JPH10299421A - Combined cycle power generating plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To safely restart a plant after shutdown, by providing a by-pass passage which connect an overheated steam supplying passage which supplies overheated steam to a high-pressure turbine with a cooling steam supplying passage which supplies exhaust gas from the high-pressure turbine as cooling steam to a high-temperature cooling part of a gas turbine. SOLUTION: In order to start a plate, a high-pressure turbine by-pass passage 21 is opened when self steam starts to be generated from an exhaust recovery boiler 30, initial steam is passed from a high-pressure heater 31b through a gas turbine plant 10, a reheaters 32a, 32b, and then the steam is dropped onto a condenser 25 through a intermediate-pressure turbine by-pass passage 35. When temperature of cooled steam through the by-pass route 21 increases and it is required to avoid this rising, a warm water spray 26 injects warm water into the by-pass passage 21 to adjust the temperature. Then, when self steam starts to be stably generated from the exhaust recovery boiler 30, the by-pass passage 21 is closed and high-pressure overheated steam supply passage 24 is introduced into the high-pressure turbine 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for supplying cooling steam to a gas turbine cooling unit in 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.

[0003] In such a combined cycle power plant, the cooling technique of the gas turbine is one of the major themes of the technical development. In particular, when the plant is started after inspection work, the WSS which stops the operation every week, the daily operation, etc. When restarting after a plant stop in a DSS or the like that shuts down, there is a situation in which trial and error are being repeated in search of a device that operates more effectively.

In the case of a conventional operation in which the cooling system is an air cooling system using compressed air, the main flow or bleed air of the compressor is automatically supplied as cooling air when the gas turbine is started. Even without any treatment, the combustor or wings started to cool down and could be safely operated without any particular problems.

[0005] However, the improvement of the thermal efficiency of the plant has been demanded and the use of the cooling steam instead of the compressed air as the cooling medium has been studied. However, there is no established one, and even more trial and error is being conducted.

[0006]

In a conventional steam-cooled gas turbine for cooling a combustor or a blade as described above, the generation of steam from the exhaust heat recovery boiler is delayed even when the gas turbine is started. Until this situation reaches a steady state, various problems remain, such as warm air in the cooling steam passage.

The present invention solves such a problem in the prior art, and makes it possible to restart the plant after stopping it more quickly and accurately and safely by suppressing the occurrence of thermal shock and the like. It is an object to provide a combined cycle power plant.

[0008]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a combination of a gas turbine plant and a steam turbine plant, and a steam turbine driving steam utilizing exhaust heat of the gas turbine. In a combined cycle power plant that is equipped with an exhaust heat recovery boiler that generates heat, a superheated steam supply path that supplies superheated steam from the high-pressure superheater to the high-pressure turbine, and the high-pressure turbine exhaust as cooling steam to the high-temperature cooling section of the gas turbine An object of the present invention is to provide a combined cycle power plant provided with a high-pressure turbine bypass path communicating with a cooling steam supply path to be supplied.

That is, when starting up a plant in accordance with an operating procedure such as WSS or DSS, a gas turbine which has been warmed up in advance by, for example, using an auxiliary boiler or using its own compressed air is used. Initial steam generated from the canister is supplied to the steam cooling passage through a high-pressure turbine bypass path to assist the warm-up.

When the self-starting steam starts to be generated stably, the bypass passage is closed, high-pressure superheated steam is introduced into the high-pressure turbine, and the gas turbine is cooled by using the high-pressure exhaust gas. Is performed stably without generating thermal shock or the like.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIG. The figure schematically shows the relative arrangement of the three components of the combined cycle power plant including the gas turbine, the steam turbine, and the exhaust heat recovery boiler, including the main piping system.

Reference numeral 10 denotes a gas turbine plant, which comprises a gas turbine, a combustor for supplying a working gas to the gas turbine, an air compressor for supplying compressed air, and the like. In other words, a high-temperature cooling section centered on the moving blade, a high-temperature cooling section centered on the stationary blade, and a high-temperature cooling section formed on the wall surface of the combustor are provided.

Reference numeral 20 denotes a high-pressure turbine.
Alternatively, a steam turbine portion as a bottoming cycle of a combined cycle is configured in combination with a low-pressure turbine or the like (not shown).

Reference numeral 21 denotes a high-pressure turbine bypass path, which is a superheated steam supply path 24 for supplying steam from an exhaust heat recovery boiler 30 to be described later to the high-pressure turbine 20, and a high-pressure exhaust gas from the high-pressure turbine 20 to a high temperature of the gas turbine plant 10. It is in communication with a cooling section or a cooling steam supply path 22 to be supplied to a first reheater 32a in the exhaust heat recovery boiler 30 described later.

Reference numeral 23 denotes a recovery path which directly cools the cooling steam which has cooled the high-temperature cooling section of the gas turbine plant 10.
Alternatively, a second reheater 32 in an exhaust heat recovery boiler 30 described later
b, and constitutes a path to be supplied to the intermediate-pressure turbine 27.

Reference numeral 24 denotes a superheated steam supply path, and reference numeral 25 denotes a condenser. The superheated steam supply path 24 supplies the superheated steam of the second superheater 31b in the exhaust heat recovery boiler 30 to the high-pressure turbine 20. The water dispenser 25 is arranged so as to communicate with each steam turbine section through a path not shown, and to be able to communicate with the recovery path 23 via a medium-pressure turbine bypass path 35.

Reference numeral 26 denotes a hot water spray, which is connected to a high-pressure evaporator or a economizer (not shown) in the exhaust heat recovery boiler 30, receives hot water as required, and It is configured to inject.

Reference numeral 30 denotes a waste heat recovery boiler, which is generally of a three-pressure type of a low pressure, a medium pressure and a high pressure. Here, for the sake of explanation, a high pressure first superheater 31a and a high pressure second superheater 31 are used.
b, the first reheater 32a and the second reheater 32b are shown as representatives, and other details are omitted.

Reference numeral 33 denotes a high-pressure steam path, reference numeral 34 denotes a reheat steam path, and high-pressure steam path 33 transfers high-pressure steam from a high-pressure evaporator (not shown) to a high-pressure first superheater 31a, and further to a high-pressure second superheater 3a.
1b, and the reheat steam path 34 is connected to the second reheater 32.
A path for supplying the reheated steam from b to the intermediate-pressure turbine 27 is formed.

In each of the above steam paths, valves are shown in the figure at positions that are particularly necessary. Valves are provided as appropriate at various points in the paths, and are provided from the start-up of the plant to steady operation. Necessary steam paths are appropriately configured.

The present embodiment is formed as described above. The operation of the embodiment will be described below. That is, the power plant stops operating once a week and restarts again.
SS or DSS, which is stopped every day and restarted the next day, and so-called plant startup is often performed, such as after completion of periodic inspection work.

When starting up the plant, the gas turbine plant 10 is warmed up in advance by using an auxiliary boiler or using its own compressed air.

After that, it takes time for sufficient steam to be generated from the exhaust heat recovery boiler 30. Therefore, when so-called self-canned steam starts to be generated from the exhaust heat recovery boiler 30, the high-pressure turbine bypass path 21 is opened. , The initial steam from the high-pressure second superheater 31b to the high-pressure turbine bypass path 21,
After passing through the gas turbine plant 10 and further through the first reheater 32a and the second reheater 32b, a path is formed to drop to the condenser 25 via the intermediate pressure turbine bypass path 35.

At this time, the valve of the recovery path 23 is controlled so that this steam does not pass through the intermediate pressure turbine. Therefore, in the intermediate pressure turbine bypass path 35 leading to the condenser 25, a control valve provided in front thereof is provided. Thus, the pressure of the gas in the cooling section of the gas turbine is maintained at or above the gas pressure, and the gas is controlled so as not to flow back into the steam passage.

On the other hand, the high-pressure turbine bypass path 21
When it is necessary to prevent the high temperature, the cooling water flowing from the high-pressure evaporator or the economizer (not shown) is injected into the high-pressure turbine bypass path 21 by the hot water spray 26 when it is necessary to prevent the high temperature. The temperature is adjusted.

When the self-starting steam starts to be generated stably from the exhaust heat recovery boiler 30, the bypass path 21 is closed, and the high-pressure superheated steam is introduced into the high-pressure turbine 20 via the superheated steam supply path 24, and the high-pressure exhaust gas is discharged. Is supplied from the cooling steam supply path 22 to the gas turbine plant 10 to cool a high-temperature cooling section such as a moving blade, a stationary blade, or a combustor, and thereafter, is recovered by the medium-pressure turbine 27 via the recovery path 23.

As described above, according to the present embodiment,
Since the turbine plant 10 is gradually heated after being surely warmed up, even if normal cooling steam enters and the normal cooling steam enters, there is no fear that a thermal shock will occur there, and the cooling system is maintained safely. The intended cooling can be performed accurately.

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

[0029]

As described above, according to the present invention, a gas turbine plant and a steam turbine plant are combined, and an exhaust heat recovery boiler for generating steam for driving the steam turbine by using exhaust heat of the gas turbine is provided. In a combined cycle power plant, a connection was made between a superheated steam supply path that supplies superheated steam from the high-pressure superheater to the high-pressure turbine and a cooling steam supply path that supplies high-pressure turbine exhaust as cooling steam to the high-temperature cooling section of the gas turbine. A high-pressure turbine bypass path is provided, and when starting up the plant, the steam canister of the gas turbine, which has been warmed up in advance by using, for example, an auxiliary boiler or using its own compressed air, The generated initial steam is supplied through a high-pressure turbine bypass path to assist the warm-up, When stable generation starts, the high-pressure turbine bypass path is closed, high-pressure superheated steam is introduced into the high-pressure turbine, and the high-pressure exhaust gas is used to cool the gas turbine. As a result, the stability of operation was improved, and a highly reliable plant was obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory view schematically showing a main part of a combined cycle power plant according to an embodiment of the present invention.

[Explanation of symbols]

 10 Gas Turbine Plant 20 High Pressure Turbine 21 High Pressure Turbine Bypass Path 22 Cooling Steam Supply Path 23 Recovery Path 24 Superheated Steam Supply Path 25 Condenser 26 Hot Water Spray 27 Medium Pressure Turbine 30 Waste Heat Recovery Boiler 31a High Pressure First Superheater 31b High Pressure 2 superheater 32a first reheater 32b second reheater 33 high-pressure steam path 34 reheat steam path 35 medium-pressure turbine bypass path

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02C 7/26 F02C 7/26 Z

Claims (1)

[Claims] 1. A combined cycle power plant comprising a gas turbine plant and a steam turbine plant and comprising a waste heat recovery boiler for generating steam for driving a steam turbine by using waste heat of the gas turbine. A high-pressure turbine bypass path communicating between a superheated steam supply path that supplies superheated steam from the superheater to the high-pressure turbine and a cooling steam supply path that supplies high-pressure turbine exhaust as cooling steam to the high-temperature cooling section of the gas turbine is provided. A combined cycle power plant comprising: