JPS59126034A - Cooling system for gas turbine - Google Patents

Abstract

PURPOSE:To reduce the consumption of cooling air used for cooling the blades of a gas turbine, by introducing cooling air to the inside of first-stage stator blades, carrying cooling air discharged from the inside of the first-stage stator blades to a heat exchanger, and then carrying cooling air, the temperature of which is lowered at the heat exchanger, to first-stage rotor blades. CONSTITUTION:Compressed cooling air B' supplied from a compressor is introduced into first-stage stator blades 2 from the inside thereof, and cooling air, the temperature of which is raised by cooling the stator blades 2, is discharged from the outside of the stator blades 2 and then carried to a heat exhcanger 14 via a cooling-air discharge pipe 13. In the heat exchanger 14, heated cooling air is cooled by a coolant C. Thereafter, the cooling air is carried to a wheel space 17 of turbine through a cooling-air supply pipe 15 and an air supply hole 16 formed in a rotating stub shaft and then supplied to first-stage rotor blades 3 and the rotor blades of the second and rearward stages through a groove 18 formed between a wheel 8 and a spacer 9. Further, cooling air may be supplied also to the stator blades 4 of the second and rearward stages through the spacer 9 and an air hole 19 formed in a diaphragm 10.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a cooling system for a gas turbine, and more particularly to a cooling device suitable for a high-temperature gas turbine that requires continuous cooling.

[Prior art]

In gas turbines, improvements in turbine inlet temperature are being pursued in order to improve performance such as thermal efficiency and output characteristics.

If the turbine inlet temperature is completely increased, the temperature of the turbine blades may rise and exceed the heat resistance limit of the constituent materials, so the turbine blades must be cooled. Conventionally, cooling is generally performed by feeding cooling air into a hollow tube, and the cooling air is discharged and mixed into the working fluid. For this reason, (1) the temperature of the mainstream gas is completely lowered; (2) Total pressure loss due to mixing is the main cause. etc., leading to a decrease in the performance of the gas turbine.Therefore, in high-temperature gas turbines, the merits of increasing the combustion gas temperature) 1
To avoid damage, a design is required that reduces cooling air consumption and minimizes the effects of mixing.

In particular, the first stage stationary vane has the highest mainstream gas temperature and needs to be strengthened in cooling, but the more the cooling is strengthened, the more the temperature of the mainstream gas leaving the first stage stationary vane will decrease in total pressure and total temperature due to mixing with cooling air. This causes a problem.

FIG. 1 is a cross-sectional view of a conventional gas turbine, where solid arrows A indicate mainstream gas and dashed arrows B indicate cooling air flow. Air that has become highly pressurized by an air compressor (not shown) becomes high-temperature combustion gas in the combustor 1 and enters the turbine, where it passes through the first stage stator vanes 2 and the first stage excitation 1 arranged in the casing 12.
43. Stator blades from second stage onward 4. The air is exhausted through the rotor blades 5 and through the diffuser user 6 . The moving blade is wheel 8. It rotates together with the stub shaft 11 to generate power. Is 9 great?
, 12 is a casing, and 17 is a wheel space.

The cooling air indicated by the broken line arrow B uses the discharge air of an air compressor (not shown) or the intermediate stage extracted air, and a part of it is guided to the observation cavity formed inside the first stage stator vane 2. After the first-stage stills 11 & 2 have been completely cooled, they are discharged and mixed into the mainstream gas. In parallel with the cooling of the first stage stationary blades 2, a part of the cooling air is divided into the first stage rotor blades 3 and the 4-degree moving JK5 on the downstream side, and live air cooling is performed in parallel.

The amount of cooling air required for the first stage stationary vane 2, which has the highest temperature among the turbine blades, is 4 to 5% of the mainstream gas when the combustor outlet gas temperature is 1200C', and the air that has completed the cooling action is 600C. It reaches ~800C and is discharged into the mainstream gas. For this reason, the mainstream gas temperature drops by 30 to 40 C when passing through the first stage stationary blade 2.

As mentioned above, in the conventional gas turbine cooling system, by air cooling the first stage stationary vane 2, the temperature of the mainstream gas is lowered, resulting in a decrease in output, as well as a mixing loss, and a large power loss in the air compressor. .

[Purpose of the invention]

An object of the present invention is to provide an entire cooling system that can reduce the cooling air consumption of the blades of a high-temperature gas turbine and reduce the negative effects of mixing of mainstream gas and cooling air, thereby contributing to improving the efficiency and output characteristics of the gas turbine. There is something to do.

[Summary of the invention]

In order to achieve the above object, the cooling system of the present invention focuses on the first stage stator vane, which is under the most severe thermal conditions and consumes the largest amount of cooling air, and uses the cooling air flowing through the first stage stator vane. Without discharging it into the mainstream gas, it is guided to a heat exchanger installed outside the turbine to cool it down, and then guided to the first stage rotor blades so that it can be reused as cooling air for the first stage rotor blades. It is characterized by configuration 1-. However, not only the first stage moving blades, but also the second stage moving blades, stationary blades, and subsequent moving blades,
This does not preclude its use in conjunction with cooling of stationary blades.

[Embodiments of the invention]

Next, one embodiment of the present invention will be described with reference to FIG. This embodiment is an improved version of the conventional gas turbine shown in FIG. 1 by applying the cooling system of the present invention, and the combustor 1. 1st stage rotor blade3. 2nd stage stationary blade 4. 2nd stage rotor blade 5, diffuser 6, shaft 7,
and wheels 8 are the same or similar components as in FIG. 1 (prior device).

Introducing compressed air for cooling supplied from a compressor (not shown) into the blade from the inner diameter side of the first stage stationary blade 2,
The stator vanes 2 are cooled and heated to flow out from the outer diameter side of the cooled air supply pipe 2, and are led to the heat exchanger 14 through the cooled air discharge pipe 13. In the heat exchanger 14, the heated cooling air is cooled by the refrigerant arrow C, and then transferred to the cooling air supply pipe 15ff.
Air supply hole 1 provided in rotating stub shaft 11 through i
6 into the wheel space 17 of the rotor blade 3.6 and the first stage rotor blade 3. It is also supplied to the second and subsequent stages of rotor blades that require cooling. 5 Spacers 9 are also provided for the stator blades 4 in the second and subsequent stages. Cooling air may be supplied from the inner diameter side of the stationary blade 4 through all the ventilation holes 19 provided in the diaphragm 1. The cooling air that has cooled the blades after the first stage rotor blade 3 is discharged and mixed into the mainstream gas.

In the cooling system configured as described above, the air used for cooling the first stage stator blades 2 is lowered in temperature by the heat exchanger 14 and reused for cooling the first stage rotor blades 3. Relatively low temperature cooling air sound can be used for cooling. Therefore, the amount of cooling air consumed by the first stage stationary blades 2 is zero, and the amount of air required to cool the first stage rotor blades 3 is also reduced (by the amount that the cooling air has become colder). It's done.

On the other hand, since the cooling air sent to the first stage stator blades 2 does not pass through a heat exchanger, its temperature is almost the same as the discharge temperature of the air compressor (not shown). Since the total amount of cooling air used for the cooling blades can be used as cooling air for the first stage stationary blades 2, a large amount of cooling air can be used for cooling the first stage stator vanes lj&2. For this reason,
It is possible to increase the desired cooling air flow velocity within the first stage stator vane 2,
It is easy to obtain a sufficient cooling effect. In addition, the pressure difference in the cooling air system can utilize the maximum pressure difference at the outlet of the compressor outlet pressure car first stage rotor blade, so there is no pressure loss to some extent in the cooling structure inside the blade or in the heat exchanger 14 section. However, the amount of cooling air that should be used for the cooling blades after the first stage rotor blade can be secured.

Regarding the first stage stationary blade 2, the cooling air may be introduced from the outer diameter side and guided from the inner diameter side to the outside of the gas turbine by passing through the outer cylinder of the combustor. Regarding the cooling system for the stator vanes 4 in the second and subsequent stages, the compressor discharge air or the cooling air extracted from the intermediate stage of the compressor may be directly introduced through the outer diameter side of the stator R4 as in the conventional system.

In this embodiment, the mainstream gas passing through the first stage stator vane 2 is as follows:
The temperature drops slightly when it comes into contact with the first stage stationary blade 2, but is it possible that cooling air is mixed in? Since it is not exposed to heat, the amount of temperature drop is small, only a few degrees Celsius. This amount of temperature drop is only 5 to 10 inches compared to the amount of temperature drop when the first stage stator blades flow in the conventional device. Furthermore, since cooling air is not discharged from the first stage stationary vane 2 into the mainstream gas, no mixing loss of the mainstream gas occurs at this location.

〔Effect of the invention〕

As described above in detail, the cooling system of the present invention has cooling air inside the first stage stationary blades of the gas turbine. At least a portion of the cooling air flowing out from the stationary blades is guided to a heat exchanger, and the cooling air whose temperature has been lowered by the heat exchanger is guided to the first stage rotor blades for cooling. It can reduce the consumption of blade cooling air in high-temperature gas turbines, and prevent loss due to mixing of mainstream gas and cooling air, improving the thermal efficiency of gas turbines and increasing the output percentage.
It makes a huge contribution to improving sexuality.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a gas turbine equipped with a conventional cooling system, and FIG. 2 is a cross-sectional view of a gas turbine equipped with an embodiment of the cooling system of the present invention. DESCRIPTION OF SYMBOLS 1... Combustor, 2... 1st stage stator blade, 3... 1st stage moving blade, 4... 2nd stage calming, 5... 2nd stage moving blade, 6...
...Diffuser, 7...Shirt), 8-...Wheel, 9...Shasa, 10...Diafrano...
11... Stub shaft, 12... Casing, 1
3... Cooling air discharge piping, 14... Heat exchanger, 17
...Wheel space. Agent Patent Attorney Masami Akimoto 1 Figure

Claims (1)

[Claims] (2) Cooling air is circulated inside the first stage stator vanes of the gas turbine, at least a portion of the cooling air flowing out from the stator vanes is guided to a heat exchanger, and the cooling air whose temperature has been lowered by the heat exchanger is transferred to the first stage. A cooling system for a gas turbine characterized in that it is configured to conduct cooling by guiding the moving blades to the rotor blades.