in this case, an axially aligned end of an elbow 70 which is connected at its opposite end to the radially outer axial tube 57. This is a conventional seal connection between adjacent tubular members, but is especially useful here, where the connector is subjected to centrifugal forces, tending to move the connector tube 58 in a radial outward direction. In other words, the spherical end of the tube 58 will maintain sealing contact with the mating surface 68 of the elbow 70, adjusting as necessary to any relative movement between the parts. The B-nut itself may be welded to the end of the tube 58 opposite the half-spoolie 62, or formed integrally therewith.