JPH0565802A - Gas turbine - Google Patents

Abstract

PURPOSE:To provide a gas turbine which is capable of improving the cooling power of each of turbine stator blades, thereby performing favorable cooling even at high combustion gas temperatures, improving the thermal efficiency of the turbine and therefore the thermal efficiency of and capable of an electric power plant, etc., using fuel of poor quality, etc. CONSTITUTION:Cooling passages for distributing a cooling medium is provided in each tutbine stationary blade 20. As the cooling medium, steam is employed. The cooling passages are comprised of asteam supplying cavity 24 provided in an end wall 22 on the outside diameter side of the stationary blade 20, plural blade effective part cooling holes 25 formed in the blade effective part 21 at the positions close to the surface, a cooling duct 26 formed in an end wall 23 on the inside diameter side, steam return holes 27 formed on the center side in the blade effective part 21, a steam exhausting cavity 28 formed in the end wall 22 on the outside diameter side.

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 of turbine vanes.

[0002]

2. Description of the Related Art A gas turbine used in a power plant, for example, has a turbine 1 and a compressor 2 coaxial with the turbine 1 as shown in FIG. 6, and air compressed by driving the compressor 2 burns. The fuel is supplied to the vessel 3 and the fuel is burned in the liner portion 3a. Then, the high-temperature combustion gas is guided to the moving blade 6 through 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.

By the way, it is known that the thermal efficiency of such a gas turbine can be improved by increasing the turbine inlet temperature, and the turbine inlet temperature has already been raised. In this case, as the inlet temperature rises, turbine components such as the combustor 3 and the vanes 6 of the gas turbine 1 are required to have high temperature resistance, and various heat resistant superalloy materials are applied.

However, the heat-resistant superalloy materials that have hitherto been used as high temperature members for turbines have a limit temperature of 800 to 900 ° C. and a desired turbine inlet temperature (about
It is lower than about 1300 ℃). For this reason, particularly for the stationary blade, the cooling structure is adopted to cool it to the limit temperature by adopting the cooling structure, thereby maintaining the reliability of the gas turbine.

FIGS. 7 and 8 show a conventional example of a turbine vane that employs such a cooling vane structure. This turbine vane is adopted in a gas turbine having a turbine inlet temperature of 1300 ° C., and an impingement cooling insert 7 is installed in the vane 5 having a hollow blade structure. Small holes 8 and 9 for blowing out air are provided on the peripheral walls of the insert 7 and the vane 5, respectively.

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

Further, sufficient cooling is difficult only by air convection inside the stationary blade 5, and the small holes 9 formed on the blade surface as described above.
There is no choice but to rely on a film cooling system that blows cooling air from the blade to the outer surface of the blade. Therefore, this also increases the amount of cooling air and causes low-temperature air to blow out into the high-temperature gas, leading to a decrease in the thermal efficiency of the gas turbine and thus a decrease in the heat exchange rate of the power plant using the gas turbine. .. Further, for a poor fuel in which impurities are mixed, such a fuel cannot be applied because the small holes 9 formed on the surface of the stationary blade 5 are likely to be clogged.

The present invention has been made in view of the above circumstances, and it is possible to improve the cooling property of a turbine vane, thereby performing good cooling even at a high combustion gas temperature, and at the same time, improving turbine thermal efficiency and eventually power generation plant. An object of the present invention is to provide a gas turbine which can improve thermal efficiency and can be applied with poor fuel.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a turbine vane with a cooling passage for circulating a cooling medium, thereby cooling the vane by supplying the cooling medium. In a gas turbine with a wing structure,
The cooling medium is steam, and the cooling passage has a plurality of steam supply cavities as a steam inlet formed in an outer diameter side end wall of the vane and a surface vicinity position in the vane effective portion of the vane. A blade effective portion cooling hole formed to flow steam from the steam supply cavity to the inner diameter side end wall side, and steam passing through the blade effective portion cooling hole formed inside the inner diameter side end wall to the blade center side A cooling duct for cooling the inner diameter side end wall, a steam return hole which is formed on the center side in the blade effective portion and which causes the steam passing through the cooling duct to flow to the outer diameter side end wall side, and the stationary blade. A steam discharge cavity is formed in the outer diameter side end wall and serves as a steam outlet for guiding the steam passing through the steam return hole to the outside of the stationary blade.

[0011]

According to the present invention, the specific heat of the cooling medium is about 2 that of air.
By using steam with twice the excellent cooling characteristics, it is possible to cool the blade effective part, outer diameter side end wall and inner diameter side end wall with a smaller supply amount compared to air, and turbine inlet temperature Even when the temperature becomes 1300 ° C or higher, sufficient cooling performance can be obtained. Therefore, it is possible to improve the thermal efficiency of the gas turbine, and further improve the thermal efficiency of the power generation plant using the gas turbine.

Further, it is possible to recover the entire amount of steam through the steam discharge cavity of the outer diameter side end wall without blowing into the high temperature gas. Therefore, it is possible to prevent the temperature from decreasing 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. Moreover, since there are no small holes for blowing the cooling medium on the blade surface, even poor fuel containing impurities can be applied without causing problems such as clogging.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. The overall configuration of the gas turbine is the same as that shown in FIG. 6, and therefore its description is omitted.

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 provided in the vane 20 for circulating the cooling medium continuously circulates the steam over the blade effective portion 21, the outer diameter side end wall 22 and the inner diameter side end wall 23. The passage is used and the cooling medium is steam.

As shown in FIGS. 1 and 2, the cooling passages of the stationary blade 20 are roughly classified into a steam supply cavity 24 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 are formed in the vicinity to allow steam to flow from the steam supply cavity 24 to the inner diameter side end wall 23 side, and pass through the blade effective portion cooling hole 25 formed inside the inner diameter side end wall 23. The cooling duct 26 for cooling the inner diameter side end wall that causes the generated steam to flow toward the blade center side, and the steam that is formed in the center side inside the blade effective portion 21 and that has passed through the cooling duct 26 flows toward the outer diameter side end wall 23 side. The steam return hole 27 and the steam discharge cavity 2 as a steam outlet for guiding the steam formed in the outer diameter side end wall 23 and passing 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, the steam supply cavities 24 are provided at two locations on the trailing edge side of the outer diameter side end wall 22 and on the combustor side. A branched tubular supply pipe 29 for introducing steam is connected to these.

As shown in FIG. 3, each supply cavity 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 distributed through a plurality of connecting passages 32. Connected to 33. The distribution cavity 33 is formed by the blade effective portion 21 of the stationary blade 20.
It has a curved shape along the cross-sectional shape of. The blade effective portion cooling hole 25 communicates with the distribution cavity 33 and is connected to the blade effective portion 21.
Many are formed in the vicinity of the wing surface.

Cooling duct 2 for inner end wall 23
As shown in FIG. 4, 6 is divided into, for example, three pieces, each of which has a collection cavity 34 that communicates with a predetermined number of blade effective part cooling holes 25, and a large number of communication holes that communicate with each collection cavity 34. 35 and the blade effective portion cooling hole 2
Connected to 5. In each collection cavity 34, the steam used for cooling the blade effective portion 21 is collected by the blade effective portion cooling hole 25, and the vapor is sent to each cooling duct 26 through the communication hole 35.

The steam return hole 27 is for recovering the steam used for cooling, and is provided, for example, in the central portion of the blade effective portion 21 with three holes.
It is provided in parallel with the book. These vapor return holes 27 are shown in FIG.
As shown in FIG. 4 and FIG. 4, each cooling duct 26 of the inner diameter side end wall 23 is connected 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, the outer diameter side end wall 22 is provided at one place. In the vapor discharge cavity 28,
A discharge pipe 37 for guiding the steam to the outside of the stationary blade 20 is continuously provided. Next, the operation will be described.

First, when the cooling steam supplied from the supply pipe 22 to the two supply cavities 24 of the outer diameter side end wall 22 passes through the outer diameter side end wall cooling holes 31, as shown by the arrows in the figure. The outer diameter side end wall 22 is cooled.

Thereafter, the steam is guided to the blade effective portion cooling hole 25 through the distribution cavity 33, and the blade effective portion cooling hole 2 is formed.
The blade effective portion 21 is cooled while flowing toward the inner diameter side end wall 23 side in
Are collected in the collecting cavity 34.

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

The recovered steam passes through the return hole 27, merges in the steam discharge cavity 28 of the outer diameter side end wall 22, is guided to the outside of the stationary blade 20 via the discharge pipe 37, and is discharged to the steam turbine and other parts. It is collected in a collection facility.

According to the present embodiment, the cooling medium is steam having a specific heat of about twice that of air and excellent cooling characteristics, so that by supplying a smaller amount of steam than that of air, only the blade effective portion 21 of the stationary blade 20 is supplied. However, 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 a high temperature of 1300 ° C. or higher. Therefore, it is possible to improve the thermal efficiency of the gas turbine, and further improve the thermal efficiency of the power generation plant using the gas turbine.

When the gas turbine according to the present embodiment was applied to a combined plant and the efficiency with respect to the turbine inlet temperature was investigated, as shown by the characteristic line a in FIG. 5, the efficiency was remarkably higher than that of the conventional characteristic line b. It was confirmed to be obtained.

Moreover, the steam is not blown into the high temperature gas, and the cavity 28 for exhausting steam on the outer diameter side end wall is provided.
It is possible to recover the entire amount through the. Therefore,
It is possible to prevent the temperature from decreasing 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 the present invention, in order to uniformly cool the metal temperature of the blade surface, the flow distribution of the cooling steam is important, but in this embodiment, the steam supply cavity 24 is separated into two. Along with the arrangement, the blade effective cooling hole 2
5, the cooling duct 26, the return hole 27, and the like are also divided into a plurality of parts, and the orifice hole 36 is formed at the inlet portion of the return hole 27, so that accurate flow distribution of the cooling steam can be realized.

[0029]

As described above, according to the present invention, since the cooling medium is steam having a high cooling characteristic, the blades can be sufficiently and uniformly cooled even at a high gas temperature, and the gas turbine thermal efficiency can be 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 diameter side end wall without blowing the steam into the high temperature gas. It is possible to prevent the temperature from dropping due to the mixing of the cooling medium into the gas, and also to reuse the recovered steam, etc. Furthermore, by omitting the small holes for blowing the cooling medium to the blade surface, poor fuel with impurities mixed Even in such a case, there is an effect that it can be applied without causing a problem such as clogging.

[Brief description of drawings]

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

FIG. 2 is a vertical cross-sectional view showing a turbine cooling blade of the same embodiment.

3 is a cross-sectional view taken along the line AA of FIG.

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

FIG. 5 is a graph showing the 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.

8 is a cross-sectional view taken along the line CC of FIG.

[Explanation of symbols]

 20 Turbine stationary blade 22 Outer diameter side end wall 24 Steam supply cavity 21 Blade effective part 23 Inner diameter side end wall 25 Blade effective part Cooling hole 26 Cooling duct 27 Steam return hole 28 Steam discharge cavity

Claims (1)

[Claims] 1. A gas turbine having a cooling vane structure in which a cooling passage for circulating a cooling medium is provided in a turbine vane, thereby cooling the vane by supplying the cooling medium, and the cooling medium is steam. The cooling passage has a plurality of steam supply cavities as steam inlets formed on the outer diameter side end wall of the vane, and a plurality of cooling passages formed near the surface in the vane effective portion of the vane. Blade effective portion cooling hole for flowing steam to the side end wall side, and an inner diameter side end wall for cooling steam formed inside the inner diameter side end wall and passing through the blade effective portion cooling hole to the blade center side A cooling duct; a steam return hole formed on the center side in the blade effective portion for flowing steam passing through the cooling duct to the outer diameter side end wall side; And a cavity for steam discharge as a steam outlet for guiding the steam passing through the steam return hole to the outside of the vane, which is formed on the outer diameter side end wall of the gas turbine.