JP3362643B2 - Shaft end refrigerant flow type gas turbine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas turbine for cooling moving blades using a refrigerant, and more particularly to a gas turbine configured to supply or recover the refrigerant from a shaft end.

[0002]

2. Description of the Related Art In a gas turbine, in order to increase the temperature of the combustion gas (turbine inlet temperature) to increase the efficiency of the turbine, blades forming passages for working gas (hereinafter abbreviated as gas paths), The inner and outer wall end walls and shrouds are cooled. Further, in order to prevent the hot combustion gas from bypassing the gap between the inside of the diaphragm supporting the stationary blade and the rotor and overheating the rotor,
A seal gas having a temperature equal to or lower than the rotor allowable temperature is supplied to the same portion.

Combustion air extracted from a compressor is usually used as the refrigerant or seal gas.

Recently, as the cooling technology of blades has been improved, the temperature of combustion gas is raised to 1500 ° C. level,
For example, as shown in Japanese Patent Laid-Open Publication No. 8-14064, in order to reduce the loss caused by discharging the air after cooling the blade into the gas path, the air after cooling is Gas turbines recovered and returned to the combustor, Ref. 95-Y
OKOHAMA-IGTC-143: “H” Gas Turbine Combined Cycles
As shown in the Power Generation System for the Future, etc., the blades are cooled by using part of the steam generated using the exhaust heat of the gas turbine, and the cooled refrigerant is recovered as the working medium of the steam turbine. It is under development as a so-called closed cooling type gas turbine.

[0005]

SUMMARY OF THE INVENTION To construct a turbine rotor of a closed cooling type gas turbine, a supply passage for supplying a refrigerant for cooling a moving blade inside the rotor,
It is necessary to form a recovery channel for recovering the refrigerant after cooling the moving blades. By cooling the blades, the temperature of the refrigerant is 2
Since the temperature rises by 0 to 250 degrees, it is advantageous to arrange the refrigerant supply port or recovery port for the rotor at the shaft end from the viewpoint of minimizing the thermal stress generated in the rotor constituent member due to this temperature difference. is there.

However, in order to supply the refrigerant required for blade cooling in the closed air cooling type gas turbine (utilizing the air compressed by the compressor as the cooling medium) and recovering it to the combustor, the recovery pressure is at least the compressor. It is necessary to increase the air pressure from the compressor with a boost compressor before the supply because of the need to increase the discharge pressure above the discharge pressure of the compressor. A large pressure loss occurs in the recovery channel. In the closed steam cooling type gas turbine, the working steam of the steam turbine is also used for cooling the blades, so it is necessary to maintain high purity of the steam. The pressure needs to be higher than the pressure of the combustion gas to prevent the combustion gas from the gas path from leaking into the refrigerant passage. Therefore, a high supply pressure or the like is required in any case.

On the other hand, since a non-contact seal such as a labyrinth seal or a honeycomb seal is generally used as the seal between the stationary portion and the rotating portion at the shaft end used in the gas turbine, the seal from the refrigerant path at the shaft end is not used. It is inevitable that a considerable amount of refrigerant will leak, and in an air-cooled gas turbine, the efficiency of the turbine will be reduced due to the waste of the refrigerant generated by spending compression power, and in the steam-cooled type, the consumption of pure water will be further increased. The operating cost will increase as the number increases.

The present invention prevents leakage from the rotor shaft end seal.
The compressed refrigerant is recovered by the air-cooled gas turbine.
Efficiency of the turbine by wasting the generated refrigerant
Solves the problem of low
Solved the problem of increased operating costs due to increased costs
In addition, it becomes possible to effectively utilize the leaked refrigerant.
Therefore, it is an object of the present invention to provide a more efficient gas turbine.

[0009]

SUMMARY OF THE INVENTION The present invention is directed to a compressor for compressing air, a combustor for combusting compressed air and fuel discharged from the compressor, and a turbine driven by exhaust gas from the combustor. In a gas turbine provided with, a rotor having a rotor blade internally provided with a refrigerant flow passage on the outer peripheral side and having a refrigerant flow passage communicating with the refrigerant flow passage therein, and the refrigerant flow passage in the rotor. A seal for suppressing leakage of the refrigerant flowing through the refrigerant flow passage to the outside of the refrigerant flow passage, and a route for collecting the refrigerant leaked from the refrigerant flow passage in the rotor through the seal for cooling the high temperature part of the gas turbine. It is characterized by having.

Part of the refrigerant leaking from the seal is recovered,
It can be used as a cooling medium for structural members of a gas turbine.

In this way, by collecting the leaked gas and supplying it to another member, the recovery port of the route for guiding the refrigerant to the other member in the area separated by the seal is arranged in the middle. Since the pressure in the area decreases and the leakage flow rate through the seal on the downstream side of the leaking refrigerant from the intermediate area decreases, the leaked refrigerant can be effectively utilized.

Further, in a gas turbine provided with a compressor for compressing air, a combustor for combusting compressed air and fuel discharged from the compressor, and a turbine driven by exhaust gas from the combustor, A rotor having a rotor blade internally provided with a refrigerant flow passage on the outer peripheral side and having a refrigerant flow passage communicating with the refrigerant flow passage therein, and a refrigerant from the refrigerant flow passage in the rotor to the outside of the refrigerant flow passage. A first seal for suppressing the leakage of the refrigerant, an intermediate chamber to which the refrigerant leaked through the first seal is supplied, and a second seal for suppressing the leakage of the refrigerant in the intermediate chamber to the outside of the intermediate chamber. And a path for guiding the refrigerant in the intermediate chamber to a high temperature portion of the gas turbine.

For example, the seal is composed of a plurality of seals,
Among them, at least one seal is arranged on the inner side where the central hole through which the refrigerant flows is formed, and the remaining seals are arranged on the outer side of the shaft, and are arranged in series along the refrigerant leakage path. It is necessary to form a recovery path for extracting and recovering a part of the gas leaked from the leak path between the seals of the seals, and to cool the leaked gas recovered from the recovery path by piping etc. Supply as a refrigerant to various places.

It is preferable that the high temperature portion of the gas turbine for supplying the leaked refrigerant is lower than the pressure of the intermediate chamber in the state where the refrigerant is not recovered in order to reduce the power.

When all the seals are arranged outside the shaft, the pressure of the intermediate chamber into which the refrigerant leaking from the first seal in the intermediate region flows is reduced, and the leaked steam is further downstream from the intermediate chamber. Although the leakage amount of the second seal that suppresses leakage to the first seal decreases, the leakage flow rate of the first seal increases.

By arranging the first seal on the side of the central hole (on the side of the axial center of the rotor) with respect to the second seal, the sealing area can be small and the flow passage cross-sectional area of the gap can be reduced, resulting in leakage. The gas can be effectively recovered and the leak flow rate from the leak can be reduced.

Further, by supplying the refrigerant from the shaft column, a large thrust load is generated in the rotor, but seals are arranged on the inner side and the outer side of the shaft to form an intermediate substance, thereby reducing the pressure. As a result, the thrust load acting on the shaft end face is reduced, so that the bearing loss can be reduced.

In a gas turbine provided with a compressor for compressing air, a combustor for combusting compressed air and fuel discharged from the compressor, and a turbine driven by exhaust gas from the combustor, A rotor having a moving blade provided internally with a refrigerant flow passage on the outer peripheral side and having a refrigerant flow passage communicating with the refrigerant passage therein, and from the end of the refrigerant flow passage in the rotor to the outside of the refrigerant flow passage. A seal for suppressing the leakage of the refrigerant, the refrigerant of the refrigerant flow passage leaked through the seal is guided, lower than the pressure of the refrigerant flowing through the refrigerant flow passage, an intermediate chamber having a pressure higher than atmospheric pressure, And a path for guiding the refrigerant in the intermediate chamber to the high temperature portion of the gas turbine as a refrigerant.

The effect of the guide for introducing the leaked cooling medium is greater if the supply pressure of the guide is close to the outlet pressure within a range where the supply pressure of the guide is higher than the pressure (atmospheric pressure) at the seal outlet.

Further, in the gas turbine, the high temperature portion of the gas turbine is a stationary blade located on the outer peripheral side of the rotor, walls (end rolls, shrouds, etc.) forming a flow path of combustion gas flowing through the turbine, and stationary blades. It is characterized in that it is either a diaphragm (which can also be used as a seal gas) that supports the exhaust gas, or an exhaust duct through which the combustion gas flowing through the turbine is guided.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described in detail below with reference to FIG.

FIG. 1 shows a sectional structure of the upper half of a closed air cooling type four-stage gas turbine. The gas turbine is mainly composed of a compressor 2 for compressing air, and a combustor in which fuel is burned by compressed air. 3. A turbine 100 driven by combustion exhaust gas is a main component, and specifically, FIG.
As shown in FIG. 1, the casing 1, the compressor 2, the combustor 3, and the turbine vanes 41 and the rotor blades 45 disposed inside the casing 1.
The gas path 4, the turbine rotor 5, the bearing 6, the exhaust duct 7 and the like, which are formed by alternately arranging the above, are provided. 1 to
The three-stage stationary blades 41 and the moving blades 45 are cooled from the inside of the blades by forming a cooling flow path 46 so as to withstand the heat load of the combustion gas flowing through the gas path 4.

In the turbine rotor 5, four discs 51 having rotor blades 45 planted on the outer periphery are overlapped with each other via a spacer 52, and a shaft 53 is connected to the end portion thereof. The discs and spacers are closely bonded to each other at a so-called hub portion which is formed with a space from the center of each disc to the outer peripheral side. The hub portion is integrally fastened to the rotor of the compressor 2 via the distant piece 54. The turbine rotor 5 is a shaft 53 and is rotatably supported by a bearing 6.

A shaft end 53a of the shaft 53 is formed with a shaft end supply port 8 for introducing a refrigerant into the rotor from a supply pipe 81 through a seal 82.
As indicated by 99a, the axial center hole 53b, the supply passage 55a formed in the hub of the disc and the spacer, and the slit 5
6a, through the cavity between the disks, etc., the first stage moving blade 45
It is supplied to the cooling flow path 46 formed inside a, and after cooling, the discharge air of the compressor 2 is diverted through the slit 56b, the recovery flow path 57, etc., and is recovered in the combustion chamber 31. Two-stage moving blade 4
5b is also supplied and recovered through a similar route, but the third-stage rotor blade 45c, which is the most downstream rotor blade having a cooling channel.
For the purpose of relaxing the thermal stress of the turbine rotor disk, cooling the compressor rotor high-stage side disk, warming up the rotor at the time of startup, etc., the air extracted from the compressor 2 is flown toward the center of the distant piece 54. It is configured to be supplied to the blade via the center side of the rotor 5 and to be discharged into the gas path 4 after cooling the blade.

On the other hand, the stationary vanes 41 are cooled from the inside of the vanes by the refrigerant supplied from the supply pipe 91 outside the gas path, and after cooling, the first-stage stationary vanes directly from the inside of the gas path to the combustion chamber 31 in the second and third stages. The stationary vanes of the stage are recovered in the combustion chamber 31 via the recovery pipe 92 outside the gas path.

The outer wall of the gas path 4 has a tip end wall 42 integrally formed with the vane and a shroud 11.
The inner wall is partitioned by the hub end wall 43. The walls of the gas path 4 are constituted by these, and these members are exposed to the hot combustion gas similarly to the blades. It is cooled by the convection cooling from the chambers 12 and 13 and the film cooling in which the end wall is provided with the blowing holes 44 to blow out the refrigerant.

Further, the end walls 42 and 43, the shroud 11, and the diaphragm 14 which supports the vanes from the inside are divided in the circumferential direction to absorb the thermal deformation, and further, the diaphragm and the rotor. The non-contact seal 15 is installed in the gap portion of the arrow 99. In order to prevent the combustion gas in the gas path from bypassing the slight gap between the dividing surface and the seal surface and heating the surrounding area, the arrow 99 is formed.
As indicated by b, 99c, etc., the refrigerant is discharged as a seal gas from the refrigerant flow path to the gas path side through the gap between the members forming the flow path wall.

As the refrigerant and the seal gas, all the extracted air from the compressor is not supplied, but in the present embodiment, the inner seal 82a of the rotor shaft end supply port 8 described above is provided for the four-stage vane. And a chamber 83 formed at an intermediate position between the outer seal 82b and the outer seal 82b
d is connected by a recovery passageway 84 and a recovery pipe 85, and a part of the air leaking from the seal is extracted and introduced.

In the seal portion, a plurality of series of seals are formed outward from the supply flow passage, and a chamber (intermediate chamber) filled with the refrigerant leaked from one seal is provided between the seals. It is configured. The pressure of the refrigerant is the pressure of the supply passage, the pressure of the intermediate chamber in which the refrigerant leaked from the first seal on the supply system passage side is stored, or the other intermediate or outside air in which the refrigerant in the intermediate chamber leaks through the second seal. Up to
The pressure gradually decreases. The seal may be formed in multiple series.

This supply flow is generated under the condition that the pressure in the chamber 12d is lower than the pressure in the middle position of the seal, and the pressure in the chamber 83 is lowered by the connection, so that the outer seal 82b whose outlet is open to the atmosphere is formed. The leak flow rate of is reduced, and the reduced amount of refrigerant is supplied to the chamber 12d along the path 99d. If the supply flow rate satisfies the four-stage cooling and the flow rate required as the seal gas, it is possible to save the consumption amount of the refrigerant, which greatly affects the efficiency of the gas turbine, and contribute to the efficiency improvement.

When a cooling medium is supplied to the rotor blades, etc., when a coolant supply port or a coolant supply port and a recovery port are provided at the shaft end of the rotor, a seal is provided to prevent the coolant from leaking to the outside. is important.

For example, in a high temperature combustion type gas turbine having a high combustion temperature, the flow rate of the refrigerant is large and the leakage is large, so that the effect of utilizing the leaked refrigerant is great. For example, if the combustion temperature is
Suitable for 1500 degree class gas turbine.

Further, even in a high compression type gas turbine having a high compression ratio in the compressor, the refrigerant pressure is high and there are many leaks, so that the effect of utilizing the leaked refrigerant is great. For example, it is applied to a gas turbine having a compression ratio of about 20 to 30.

It is preferable to apply to a gas turbine having a rotor having a structure in which a coolant supply port is provided at the shaft end.

Since the refrigerant having a high pressure exists near the seal portion, the amount of leakage from the seal is large and the effect of utilizing the leakage refrigerant is great.

As one example, a gas turbine having an average diameter of a gas path of 2.2 m is constructed, and a pressure ratio of 25 and a discharge flow rate of about 150 kg generated by compressed air of 600 kg / s.
When the combustion gas at 0 ° C is passed through the gas path, the rotor rotates to output about 280 MW of power, but at this time, the air required for cooling the turbine reaches about 25% of the compressor discharge flow rate. 10% of this is released into the gas path as cooling gas and sealing gas for the end wall and shroud. About 0.3 for 4 stages of cooling and sealing gas
% Of air must be supplied to the chamber 12a at a pressure of about 3.0ata, and if this air consumption is reduced, it will be 0.1%.
Will improve turbine efficiency.

In FIG. 2, a labyrinth seal is used as the seal, the inner seal 82a has a seal diameter of 260 mm, the outer seal 82b has a seal diameter of 540 mm, and the number of seal pieces is 1.
2. The calculated value of the leak amount from the seal when the seal gap is 1.0 mm and the supply pressure at the shaft end is 40 ata considering the pressure loss in the rotor internal flow path is shown.

A shows a leak flow rate in the case where a leak occurs by flowing in a gap between both seals in series without recovering. On the other hand, by connecting the chamber 83 to the chamber 12d, the leak flow rate of the inner seal 82a is slightly increased as shown in B, but the leak flow rate of the outer seal 82b is significantly increased as shown in C. The leak amount ΔG of the difference between the two is the recovery amount, and the chamber 1
2d.

The leak amount ΔG is equal to the compressor discharge air flow rate of 0.
It is equivalent to 32%, and it can be seen that the refrigerant for the four stages of cooling and sealing gas can be supplemented. This ensures a turbine efficiency improvement of about 0.1%.

As described above, the leak flow rate of the outer seal 82b decreases because the pressure Pa of the chamber 83 is connected to the chamber 12d as shown in FIG. 3 which shows the pressure change from the inlet to the outlet of the seal leak passage. The reason is that the leak flow rate of the inner seal 82a does not change so much because the inlet pressure is high and the flow in the seal gap is close to the choke flow that is not affected by the outlet pressure. This means that leak air can be collected without increasing the amount of leak from the shaft end supply port.
Works in an advantageous manner.

Further, the refrigerant flowing out from the seal outlet is discharged to the space inside the exhaust duct 7, but the discharge flow rate is considerably reduced as compared with the conventional case, so the environment such as noise in the space is greatly improved. Benefits are obtained.

Further, when the leaked refrigerant is not recovered only by the outer seal, a thrust load of about 71 tons acts on the shaft end, and in order to support this load, the diameter of the thrust bearing must be made considerably large. On the other hand, at the shaft end of the gas turbine described above, the thrust load is about 27 tons because the pressure in the chamber 83 drops, and the bearing load is significantly reduced. Therefore, according to the present invention, not only the bearing diameter of the thrust bearing can be reduced, but also the bearing loss can be significantly reduced.

When the inner seal cannot be installed due to the restriction on the seal layout, a plurality of seals are arranged on the outer side in a series and collected from the middle, or even in the case of one seal, the middle part of the seal is It can be collected by partially removing it and providing an extraction port. In this case, the thrust load cannot be reduced and the amount of leaked refrigerant recovered also decreases, but it goes without saying that the present invention can be applied since the functions are the same.

Further, although the labyrinth seal is used as the seal in the above-mentioned embodiment, the present invention does not limit the kind of the seal, and other types of seals such as a honeycomb seal can be used for the same function. Can be obtained.

Further, in the above-mentioned embodiment, the recovered refrigerant is used as the seal gas inside the four-stage vane and the diaphragm, but for example, the cooling of the three-stage vane and the supplement of the seal gas inside the same-stage diaphragm and the exhaust duct are used. If the cooling flow path is formed and used as the cooling medium, the cooling flow path is appropriately selected according to the required flow rate and pressure, and a sufficient effect can be obtained according to the purpose.

In the embodiment shown in FIG. 1, the structure is shown in which the disks 52 of the turbine rotor 5 are arranged via the spacer 52, but the disks may be adjacent to each other without the spacer.

In the embodiment of FIG. 1, the refrigerant for the moving blades supplied from the shaft end is recovered from the front side of the rotor in the combustor.
Shows an embodiment in the case of supplying the refrigerant for the moving blade from the shaft end and recovering it from the shaft end. This example is suitable for steam cooled gas turbines and the like, as also shown in the cited reference.

That is, the supply portion at the shaft end has a double pipe structure, and in addition to the coolant supply passage 91 to the moving blade, an inner recovery flow for recovering the refrigerant after cooling the moving blade from the inside of the rotor. A passage 92 is formed. In this case, a new seal 93
It is necessary to provide a seal between the supply flow passage 91 and the recovery flow passage 92, but the seal configuration between the supply flow passage and the atmosphere side is shown in FIG.
The present invention can be applied to the present invention, since the leak refrigerant can be recovered from the chamber 98 by installing the supply pipe 94 and the seals 95 and 96 and forming the recovery path 97, as in the case of the above embodiment.

[0049]

As described above, according to the present invention, according to the present invention, to recover the refrigerant leaked from Russia over motor shaft end seals, empty
Generated by using compression power in air-cooled gas turbine
Solves the problem of reduced turbine efficiency due to waste of refrigerant
However, the steam-cooled type consumes more pure water.
Solve the increase in the problems of operating costs by, and to effectively utilize the leaked refrigerant, it is possible to provide a more efficient gas turbine.

[Brief description of drawings]

FIG. 1 is an upper half sectional view of a closed cooling type gas turbine showing an embodiment of the present invention.

FIG. 2 is a relationship diagram between a leak flow rate of a shaft end seal and a calculated value of a recovery flow rate.

FIG. 3 is a flow direction pressure change model diagram of a shaft end seal.

FIG. 4 is a sectional structural view of a shaft end supply port according to another embodiment of the present invention.

[Explanation of symbols]

1 ... Casing, 2 ... Compressor, 3 ... Combustor, 4 ... Gas path, 5 ... Turbine rotor, 6 ... Bearing, 7 ... Exhaust duct,
8 ... Shaft end supply port, 11 ... Shroud, 12, 83, 98
... Chamber, 14 ... Diaphragm, 15 ... Non-contact seal, 42, 43 ... End wall, 53 ... Shaft, 53a ...
Shaft end, 53b ... shaft center hole, 82a, 95a ... inner seal,
82b, 95b ... Outer seal, 84, 97 ... Recovery channel,
85 ... Recovery pipe, 99 ... Arrow.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Ikeguchi 7-2-1, Omika-cho, Hitachi-shi, Ibaraki Hitachi, Ltd. Electric Power and Electric Machinery Development Division (56) Reference JP-A-58-96105 (JP, A) JP-A-9-60531 (JP, A) JP-A-8-14064 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) F02C 7/16 F01D 5/08

Claims (5)

(57) [Claims] 1. A gas turbine comprising a compressor for compressing air, a combustor for combusting compressed air and fuel discharged from the compressor, and a turbine driven by exhaust gas from the combustor, A rotor having a moving blade having a refrigerant flow path inside thereof on the outer peripheral side and having a refrigerant flow path communicating with the refrigerant flow path inside thereof, and the outside of the refrigerant flow path of the refrigerant flowing through the refrigerant flow path inside the rotor A seal that suppresses leakage to the rotor, and a coolant that leaks from the coolant flow passage in the rotor through the seal to cool the high temperature portion of the gas turbine.
A gas turbine having a recovery path. 2. A gas turbine comprising a compressor for compressing air, a combustor for combusting compressed air and fuel discharged from the compressor, and a turbine driven by exhaust gas from the combustor, A rotor having a rotor blade internally provided with a refrigerant flow passage on the outer peripheral side and having a refrigerant flow passage communicating with the refrigerant flow passage therein, and a refrigerant from the refrigerant flow passage in the rotor to the outside of the refrigerant flow passage. A first seal for suppressing the leakage of the refrigerant, an intermediate chamber to which the refrigerant leaked through the first seal is supplied, and a second seal for suppressing the leakage of the refrigerant in the intermediate chamber to the outside of the intermediate chamber. And a path for guiding the refrigerant in the intermediate chamber to a high temperature portion of the gas turbine. 3. The gas turbine according to claim 2, wherein the first seal is arranged closer to the rotor axial center side than the second seal. 4. A gas turbine comprising a compressor for compressing air, a combustor for combusting compressed air and fuel discharged from the compressor, and a turbine driven by exhaust gas from the combustor, A rotor having a moving blade provided internally with a refrigerant flow passage on the outer peripheral side and having a refrigerant flow passage communicating with the refrigerant passage therein, and from the end of the refrigerant flow passage in the rotor to the outside of the refrigerant flow passage. A seal for suppressing the leakage of the refrigerant, the refrigerant of the refrigerant flow passage leaked through the seal is guided, lower than the pressure of the refrigerant flowing through the refrigerant flow passage, an intermediate chamber having a pressure higher than atmospheric pressure, A path for guiding the refrigerant in the intermediate chamber as a refrigerant to a high temperature portion of the gas turbine. 5. The gas turbine according to any one of claims 1 to 4, wherein the high temperature portion of the gas turbine includes a stationary blade located on the outer peripheral side of the rotor, a wall forming a flow path of combustion gas flowing through the turbine, and a stationary blade. A gas turbine characterized by being either a supporting diaphragm or an exhaust duct through which combustion gas flowing through the turbine is guided.