JP3015531B2 - 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 applied to a power plant or the like, and more particularly, to a gas turbine having an improved cooling structure for turbine vanes.

[0002]

2. Description of the Related Art As shown in FIG. 6, for example, a gas turbine used in a power plant has a turbine 1 and a compressor 2 coaxial with the turbine 1, and air compressed by driving the compressor 2 burns. The fuel is supplied to the vessel 3 and combustion of the fuel is performed in the liner portion 3a. Then, the high-temperature combustion gas is guided to the moving blade 6 via the transition piece 4 and the turbine stationary blade 5, and the moving blade 6 is rotationally driven to perform the work of the turbine 1.

[0003] It is known that the thermal efficiency of such a gas turbine can be improved by increasing the turbine inlet temperature, and this turbine inlet temperature has already been increased. In this case, as the inlet temperature rises, turbine components such as the combustor 3 and the stationary blade 6 of the gas turbine 1 are required to have high temperature resistance, and various heat-resistant superalloy materials are applied.

However, in the case of heat-resistant superalloy materials which have been used as high-temperature components for turbines, the limit temperature is 800 to 900 ° C., and the desired turbine inlet temperature (approx.
1300 ° C). For this reason, particularly for the stationary blade, a cooling blade structure for cooling to a limit temperature by adopting a cooling structure is performed, thereby maintaining the reliability of the gas turbine.

FIGS. 7 and 8 show a conventional example of a turbine vane employing such a cooling blade structure. The turbine vane is employed in a gas turbine having a turbine inlet temperature of 1300 ° C. class. An impingement cooling insert 7 is provided in a hollow vane structure vane 5. Small holes 8 and 9 for blowing air are provided on the peripheral walls of the insert 7 and the stationary blade 5, respectively.

Then, air is used as a cooling medium,
The cooling air “a” supplied from the air supply device (not shown) to the outer diameter side cavity 10 of the stationary blade 5 is supplied to the small holes 8 of the insert 7.
Convection in the cavity 11 on the inner surface of the peripheral wall of the stationary blade 5 through which impingement cooling is performed and a considerable amount of air is blown outward from the small hole 9 on the blade surface, whereby the stationary blade 5 is film-cooled, A cooling action is performed to lower the material temperature below the limit temperature.

[0007]

However, air conventionally used as a cooling medium has low cooling characteristics, and when the gas turbine inlet temperature exceeds 1300 ° C., the amount of air required for cooling significantly increases.

Further, it is difficult to sufficiently cool the convection only by the air convection inside the stationary blade 5, and the small holes 9 formed in the blade surface as described above are formed.
From the film cooling system that blows cooling air to the outer surface of the wing. Accordingly, this also increases the amount of cooling air and blows out low-temperature air into the high-temperature gas, which causes a decrease in the thermal efficiency of the gas turbine and, consequently, a decrease in the heat exchange rate of the power plant using the gas turbine. .

Further, with respect to a poor fuel containing impurities, the small holes 9 formed on the surface of the stationary blade 5 are apt to be clogged, so that such a fuel cannot be applied.

[0010] The present invention has been made in view of such circumstances, and it is possible to improve the cooling performance of a turbine vane, thereby achieving good cooling even at a high combustion gas temperature, and to improve the thermal efficiency of a turbine and hence the power plant. It is an object of the present invention to provide a gas turbine capable of improving thermal efficiency and enabling the use of a poor fuel or the like.

[0011]

According to the present invention, in order to achieve the above-mentioned object, a cooling passage for circulating a cooling medium is provided in a turbine vane, thereby cooling the vane by supplying a cooling medium. In a gas turbine with a wing structure,
The cooling medium is steam, and the cooling passage is formed in an outer diameter end wall of the stationary blade and serves as a steam inlet and a steam supply cavity connected to the steam supply cavity. Holes, a plurality of communication paths connected to the outer diameter side end wall cooling holes,
A distribution cavity connected to the communication path, a blade effective portion cooling hole formed at a position near a surface in the blade effective portion of the vane, and for allowing steam to flow from the distribution cavity to the inner diameter side end wall side; A collection cavity that is formed inside the side end wall and collects the steam that has passed through the wing effective portion cooling hole, a number of communication holes communicating with the collection cavity, a cooling duct connected to the communication hole, A steam return hole formed at the center side in the blade effective portion and flowing the steam passing through the cooling duct to the outer diameter side end wall side, and passing through the steam return hole formed at the outer diameter side end wall of the stationary blade And a steam discharge cavity as a steam outlet for guiding the steam to the outside of the stationary blade.

[0012]

According to the present invention, the cooling medium has a specific heat of about 2 times that of air.
As a result, the effective portion of the vane, the outer end wall and the inner end wall can be cooled with a smaller supply volume than air, and the turbine inlet temperature is reduced. Even when the temperature is as high as 1300 ° C. or more, sufficient cooling performance can be obtained.

Therefore, the thermal efficiency of the gas turbine can be improved, and the thermal efficiency of the power plant using the gas turbine can be improved.

Further, the entire amount of steam can be recovered through the steam discharge cavity of the outer end wall without blowing out into the high-temperature gas. Therefore, it is possible to prevent the temperature from dropping due to the mixing of the cooling medium into the high-temperature gas, and the recovered steam can be reused in the steam turbine of the power plant.

In addition, since there are no small holes on the blade surface for blowing out the cooling medium, even a poor fuel containing impurities can be applied without causing a problem such as clogging.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. Note that the overall configuration of the gas turbine is the same as that shown in FIG.

FIGS. 1 to 4 show a stationary blade structure of a gas turbine according to this embodiment. In the gas turbine of the present embodiment, the cooling passage for cooling medium distribution provided in the stationary blade 20 is a cooling passage for continuously flowing steam through the blade effective portion 21, the outer diameter side end wall 22 and the inner diameter side end wall 23. It is a passage and the cooling medium is steam.

As shown in FIGS. 1 and 2, the cooling passage of the stationary blade 20 is roughly divided into a steam supply cavity 24 formed as a steam inlet formed in the outer diameter side end wall 22, and a surface inside the blade effective portion 21. A plurality of blade effective portion cooling holes 25 formed in the vicinity of the steam supply cavity 24 for flowing steam from the steam supply cavity 24 to the inner diameter side end wall 23, and passing through the blade effective portion cooling holes 25 formed inside the inner diameter side end wall 23. A cooling duct 26 for cooling the inner diameter side end wall for flowing the generated steam to the blade center side, and a steam formed on the center side in the blade effective portion 21 and passing through the cooling duct 26 to the outer diameter side end wall 23 side. A steam return hole 27 and a steam discharge cavity 2 as a steam outlet formed in the outer diameter side end wall 23 and serving as a steam outlet for guiding the steam having passed through the steam return hole 27 to the outside of the stationary blade 20. It is configured to have and.

As shown in FIGS. 1 and 2, two steam supply cavities 24 are provided on the rear edge side of the outer diameter side end wall 22 and on the combustor side. A branch pipe-shaped supply pipe 29 for introducing steam is connected to these pipes.

As shown in FIG. 3, each of the steam supply cavities 24 is connected to an elongated outer diameter side end wall cooling hole 31, and these outer diameter side end wall cooling holes 31 are connected through a plurality of communication paths 32. It is connected to the distribution cavity 33. The distribution cavity 33 is provided for the blade effective portion 2 of the vane 20.
1 has a curved shape along the cross-sectional shape.

The blade effective portion cooling hole 25 is provided in the distribution cavity 3.
3 are formed in the vicinity of the blade surface of the blade effective portion 21.

Cooling duct 2 of inner peripheral side end wall 23
As shown in FIG. 4, reference numeral 6 denotes a plurality of cavities 34 which are provided, for example, divided into three and communicate with a predetermined number of blade effective portion cooling holes 25, and a plurality of communication holes which communicate with each of the cavities 34. 35, the cooling hole 2 for the blade effective portion.
5 is connected. In each collection cavity 34, the steam used for cooling the blade effective portion 21 is collected in the blade effective portion cooling holes 25, and the steam is sent to the respective cooling ducts 26 through the communication holes 35.

The steam return hole 27 is for recovering steam used for cooling.
They are provided in parallel. These steam return holes 27 are shown in FIG.
As shown in FIG. 4, the cooling steam is connected to each cooling duct 26 of the inner end wall 23 via an orifice hole 36 for distributing the flow rate of the cooling steam.

The steam discharge cavity 28 is for collecting and collecting the steam that has passed through the steam return hole 27.
As shown in FIG. 3, one portion is provided on the outer diameter side end wall 22. In this steam discharge cavity 28,
A discharge pipe 37 for guiding the steam to the outside of the stationary blade 20 is provided continuously.

Next, the operation will be described.

First, the cooling steam supplied from the supply pipe 29 to the two steam supply cavities 24 on the outer diameter side end wall 22 passes through the outer diameter side end wall cooling holes 31 as shown by arrows in FIG. At this time, the outer diameter side end wall 22 is cooled.

Thereafter, the steam is guided to the blade effective portion cooling holes 25 via the distribution cavity 33, and the blade effective portion cooling holes 2
5, while flowing toward the inner diameter side end wall 23 side, the blade effective portion 21 is cooled, and the inner diameter side end wall 23 is cooled.
In the collection cavity 34. In this case, a large number of blade effective portion cooling holes 25 are formed near the blade surface of the blade effective portion 21, and the cooling area is set by the diameter and the number of these blade effective portion cooling holes 25. Therefore, the wing effective part 2
1 by changing the diameter and the number of the effective blade cooling holes 25 and changing the position of the effective cooling holes 25 in accordance with the degree of temperature rise during the operation of each part of the blade surface, to optimize the respective parts of the blade surface. Cooling settings can be made.

The vapor collected in the collection cavity 34 is
The inner peripheral side end wall 22 is cooled while flowing through the communication hole 35 and the cooling duct 26, and is guided to the three return holes 27 via the orifice holes 36, and becomes recovered steam.

The recovered steam passes through the return hole 27, joins in the steam discharge cavity 28 of the outer diameter side end wall 22, is guided to the outside of the stationary blade 20 through the discharge pipe 37, and is used for the steam turbine and other components. Collected in the collection facility.

According to this embodiment, since the specific heat of the cooling medium is about twice that of air and the cooling medium is excellent in cooling characteristics, the steam is supplied in a smaller amount than the air, so that only the blade effective portion 21 of the stationary blade 20 is supplied. Instead, the outer diameter side end wall 22 and the inner diameter side end wall 23 can be cooled at the same time, and sufficient cooling performance can be obtained even when the inlet temperature is as high as 1300 ° C. or more. In particular, in this embodiment, a large number of effective blade cooling holes 25 are formed near the blade surface of the effective blade portion 21.
The cooling area is set according to the diameter and the number of pieces. Therefore, the diameter and number of the cooling blades 25 in the effective blade portion are increased or decreased according to the degree of temperature rise in each portion of the blade surface of the effective blade portion 21 during operation, and the position of the cooling hole 25 in the effective blade portion is changed. Since the optimal cooling setting for each part of the surface can be performed, the cooling setting corresponding to the temperature difference of each part of the blade effective part 21 based on experimental values or empirical values, etc. Can be sufficiently cooled to a uniform wall temperature.

This eliminates the need for cumbersome additional means such as incorporating a complicated flow regulating member for eliminating a thermal stress difference, particularly in the case of a gas turbine stationary blade made of an integral material. This leads to a high-temperature countermeasure by a relatively easy means only by forming a flow path, which brings an extremely effective advantage as a practical gas turbine.

Therefore, the thermal efficiency of the gas turbine can be improved, and the thermal efficiency of the power plant using the gas turbine can be improved.

When the efficiency of the gas turbine according to the present embodiment with respect to the turbine inlet temperature was examined by applying the gas turbine to a combined plant, as shown by the characteristic line a in FIG. 5, the efficiency was significantly higher than the conventional characteristic line b. Was obtained.

Further, the steam is not blown into the high-temperature gas, and the steam discharge cavity 28 of the outer diameter side end wall is formed.
Through the system. Therefore,
The decrease in temperature due to the mixing of the cooling medium into the high-temperature gas can be prevented, and the recovered steam can be reused in a steam turbine or the like of a power plant.

In the present invention, in order to uniformly cool the metal temperature on the blade surface, it is important to distribute the flow rate of the cooling steam. In this embodiment, the steam supply cavity 24 is divided into two parts. The cooling holes 2
5. The cooling duct 26 and the return hole 27 are also divided into a plurality of parts, and the orifice hole 36 is formed at the entrance of the return hole 27, so that the flow rate of the cooling steam can be accurately distributed.

[0036]

As described above, according to the present invention, since the cooling medium is steam having high cooling characteristics, the blades can be sufficiently and uniformly cooled even at a high gas temperature, and the heat efficiency of the gas turbine is improved. As a result, the thermal efficiency of the power plant using the gas turbine can be improved, and the entire amount can be recovered through the steam discharge cavity of the outer end wall without blowing steam into the high-temperature gas. In addition to preventing the temperature drop due to the mixture of the cooling medium into the gas, it is also possible to reuse the recovered steam, etc. Furthermore, the omission of small holes for blowing the cooling medium on the blade surface has resulted in poor fuel containing impurities. Even in this case, effects such as being applicable without causing a problem such as clogging are exhibited.

Further, according to the present invention, a large number of blade effective portion cooling holes are formed near the blade surface of the blade effective portion, and the cooling area can be set by the diameter and the number of these blade effective portion cooling holes. Therefore, by increasing or decreasing the diameter and number of cooling blades in the effective part of the wing in accordance with the degree of temperature rise during operation in the various parts of the effective surface of the wing, or by changing the position of the cooling hole in the effective wing, Optimal cooling settings can be made. Therefore, by performing the cooling setting corresponding to the temperature difference between the respective portions of the blade effective portion, the entire cooling effective portion can be sufficiently and uniformly cooled to the wall surface temperature, and is relatively easy only by forming the flow path. High temperature countermeasures can be taken by this means, which brings an extremely effective advantage as a practical gas turbine.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of a turbine cooling blade according to the present invention.

FIG. 2 is a longitudinal sectional view showing the turbine cooling blade of the embodiment.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a sectional view taken along line BB of FIG. 2;

FIG. 5 is a graph showing a relationship between turbine inlet temperature and power plant efficiency.

FIG. 6 is a schematic configuration diagram of a gas turbine.

FIG. 7 is a sectional view of a conventional turbine vane.

FIG. 8 is a sectional view taken along line CC of FIG. 7;

[Explanation of symbols]

 Reference Signs List 20 turbine stationary blade 22 outer diameter end wall 24 steam supply cavity 21 blade effective portion 23 inner diameter side end wall 25 blade effective portion cooling hole 26 cooling duct 27 steam return hole 28 steam discharge cavity

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F01D 9/02 F01D 5/18 F02C 7/16

Claims (1)

(57) [Claims] 1. A gas turbine having a cooling vane structure in which a cooling passage for cooling medium circulation is provided in a turbine vane, whereby the vane is cooled by supplying a cooling medium, wherein the cooling medium is steam, and A cooling passage formed on the outer diameter side end wall of the stationary blade as a steam inlet; an outer diameter side end wall cooling hole connected to the steam supply cavity; and an outer diameter side end wall. A plurality of communication paths connected to the cooling holes, a distribution cavity connected to the communication path, and a plurality of the plurality of communication paths formed at positions near the surface in the blade effective portion of the vane, and from the distribution cavity to the inner diameter side end wall side. A blade effective portion cooling hole for flowing steam, and a collection cavity formed inside the inner diameter side end wall and collecting steam passing through the blade effective portion cooling hole, A number of communication holes communicating with the collection cavity, a cooling duct connected to the communication holes,
A steam return hole formed on the center side in the blade effective portion and flowing the steam passing through the cooling duct to the outer diameter side end wall side, and the steam return hole formed on the outer diameter side end wall of the stationary blade. A gas turbine having a steam discharge cavity as a steam outlet for guiding the passed steam to the outside of the stationary blade.