JPH11200801A - Rotor cooling system of steam turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a cooling effect by a minimum steam quantity by arranging a cooling passage hole to communicate with a cooling space faced with the side surface of a rotor disk on and after a second stage, on the inside of a rotor in a rotor cooling system to supply a cooling fluid to the cooling space between both side surfaces of the rotor disk and the stationary blade inside surface. SOLUTION: When operating an intermediate pressure steam turbine, high temperature reheat steam from a boiler enters a first stage stationary blade 6 to be introduced to a low pressure turbine after performing expanding work through the first stage stationary blade 6 and a moving blade 2. At this time, low temperature cooling steam is introduced to a cooling steam supply passage 20 from an outlet of a high pressure turbine so that this cooling steam enters a cooling space 26 between the first stage moving blade 2 and the stationary blade 6 to cool the embedding part of the first stage moving blade 2 by passing through a cooling steam passage 3 by differential pressure between front/rear parts of the first stage moving blade 2. Next, the cooling steam is introduced to a cooling space 27 between a first stage rotor disk 41 and a second stage stationary blade 7 to cool the moving blade embedding part and the first stage moving blade 2 of the first stage rotor disk 41.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam turbine, and more particularly to a cooling device for cooling a rotor disk in the vicinity of a blade implant in a medium-pressure turbine.

[0002]

2. Description of the Related Art In a steam turbine, steam at a high-pressure turbine outlet is reheated and heated by a boiler and guided to a medium-pressure turbine to improve turbine efficiency. For this reason, in the medium pressure turbine, the vicinity of the rotor blade implantation portion of the medium pressure first to third stage rotor disks exposed to the high temperature steam is cooled at the high pressure turbine outlet at the low temperature cooling steam (steam before reheating). Cooling is being performed.

FIGS. 3 and 4 show a conventional example of a rotor disk cooling structure in such a medium pressure turbine. FIG. 3-
4, reference numeral 1 denotes a rotor of a medium pressure turbine, 16 denotes a casing, 6 denotes a first stage stationary blade, 7 denotes a second stage stationary blade, and 9 denotes a third stage stationary blade. Reference numerals 41, 42, and 43 denote a first-stage rotor disk, a second-stage rotor disk, and a third-stage rotor disk formed on the outer periphery of the rotor 1, respectively. A plurality of first-stage moving blades 2, second-stage moving blades 4, and third-stage moving blades 10 are provided on the outer periphery of the disks 41, 42, and 43.
Are implanted at equal intervals in the circumferential direction.

Reference numeral 5 denotes a medium-pressure dummy ring for supporting the inner peripheral portion of the first-stage stationary blade 6. Reference numeral 23 denotes a seal ring provided on the inner peripheral portion of the first-stage stationary blade 6 for sealing between the first-stage stationary blade 6 and the intermediate-pressure dummy ring 5. It is. Reference numerals 24 and 25 denote labyrinth mechanisms for sealing between the inner peripheral portion of the second-stage stationary blade 7 and the third-stage stationary blade 9 and the outer peripheral portion of the rotor 2, respectively.

[0005] Reference numerals 26 and 27 denote both side surfaces of the first-stage rotor disk 41, the inner surface 6 of the first-stage stationary blade, and the second-stage stationary blade 7.
The cooling spaces 28 and 29 formed between the inner surfaces of the second stage rotor disk 42 and the second stage stationary blades 7
A cooling space formed between the inner peripheral portion of the third stage stationary blade 9 and the inner surface of the third stage stationary blade 9; and a cooling space 30 formed between the side surface of the third stage rotor disk 43 and the inner surface of the third stage stationary blade 9. It is.

Reference numeral 20 denotes a cooling steam supply passage formed between the outer peripheral surface of the rotor 1 and the medium-pressure dummy ring 5, into which low-temperature cooling steam from the high-pressure turbine outlet is introduced. Cooling space 26 on the first stage stationary blade side of first stage rotor disk 41
Are connected to the cooling steam supply path 20, and the cooling steam is directly supplied to the cooling space 26 from the supply path 20. A plurality of cooling steam passages 3 are provided in the first stage rotor disk 41 in the circumferential direction in the first stage rotor disk 41, and are located between the lower end surface of the implanted portion of the first stage blade 2 and the groove bottom surface of the first stage rotor disk. And the first-stage rotor disk 41
Are opened to the cooling spaces 26 and 27 on both sides of the cooling device.

[0007] During operation of the medium pressure steam turbine,
The high-temperature reheated steam reheated by the boiler (not shown) enters the first stage stationary blade 6 as shown by the arrow in FIG. The blades perform expansion work and are guided to a low-pressure turbine (not shown).

On the other hand, low-temperature cooling steam is guided to the cooling steam supply passage 20 from a high-pressure turbine (not shown). The cooling steam enters the cooling space 26 between the first stage moving blades 2 and the first stage stationary blades 6 from the cooling steam supply path 20 as shown by arrows in FIG. The implanted portion of the first stage rotor blade 2 is cooled by the front and rear differential pressure through the cooling steam passage 3 and is introduced into the cooling space 27 between the first stage rotor disk 41 and the second stage stationary blade 7. Thereby, the rotor blade implanted portion of the first-stage rotor disk 41 and the first-stage rotor blade 2
Is cooled by the low-temperature cooling steam guided to the cooling space 26 as described above or to the cooling space 27 through the cooling steam passage 3.

Further, a part of the cooling steam passing through the cooling steam passage 3 passes through a gap between the inner periphery of the labyrinth mechanism 24 of the second stage stationary blade 7 and the outer periphery of the rotor 1 and the second stage rotor disk 42 and the second stage rotor disk 42 It enters the cooling space 28 between the stage stator vanes 9 and cools the second stage rotor disk 42.

FIGS. 5 and 6 show another conventional example of the cooling structure of the rotor disk portion of the intermediate pressure turbine. 5 to 6 show that the first stage rotor disk 4 is located between the lower surface of the implanted portion of the second stage rotor blade 4 and the bottom surface of the implantation groove of the second stage rotor disk 42.
A cooling steam passage 11 similar to the cooling steam passage 3 of FIG.
A part of the cooling steam flowing through the labyrinth mechanism 24 on the inner periphery of the second stage stationary blade 7 is guided to the cooling steam passage 11 to cool the vicinity of the moving blade implanted portion of the second stage rotor disk 42.

Other structures are the same as those in FIGS. 3 and 4, and the same members are denoted by the same reference numerals.

[0012]

In the medium pressure turbine, it is necessary to increase the temperature of the high-temperature reheat steam in order to improve the turbine efficiency. ~ 3rd stage rotor disk 41 ~ 4
The temperature in the vicinity of the rotor blade implanted portion 3 rises, and the strength of the rotor decreases.

In order to avoid this, in the conventional example shown in FIGS.
The cooling steam from the cooling steam supply passage 20 is introduced to cool the vicinity of the rotor blade implanted portion of the first-stage rotor disk 41, and a part of the steam passing through the cooling steam passage 3 is labyrinthized. Through the mechanism 24 to the cooling space 28 on the inlet side of the second-stage rotor disk 42 to cool the second-stage rotor disk.

However, in FIGS. 3 and 4, the third-stage rotor disk 43 is not cooled, and a decrease in strength due to the temperature rise of the rotor disk 43 cannot be avoided.
Also, the second stage rotor disk 42 does not provide a sufficient cooling effect because only the inlet side is cooled by a part of the cooling steam heated by cooling the first stage rotor disk 41.

FIGS. 5 and 6 are different from those of FIGS. 3 and 4 in that the cooling steam passage 11 is additionally provided in the second-stage rotor disk 42. The second compared to
Although the cooling effect of the step rotor disk 42 can be improved,
Since the second-stage rotor disk 42 is cooled by the first-stage rotor disk 41 and cooled by the increased cooling steam, a sufficient cooling effect cannot be obtained against a further increase in the reheat steam temperature. Third stage rotor disk 43
With regard to the third stage rotor disk, since the first stage rotor disk 41 and the second stage rotor disk 42 are sequentially cooled and the further raised cooling steam is guided to the inlet side cooling space 30 and only the inlet side is cooled. The cooling effect is also insufficient.

In FIGS. 5 and 6, in order to solve the above-mentioned problem of a decrease in the cooling effect, a first method is required.
The area of the cooling steam passages 3 and 11 provided in the second and third stage rotor disks 41 and 42 is increased, and the labyrinth mechanism 24 of the second stage stationary blade and the labyrinth mechanism 25 of the third stage stationary blade are increased.
It is conceivable to take measures to increase the supply amount of cooling steam by enlarging the gap between them, but if such means are used, the amount of leaked steam between each stage will increase, and the turbine efficiency will decrease. Occurs.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a cooling effect of cooling steam of a first to third stage rotor disks through which high-temperature reheat steam flows in a steam turbine, particularly a medium-pressure turbine in which a rotor disk is cooled by cooling steam. It is an object of the present invention to provide a steam turbine rotor cooling device which can be improved without a decrease in turbine efficiency due to steam leakage or the like and with a minimum amount of steam.

[0018]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the first aspect of the present invention is to provide a disk drive having a stationary blade formed on an outer periphery of a rotor and having rotor blades implanted thereon. In a steam turbine in which a cooling fluid is supplied from a cooling fluid supply passage to a cooling space formed between the blade and an inner side surface of the blade, a side surface of the second or later stage rotor disk faces the inside of the rotor. The rotor cooling device is provided with a cooling passage hole for directly supplying a cooling fluid from the cooling fluid supply passage in the cooling space.

A second means is the first means, wherein the cooling passage hole is communicated from the cooling fluid supply path to the cooling space between the second stage stationary blade and the second stage rotor disk. In addition, cooling passages are provided to communicate the cooling spaces on both sides of the first-stage rotor disk and the cooling spaces on both sides of the second-stage rotor disk.

According to the above means, the low-temperature cooling fluid from the cooling fluid supply passage is directly guided to the inlet of the cooling space after the first-stage rotor disk through the cooling passage hole formed in the rotor. The vicinity of the rotor blade implanted portion of each stage rotor disk is cooled through the cooling passage in each rotor disk.

Therefore, the rotor disk of each stage, especially the second stage
Since the low-temperature cooling fluid is directly supplied to the cooling space of the rotor disk after the stage and the cooling passage in the rotor disk,
The rotor disk can be cooled to a required temperature with a minimum necessary cooling fluid amount, so that the cooling effect is improved and the strength of the rotor can be increased.

Further, since the amount of cooling fluid can be minimized, the area of the cooling passage in each rotor disk and the gap between the labyrinth mechanisms of the stationary blades are increased as in the conventional case.
It is not necessary to increase the amount of cooling fluid that causes fluid leakage at each stage, and it is possible to prevent a decrease in turbine efficiency.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to FIG. FIG. 1 is a longitudinal sectional view of a main part of a rotor disk cooling unit of a medium pressure turbine in a steam turbine according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a rotor of a medium pressure turbine, 16 denotes a casing, 6 denotes a first stage stationary blade, 7 denotes a second stage stationary blade, and 9 denotes a third stage stationary blade.

Reference numerals 41, 42, and 43 denote a first-stage rotor disk, a second-stage rotor disk, and a third-stage rotor disk formed on the outer periphery of the rotor 1, respectively. A plurality of first-stage moving blades 2, second-stage moving blades 4, and third-stage moving blades 10 are provided on the outer periphery of the three-stage rotor disks 41, 42, 43.
Are implanted at equal intervals in the circumferential direction.

Reference numeral 5 denotes a medium-pressure dummy ring for supporting the inner peripheral portion of the first-stage stationary blade 6, and reference numeral 23 denotes a seal ring provided on a circumferential portion of the first-stage stationary blade 6 for sealing between the first-stage stationary blade 6 and the intermediate-pressure dummy ring 5. It is. Reference numerals 24 and 25 denote labyrinth mechanisms for sealing between the inner peripheral portion of the second stage stationary blade 4 and the third stage stationary blade 9 and the outer peripheral portion of the rotor 2, respectively.

Reference numerals 26 and 27 denote both side surfaces of the first-stage rotor disk 41, the inner surface 6 of the first-stage stationary blade, and the second-stage stationary blade 7.
The cooling spaces 28 and 29 formed between the inner surfaces of the second stage rotor disk 42 and the second stage stationary blades 7
The cooling space 30 formed between the inner surface of the third stage stationary blade 9 and the inner surface of the third stage stationary blade 9 is a cooling space formed between the side surface of the third stage rotor disk 43 and the inner surface of the third stage stationary blade 9. is there.

Reference numeral 20 denotes a cooling steam supply passage formed between the outer peripheral surface of the rotor 1 and the medium-pressure dummy ring 5, and low-temperature cooling steam at the outlet of the high-pressure turbine is introduced. Cooling space 26 on the first stage stationary blade side of first stage rotor disk 41
Are connected to the cooling steam supply path 20, and the cooling steam is directly supplied to the cooling space 26 from the supply path 20. A plurality of cooling steam passages 3 are provided in the first stage rotor disk 41 in the circumferential direction in the first stage rotor disk 41, and are located between the lower end surface of the implanted portion of the first stage blade 2 and the groove bottom surface of the first stage rotor disk. And the first-stage rotor disk 41
Are opened to the cooling spaces 26 and 27 on both sides of the cooling device. The above configuration is the same as the conventional configuration shown in FIGS.

In the embodiment of the present invention, means for supplying cooling steam to each cooling space is improved. That is, in FIG. 1, reference numerals 21 and 22 are cooling passage holes formed in the rotor 2. The cooling passage hole, that is, the horizontal cooling passage hole 2
1 and the radial cooling passage hole 22 communicating therewith are:
The cooling steam supply path 20 is provided with a plurality of cooling pipes, which are preferably provided at equal intervals along the circumferential direction inside the rotor 2.
The cooling steam is communicated with the cooling space 28 between the stage rotor disk 42 and the second stage stationary blade 7, and the low-temperature cooling steam in the cooling steam supply passage 20 is directly supplied to the inlet of the cooling space 28.

Numeral 11 denotes a cooling steam passage formed between the lower end face of the implanted portion of the second stage rotor blade 2 and the bottom face of the implanted groove of the second stage rotor disk 42.
Cooling space on both sides of the second stage rotor disk 42
A cooling space 28 between the second stage stationary blade 7 and the cooling space 29 between the second stage rotor disk 42 and the third stage stationary blade 9 communicates with each other.

During operation of the intermediate-pressure steam turbine configured as described above, the high-temperature reheated steam reheated by the boiler (not shown) enters the first-stage stationary blade 6 as shown by an arrow in FIG. After passing through the stationary blades 6 and the first-stage moving blades 2, the stationary blades and the moving blades at each stage perform expansion work and are guided to a low-pressure turbine (not shown).

On the other hand, low-temperature cooling steam is led into the cooling steam supply passage 20 from a high-pressure turbine outlet (not shown). The cooling steam enters the cooling space 26 between the first stage moving blade 2 and the first stage stationary blade 6 from the cooling steam supply path 20 as shown by the arrow in FIG.
The implanted portion of the first stage rotor blade 2 is cooled by the differential pressure between the front and rear through the cooling steam passage 3, and the first stage rotor disk 41 and the second stage rotor disk 41 are cooled.
It is introduced into the cooling space 27 between the step stationary blade 7. As a result, the blade impeller portion of the first-stage rotor disk 41 and the first-stage blade 2 are guided to the cooling space 26 as described above, or are guided to the cooling space 27 through the cooling steam passage 3. Cooled by cold cooling steam.

The cooling steam in the cooling steam supply passage 20 is directly guided to the inlet of the cooling space 28 between the second-stage rotor disk 42 and the second-stage stationary blade 7 through the cooling passage holes 21 and 22. Further, a part of the cooling steam in the cooling passage hole 22 passes through the cooling steam passage 11 in the second-stage rotor disk 42 due to a pressure difference between the second-stage rotor blades 2 and the second-stage rotor disk 42 and the second-stage rotor disk 42. The implantation part of the two-stage bucket 4 is cooled.

Further, the cooling air enters the cooling space 29 between the second-stage rotor disk 42 and the third-stage stationary blade 3,
The second-stage rotor disk 42 is cooled, and a part of the second-stage rotor disk 42 passes through the gap between the inner periphery of the labyrinth mechanism 25 of the third-stage stationary blade 9 and the outer periphery of the rotor 1, and the third stage rotor disk 43 and the third-stage stationary blade 9 It enters the cooling space 30 in between and cools the third stage rotor disk 43. Each cooling space 26, 2
The cooling steam that has passed through 7, 28, 29, 30 is combined with the working steam (reheated steam).

Therefore, according to the above-described embodiment, since the low-temperature cooling steam from the cooling steam supply passage 20 is directly supplied to the cooling steam inlet of the second-stage rotor disk, that is, the inlet of the cooling space 28, the required minimum is obtained. The second-stage rotor disk 42 and the third-stage rotor disk can be reliably cooled with a limited amount of cooling steam.

The cooling steam supply passage 20 is provided in the rotor 2.
And the cooling space 3 at the entrance of the third-stage rotor disk 43
The third stage rotor disk 43 is provided with a cooling passage hole communicating the inlet of the third stage rotor disk and a cooling passage hole communicating the inlet of the fourth and subsequent rotor disks with the cooling steam supply passage 20.
Low-temperature cooling steam may be supplied directly to the rotor disk inlet of the subsequent stage.

[0036]

The present invention is configured as described above.
According to the present invention, since a low-temperature cooling fluid can be directly supplied to the cooling fluid inlets of the rotor disks of the respective stages, particularly the second and subsequent stages, the rotor disks of the respective stages can be supplied with the minimum necessary amount of the cooling fluid. It can be cooled to a required temperature, the cooling effect is improved as compared with the conventional one, and a high rotor strength can be maintained.

Further, since the required cooling effect can be obtained with the minimum amount of cooling fluid, it is not necessary to increase the passage area of the cooling fluid such as the gap size of the labyrinth portion. Can be prevented from lowering due to leakage of water. In addition, the improvement of the cooling effect makes it possible to raise the reheat steam temperature, thereby improving the turbine efficiency.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main part of a steam turbine rotor cooling device according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a vertical sectional view showing a main part of a first conventional example of a rotor cooling device for a steam turbine.

FIG. 4 is a sectional view taken along line BB of FIG. 3;

FIG. 5 is a drawing corresponding to FIG. 4, showing a second conventional example of a rotor cooling device for a steam turbine.

FIG. 6 is a sectional view taken along line CC of FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotor 2 1st stage moving blade 3 Cooling steam passage 4 2nd stage moving blade 6 1st stage stationary blade 7 2nd stage stationary blade 9 3rd stage stationary blade 10 3rd stage moving blade 11 Cooling steam passage 16 Casing 20 Cooling steam supply passage 21, 22 Cooling passage holes 24, 25 Labyrinth mechanism 26, 27, 28, 29, 30 Cooling space 41 First stage rotor disk 42 Second stage rotor disk 43 Third stage rotor disk

Claims (2)

[Claims] A cooling fluid is supplied from a cooling fluid supply passage to a cooling space formed between both side surfaces of a rotor disk formed on the outer periphery of a rotor and having rotor blades implanted therein and an inner surface of a stationary blade. In the steam turbine described above, a cooling passage hole for directly supplying a cooling fluid from the cooling fluid supply passage is provided in the cooling space facing the side surface of the rotor disk of the second stage or later inside the rotor. Steam turbine rotor cooling system. 2. The cooling passage hole is communicated from the cooling fluid supply passage to the cooling space between the second stage stationary blade and the second stage rotor disk, and the cooling space on both sides of the first stage rotor disk. 2. The steam turbine rotor cooling device according to claim 1, further comprising cooling passages for communicating the cooling spaces on both sides of the second-stage rotor disk.