JPH0133647B2 - - Google Patents

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a gas turbine in which a part of the air compressed by a gas turbine compressor is effectively cooled with spray water and then used as cooling air. It is related to.

[Prior art]

In recent years, in order to improve the performance and output of gas turbines, the gas temperature used in gas turbines has tended to become higher and higher.

However, the turbine blades of a gas turbine are
In order to maintain its strength, it is necessary to maintain the temperature below a certain level, and a method of cooling the turbine blades is used as a means for this purpose.

To cool the turbine blades, a portion of the air compressed by the compressor is introduced into the turbine blades as cooling air, and cooling such as film cooling, impingement cooling, and countercooling is performed. Here, the amount of cooling air used is
In order to keep the turbine blades below a certain temperature, it is necessary to increase the temperature as the gas temperature increases.

However, an increase in cooling air usage leads to a decrease in gas turbine cycle efficiency due to an increase in the power required for cooling air compression and a decrease in average gas temperature due to the increase in the amount of cooling air mixed with the mainstream gas. There is a problem.

In addition, the cooling air uses air compressed by the compressor driven by the gas turbine, so although its temperature is lower than that of the combustion gas, the high output of the gas turbine causes the compressor to compress the air. As the ratio increases, so does the temperature.

Therefore, when cooling the turbine blades, the temperature difference between the cooling air and the mainstream gas becomes correspondingly smaller, resulting in a disadvantage that the cooling effect deteriorates.

Furthermore, the temperature of the cooling air increases as it is exposed to the surrounding atmosphere on the way to the turbine blades, and this tendency increases as the temperature of the combustion gas increases.

Therefore, when using the air compressed by the compressor as cooling air, the temperature of the turbine blades is
Under conditions where the temperature is kept below a certain level necessary to maintain its strength, it is impossible to raise the mainstream gas temperature above a certain value even if the amount of cooling air is increased.

As a countermeasure to this problem, some devices are configured to first guide the cooling air outside the gas turbine and cool it using an air-fin cooler, etc., but in this case, although the cooling air temperature decreases, the structure becomes complicated and there is also pressure loss. increases, and the difference between the pressure of the cooling air and the gas pressure at the turbine inlet becomes small, which poses a problem in that film cooling of the first stage stationary blade is impossible.

Furthermore, as the temperature of the gas used in the gas turbine increases, the temperature of the combustor also increases, which poses a problem in the heat resistance of the members that make up the combustor.

That is, increasing the temperature of the gas used in the gas turbine means increasing the combustion temperature, and each part of the combustor is exposed to higher temperature combustion gas.

Here, a large amount of dilution air flows into the inner cylinder of the combustor from the surroundings, and this dilution air blocks the heat of the combustion gas and protects the inner cylinder from exceeding an allowable temperature.

However, the transition piece of the combustor has a double-tube structure consisting of an inner and outer plate with a gap of several millimeters, for example, and a small hole is made in the outer plate, and air compressed by a compressor is guided through the inner plate. In addition, small holes are made in the inner plate, and air is blown into the passage through these holes to form an air film that blocks the heat of the combustion gas. However, the temperature of the air itself compressed by the compressor becomes high, and a sufficient cooling effect cannot be obtained. As a countermeasure to this problem, if the amount of air for cooling the transition piece is increased, the power required for the compressor increases and the average temperature of the mainstream gas also decreases, resulting in a problem that the efficiency of the gas turbine cycle decreases.

In order to solve the various problems mentioned above, the present inventors partitioned the combustor chamber of a gas turbine into the combustor main body side and the combustor chamber tail tube side, and installed an air cooling tube that penetrated the partition to cool the air. We have repeatedly studied a device equipped with a spray device to spray water into the cooling cylinder.

It has been confirmed that this device is capable of effective cooling because it sprays water into the cooling air and utilizes its latent heat through evaporation of the water.

A nozzle is used as a means for spraying water into the cooling air, and the state of the spray changes depending on the spray conditions from this nozzle. That is, in a nozzle having a hole diameter of a certain size, a pressure of a certain cooling water is required to be higher than a certain value, and when this water pressure changes, the state of the spray naturally changes. If the conditions for this spraying are poor, the water droplets may become large and adhere to the wall of the cooling cylinder, or may be discharged with water droplets mixed into the cooling air.

The sprayed water must be completely evaporated while the cooling air passes through the cooling cylinder and be discharged to the combustor chamber transition cylinder side. If this condition cannot be achieved, the turbine There is a risk of adversely affecting each part.

The phenomenon of worsening the spray condition is likely to occur as the load on the turbine changes, and it has been very difficult to set the nozzle dimensions and the pressure to apply the cooling water in order to eliminate this phenomenon.

In addition, the dimensions of the nozzle and the pressure of the cooling water are designed based on the conditions of steady operation, and there is a drawback that large water droplets are generated in the spray because the amount of cooling water decreases, especially when the load is low. It was hot.

[Purpose of the invention]

Therefore, the present invention solves the problems of the conventional turbine, and uses a plurality of water spray devices installed in the gas turbine to effectively cool the cooling air of the gas turbine. The purpose is to improve the cycle efficiency of

[Summary of the invention]

The configuration of the present invention to achieve the above object is such that a part of the air compressed by the compressor of the gas turbine is guided to the turbine blades as cooling air, and the combustion of the gas turbine is performed in the gas turbine that cools the turbine blades. The combustion chamber is divided into the combustor main body side and the combustor chamber transition cylinder side, cooling air is formed on the combustor transition cylinder side, and an air cooling cylinder is provided that penetrates the partition, and water can be sprayed into this cylinder. The present invention is characterized in that it includes a plurality of spray devices and is configured to control these spray devices in accordance with the output of the gas turbine.

That is, in the present invention, a plurality of nozzles are provided in the air cooling cylinder, and the number of nozzles is changed according to the output of the turbine. It is unique in that it is configured to maintain the optimum spray condition without causing any change.

〔Example〕

Embodiments of a gas turbine according to the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic system diagram of a gas turbine. The lower half shows the AA cross section in FIG. 3, which will be described later, and the upper half shows the BB cross section in FIG. 3, which will be described later. , a compressor 2, a combustor 3, and a turbine 4.

Next, FIGS. 2A and 2B are side sectional views showing the main parts of the gas turbine 1, and FIG.
Corresponds to the lower half of the figure, that is, the A-A cross section in Figure 3,
Figure 2B is the upper half of Figure 1, that is, B-B in Figure 3.
A portion corresponding to a cross section is shown.

Here, in the combustor chamber 10, as shown in the vertical cross section of the main part in FIG. 2A and FIG. It is divided into a combustor main body 31 side having a combustor inner cylinder 11 and a combustor flow guide 12, and a combustor transition piece 14 side, and a cooling air chamber 30 is formed on the combustor transition piece 14 side.

As shown in FIG. 2B, the combustor chamber 10 has a combustor main body 31 that passes through the combustor intermediate support plate 13.
Air cooling pipe 5 that opens to the side and the combustor transition pipe 14 side
is provided, and a plurality of (three in this embodiment) spray devices 6, 6-1, 6 spray water into the cylinder 5.
-2, 6-3, and the spray device 6 is connected to a water supply source 9 outside the gas turbine 1, as shown in FIG.
are connected to by piping 7, 7-1, 7-2, 7-3,
Valves 8, 8-1, 8-2, 8 which are controlled by a controller 81 and stop spraying are provided in the middle of the piping.
-3 is provided.

The turbine output is inputted to the controller 81, and when the output falls below the rated value, the valves 8, 8-1, 8-2, and 8-3 are controlled to be closed in sequence according to the output, and the amount of water to be sprayed is controlled. reduce

In addition, the combustor transition piece 14 has an inner plate 15 and an outer plate 16.
It has a double cylinder structure with a large number of small holes 18 and 19 in both plates, and a spacer 17 in between.
The structure is such that a gap is maintained by providing a gap.

As shown in FIG. 2A, a space 27 sealed by a compressor high pressure side seal ring 23 and a turbine inlet side seal ring 24 is formed between the connecting member 21 and the torque tube 22, and a space 27 is formed between the connecting member 21 and the torque tube 22.
and 26 communicate the cooling air chamber 30 with a space 28 within the torque tube 22.

Here, in FIG. 2B, the spray device 6 is provided inside the cylinder 5, but it may also be provided on the wall.

The air compressed by the compressor 2 flows into the combustor chamber 10, and most of the air is supplied to the combustor main body 31, but some of the air is supplied to the air cooling tube shown in FIG. 2B. 5, where it is cooled by evaporation of water sprayed from a spray device 6 provided in this cylinder 5.

The air cooled by the water sprayed from the spray device 6 in the air cooling cylinder 5 as described above is
A portion of the cooling air enters the cooling air chamber 30 as shown by arrow C, and is supplied to the turbine stationary blades 35 and 37 through the cooling air hole 34 of the turbine blade ring 33, and a portion of the air is supplied to the combustor transition piece 14 (the second It flows into the double structure space 20 from the small hole 19 of the outer plate 16 in Figure A), and then blows out from the small hole 18 of the inner plate 15 into the main stream M, and a part of the cooling air extracts from the connecting member 21. Space 27 from pore 25
and the cooling bleed hole 26 of the torque tube 22.
It flows into the space 28 in the torque tube 22 from the air, enters the space 45 between the turbine disks 40 and 42 through the ventilation hole 43 of the turbine disk 40 and the ventilation hole 44 of the spacer disk 41, and cools the cooling air holes 46 and 47. 48 to the turbine rotor blades 36, 38.

〔Effect of the invention〕

As described above, the present invention partitions the inside of the combustor chamber 10 of a gas turbine into the combustor main body 3 side and the combustor transition piece 14 side by the combustor intermediate support plate 13, and the air cooling tube is inserted through the partition. 5 is provided, and this cooling cylinder 5
A plurality of water spray devices 6 are provided inside the gas turbine, the number of spray devices 6 is adjusted according to the output of the gas turbine, and an amount of water corresponding to the output is sprayed to cool the air. This is a characteristic feature.

(a) As a result, the temperature compressed by the compressor increases, and water is sprayed according to the flow rate of the air, which has become even hotter due to exposure to the surrounding high temperature atmosphere, and therefore the amount of air increases. Even if it changes depending on the turbine output, the air temperature can be adjusted to the best condition.

Moreover, since water is directly sprayed into the hot air, the air loses about 600 Kcal/Kg of heat as the latent heat of evaporation, so air fin coolers etc. are used to spray water indirectly. It has the advantage that it can provide sufficiently effective cooling compared to the conventional case of cooling. If cooling air can be cooled and its temperature can be lowered, it is possible to increase the temperature of the gas used by the gas turbine without increasing the amount of cooling air.

(b) In addition, the present invention particularly provides a plurality of water spray devices in the cooling air passage in the gas turbine, and performs water spray by changing the number of nozzles that spray water according to the output of the turbine. . Therefore, in order to adjust the temperature of the cooling air in an optimal state, it is possible to perform cooling with less pressure loss than in the conventional gas turbine, which cools the cooling air by first introducing it to the outside of the gas turbine.

Next, important points taken into consideration when implementing the present invention will be explained.

[1] When spraying water into gas turbine cooling air to cool it, it is necessary to reliably cool the entire amount of cooling air, but if the turbine blades are guided as they are without being cooled, the turbine If the blades cannot be cooled sufficiently, the heat resistance strength of the turbine blades will decrease, and if a mixture of cooled and uncooled air is supplied into the combustor transition piece 14, the turbine blades will be damaged. As in the case,
At the same time as its strength decreases, a temperature distribution occurs in the transition piece 14, which generates thermal stress.

However, in the present invention, since the combustor chamber 10 is partitioned by the combustor intermediate support plate 13 and the air cooling cylinder 5 is provided passing through this, all the air reaching the cooling air chamber 30 is transferred to the air cooling cylinder 5. pass through the inside.

On the other hand, since a plurality of spray devices 6, 6-1, 6-2, 6-3, etc. are provided in the air cooling cylinder 5, the nozzles are opened according to the output of the turbine. This ensures that the entire amount of cooling air is cooled under optimal conditions.

[2] When spraying water into the cooling air, it is necessary to completely evaporate the water so that the unevaporated water droplets do not directly hit the turbine components that have become hot, especially the combustor transition pipe. 14 is in direct contact with the combustion gas, so its temperature is high, and it is made up of a relatively thin plate, so even the slightest drop of water cools down this area rapidly, causing a crack due to thermal stress. If this occurs, combustion gas will leak, and if water droplets come into contact with other parts directly, those parts will be rapidly cooled and their strength will decrease.

However, in the present invention, a water injection device 6 is provided in the cooling air cylinder 5 and water is sprayed there, so that the sprayed water evaporates while flowing inside the cylinder 5, and the water is evaporated into the cooling air chamber 30. By this time, the water has completely evaporated, and the water no longer comes into direct contact with the hot turbine components.

Note that even if the air cooling cylinder 5 is directly hit by water droplets, no problem will occur because this is not a strength component.

Here, in order to completely evaporate the injected water while the air flows inside the air cooling cylinder 5,
It is preferable to make the length of the air cooling cylinder 5 long and to spray water near the inlet thereof.

[3] When cooling cooling air, the air supplied to the combustor 3 must not be cooled, and when the air supplied to the combustor 3 is cooled and its temperature drops, the gas at the combustor outlet will decrease. The temperature decreases and the turbine output decreases.

However, in the present invention, the inside of the combustor chamber 10 is partitioned by the combustor intermediate support plate 13,
Since the air sprayed with water and cooled does not flow into the combustor main body 31 side, the air supplied to the combustor 3 is not cooled.

[4] When the flow rate of the mainstream gas decreases during partial load operation of the gas turbine, the amount of cooling air flowing through the air cooling cylinder 5 also decreases, and the capacity to evaporate the sprayed water decreases, resulting in a decrease in the flow rate from that during rated operation. Since the same amount of water cannot be completely evaporated, it is necessary to reduce the amount of water sprayed.

Here, if the water pressure is lowered to reduce the amount of water sprayed into the air, the diameter of the sprayed water droplets will increase due to the characteristics of the spray, making it even more difficult to evaporate.

From this point of view, in the present invention,
A plurality of spray devices 6 are provided in the air cooling cylinder 5, and the turbine output is inputted to the controller 81. When the flow rate of the mainstream gas decreases, the valves 8 of the spray devices 6 are sequentially closed in accordance with this. Even if the gas flow rate decreases, the amount of spray water can be reduced accordingly without lowering the spray pressure. Therefore, the diameter of the sprayed water droplets does not increase and the sprayed water droplets can be completely evaporated.

Here, the valve 8 may not be provided for all of the plurality of spray devices 6, but the valve 8 may be provided for every several spray devices 6.

Since the flow rate of the mainstream gas corresponds to the output of the turbine, by controlling the valve 8 based on the turbine output, it is possible to control the amount of water to be sprayed (the number of valves of the spray device 6 to be opened) according to the flow rate of the mainstream gas M. can. Further, since the turbine output is always detected in order to control the entire gas turbine, this signal may be used.

In conventional gas turbines, increasing the amount of cooling air increases the ability to cool the turbine blades and increases the temperature of the gas used. As a result, while the amount of heat received by the turbine blades increases, the temperature of the cooling air itself also becomes considerably higher, and the temperature difference between it and the turbine blades becomes smaller, so even if the amount of cooling air is increased, the cooling effect can be significantly improved. I can't.

However, if the temperature of the cooling air is lowered by water spray as in the gas turbine according to the present invention, the temperature difference between the cooling air and the turbine blades will increase, and the cooling effect will be significantly improved. Moreover, if the cooling effect is improved, there is no need to increase the amount of cooling air.

Therefore, according to the present invention, the temperature of the gas used can be increased without increasing the amount of cooling air, and the gas turbine cycle efficiency is improved.

Furthermore, according to the present invention, the inside of the combustor chamber 10 is partitioned by the combustor intermediate support plate 13, and the cooling air chamber 30 is configured so as to wrap around the combustor transition piece 14.
Air at a reduced temperature can be used to cool the combustor transition piece 14.

Therefore, the temperature difference between this air and the combustor transition piece is large and the cooling effect is high, so the combustor transition piece can be effectively cooled and the gas temperature used by the gas turbine can be reduced without increasing the amount of cooling air. It has the advantage of being able to increase

Furthermore, according to the present invention, since water is sprayed into the cooling air, the capacity of the cooling air increases accordingly, reducing the amount of cooling air compressed by the compressor 2 and improving the cycle efficiency of the gas turbine. do.

In addition, according to the present invention, since water is sprayed into the cooling passage inside the gas turbine, a large increase in pressure drop is avoided, unlike when cooling air is once guided outside the gas turbine and cooled with an airfin cooler or the like. Without,
Another advantage is that film cooling of the leading edge of the first stage stator blade of the turbine, which was impossible with this method, can be performed without any problem.

Here, in the embodiment of the present invention, the turbine output is input to the controller, but the air volume of the compressor may also be input, and similar control can be performed in this case as well.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram of a gas turbine in one embodiment of the present invention, and FIGS. 2A and 2B are
This is an enlarged side sectional view of the main parts of the gas turbine shown in the figure.
FIG. 3 is a front view showing essential parts of the combustor intermediate support shown in FIG. 2. 1...Gas turbine, 2...Compressor, 3...Combustor, 4...Turbine, 5...Air cooling tube, 6...
...Spraying device, 8, 8-1, 8-2, 8-3...
Valve, 9...Water supply source, 10...Combustor chamber, 11
...Combustor inner cylinder, 13...Combustor intermediate support, 1
4...Combustor tail piece, 15...Inner plate, 16...Outer plate, 22...Torque tube, 25, 26...Cooling air bleed hole, 30...Cooling air chamber, 31...Combustor main body, 33... Turbine blade ring, 34... Cooling air hole, 35, 37... Turbine stationary blade, 36, 3
8... Turbine rotor blade, 40, 42... Turbine disk, 46, 47, 48... Cooling air hole.

Claims (1)

[Claims] 1. In a gas turbine that cools the turbine blades by introducing a part of the air compressed by the compressor of the gas turbine as cooling air to the turbine blades, the combustor chamber of the gas turbine is divided into the combustor main body side and the combustor chamber tail. A cylinder side is partitioned, an air cooling cylinder is provided passing through the partition, a plurality of spray devices are provided for spraying water into the air cooling cylinder, and the amount of water to be sprayed is adjusted according to the output of the gas turbine. A gas turbine characterized in that it is configured to control.