JP3034519B1 - Gas turbine with improved cooling structure of turbine rotor - Google Patents

Abstract

A gas turbine is provided that reduces the pressure loss of cooling air and increases the cooling effect of a rotor of a turbine by a pre-swirling nozzle that is easy to manufacture. SOLUTION: A compressor 2 for compressing air, a combustor 3 for mixing and burning fuel F with compressed air A from the compressor 2, and a turbine for extracting power from combustion gas G from the combustor 3 4 is configured as follows. A stationary pre-swirl nozzle 37 is provided, and the pre-swirl nozzle 37 supplies cooling air CA swirling in the rotation direction of the rotor 13A to the rotor 13A of the turbine 4. The pre-swirl nozzle 37 is provided with the cooling air C
A conical nozzle hole 39 whose passage width is narrowed from the inlet to the outlet of A is formed so that the pressure loss of the cooling air CA at the inlet of the nozzle hole 39 is reduced, and the cooling air CA for the rotor 13A is reduced. _Lower the relative total temperature T _rel .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas turbine in which a rotor of a turbine is cooled by cooling air pre-rotated by a pre-rotation nozzle.

[0002]

2. Description of the Related Art The thermal efficiency and specific power of gas turbines are:
The improvement can be achieved by increasing the turbine inlet gas temperature and the pressure ratio of the compressor.However, there is a limit to the heat-resistant temperature of the metal material used for the turbine blades. Can't take measures. By the way, a part of the compressed air from the compressor is generally used as a cooling medium for the turbine blades. However, when the pressure ratio of the compressor is increased, the compressed air from the compressor becomes high temperature. Wings cannot be cooled sufficiently. In this case, if a large amount of cooling air is used to enhance the cooling effect, the amount of compressed air used to generate power is reduced, and as a result, performance cannot be improved.

In order to overcome such a situation, among the various parts of the turbine, as a method of efficiently cooling the rotor rotating at a high speed, a method in which a pre-swirl nozzle is provided in a passage of cooling air supplied to the rotor is known. Are known. In this method, cooling air is pre-swirled by a pre-swirl nozzle in the direction of rotation of the rotor and then supplied to the rotor, whereby the relative speed of the cooling air with respect to the rotor is reduced, and the relative total temperature of the cooling air impinging on the rotor Is to reduce.

That is, assuming that the total temperature of the cooling air impinging on the rotor of the turbine is T, and the total temperature relative to the rotor is T _rel , there is a relational expression T _rel = T between the relative total temperature T _rel and the total temperature T. −C ² / (2C _P ) + W ² / (2C _P ) (1) where C: Absolute velocity of cooling air W: Relative velocity of cooling air with respect to rotor C _P : Constant pressure specific heat of cooling air the smaller the relative speed W of the cooling air by the pre-rotation nozzle, it is possible to lower the relative total temperature T _rel of cooling air impinges on the turbine rotor.

The pre-swirl nozzle is configured such that cooling air is pre-swirled and supplied to a rotor of a turbine by passing through a round nozzle having a uniform diameter from an inlet to an outlet. JP-A-53-12
No. 5517) and a cascade type pre-swirl nozzle (ASME Paper 81-GT-132) in which a plurality of blades are arranged along the circumferential direction on the peripheral surface of a ring body arranged concentrically with the rotation axis of the rotor. Are known.

[0006]

However, when the cooling air is pre-rotated by passing through a nozzle hole having a uniform hole diameter,
Since the inlet of the nozzle hole is narrow, the pressure loss of the cooling air at the inlet increases, so that the flow velocity (absolute speed) of the cooling air decreases accordingly. As a result, as apparent from the above equation (1), the relative total temperature T _rel of the cooling air impinging on the rotor of the turbine increases, and the rotor cannot be sufficiently cooled. Further, in the drilling of a nozzle hole having a uniform hole diameter, the rigidity of the cutting tool is reduced, and the processing is not easy.

In the case of using a cascade type pre-swirl nozzle, the pressure loss of the cooling air can be reduced, but the cascade must be formed by precision casting or complicated machining.
Not easy to manufacture.

The present invention has been made in view of the above circumstances, and provides a gas turbine capable of reducing the pressure loss of cooling air and improving the cooling effect of a rotor of a turbine by a pre-swirling nozzle which is easy to manufacture. The purpose is to provide.

[0009]

To achieve the above object, a gas turbine according to a first aspect of the present invention comprises a compressor for compressing air, and a fuel mixed with compressed air from the compressor. And a turbine for extracting power from combustion gas from the combustor, wherein the stationary pre-swirl nozzle supplies cooling air to the rotor of the turbine in the direction of its rotation. And the pre-swirl nozzle has a conical nozzle hole whose passage width decreases from the inlet to the outlet of the cooling air.

According to the gas turbine, since the nozzle hole of the pre-rotation nozzle is conical, the passage area at the inlet of the nozzle hole is large, the flow velocity of the cooling air is low, and the cooling air in the nozzle hole is reduced. Pressure loss is reduced. As a result, the flow velocity (absolute velocity) of the cooling air impinging on the rotor of the turbine after being pre-swirled by the pre-swirling nozzle is increased, and the relative total temperature of the cooling air impinging on the rotor is reduced, thereby improving the cooling effect of the turbine rotor. In addition, the conical nozzle hole of the pre-rotation nozzle can be easily processed by using a conical cutting tool.

Further, in the gas turbine according to a second aspect of the present invention, in the configuration of the first aspect, a large number of the nozzle holes are provided along a circumferential direction of the turbine.

According to this structure, the cooling air is uniformly supplied over the entire circumference of the rotor of the turbine, so that the rotor can be cooled more efficiently.

According to a third aspect of the present invention, in the gas turbine according to the first or second aspect, the pre-swirl nozzle is located on an outer peripheral side of a rotation shaft of the gas turbine and is provided from the compressor to the combustor. It is supported by an inner peripheral wall that forms a passage for the compressed air to flow.

According to this configuration, there is no need to provide a special support member for supporting the pre-swirling nozzle, and the entire structure of the gas turbine can be simplified.

According to a fourth aspect of the present invention, in the gas turbine according to the third aspect, an introduction hole for introducing compressed air from the compressor to a pre-rotation nozzle is formed in the inner peripheral wall. I have.

According to this configuration, a part of the compressed air compressed by the compressor and heading to the combustor is introduced from the introduction hole to the pre-rotation nozzle, so that the passage for supplying the cooling air can be simply configured. .

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram illustrating a part of a gas turbine power generation facility including a gas turbine 1 according to an embodiment of the present invention. In FIG. 1, a gas turbine 1 compresses air IA by a compressor 2 and guides the compressed air IA to a combustor 3.
The turbine 4 is driven by the energy of the high-temperature and high-pressure combustion gas. This turbine 4 drives the compressor 2 and reduces the speed of the reduction gear 7.
The generator 9 is driven via the coupling 8. The generated power from the generator 9 is supplied to various power loads.

FIG. 2 shows a side view of the gas turbine 1 with a part cut away. Although FIG. 1 illustrates a gas turbine 1 having an axial compressor as the compressor 2, the present invention can be applied to a gas turbine having a centrifugal compressor. The axial-flow compressor 2 is composed of a plurality of moving blades 23 arranged on the outer peripheral surface of the rotating shaft 22 and a plurality of stationary blades 27 arranged on the inner peripheral surface of the housing 24 in a plurality of stages. The compressed air A is supplied to the casing 29 formed in an annular shape.

A plurality (for example, six) of the combustors 3 are arranged at equal intervals along the circumferential direction in the annular casing 29, and the compressed air A supplied to the casing 29 is Arrow a,
As shown by b, it is guided into the combustion chamber 32 in the combustion cylinder 31. On the other hand, fuel F is injected into the combustor 3 from the fuel nozzle 34 into the combustion chamber 32, the fuel F is mixed with the compressed air A and burned, and the high-temperature and high-pressure combustion gas G is sent to the turbine 4. .

As shown in FIG. 3, a plurality of stages of turbine vanes 15A to 15C are arranged at predetermined intervals in a housing 11 of a turbine 4 and a turbine disk 1 is provided.
A plurality of stages of turbine rotors 13A, 13B having turbine blades 16 formed on the outer periphery of the rotor 4 are connected to the rotating shaft 22, and each of the turbine rotors 13A, 13B is connected to each of the turbine rotor blades 16 by the respective stage. Turbine stator blade 15A ~
It is arranged so as to be located between C. Each turbine blade 16 is covered with shrouds 17 and 18 supported on the inner peripheral side of the housing 11.

On the outer peripheral side of the rotary shaft 22, there is formed an inner peripheral wall 20 which forms a passage of the compressed air A from the compressor 2 to the casing 29 of the combustor 3. The outer periphery of this passage is formed by the housing 24. On the inner peripheral side of the inner peripheral wall 20, a pre-rotation nozzle 37 for pre-circulating the cooling air in the rotation direction of the turbine rotor 13 and supplying the cooling air to the first-stage first-stage turbine rotor 13A is stationary. It is supported by. This eliminates the need for a special support member for supporting the pre-rotation nozzle 37,
The entire structure of the gas turbine 1 can be simplified.

The pre-rotation nozzle 37 is separate from the inner peripheral wall 20 and is composed of a plurality of segments divided into two or more in the circumferential direction. These segments are formed by a band-shaped spring member 43 wound around the outer periphery. They are connected in a ring by tightening.
The seal between the inner peripheral portion of the pre-rotation nozzle 37 and the outer peripheral portion of the rotary shaft 22 is sealed by a seal portion 43 such as a labyrinth seal provided on the pre-rotation nozzle 37 side. Also,
At a position upstream of the support position of the pre-swirl nozzle 37 on the inner peripheral wall 20, a part of the compressed air A sent from the compressor 2 to the combustor 3 is used as the cooling air CA as the pre-swirl nozzle 37. An introduction hole 38 for introducing the gas into the air is formed. Thereby, a passage for supplying a part of the compressed air A from the compressor 2 to the pre-rotation nozzle 37 can be simply configured.

The pre-swirl nozzle 37 has a number of nozzle holes 39 formed along its circumferential direction. Thereby, the cooling air CA from the pre-swirl nozzle 37 can be uniformly supplied over the entire circumference of the first-stage turbine rotor 13A,
The turbine rotor 13A can be cooled more efficiently. These nozzle holes 39 have a conical shape in which the passage width decreases from the inlet to the outlet of the cooling air CA, and the apex angle of the cone is 4 ° or more. Although there is no particular upper limit for the vertical angle,
The size can be increased to such a degree that the entrance of the adjacent nozzle hole 39 cannot be connected. Further, as shown in FIG. 4A, the direction of the nozzle hole 39 is the same as that of the turbine rotor 13A.
A predetermined inclination angle θ (15 to
25 °). Note that the inner peripheral surface of the pre-rotation nozzle 37 is opposed to the outer periphery of the rotating shaft 22 shown in FIG. 3 via a labyrinth seal.

Of the turbine rotors 13, at least the first and second stage turbine rotors 13A, 13A
B, the pre-swirl nozzle 37
A plurality of ventilation holes 40 through which the cooling air CA supplied from is passed are provided in the axial direction of the rotating shaft 22. These ventilation holes 40 are distributed along the circumferential direction of the turbine disk 14.

The turbine rotor blade 16 of the first stage turbine rotor 13 has a film cooling structure, in which a cooling passage 16a is formed inside as shown in a sectional view of FIG. Are provided, and cooling air CA is flowed in a film form on the blade surface to cool the blade. At the radially inner end, as shown in FIG.
a entrance 16b is provided. Further, a part of the cooling air CA that has passed through the ventilation holes 40 is added to the turbine rotor blades 16 of the turbine disk 14 of the first stage turbine rotor 13.
Are formed in the cooling passage 16a.

In the turbine disk 14 of the first-stage turbine rotor 13A, a ring-shaped seal portion 14a is formed on the inner periphery of the inner peripheral wall 20 at a downstream end portion with a labyrinth seal therebetween. ing. Thereby, the communication between the combustion gas passage in the turbine 4 and the cooling air passage formed between the inner peripheral wall 20 and the rotary shaft 22 is shut off.

In the gas turbine having the above structure, a part of the compressed air A supplied from the compressor 2 to the combustor 3 shown in FIG. And introduced cooling air CA
As shown in FIG. 4A, is supplied to the first stage turbine rotor 13A by rotating in the rotation direction R of the turbine rotor 13A by passing through the nozzle hole 39 of the pre-rotation nozzle 37. Is done. That is, in this case, with respect to the rotation direction R of the turbine rotor 13A, the direction of the nozzle hole 39 of the pre-swirling nozzle 37 is set at a predetermined inclination angle θ (15 to
25 °), the absolute speed C and the relative speed W of the cooling air CA passing through the nozzle hole 39 and impinging on the turbine rotor 13A, and the peripheral speed U of the turbine rotor 13 are shown in FIG. It becomes the relationship shown by the velocity vector,
The relative speed W of the cooling air CA is kept low. The total temperature T and the relative total temperature T of the cooling air CA impinging on the turbine rotor 13
_Since the above-described relationship (1) is established with respect to _rel , the lower the relative speed W of the cooling air CA, the lower the relative total temperature _Trel of the cooling air CA impinging on the turbine rotor 13.

In the velocity vector of FIG. 4A, the relative speed W of the cooling air CA pre-swirled by the pre-swirling nozzle 37 is close to the axial direction, and is formed in the axial direction. The cooling air CA easily enters the ventilation holes 40 of the turbine rotor 13A.

When the cooling air CA is supplied to the turbine rotor 13A in the axial direction, the cooling air CA
Absolute speed C and relative speed W of the turbine rotor 13
The relationship between the peripheral speed U of A and the peripheral speed U is represented by a vector in FIG. 4B. The relative speed W becomes larger than that in the case of FIG. The cooling air CA does not easily enter the ventilation holes 40 of the turbine rotor 13A.

The first stage turbine rotor 13A shown in FIG.
A portion of the cooling air CA that has passed through the ventilation holes 40 formed in the turbine disk 14 and penetrated to the downstream side of the turbine rotor 13 passes through the introduction holes 41 formed in the turbine disk 14 and 16 cooling passages 16
a. Thereby, the turbine rotor blades 16 of the first stage turbine rotor 13 are efficiently cooled by the cooling air CA. The remainder of the cooling air CA that has passed downstream through the ventilation holes 40 of the first-stage turbine rotor 13A is further supplied to the second-stage turbine rotor 13B.

In the present invention, since the conical shape is such that the passage narrows from the inlet to the outlet of the nozzle hole 39 in the pre-swirling nozzle 37, the flow velocity of the cooling air CA at the inlet having a large passage area decreases. , The cooling air CA due to the wall friction when passing through the nozzle hole 39
The pre-swirl can be given to the cooling air CA while keeping the pressure loss of the cooling air small. That is, the cooling air CA that passes through the nozzle holes 39 and hits the first-stage turbine rotor 13A
Of the absolute velocity C of the motor increases as the pressure loss decreases. When this is applied to the above-described equation (1), it is understood that the relative total temperature T _rel of the cooling air CA impinging on the turbine rotor 13 is further reduced by the reduced pressure loss. As a result, the turbine blade 1 using the cooling air CA
6 can be more effectively cooled.

Since the nozzle hole 39 of the pre-rotation nozzle 37 has a conical shape, the use of a conical blade makes it easy to form the nozzle hole 39.

In this embodiment, the pre-swirl nozzle 3
The cooling air CA pre-rotated in Step 7 is supplied to the turbine disk 1
4 through the vent hole 40 of the turbine rotor 13A, and a part of it is introduced through the introduction hole 41 of the turbine disk 14 to be cooled by the cooling passage 16 of the turbine blade 16.
a, the introduction opening of the introduction hole 41 is opened on the upstream side of the turbine rotor 13A of the first stage, and the pre-swirled cooling air CA is temporarily supplied to the downstream side of the turbine disk 14. Instead of being fed, it may be introduced directly from the introduction hole 41 and supplied to the cooling passage 16 a of the turbine bucket 16.

[0034]

As described above, according to the gas turbine of the present invention, the passage area at the inlet of the nozzle hole in the pre-swirling nozzle increases, so that the flow velocity of the cooling air CA decreases, and The pressure loss of the cooling air CA becomes smaller, and as a result, the flow velocity (absolute speed) of the cooling air CA that is pre-swirled by the pre-swirl nozzle and hits the rotor of the turbine increases, and the relative total temperature of the cooling air CA that hits the rotor is reduced. The cooling effect of the turbine rotor can be improved. Moreover, the conical nozzle hole of the pre-rotation nozzle can be easily processed by using a conical blade.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating a gas turbine power generation facility using a gas turbine according to an embodiment of the present invention.

FIG. 2 is a partially broken schematic side view showing the gas turbine.

FIG. 3 is an enlarged longitudinal sectional view showing a turbine portion of FIG. 2 in detail.

4A is a sectional view taken along a circumferential direction showing a relationship between a nozzle hole of a pre-swirling nozzle and a turbine rotor in FIG. 3, and FIG. 4B is a velocity vector diagram.

FIG. 5 is a cross-sectional view along the circumferential direction showing the turbine bucket in FIG. 3;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Gas turbine, 2 ... Compressor, 3 ... Combustor, 4 ... Turbine, 13A-C ... Turbine rotor, 20 ... Inner peripheral wall, 2
2 ... rotating shaft, 37 ... pre-rotation nozzle, 38 ... introduction hole, 39
… Nozzle hole, A… Compressed air, CA… Cooling air

Claims (4)

(57) [Claims] 1. A gas turbine comprising: a compressor for compressing air; a combustor for mixing and burning fuel with compressed air from the compressor; and a turbine for extracting power from combustion gas from the combustor. It has a stationary pre-swirl nozzle that supplies cooling air that swirls in the direction of rotation to the rotor of the turbine, wherein the pre-swirl nozzle narrows in passage width from an inlet of the cooling air toward an outlet. A gas turbine having a conical nozzle hole. 2. The gas turbine according to claim 1, wherein a large number of the nozzle holes are provided along a circumferential direction of the turbine. 3. The pre-swirling nozzle according to claim 1, wherein the pre-swirl nozzle is supported on an inner peripheral wall which is located on an outer peripheral side of a rotating shaft of the gas turbine and forms a passage of compressed air from the compressor to the combustor. Gas turbine. 4. The gas turbine according to claim 3, further comprising an introduction hole for introducing compressed air from the compressor to a pre-rotation nozzle in the inner peripheral wall.