JPH03189333A - Water cooling type gas turbine unit - Google Patents

Abstract

PURPOSE:To recover cooling water so effectively for reusing by installing a filling pipe, spraying the cooling water as water droplets, and a return pipe inhaling cooling water vapor generated by heat absorption both in a blade with small holes scattered, and setting up a connecting passage for these pipes and a turbine jacket. CONSTITUTION:When cooling water in a tank 15 is fed to a conduit 19, under pressure, by a pump 16, it enters a filling pipe 11 by way of a coupling 20 and a passage 21, and is spouted spraylike out of each small hole 12, cooling a blade, and a part of it flows out of each small hole 7 of the blade. The cooling water remaining in the blade turns into superheated steam and it is taken to the outside of a gas turbine from a conduit 24 by way of a return pipe 22, a passage 23 and the coupling 20. Since the cooling water recovered from the gas turbine is turned to high pressure steam, this steam is guided to a steam turbine 28, thereby generating its power. With this constitution, heat absorbed out of the blade by the cooling water is thus recoverable as power.

Description

Detailed Description of the Invention (Industrial Field of Application) This invention relates to a gas turbine in which a stationary vane forming a nozzle and a movable rotor installed around a rotor are exposed to a high-temperature combustion gas flow and become hot. Blades (stationary blades and rotor blades are attached to the gas turbine in different ways, but they have the same structure, so unless it is necessary to distinguish them, they will be collectively referred to as blades in this specification) to utilize water with high enthalpy. The present invention relates to a water-cooled gas turbine device in which heat from blades is transferred to turn into high-temperature steam, and lid cooling water is effectively used to improve thermal efficiency.

(Prior art) As implied in FIG. 4, a gas turbine sends air compressed by a compressor 1 to a combustor 2, burns fuel 3, and produces high-temperature combustion gas, which is then sent to a gas turbine 4. A power device that rotates the rotor 4c by spraying air through a nozzle formed by the stationary blades 4a onto the moving blades 4b planted around the rotor 4c, and drives a load 5 such as a generator connected to the rotor by a rotating shaft 4d. be. The compressor 1 is connected to a rotating shaft 4d and is driven using part of the output of the gas turbine 4.

The thermal efficiency of a gas turbine increases as the combustion gas temperature increases, so blade materials are improved to have higher heat-resistant strength and are cooled so that higher-temperature combustion gas can be used.

For this reason, conventionally, the blades were made hollow and compressed air was fed inside to cool the blades from the inside.
This flows out along the outer surface of the blade through numerous small holes drilled in the blade, and also flows out from a slit formed at the trailing edge of the blade, cooling the outer surface of the blade by contact heat transfer with compressed air. The temperature of the blade was kept from rising by the heat shielding effect of the air film flowing through the blade and by cooling via fins provided in the trailing edge of the blade.

Advances in the heat resistance of blade materials have not progressed rapidly, and currently only about 550 to 650 tons. However, as a result of the gradual development of air cooling technology, the temperature of combustion gas has decreased from below 900 degrees Celsius. However, it has become possible to use a high temperature one of 1350°C. When air cooling is performed intensively in this manner, the air used is more than 20% of the compressed air discharged by the compressor, and therefore, the output of the gas turbine must be used in excess for blade cooling.

Therefore, in order to further enhance the blade cooling effect, the present inventor considered using water, which has a higher specific heat than air and can utilize a large latent heat of evaporation, for blade cooling (Japanese Patent Application No. 63-204640, No. 204641, Patent Application No. 1
-84696, 312914, 265039).

FIG. 5 is a sectional view of a blade illustrating the structure of a gas turbine in which such a blade is water-cooled. A large number of small holes 7 are bored in the hollow blade 6, and a partition wall 9 is supported within the blade by support fins 8. A water injection pipe 11 having a large number of water injection holes 10 is inserted into the partition wall 9 and squirts water toward the inner surface of the partition wall 9. This jet water first collides with the partition wall 9 to cool it and turns into minute water droplets due to the collision with the partition wall, but since the temperature of the partition wall 9 is lower than the blade 6, the water droplets explode before they come into contact with the partition wall. It is less likely to cause the Leidenfrost phenomenon in which water is scattered and insufficient cooling can be performed, and it is also possible to avoid causing large thermal distortions to the blades as would be the case when water is injected directly onto the blades.

The partition wall 9, whose temperature has increased due to heat transmitted through the support fins 8, radiant heat from the blades, etc., is thereby cooled.
Along with this, the temperature of the blade 6 also decreases. The cooling water that cools the partition wall 9 and becomes steam due to its temperature rising and the remaining minute water droplets flow into the blade through the small holes 12 in the partition wall and cool the inner surface of the blade directly and indirectly via the support fins 8. A part of it flows out of the blade from the small holes 7, flows along the outer surface of the blade due to the flow of combustion gas, cools the outer surface of the blade by heat transfer, and forms a heat-insulating film on the outer surface of the blade. reduce the degree to which the gas is heated by the combustion gas. A portion of the cooling water jetted into the blade from the small holes 12 in the partition wall passes between the rear fins 13 and cools the inner surface of the blade, and then flows out from the slit 14 in the pressure section.

To supply cooling water to the blades, as shown in FIG. 4, the cooling water in the tank 15 is pumped through the control valve 17 and through the passage 19 in the casing 18 to the water injection pipe 11 in the stationary blade 4a. The rotor blades 4b are connected to a passage 21 in the shaft via a coupling 20 provided on the rotating shaft 4d.
to be pumped through.

(Problem to be solved by the invention) Water used for blade cooling is released into the gas flow through small holes drilled in the blade or slits formed in the blade pressure part. When a large amount of cooling water is used, it becomes an important issue to smoothly collect and treat the cooled water.

The water that cools the blades contains a large amount of heat and is turned into high-temperature steam, so the use of this water is important from the standpoint of thermal economy.

The present invention aims to provide a gas turbine device that effectively recovers and utilizes this cooling water.

(Means for Solving the Problems) This invention extracts cooling water that has taken heat from high-temperature blades and turned into high-temperature steam through a return pipe, drives a steam turbine with this steam, and uses the thermal energy of the cooling water. By recovering the power as motive power, the above-mentioned problem is solved by increasing the thermal efficiency of the gas turbine device as a whole.

(Function) The water that cools the blades, which have been heated to a high temperature due to the combustion gas, becomes superheated steam at a temperature of around 500°C, and the pressure also increases to 10°C.
~15 kg/cm2.

So, if this steam is put into a separate steam turbine,
The energy contained in steam can be recovered as power. After leaving the steam turbine, the steam whose temperature and pressure have decreased is led to a condenser where it is condensed and used again to cool the blades.

(Example) Figure 1 shows a blade (moving blade 4b) for recovering cooling water.
) implies the structure of

A water injection pipe 11 and a return pipe 22 are inserted into the blade 4b which is hollow and has a large number of small holes 7, and the multi-tubes are connected to passages 21 and 23 provided in the rotor 4C and the rotating shaft 4d, respectively.
This communicates with the outside of the rotor 4c via the coupling 20.

Similar to the conventional device shown in FIG. 4, when the cooling water in the tank 15 is pumped by the pump 16 through the control valve 17 and into the conduit 19, the cooling water passes through the coupling 20 and the passage 21, enters the water injection pipe 11, and enters the water supply pipe 11. (The explanation about the interposition of the partition wall 9 to cool the blade by ejecting it in a spray form from the small hole 12 is omitted)
, a portion flows out from the small hole 7 of the blade. The process up to this point is similar to the blade water cooling in the previous invention, but in the present invention, the cooling water that has become superheated steam remaining in the blades is recovered to drive a separately provided steam turbine. . That is, the cooling water remaining in the blade becomes superheated steam and enters the return pipe 22, passes through the passage 23, passes through the coupling 20, and is taken out from the gas turbine through the conduit 24.

Since the blade cooling water decreases little by little, the tank 15 is replenished with water from the replenishment tank 26 using the pump 27 as shown in FIG.

The cooling water recovered from the gas turbine is 500℃, 10~1
Since it becomes high pressure steam of about 5 kg/cm2, in the present invention, as shown in FIG. 2, this steam is guided to a steam turbine 28 to generate power.

In FIG. 2, the cooling water vapor taken out through the conduit 24 is
The steam turbine 28 is rotated to drive the second load 29 , and the steam that exits the steam turbine 28 and has a reduced temperature and pressure is guided to the condenser 25 where it is condensed and put into the tank 15 .

In the embodiment of FIG. 3, the exhaust gas of the gas turbine 4 (approximately 80
This exhaust gas is passed through the heat exchanger 30, and the water pumped from the tank 15 by the pump 31 is heated and turned into steam.This steam is then passed through the blade as described above. The output of the steam turbine 28 is increased by injecting it into an appropriate stage of the steam turbine 28 which is driven by the steam generated by cooling.

(Effects of the Invention) (1) It is possible to recover and utilize the steam of cooling water that has turned into high-temperature superheated steam by cooling the blades of a gas turbine exposed to a high-temperature combustion gas flow.

(2) By introducing the steam of this cooling water into the steam turbine, the heat taken from the blades by the cooling water can be recovered as force.

(3) Furthermore, the exhaust gas of the gas turbine was passed through a heat exchanger to heat the water sent separately to generate steam, which was used together with the steam generated by blade cooling to drive the steam turbine and taken away from the blades. Heat can be recovered as power.

(4) The blade cooling effect can be improved by increasing the amount of water for cooling the blade.

[Brief explanation of drawings]

1 to 3 schematically show embodiments of the present invention, FIG. 1 is a cross-sectional view of the rotor section showing the cooling water injection and recovery structure for the blades, and FIG. 2 is a steam turbine using cooling water that has become superheated steam. Fig. 3 is a schematic diagram of a device that can also utilize the heat of gas turbine exhaust, Figs. The schematic diagram shown in FIG. 5 is a sectional view showing the structure of the blade. Nigas turbine, 4a: Stator blade, 4b: Moving blade, 4c: Rotor, 4d: Rotating shaft, 5: Load, 6: Blade, 7: Small hole, 8: Support fin, 9: Partition, 10: Water injection hole, 11: Water injection pipe, 12: Small hole, 13: Fin, 14 Nislit, 1
5: Tank, 16: Pump, 17: Control valve, 18: Casing, 19: Conduit, 20: Coupling, 21: Passage, 22: Return pipe, 23: Passage, 24: Conduit, 25: Capacitor, 26: Refill tank, 27: pump, 28: steam turbine, 29: second load, 30: heat exchanger, 31:
pump.

Claims (1)

[Claims] 1) A gas turbine blade (
4a) (4b) includes a water injection pipe (11) that spouts cooling water as minute water droplets toward the inner surface of the blade, and a return pipe (2) that sucks cooling water vapor generated by absorbing heat within the blade.
2), a water cooling type characterized by having a passage for sending cooling water from outside the gas turbine to the water injection pipe (11), and a passage for taking cooling water vapor out of the gas turbine from the return pipe (22). Gas turbine equipment. 2) Gas turbine blades with scattered small holes (7) (
4a) (4b) includes a water injection pipe (11) that spouts cooling water as minute water droplets toward the inner surface of the blade, and a return pipe (2) that sucks cooling water vapor generated by absorbing heat within the blade.
2), a passage for sending cooling water from outside the gas turbine to the water injection pipe (11), and a passage for taking cooling water vapor out of the gas turbine from the return pipe (22), and collecting water vapor from the return pipe (22). A water-cooled gas turbine device characterized in that cooling water vapor is introduced into a steam turbine and the heat transferred to the cooling water by cooling the blades is recovered as the output of the steam turbine. 3) The exhaust gas of the gas turbine is passed through a boiler to generate steam, which is then input into the steam turbine together with the cooling steam generated by cooling the blades to generate power.
The water-cooled gas turbine device described in Section 1.