JPH1037710A - Combined cycle power plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To certainly cool the high temperature cooled part of a gas turbine, and certainly recover heat quantity obtained by cooling, by forming a steam turbine plant of at least a high pressure turbine and a low pressure turbine, and introducing the exhaust of the high pressure turbine to a steam cooling system. SOLUTION: The high temperature cooled part of a gas turbine plant is cooled. At this time, it pays attention to the high pressure exhaust of a high pressure turbine 301 out of high pressure exhaust, intermediate pressure exhaust and low pressure exhaust in a steam turbine plant 300 or high pressure steam, intermediate pressure steam and low pressure steam in an exhaust heat recovery boiler 200. The pressure exhaust of the high pressure turbine 301 is the best from the viewpoint of quantity, pressure or temperature. The substantial whole quantity of the high pressure exhaust is used as a cooling medium. Hereby, heat quantity obtained by the cooling of the cooled part of the gas turbine plant is brought to an intermediate pressure turbine 302, and recovered without being thrown away to the outside of the system, and heat efficiency can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combined cycle power plant combining a gas turbine plant and a steam turbine plant.

[0002]

2. Description of the Related Art A combined cycle power plant is
This is a power generation system that combines a gas turbine plant and a steam turbine plant.The high-temperature area of thermal energy is shared by the gas turbine, and the low-temperature area is shared by the steam turbine. This is a power generation system that has been particularly spotlighted in recent years.

In this combined cycle power plant, research and development have been promoted with one point for improving the efficiency being a point of how high the high temperature region can be increased.

On the other hand, a cooling system must be provided for the formation of a high temperature region in view of the heat resistance of the turbine structure, and air has conventionally been used as a cooling medium in this cooling system.

However, as long as air is used as the cooling medium, even if a high temperature range can be achieved, the power loss required to raise the air required for cooling to the required pressure by its own air compressor, and Considering both the fact that the air used for cooling the components is finally mixed into the turbine flow path through which the high-temperature gas passes, thereby lowering the average gas temperature and reducing the energy possessed by the gas. No further improvement in thermal efficiency can be expected.

In order to solve this problem and to further improve the efficiency, a gas turbine which employs steam instead of the above-described air as a cooling medium has appeared.
No. 63960 has been proposed.

The main structure of the device disclosed in Japanese Patent Application Laid-Open No. Hei 5-163960 is shown in FIG.

A gas turbine plant 11 mainly including a gas turbine 13, an air compressor 18, and a combustor 19, and exhaust gas of the gas turbine plant 11 is used as a heating source.
An exhaust heat recovery boiler 14 mainly including a high pressure drum 20, an intermediate pressure drum 21, and a low pressure drum 22, and a high pressure turbine 15a, an intermediate pressure turbine 15b, and a low pressure turbine 15c to which steam is supplied from the exhaust heat recovery boiler 14. The combined cycle power plant 10 is configured by the steam turbine plant 12 having the configuration.

The cooling system incorporated therein is a steam cooling system 50, which uses the medium-pressure steam that has exited the medium-pressure drum 21 of the exhaust heat recovery boiler 14 as cooling steam and passes through a steam supply path 51 through a steam supply path 51. The cooling steam is guided to a steam cooling system 52 provided in a high-temperature cooled portion of the turbine 13 and cooled by the high-temperature cooled portion. 12 is supplied to the intermediate pressure turbine 15b and is effectively recovered.

The steam system 60 is a backup system which can supply backup steam from the high-pressure drum 20 of the exhaust heat recovery boiler 14 through the high-pressure steam line 42, and is used immediately after the gas turbine 13 is started. Things.

[0011]

As described above, the conventional apparatus uses medium-pressure steam that has exited the medium-pressure drum 21 as cooling steam, so that the turbine inlet temperature of the gas turbine further increases. Or, the high-temperature cooled portion of the gas turbine expands, and the range of the cooled portion of the turbine portion expands with the moving blades, the stationary blades, and the annular portion, and as the heat load of these high-temperature cooled portions increases, With medium-pressure steam, the cooling capacity of the high-temperature cooled part of the gas turbine is insufficient due to the limit of the amount of steam generated in the exhaust heat recovery boiler. There is a problem that you can not do it.

The present invention solves such a problem in the prior art, always and reliably cools a high-temperature portion to be cooled of a gas turbine, and reliably recovers the amount of heat obtained by this cooling to improve efficiency. It is an object of the present invention to provide a product which is designed to improve the quality.

[0013]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and is intended to combine a gas turbine plant and a steam turbine plant and utilize the exhaust heat from the gas turbine to drive steam for driving a steam turbine. A combined cycle comprising an exhaust heat recovery boiler for generating steam and a steam cooling system for cooling a high-temperature part to be cooled of the gas turbine with steam, and allowing the steam turbine to recover superheated steam from the steam cooling system. In a power plant, a combined cycle power plant is provided in which the steam turbine plant includes at least a high-pressure turbine and a low-pressure turbine, and the exhaust of the high-pressure turbine is guided to the steam cooling system. Steam cooling system that cools the section with steam High-pressure turbine exhaust is specified as cooling steam, and the high-temperature exhaust-cooled portion of the gas turbine is efficiently and appropriately cooled by utilizing the quantitative, pressure, or temperature characteristics of the high-pressure exhaust. It was made.

Further, the present invention provides an exhaust heat recovery boiler that combines a gas turbine plant and a steam turbine plant to generate steam for driving a steam turbine using exhaust heat from the gas turbine. Provide a steam cooling system that cools the high temperature cooled part with steam,
In a combined cycle power plant configured to allow superheated steam from the steam cooling system to be recovered by a steam turbine, the steam turbine plant includes at least a high-pressure turbine and a low-pressure turbine, and the exhaust of the high-pressure turbine is steam-cooled. To provide a combined cycle power plant that leads to the system and supplies it directly to the downstream steam turbine after exiting the steam cooling system, and provides a steam cooling system that cools the hot cooled part of the gas turbine with steam. The exhaust of the high-pressure turbine specified as the guided cooling steam, after performing a predetermined work in the high-temperature cooled part, does not drop to equipment such as a reheater of a boiler, for example, and is discharged, for example, at a medium pressure directly downstream. Is supplied to a steam turbine, such as a turbine, where it can perform a predetermined task sufficiently. Those were Unishi.

The present invention also provides a combined cycle power plant in which the exhaust heat recovery boiler is at least a three-pressure system of high pressure, medium pressure and low pressure. Since it is cooled by the exhaust gas and then introduced into the intermediate-pressure turbine, it is not necessary to provide a reheater even if the exhaust heat recovery boiler is a three-pressure system of high, medium and low pressure.

Still further, the present invention provides a combined cycle power plant in which exhaust gas of the high-pressure turbine flows in parallel to a plurality of cooled portions of the high-temperature cooled portion. Since the flow is divided and flows through the high-temperature cooled portions arranged in parallel, the pressure loss of a specific path is shared only by the branch flowing through the specific path.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIG.

Reference numeral 101 denotes a gas turbine, 102 denotes an air compressor driven by the gas turbine 101, and 103 denotes a combustor which burns compressed air supplied from the air compressor 102 together with fuel to drive the gas turbine 101. . 10
A generator 4 is driven together with the air compressor 102. The gas turbine 101, the air compressor 102, the combustor 103, and the power generator 104 constitute a gas turbine plant 100.

The exhaust gas of the gas turbine 101 is guided to an exhaust heat recovery boiler 200 through an exhaust duct 105. The exhaust heat recovery boiler 200 includes a high-pressure superheater 204,
High pressure evaporator 205, high pressure economizer 206, medium pressure superheater 20
7, low-pressure superheater 208, medium-pressure evaporator 209, high-medium-pressure economizer 210, low-pressure evaporator 211, low-pressure economizer 212, and also the high-pressure evaporator 205, medium-pressure evaporator 209, and low-pressure evaporator 211. The exhaust gas is used as a heating source to generate high-pressure, medium-pressure, and low-pressure steams, each of which includes a high-pressure drum 201, a medium-pressure drum 202, a low-pressure drum 203, and the like.

Reference numeral 301 denotes a high-pressure turbine, 302 denotes a medium-pressure turbine, and 303 denotes a low-pressure turbine.
Is driven by high-pressure steam supplied from a high-pressure superheater 204 of the exhaust heat recovery boiler 200 via a high-pressure steam line 306, and the low-pressure turbine 303 is driven by the exhaust heat recovery boiler 20.
It is driven by a mixed steam of the low-pressure steam supplied from the low-pressure superheater 208 through the low-pressure steam line 307 and the exhaust of the medium-pressure turbine 302 described later.

On the other hand, the intermediate pressure turbine 302 does not depend only on the medium pressure steam supplied from the exhaust heat recovery boiler 200 through the medium pressure steam line 311, And is driven by steam mainly composed of high-pressure exhaust of the high-pressure turbine 301 supplied from the steam recovery system 405.

The high-pressure turbine 301, the medium-pressure turbine 302, and the low-pressure turbine 303 are directly connected to a shaft together with a generator 304, and a steam turbine plant 300 includes a condenser 305 connected to the low-pressure turbine 303. You.

Numeral 401 denotes a cooling steam supply system which is connected to the exhaust part 310 of the high-pressure turbine 301 and is configured to receive the exhaust of the high-pressure turbine 301. A first steam cooling system 402 branches from the cooling steam supply system 401 to cool the combustor 103.
Reference numeral 403 denotes a second steam cooling system, and 404 denotes a third steam cooling system, which is disposed in parallel with the first steam cooling system 402, and branches from the cooling steam supply system 401 to form the gas turbine 101. Cool the part to be cooled.

A steam cooling system 400 is constituted by the first, second and third steam cooling systems 402, 403, and 404 branched in parallel. After cooling, the cooling medium is joined again and supplied to the intermediate-pressure turbine 302 via the steam recovery system 405.

In the figure, 106 is an air supply system to the air compressor 102, 308 is a cooling water supply system for the condenser 305, and 309 is condensed water obtained by the condenser 305 is supplied to the exhaust heat recovery boiler 200. Shows the water supply system.

As described above, according to the present embodiment, when cooling the high-temperature part to be cooled of the gas turbine plant 100, the high-pressure exhaust, the medium-pressure exhaust and the low-pressure exhaust in the steam turbine plant 300, or the exhaust heat recovery boiler Of the high-pressure steam, medium-pressure steam and low-pressure steam in 200, focusing on the high-pressure exhaust of a high-pressure turbine, which is optimal in terms of quantity, pressure, or temperature, the substantially entire amount is used as a cooling medium. As a result, the amount of heat obtained by cooling the cooled portion of the gas turbine plant 100 is
This is collected without being discarded outside the system, thereby improving thermal efficiency.

That is, among the steams obtained by the exhaust heat recovery boiler 200, first, when high pressure steam is considered, the steam amount is satisfactory but the pressure is high. It is necessary to have a strong structure, and the wall thickness increases by that much, which in turn causes an increase in thermal stress, and the structural design of the cooled portion becomes extremely expensive and difficult.

As for the medium-pressure steam, the amount of steam is insufficient for the required heat amount of the part to be cooled. Therefore, it is conceivable to increase the medium-pressure steam amount by changing the design of the boiler side. This has the contradictory result of reducing the efficiency of exhaust heat recovery in the boiler.

Further, the low-pressure steam normally has a pressure lower than the atmospheric pressure of the high-temperature cooled part of the gas turbine plant 100, and the safety design principle of preventing the high-temperature gas of the gas turbine from leaking to the steam system side cannot be maintained.

In this way, individual pursuits reveal that anything other than high pressure exhaust is ineligible.
Furthermore, it was a great discovery here how well the high pressure exhaust of the high pressure turbine is suitable for cooling the hot cooled part of this gas turbine plant.

The working steam of the intermediate pressure turbine 302 is
Since most of the heat is supplied from the steam cooling system 400 of the gas turbine plant 100, there is no need to install a reheater in the exhaust heat recovery boiler 200, which is indispensable for a normal plant of this type, and the design and production of the plant are greatly reduced. This results in significant cost reduction.

When the high-pressure exhaust gas of the high-pressure turbine is directly used, it is desirable to minimize the pressure loss in the cooled part of the gas turbine plant 100 in order to maintain the plant efficiency. Then, the first, second, and third steam cooling systems 402, 403, and 404 are of course branched and configured in parallel. And the danger of overheating due to local blockage could be dispersed .

Although the present invention has been described with reference to the illustrated embodiments, the present invention is not limited to such embodiments.
It goes without saying that various changes may be made to the specific structure within the scope of the present invention.

[0034]

As described above, according to the present invention, the cooling of a high-temperature portion to be cooled of a gas turbine plant is performed quantitatively as cooling steam.
By using the high-pressure exhaust of the high-pressure turbine that is optimal from the viewpoint of pressure or temperature, even if the temperature of the high-temperature cooled part increases, and even if the range of the cooled part expands, it is possible to follow up, and By making the high-temperature part to be cooled a part of a reheater, there is no need to install a reheater in the exhaust heat recovery boiler. is there.

According to the second aspect of the present invention, the exhaust of the high-pressure turbine does not drop off to equipment such as a reheater of a boiler after performing a predetermined work in a high-temperature cooled part of the gas turbine. Obviously, no reheater is required in the aforementioned waste heat recovery boiler, since it is fed directly to the downstream steam turbine, for example a medium pressure turbine.

According to the third aspect of the present invention, the reheater is indispensable as a standard product because the exhaust heat recovery boiler has a three-pressure system of a high pressure, a medium pressure, and a low pressure. Can be omitted, and the effect of cost reduction by this is large and remarkable.

Further, according to the fourth aspect of the present invention, a plurality of high-temperature cooled parts are formed by branching in parallel, whereby pressure loss at the high-temperature cooled part is suppressed, and high-pressure exhaust of the high-pressure turbine is reduced. It could be used directly and effectively.

[Brief description of the drawings]

FIG. 1 is a system diagram of a combined cycle power plant according to an embodiment of the present invention.

FIG. 2 is a system diagram of a conventional combined cycle power plant.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 gas turbine plant 101 gas turbine 103 combustor 200 exhaust heat recovery boiler 201 high pressure drum 202 medium pressure drum 203 low pressure drum 300 steam turbine plant 301 high pressure turbine 302 medium pressure turbine 303 low pressure turbine 400 steam cooling system 401 cooling steam supply system 402 1st steam cooling system 403 2nd steam cooling system 404 3rd steam cooling system

Claims (4)

[Claims] An exhaust heat recovery boiler that combines a gas turbine plant and a steam turbine plant to generate steam for driving a steam turbine by using exhaust heat from the gas turbine, and a high-temperature cooled portion of the gas turbine. In a combined cycle power plant configured to provide a steam cooling system that cools steam with steam and recovering superheated steam from the steam cooling system to a steam turbine, the steam turbine plant includes at least a high-pressure turbine and a low-pressure turbine. A combined cycle power plant wherein the exhaust of the high-pressure turbine is guided to the steam cooling system. 2. A gas turbine plant and a steam turbine plant, comprising an exhaust heat recovery boiler for generating steam for driving a steam turbine using exhaust heat from the gas turbine, and a high-temperature cooled portion of the gas turbine. In a combined cycle power plant configured to provide a steam cooling system that cools steam with steam and recovering superheated steam from the steam cooling system to a steam turbine, the steam turbine plant includes at least a high-pressure turbine and a low-pressure turbine. A combined cycle power plant, wherein the exhaust of the high-pressure turbine is guided to the steam cooling system, and is supplied directly to a downstream steam turbine after exiting the steam cooling system. 3. The exhaust heat recovery boiler has at least a high pressure,
2. A three-pressure system of medium pressure and low pressure.
Or the combined cycle power plant according to 2. 4. The combined cycle power plant according to claim 1, wherein the exhaust of the high-pressure turbine flows in parallel to a plurality of cooled parts of the high-temperature cooled part.