JPH108993A - Cooling steam supply/discharge structure for gas turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a labyrinth seal excellent in sealing performance without requiring a large space by providing a seal retainer to retain a labyrinth ring, an elongation sensor arranged on the end face of a rotor and a servo mechanism between the elongation sensor and the seal retainer. SOLUTION: Labyrinth rings 19 encircling respective rough faces 13, 17 to form a labyrinth seal in cooperation are retained by a movable seal retainer 21. Labyrinth fins are protruded on the inner face of the labyrinth rings 19 to form a preset space between the rough faces 13, 17 and the fins and so as to constitute the favorable labyrinth seal. The seal retainer 21 is supported on a mainbody case 5 to be slidable in the axial direction. An elongation sensor 25 facing to the end face of one rotor 1 is fixed to the end face of the mainbody case 5 and electrically communicated to a servo mechanism 30. In this way, the leakage of steam is prevented, while the device is made compact.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a gas turbine, and more particularly to a structure for supplying and discharging cooling steam.

[0002]

2. Description of the Related Art In recent years, the turbine inlet gas temperature has been increasing in order to improve the efficiency of gas turbines, and it has been proposed to cool turbine rotor blades, which become hot, with steam.
The supply and discharge of steam to and from the turbine rotor blades are generally performed via a rotor to which the rotor blades are fixed. For this reason, a seal such as a labyrinth seal is used to prevent loss of steam leakage. On the other hand, the turbine rotor having the rotor blades is fixed in an axial position by a thrust bearing at one place in a vehicle compartment, a relative thermal expansion difference between the vehicle compartment and the rotor, deformation due to internal pressure in the vehicle compartment,
Since the axial contraction or the like due to the centrifugal force of the rotor is released, the relative displacement difference between the rotor shaft end and a stationary portion such as a vehicle compartment becomes large in a portion away from the thrust bearing.

[0003]

In the gas turbine having the general structure and characteristics as described above, the place where steam is supplied or recovered from the stationary side to the rotating rotor side is limited by the thrust due to other structural restrictions. It must be the end of the rotor shaft away from the bearing. However, as described above, in that part, the relative displacement between the rotor and the cabin side is large, and when using a labyrinth seal having a bent passage with a large sealing effect, a large space is required in the axial direction. . This leads to a larger device,
There is a risk of increasing costs and other related problems.
Accordingly, it is an object of the present invention to provide a cooling steam supply / discharge structure having a labyrinth seal that does not require a large space and has good sealing performance in a gas turbine.

[0004]

According to the present invention, there is provided a cooling steam supply / discharge unit structure for introducing and discharging a moving blade cooling steam for a gas turbine through a passage inside a rotor. A body case fixed to one end of a bearing box provided surrounding the rotor, a first irregular surface for labyrinth seal formed on an outer end portion of a steam introduction outer tube extending coaxially in the rotor, A second concavo-convex surface for labyrinth sealing formed on the outer surface of the end of the introduction inner tube extending inside the steam introduction outer tube, and a first surrounding surface surrounding the first and second concavo-convex surfaces, respectively.
And a second labyrinth ring, a seal retainer holding the first and second labyrinth rings and slidably provided in the main body case, and provided at an end of the main body case facing an end face of the rotor. It has an expansion sensor and a servo mechanism interposed between the expansion sensor and the seal retainer, and the seal retainer has a through hole communicating with the steam inlet of the main body case.

[0005]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Referring to FIG. 1, a body case 5 is fixed to an end face of a bearing box 3 surrounding an end of a rotor 1 of a gas turbine, and defines a cooling steam inlet 7 and an internal passage 9. . End 11a of outer steam introduction pipe 11 fitted inside rotor 1 and extending outward
Is formed with an uneven surface 13. Uneven surface 13
Are enlarged in FIG. Further, the steam introduction inner pipe 15 is provided coaxially inside the steam introduction outer pipe 11, and an uneven surface 17 is formed on an outer surface of an end 15a extending outward from the end 11a. The uneven surface 17
Also has the same shape as the uneven surface 13 shown in FIG.
As is obvious to those skilled in the art, the inner steam introducing pipe 15 and the outer steam introducing pipe 11 rotate together with the rotor 1.

Labyrinth ring 1 which surrounds concave and convex surfaces 13 and 17 and forms a labyrinth seal in cooperation with each other
9 is held by a movable seal retainer 21. As shown in FIG. 2, a plurality of labyrinth ring fins 23a and 23b are protruded from the inner surface of the labyrinth ring 19,
A predetermined gap is formed between the concavo-convex surfaces 13 and 17, thereby forming a suitable labyrinth seal. The seal retainer 21 is supported by the main body case 5 so as to be slidable in the axial direction. On the other hand, the extension sensor 25 faces the end face of the rotor 1.
Is fixed to the end face of the main body case 5, and this is electrically connected to the servo mechanism 30. The servo mechanism 30
It has a lever 31 and a servomotor 33 that are linked to the seal retainer 21. Then, the servo mechanism 30 moves the seal retainer 21 in the axial direction according to the amount of expansion detected by the expansion sensor 25.

In the above configuration, the cooling steam is supplied to the inlet 7 and the internal passage 9 of the main body case 5 and the seal retainer 21.
Through hole 27, steam introduction outer tube 11 and steam introduction inner tube 15
Is supplied to a rotor blade (not shown) through an annular passage 29 between the blades and cools it from the inside. The steam used after cooling flows through the inside of the steam introduction inner pipe 15 and is recovered from the outlet 28 at the center of the main body case 5. Thus, the expansion due to the pressure in the vehicle compartment changes quickly when the turbine is suddenly stopped, and the deformation due to the centrifugal force of the rotor 1 and the change in the expansion due to the difference in thermal expansion are slow during the sudden stop. Labyrinth ring fins 23
The distance between the a and b and the uneven surfaces 13 and 17 is determined so as to correspond to the fast-changing one, and the labyrinth seal suitably prevents the leakage in the above-mentioned steam flow.

[0008]

As described above, according to the present invention, the seal retainer is slid in the axial direction in accordance with the elongation, and the effective labyrinth seal length is optimally maintained. Leakage can be prevented.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention.

FIG. 2 is a partially enlarged sectional view of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotor 3 Bearing box 5 Main body case 7 Inlet 9 Internal passage 11 Steam introduction outer tube 11a End 13 Irregular surface 15 Steam introduction inner tube 15a End 17 Irregular surface 19 Labyrinth ring 21 Seal retainer 23a, 23b Labyrinth ring fin 25 Extension Sensor 27 Through hole 28 Exit 29 Annular path 30 Servo mechanism 31 Lever 33 Servo motor

Claims (1)

[Claims] In a structure for introducing and leading steam for cooling a moving blade of a gas turbine through a passage inside a rotor, a main body case fixed to one end of a bearing box provided surrounding the rotor; A first irregular surface for labyrinth seal formed on the outer end of a steam introduction outer tube extending coaxially in the inside, and a labyrinth seal formed on an outer end of an end of the introduction inner tube extending inside the steam introduction outer tube. A second uneven surface, and first and second surfaces surrounding the first and second uneven surfaces, respectively.
A labyrinth ring, a seal retainer holding the first and second labyrinth rings and slidably provided in the main body case, and an extension sensor provided at an end of the main body case facing an end face of the rotor And a servo mechanism interposed between the extension sensor and the seal retainer, wherein the seal retainer has a through hole communicating with the steam inlet of the main body case. Steam supply / discharge structure for gas turbine cooling.