JPH1047010A - Seal device for structure of steam feed/discharge part for cooling gas turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To constitute the seal part of a steam feed/discharge part for cooling the moving blade of a gas turbine such that the seal part is movable and to form whole structure in a compact manner. SOLUTION: The seal device of the structure of a steam feed/discharge part comprises a body case 21 fixed at one end of the wheel chamber 21 of a gas turbine; an uneven surface for a labyrinth formed on the outer surface of the end part 29a of a steam introduction outer pipe 29 extending coaxially with a rotor; an uneven surface for labyrinth formed in the outer surface of the end part 31a of an introduction inner pipe 31 extending through the steam introduction outer pipe 29; a labyrinth ring 33 with which the uneven surface is surrounded; and a seal retainer 35 slidably arranged in a manner to hold the labyrinth ring 33. Further, link arms 37 and 38 pivotally supported at the body case 23 and connected to the seal retainer 35 are connected to the rotary arm of a thermal expansion compensating link mechanism located between a wheel chamber 21 and the support foundation thereof.

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 seal device for a structure for supplying and discharging steam for cooling a moving blade.

[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 shaft to which the rotor blades are fixed. Since the axial position of the rotor shaft of the turbine rotor having the moving blades is fixed by the thrust bearing at the output end, the supply and discharge of the cooling steam to the rotor shaft is performed by the rotor shaft. This is performed at the other end. However, at the other end of the rotor shaft without the thrust bearing, the relative thermal expansion difference between the casing and the rotor, the deformation due to the internal pressure of the casing, the axial shrinkage due to the centrifugal force of the rotor, etc. are escaped. The relative displacement with respect to a stationary part such as a vehicle compartment is large. In such a steam supply / discharge section, the use of a labyrinth seal is effective in reducing the leakage of steam, but the use of a large number of fins increases the axial space. The present applicant has previously made a proposal to minimize such a space for attaching a labyrinth seal (Japanese Patent Application No. 8-158080).

In the above proposal, as shown in FIG.
A seal case 5 is fixed to an end face of a casing 3 surrounding an end of a rotor 1 of the gas turbine, and an extension sensor 7 is provided at this end facing the end face of the rotor 1. The expansion sensor 7 is electrically connected to the servomotor 9 and operates in accordance with the amount of expansion detected by the expansion sensor 7.
Moves the seal retainer 11 in the axial direction. The seal retainer 11 is a labyrinth ring 1 of a labyrinth seal.
3 is maintained, and the contact length of the labyrinth seal is maintained irrespective of the amount of elongation to perform a suitable seal.

[0004]

In the above proposal, since the position of the rotor rotating at high speed is measured, an electric or hydraulic type expansion sensor is used. Thus, since a considerably large force is required to move the seal retainer holding the labyrinth ring, a special device is required to convert the signal of the extension sensor into a large force. Such a device is inevitably an electric or hydraulic device due to the extension sensor, but may malfunction if there is an accident such as a power cut-off, so that it lacks reliability. There is. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a sealing device having a gas supply / discharge portion for cooling a gas turbine which is compact, has good sealing performance, and has high operation reliability.

[0005]

According to the present invention, in order to solve the above problems, a sealing device for a steam supply / discharge structure for cooling a gas turbine is provided at one end of a casing provided around a gas turbine rotor. , A first uneven surface for labyrinth seal formed on the outer surface of an end portion of the steam introduction outer tube extending coaxially with the rotor, and an end of the introduction inner tube extending inside the steam introduction outer tube. A second concavo-convex surface for labyrinth seal formed on the outer surface, first and second labyrinth rings respectively surrounding the first and second concavo-convex surfaces, holding the first and second labyrinth rings, and sliding on the main body case; Movably provided with a seal retainer,
A heat expansion compensating link mechanism having a support base for the gas turbine casing, a lever interposed between the gas turbine casing, and a rotating arm connected to the lever is provided, and is supported by the main body case. The drive arm connected to the seal retainer is connected to the rotation arm of the heat expansion compensation link mechanism,
The position of the seal retainer is adjusted by driving the seal retainer in the axial direction in accordance with the axial heat expansion of the cabin of the gas turbine, thereby maintaining the effective seal length of the labyrinth seal.

[0006]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Referring to FIG. 1, a main body case 23 is fixed to an end surface of a casing 21 surrounding an end of a rotor of a gas turbine, and is provided with an inlet 25 for cooling steam.
And an internal passage 27. An irregular surface for labyrinth seal is formed on an outer surface of an end portion 29a of a steam introducing outer tube 29 which is extended by attaching an end portion to a rotor (not shown). Similarly, a steam introduction inner pipe 31 having an end attached to a rotor (not shown) extends coaxially inside the steam introduction outer pipe 29, and has a labyrinth on an outer surface of an end 31a extending outward from the end 29a. An uneven surface for sealing is formed. The irregular surface for labyrinth seal is a normal one. A labyrinth ring 33 which surrounds the concave and convex surfaces of the steam introduction inner pipe 15 and the steam introduction outer pipe 11 which rotate together with the rotor and forms a labyrinth seal in cooperation therewith is held by a movable seal retainer 35. The seal retainer 35 is supported on the inner surface of the main body case 23 so as to be slidable in the axial direction. A link arm 37 is pivotally supported by the main body case 23, and the distal end thereof is connected to the seal retainer 35. Therefore, when the link arm 37 pivots, the seal retainer 35 moves in the axial direction along the sliding guide surface of the main body case 23.

Next, the heat stretching compensation link mechanism 50 will be described with reference to FIG. Before explaining the support of the entire gas turbine, the gas turbine 20 is supported by a support base 41 and a support link 43 fixed on a concrete foundation 39. The support link 43 is connected to the gas turbine 20.
Are fitted at both ends to a trunnion 45 provided on the side of the concrete foundation 39 and a support shaft 47 on the concrete foundation 39, so that the thermal expansion displacement of the gas turbine 20 with respect to the concrete foundation 39 is released. Explaining the structure of the heat elongation compensation link mechanism 50, a bracket 53 is attached to a base 51 fixed to the concrete foundation 39. A bracket 55 is also fixed to the outer surface of the passenger compartment 21, and the bracket 5
A long lever 57 is interposed between the bracket 5 and the bracket 53 via a pin shaft. Such a lever 57
The vehicle compartment 2 due to thermal expansion is similar to the support link 43 described above.
One horizontal relative displacement is allowed. A pivot link 59 is connected near the upper end of the lever 57, and is connected to the tip of a link arm 38 coaxial with the link arm 37 described above. Accordingly, when the casing 21 of the gas turbine 20 is relatively displaced (thermally elongated) to the right (in the drawing) with respect to the concrete foundation 39 due to the temperature rise, the lever 57 is tilted to the right.
Looking at the continuous contact point with the bracket 55, the lever 57
Rotates as shown by arrow A, and this movement is
The rotation indicated by arrow B is transmitted to the link arm 38 via 9. The rotation of the link arm 38 indicated by the arrow B is
As shown conceptually in FIG. 1, it is transmitted to the link arm 37 and moves the seal retainer 35.

In the above configuration, the cooling steam is supplied to the inlet 25 and the internal passage 27 of the main body case 23, the through hole of the seal retainer 35, the steam introducing outer pipe 29 and the steam introducing inner pipe 3
1 to a rotor blade (not shown) through an annular passage between
This is cooled from the inside. The steam that has been used for cooling flows through the inside of the steam introduction pipe 31, exits from the outlet at the center of the main body case 23, and is collected. And the heat expansion compensation link mechanism 5
0 moves the position of the seal retainer 35 in accordance with the amount of axial thermal expansion (thermal elongation) of the vehicle compartment 21 by the link motion described above, and secures an effective labyrinth seal length. The principle by which this effective labyrinth seal length can be ensured is explained as follows.

The axial extension difference between the shaft end of the rotor and the cabin is the amount of expansion and contraction of the rotor, which is the sum of thermal expansion and axial contraction due to the Poisson effect of centrifugal stress, and the axial component of deformation due to thermal expansion and internal pressure. It is the difference from the sum of the vehicle compartment expansion and contraction, which is the sum, and the formula of [(the amount of thermal expansion of the rotor + the amount of axial contraction due to rotation of the rotor) − (the amount of thermal expansion of the vehicle compartment + the amount of expansion and contraction due to the internal pressure of the vehicle compartment)] It is represented by Looking at the thermal expansion of the rotor and the thermal expansion of the cabin, the thermal capacity of the cabin differs from that of the rotor, and there is a difference in the rate of temperature rise. Is not proportional, but in a steady state it has a relationship that is somewhat close to it. On the other hand, the axial shrinkage of the rotor is proportional to the square of the rotation speed, but is substantially constant in a steady state. The change in the amount of expansion and contraction due to the internal pressure of the vehicle compartment is relatively small between the internal pressure when the internal pressure is not loaded and the internal pressure when the internal pressure is full. That is, the axial extension difference between the rotor shaft end and the vehicle compartment is
It is practically permissible to treat it as being proportional to the amount of thermal expansion of the passenger compartment. The thermal expansion displacement of the shaft end of the rotor appears at the ends of the outer steam introducing pipe 29 and the inner steam introducing pipe 31.

[0010]

As described above, according to the present invention, the position of the seal retainer is adjusted by the heat expansion compensating link mechanism, which is a mechanical structure, according to the heat expansion of the cabin of the gas turbine. Thus, the effective labyrinth seal length of the cooling steam supply / discharge section can be secured without being affected by the above.
In addition, since the position of the seal retainer is adjusted in consideration of the difference in thermal expansion, the length of the seal forming member of the cooling steam supply / discharge unit can be minimized, and the apparatus can be made compact.

[Brief description of the drawings]

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

FIG. 2 is a side view of a position notch showing a main part of the embodiment.

FIG. 3 is a partial cross-sectional view showing a conceptual structure proposed in the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 Cabinet 23 Main body case 25 Inlet 27 Internal passage 29 Steam introduction outer pipe 29a End 31 Steam introduction inner pipe 31a End 33 Labyrinth ring 35 Seal retainer 37, 38 Link arm 50 Heat extension compensation link mechanism 51 Base 53, 55 Bracket 57 Lever 59 Rotating link

Claims (1)

[Claims] 1. A body case fixed to one end of a vehicle room provided surrounding a gas turbine rotor, and a labyrinth seal formed on an outer surface of an end portion of a steam introduction outer tube extending coaxially with the rotor. 1 irregular surface, a second irregular surface for labyrinth seal formed on an end outer surface of an introduction inner tube extending inside the steam introduction outer tube, and first and second surfaces surrounding the first and second irregular surfaces, respectively. A gas turbine cooling steam supply / discharge unit sealing device comprising: a labyrinth ring; and a seal retainer holding the first and second labyrinth rings and slidably provided in the main body case. A heat expansion compensating link mechanism including a support base, a lever interposed between the gas turbine casing, and a rotating arm connected to the lever is provided, and is supported by the main body case. A drive arm connected to the seal retainer is connected to the rotating arm of the heat expansion compensating link mechanism, and the seal retainer is driven in the axial direction corresponding to an axial heat expansion amount of the cabin of the gas turbine. Adjust the position,
A sealing device having a steam supply / discharge unit structure for cooling a gas turbine, wherein an effective seal length of the labyrinth seal is maintained.