JP2000130108A - Starting method for combined cycle power plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform starting of a steam turbine of steam cycle in a short time when the independent operation of gas cycle is shifted to the combined cycle operation including a steam cycle. SOLUTION: An air ejecting pipe 21 for guiding air from a compressor 1 to an exhaust gas duct 9 while bypassing a combustor 2 and a gas turbine 3 and provided with a temperature adjusting valve 22 is connected to the exhaust gas duct 9 for connecting the gas turbine 3 and an exhaust heat recovery boiler 10 to each other. A temperature reducing unit 26 is provided on a steam path extending from the exhaust heat recovery boiler 10 to a steam turbine 5 and a temperature adjusting valve 28 is provided on a spray water pipe 27. In starting of a steam cycle, the opening of the temperature adjusting valve 22 is controlled to inject compressed gas into exhaust gas after the ventilating condition is met, the opening of the temperature adjusting valve 28 is controlled to inject spray water into steam, and the main steam temperature is kept to the temperature for satisfying the metal matching condition, and the steam is introduced to the steam turbine 5.

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 generation plant, and more particularly to a method in which the temperature of a main steam flowing into a steam turbine is excessively increased when a transition is made from a single gas cycle operation to a combined cycle operation including a steam cycle. And a suitable starting method for maintaining a desired temperature.

[0002]

2. Description of the Related Art In recent years, a combined cycle power plant has been widely adopted as an advantageous power generation system capable of reducing waste of energy as compared with a thermal power plant. There are two types of this combined cycle power plant that are characterized in terms of equipment layout. One is a single-shaft type, in which a gas turbine, a generator, and a steam turbine are directly connected by a common shaft. The other is referred to as a multi-shaft type, in which the gas turbine and the steam turbine are provided on separate shafts, and each turbine has a generator. In this multi-shaft combined cycle power plant, the gas turbine and the steam turbine are not connected by a common shaft, and the gas turbine can operate independently.

FIG. 5 shows an example of a conventional multi-shaft combined cycle power plant. One gas cycle of the combined cycle includes a compressor 1, a combustor 2, and a turbine 3, which constitute a gas turbine unit. Further, a generator 4 for obtaining an electric output is connected to a shaft of the gas turbine 3. The other steam cycle includes a steam turbine 5, a condenser 6, and a condensate pump 7, and a generator 8 is connected to a shaft of the steam turbine 5.

[0004] An exhaust gas duct 9 connected to an exhaust port of the gas turbine 3 is provided to guide exhaust gas from the gas cycle as a heating medium for the steam turbine. This exhaust gas duct 9
The exhaust heat recovery boiler 10 is provided in a path near the end of the boiler. The exhaust heat recovery boiler 10 includes a superheater 11, an evaporator 12, a economizer 13, and a steam drum 14.

Further, a fuel control valve 15 for controlling a fuel flow rate is provided in a fuel system connected to the combustor 2. Further, the exhaust gas duct 9 is provided with a diverter 17 at a portion connected to the bypass stack 16. Further, the exhaust gas duct 9 has a damper 18 at the entrance of the exhaust heat recovery boiler 10. In the drawings, reference numeral 19 denotes a steam control valve, and reference numeral 20 denotes a turbine bypass valve.

The air sucked into the compressor 1 is compressed while flowing in the axial direction, and is sent to the combustor 2 as combustion air. Here, the fuel is mixed with the combustion air to generate high-temperature combustion gas. The combustion gas is supplied to the gas turbine 3 and performs work while expanding inside. This work causes the generator 4 to rotate and generate an electrical output. Further, high-temperature exhaust gas from the gas turbine 3 is guided to an exhaust heat recovery boiler 10 through an exhaust gas duct 9. Exhaust gas flowing in the exhaust heat recovery boiler 10 exchanges heat with steam and feed water flowing in the superheater 11, the evaporator 12, and the economizer 13 to lower the temperature, and is discharged into the atmosphere from a chimney (not shown). .

On the other hand, the condensate extracted from the condenser 6 is pressurized by the condensate pump 7 and supplied to the economizer 13 as water supply. The feedwater flows through the economizer 13, is heated by the exhaust gas during this time, and is sent to the steam drum 14. Further, the feed water extracted from the steam drum flows to the evaporator 12, during which the water is heated by the exhaust gas to become steam. The steam flows from the steam drum 14 to the superheater 11, during which the steam is heated by the exhaust gas to become superheated steam.

This steam flows to the inlet of the steam turbine 5,
Work while expanding inside. This work causes the generator 8 to rotate, producing an electrical output. After the work is completed, the steam is discharged to the condenser 6 and is cooled by cooling water sent through a cooling system (not shown) to be condensed.

In this combined cycle power plant,
For example, when the gas turbine 3 is operated alone, the damper 18 and the diverter 17 of the exhaust gas duct 9 are fully closed, the flow of the exhaust gas to the exhaust heat recovery boiler 10 is shut off, and the exhaust gas is discharged from the bypass stack 16 to the outside of the system. Like that.

When the steam cycle is started from the gas turbine 3 alone operation, the damper 18 of the exhaust gas duct 9
And the diverter 17 is fully opened and the bypass stack 16
The flow of the exhaust gas toward the exhaust gas is shut off, and the high-temperature exhaust gas from the gas turbine 3 is guided to the exhaust heat recovery boiler 10.

[0011]

In the start-up of the combined cycle power plant described above, the generator 4 is quickly incorporated into the power system by a quick start-up operation utilizing the characteristics of the gas turbine 3 for the gas cycle, and the demand is reduced. Driving in response to the increase is possible. On the other hand, in the steam cycle, there are some processes that impose restrictions from the start to the time when the steam turbine 5 bears the rated load, and the time required for the start of the steam cycle becomes longer, and much time is required before the steam cycle is incorporated into the power system. Will spend.

The problem with the restrictions imposed by the steam cycle is that the temperature of the main steam guided to the steam turbine 5 cannot be properly controlled, so that excessive thermal stress may occur in the components. These concerns can be solved by observing the metal matching conditions, that is, the conditions where the difference between the steam temperature and the turbine metal temperature is sufficiently small and the occurrence of thermal stress is expected to be below the allowable value. Maintaining the desired temperature requires some means of accomplishing this purpose and is not easy with current start-up methods. In some situations, such as in the process of increasing the load while waiting for the establishment of ventilation conditions that meet the metal matching conditions, and in the process of increasing the load while performing metal matching, there is a possibility that wasted time may be spent on the steam cycle. The time required for it is prolonged.

An object of the present invention is to provide a method for starting a combined cycle power plant that can start a steam turbine of a steam cycle in a short time when shifting from a single operation of a gas cycle to a combined cycle operation including a steam cycle. Is to provide.

[0014]

According to a first aspect of the present invention, there is provided an exhaust gas duct connecting a gas turbine and an exhaust heat recovery boiler with compressed air from a compressor being used as a bypass for the combustor and the gas turbine. An air extraction pipe equipped with an exhaust gas temperature control valve, which leads to the exhaust gas duct, is connected to the steam path from the steam drum of the exhaust heat recovery boiler to the steam turbine. In addition, a main steam temperature control valve is installed in the spray water pipe connected to the temperature reducer, and when starting the steam cycle, the exhaust gas to the exhaust heat recovery boiler is heated without controlling the exhaust gas temperature control valve before the ventilation conditions are satisfied. At this time, the generated steam bypasses the steam turbine and escapes to the condenser, and after the ventilation conditions are established, the opening of the exhaust gas temperature control valve is controlled to control the low-temperature compression. Steam into the exhaust gas, control the opening of the main steam temperature control valve, and inject low-temperature spray water into the generated steam to maintain the main steam temperature at the desired temperature. Is introduced.

According to such a starting method, by controlling the main steam temperature control valve while maintaining the exhaust gas temperature at a desired temperature for the steam cycle, the spray water amount is adjusted in accordance with the change in the turbine metal temperature, and the main steam temperature is controlled. The temperature can be maintained at a desired temperature at which no excessive thermal stress occurs in the components. As a result, the steam turbine can be raised to the rated load in a short time, and the time required for starting the combined cycle power plant can be reduced.

According to a second aspect of the present invention, a bypass stack having a diverter is connected to an exhaust gas duct connecting a gas turbine and an exhaust heat recovery boiler, and the exhaust gas duct is connected to a steam path from a steam drum to a steam turbine of the exhaust heat recovery boiler. In addition to installing a cooler that injects spray water into the steam passing there,
A main steam temperature control valve is installed in the spray water pipe connected to the temperature reducer,
Before starting the steam cycle, the exhaust gas to the exhaust heat recovery boiler was maintained at a high temperature without controlling the diverter before the ventilation conditions were established.At this time, the generated steam bypassed the steam turbine and escaped to the condenser. After the aeration conditions are established, the opening of the divertor is controlled to guide the exhaust gas whose flow rate is adjusted to the exhaust heat recovery boiler, and the opening of the main steam temperature control valve is controlled to generate low-temperature spray water. The main steam is injected into the steam turbine so that the main steam temperature is maintained at a desired temperature that satisfies the metal matching condition.

According to such a starting method, by controlling the main steam temperature control valve while maintaining the exhaust gas temperature at a temperature desired for the steam cycle, the spray water amount is adjusted according to the change in the turbine metal temperature, and the main steam temperature is controlled. The steam temperature can be maintained at a desired temperature at which no excessive thermal stress occurs in the components. As a result, the steam turbine can be raised to the rated load in a short time, and the time required for starting the combined cycle power plant can be reduced.

Further, in the invention according to claim 3, when starting the steam cycle, the fuel control valve of the gas turbine unit is controlled in accordance with the fuel requirement determined from the operating condition of the gas cycle before the ventilation condition is satisfied, and at this time, the exhaust is controlled. After the steam generated by the heat recovery boiler is escaped to the condenser by bypassing the steam turbine and the ventilation condition is established, the fuel control valve is controlled according to the fuel demand that matches the output pattern determined based on the turbine metal temperature, and the main steam is The temperature is maintained at a desired temperature that satisfies the metal matching condition and is introduced into the steam turbine.

According to such a starting method, by adjusting the exhaust gas temperature in accordance with the fuel demand that matches the output pattern determined based on the turbine metal temperature, the main steam temperature does not cause excessive thermal stress in the constituent members. The desired temperature can be maintained. As a result, the steam turbine can be raised to the rated load in a short time, and the time required for starting the combined cycle power plant can be reduced.

Further, in the invention according to claim 4, in starting the steam cycle, before the ventilation condition is satisfied, the fuel control valve of the gas turbine unit is controlled in accordance with the fuel requirement determined from the operating condition of the gas cycle. After the steam generated by the heat recovery boiler is released to the condenser bypassing the steam turbine and the ventilation conditions are established, the fuel demand obtained from the thermal stress calculated from the superheater outlet steam temperature and the turbine metal temperature through the fuel control valve is established. The main steam temperature is maintained at a desired temperature that satisfies the metal matching condition and is introduced into the steam turbine.

According to such a starting method, the main steam temperature is adjusted by adjusting the exhaust gas temperature in accordance with the fuel demand obtained from the thermal stress calculated based on the superheater outlet steam temperature and the turbine metal temperature at that time. At a desired temperature at which no excessive thermal stress occurs. As a result, the steam turbine can be raised to the rated load in a short time, and the time required for starting the combined cycle power plant can be reduced.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, a gas turbine unit is an air extraction pipe 21 connected to an exhaust gas duct 9 by bypassing a combustor 2 and a gas turbine 3 from an outlet of a compressor 1.
Having. An exhaust gas temperature control valve 22 for adjusting the temperature of exhaust gas to the exhaust heat recovery boiler 10 is provided in the path of the air extraction pipe 21. The exhaust gas temperature control valve 22 has a control device 23 for controlling the opening degree of the exhaust gas temperature control valve 22. A temperature signal is input to the control device 23 from a temperature detector 24 for detecting the temperature of the compressed air flowing through the air extraction pipe 21. As well as
A temperature signal is input from a temperature detector 25 that detects the temperature of the exhaust gas flowing in the exhaust gas duct 9. In addition, a temperature signal is given to the control device 23 from a temperature detector that detects the steam temperature at the outlet of the superheater 11 described later.

Further, the exhaust heat recovery boiler 10 has a temperature reducer 26 in a steam path from the steam drum 14 to the superheater 11. A main steam temperature control valve 28 for controlling the main steam temperature to the steam turbine 5 is interposed in the spray water pipe 27 connected to the temperature reducer 26. This main steam temperature control valve 2
8 is provided with a control device 29 for controlling the opening degree thereof,
A temperature signal is input from the temperature detector 30 for detecting the outlet steam temperature of the superheater 11 to the control device 29, and the temperature detector 3 for detecting the turbine metal temperature of the steam turbine 5
1, a temperature signal is input.

Next, the starting procedure of the steam cycle will be described. The gas turbine 3 is started first and the generator 4 is connected to the power system. At this time, the exhaust gas of the gas turbine 3 flows out of the system from the bypass stack 16 because the damper 18 and the diverter 17 are in the fully closed state.

Next, the exhaust heat recovery boiler 10 for generating steam in the steam cycle is started. The exhaust gas is guided from the exhaust gas duct 9 to the exhaust heat recovery boiler 10 by fully opening the damper 18 and the diverter 17. In the initial stage of the start-up, the temperature of the steam generated in the exhaust heat recovery boiler 10 is low, and no steam meeting the requirements of the steam cycle is generated. At this time, the generated steam flows out to the condenser 6 through the opened turbine bypass valve 20 without going to the steam turbine 5 while the steam control valve 19 is closed.

While the steam below the aeration condition is generated, a temperature signal is input from the temperature detector 30 for detecting the steam temperature at the superheater outlet to the control device 23. However, since the steam temperature remains low, the temperature of the exhaust gas is regulated. Does not require compressed gas to be injected for the exhaust gas temperature control valve 22 from the controller 23.
Is not output, and is kept fully closed. On the other hand, the same temperature signal is input to the control device 29, but since the steam temperature remains low, spray water to be injected for adjusting the main steam temperature is not required. Therefore, the control device 29
Does not issue an opening command to the main steam temperature control valve 28 and is kept fully closed.

Further, when the high-temperature exhaust gas continues to flow into the exhaust gas boiler 10, the temperature of the generated steam increases, and the ventilation conditions satisfying the metal matching conditions are established. Control device 2
The temperature signals are given to the exhaust gas temperature control valve 22 and the main steam temperature control valve 28 to control the exhaust gas temperature and the main steam temperature, respectively.

The steam control valve 19 is opened in accordance with the establishment of the ventilation condition. When the steam control valve 19 is opened, the steam generated by the exhaust heat recovery boiler 10 flows into the steam turbine 5, and the steam turbine 5 is started. Accelerate to the rated speed according to the determined motion mode and take the initial load.

At this time, according to the deviation between the set value and the temperature signal from the temperature detector 25 for detecting the temperature of the exhaust gas in the control device 23, a flow rate request obtained by adding a correction value based on the detected temperature signal of the temperature detector 24 thereto. An opening command is generated based on the signal. This opening degree command is output to the exhaust gas temperature control valve 22, and compressed air is injected into the exhaust gas flowing through the exhaust gas duct 9 through the air extraction pipe 21. The injection of the compressed air changes the exhaust gas temperature toward the exhaust heat recovery boiler 10, and as a result, the superheater outlet steam temperature also changes according to the change.

That is, the exhaust gas temperature control valve 22 can maintain the exhaust gas temperature desired for the steam cycle, and can independently change the superheater outlet steam temperature. However, for more direct and quick main steam temperature control, the main steam control valve 28 is used to adjust the superheater outlet steam temperature. A sudden rise in the main steam temperature is not preferable because it causes excessive thermal stress on the components of the steam turbine 5.

An opening command based on a flow rate request signal corresponding to the difference between the temperature signal from the temperature detector 31 for detecting the turbine metal temperature and the set value is output from the control device 29 to the main steam temperature control valve 29. The opening degree command opens the main steam temperature control valve 28, and the spray water from the spray water pipe 27 is injected into the steam from the desuperheater 26. As a result, an excessive rise in the main steam temperature can be suppressed, and it is possible to prevent excessive thermal stress from occurring in the turbine components.

During this load increase, as the turbine metal temperature of the steam turbine 5 increases, the amount of spray water injected by the additional value control is adjusted to maintain an appropriate main steam temperature. Thereafter, the steam control valve 19 is pressure-controlled, and the turbine bypass valve 20 is gradually closed. At this time, all the main steam flows from the steam control valve 19 into the steam turbine 5, and the start of the steam cycle is completed.

As described above, the steam turbine 5 of the steam cycle
By controlling the main steam temperature control valve 29 while maintaining the exhaust gas temperature to the exhaust heat recovery boiler 10 at a temperature desired for the steam cycle, the spray water amount is adjusted according to the change in the turbine metal temperature. The steam temperature can be maintained at a desired temperature at which no excessive thermal stress occurs in the components, and the steam turbine 5 can be raised to the rated load in a short time.

Therefore, the start of the steam turbine 5 of the steam cycle can be accomplished within a short time after the start of the gas cycle, and the time required for starting the combined cycle power plant can be shortened.

Further, different embodiments of the present invention will be described. In FIG. 2, a diverter 17 is provided at the entrance of the bypass stack 16 connected to the exhaust gas duct 9.
The diverter 17 is provided with a driving device 32 for adjusting the opening.
Is linked to The drive device 32 includes a control device 33, and temperature signals are input to the control device 33 from temperature detectors 25 and 34 that detect the temperature of the exhaust gas flowing in the exhaust gas duct 9. Further, a temperature signal is given to the control device 33 from the temperature detector 30 which detects the outlet steam temperature of the superheater 11.

Further, the exhaust heat recovery boiler 10 has a temperature reducer 26 in a steam path from the steam drum 14 to the superheater 11. A main steam temperature control valve 28 for adjusting the main steam temperature to the steam turbine 5 is interposed in a spray water pipe 27 connected to the temperature reducer 26. This main steam temperature control valve 2
8 is provided with a control device 27 for controlling the opening degree thereof,
A temperature signal is input from the temperature detector 30 that detects the outlet steam temperature of the superheater 11 to the controller 29, and a temperature signal is input from the temperature detector 31 that detects the turbine metal temperature of the steam turbine 5 to the controller 29. It has become.

The starting procedure of the steam cycle according to the present embodiment proceeds in the same manner as the above-described procedure, and the steam control valve 19 is opened in accordance with establishment of the ventilation condition. At this time, the steam generated by the exhaust heat recovery boiler 10 flows into the steam turbine 5, and the steam turbine 5 starts. Furthermore, it rises to the rated speed and takes the initial load.

An opening / closing command from the control device 33 is given to a drive device 32 provided in the diverter 17. At this time, the opening degree of the diverter 17 directly connected to the activation device 32 changes from the fully open position to the slightly closed position inclined with respect to the exhaust gas flow direction. Part of the exhaust gas flowing toward the exhaust heat recovery boiler 10 flows into the bypass stack 16 by the diverter 17 at the slightly closed position, and flows out of the system.

The flow rate of the exhaust gas flowing into the exhaust heat recovery boiler 10 changes due to the outflow of the exhaust gas outside the system. At this time, the temperature of the steam at the superheater outlet also changes according to the change in the flow rate. That is, the exhaust gas temperature desired for the steam cycle is maintained by the diverter 17 which is displaced from the fully open position to the fully closed position, and the steam at the outlet of the superheater can be independently changed. However, for more direct and quick main steam temperature control, the main steam temperature control valve 28 is used to adjust the superheater outlet steam temperature. Subsequent activation procedures are the same as those in the above embodiment.

Thus, also in the present starting method, in starting the steam turbine 5 in the steam cycle, the main steam temperature control valve 29 is controlled while maintaining the exhaust gas temperature to the exhaust heat recovery boiler 10 at a temperature desired for the steam cycle. Thus, the amount of spray water can be adjusted in accordance with the change in the temperature of the turbine metal, and the main steam temperature can be maintained at a desired temperature at which no excessive thermal stress occurs in the constituent members. It is possible to rise.

Therefore, the start of the steam turbine 5 of the steam cycle can be accomplished within a short time after the start of the gas cycle, and the time required for starting the combined cycle power plant can be reduced.

Further, different embodiments of the present invention will be described. In FIG. 3, the fuel control valve 15 has a control device 35 for controlling the opening thereof. A temperature signal is input to the control device 35 from a temperature detector 25 that detects the temperature of the exhaust gas flowing in the exhaust gas duct 9. Further, a temperature signal for detecting the outlet steam temperature of the superheater 11 is input, and a temperature signal is input from a temperature detector 31 for detecting a turbine metal temperature of the steam turbine 5.

The start-up procedure of the steam cycle according to the present embodiment proceeds in the same procedure as described above, but before the ventilating condition is satisfied, the fuel control valve 15 controls the fuel determined by the control unit 35 from the operating condition of the gas cycle. It is controlled by an opening command according to the required flow signal. For this reason, the exhaust gas temperature flows into the exhaust heat recovery boiler 10 while maintaining a high temperature. The steam control valve 19 is opened in accordance with establishment of the ventilation condition. At this time, the steam generated by the exhaust heat recovery boiler 10 flows into the steam turbine 5, and the steam turbine 5 starts. Further, the steam turbine 5 is raised to the rated speed, and the initial load is taken.

At this time, the control unit 35 generates a fuel flow rate request signal that matches the output pattern determined based on the metal temperature signal from the temperature detector 31, and outputs an opening command to the fuel control valve 15 according to the signal. . As a result, the amount of fuel flowing into the combustor 2 increases and decreases, and the temperature of the exhaust gas discharged from the gas turbine 3 changes. As a result, the superheater outlet steam temperature also changes according to the change. That is, it is possible to suppress an excessive rise in the main steam temperature during an increase in the turbine load, and to prevent an excessive thermal stress from being generated in the turbine components.

Thereafter, the pressure of the steam control valve 19 is controlled, and the turbine bypass valve 20 is gradually closed. At this time, all of the main steam flows from the steam control valve 19 into the steam turbine 5, and the start of the steam cycle is completed.

Thus, the steam turbine 5 of the steam cycle
It is desirable that the temperature of the exhaust gas to the exhaust heat recovery boiler 10 is adjusted in accordance with the fuel demand that matches the output pattern determined based on the turbine metal temperature, so that the main steam temperature does not cause excessive thermal stress in the components. The temperature can be maintained, and the steam turbine 5 can be raised to the rated load in a short time.

Therefore, the start of the steam turbine 5 in the steam cycle can be accomplished within a short time after the start of the gas cycle, and the time required for starting the combined cycle power plant can be reduced.

Further, different embodiments of the present invention will be described. In FIG. 4, the fuel control valve 15 includes a control device 36 for controlling the opening. A temperature signal is input to the control device 35 from a temperature detector 25 that detects the temperature of the exhaust gas flowing in the exhaust gas duct 9. Further, a temperature signal for detecting the outlet steam temperature of the superheater 11 is input, and
A temperature signal is input from a temperature detector 31 that detects a turbine metal temperature of the steam turbine 5.

The start-up procedure of the steam cycle according to the present embodiment proceeds in the same procedure as described above, but before the ventilating condition is satisfied, the fuel control valve 15 follows the fuel demand flow rate signal determined from the operating condition from the controller 36. It is controlled by the opening command. For this reason, the exhaust gas temperature flows into the exhaust heat recovery boiler 10 while maintaining a high temperature. The steam control valve 19 is opened in accordance with establishment of the ventilation condition, and at this time, the exhaust heat recovery boiler 10 is opened.
Generated steam flows into the steam turbine 5, and the steam turbine 5
Starts.

Further, the steam turbine 5 is raised to the rated speed and the initial load is taken. At this time, the thermal stress is calculated in the control device 36 based on the superheater outlet steam temperature signal from the temperature detector 30 and the turbine metal temperature signal from the temperature detector 31, and the steam within the allowable range as viewed from the constituent materials is calculated. A temperature is determined, a fuel flow rate request signal is obtained to obtain a main steam temperature commensurate with the temperature, and an opening command in accordance with the signal is output to the fuel control valve 15. As a result, the amount of fuel flowing into the combustor 2 increases and decreases, and the temperature of the exhaust gas discharged from the gas turbine 3 changes. As a result, the superheater outlet steam also changes according to the change. That is, it is possible to prevent the main steam from rising excessively during the increase in the turbine load, and to prevent the occurrence of excessive thermal stress in the turbine components.

Thereafter, the steam control valve 19 is pressure-controlled, and the turbine bypass valve 20 is gradually closed. At this time,
All the main steam flows into the steam turbine 5 from the steam control valve 19, and the start of the steam cycle is completed.

Thus, the steam turbine 5 of the steam cycle
In the startup of the exhaust gas, the exhaust gas temperature to the exhaust heat recovery boiler 10 is adjusted according to the fuel demand obtained from the thermal stress calculated based on the superheater outlet steam temperature and the turbine metal temperature at that time, so that the main steam temperature is set to It is possible to maintain a desired temperature at which no excessive thermal stress occurs, and it is possible to raise the steam turbine 5 to the rated load in a short time.

Therefore, the start of the steam turbine 5 of the steam cycle can be accomplished within a short time after the start of the gas cycle, and the time required for starting the combined cycle power plant can be reduced.

[0054]

According to the present invention, the start of the steam turbine of the steam cycle can be accomplished in a short time when the operation is shifted from the single operation of the gas cycle to the combined cycle operation including the steam cycle. It is possible to reduce the time required for starting the plant.

[Brief description of the drawings]

FIG. 1 is a system diagram of a combined cycle power plant having means for a start-up method according to the present invention.

FIG. 2 is a system diagram of a combined cycle power plant having means for another start-up method (part 1) of the present invention.

FIG. 3 is a system diagram of a combined cycle power plant having means for another start-up method (part 2) of the present invention.

FIG. 4 is a system diagram of a combined cycle power plant having means for another start-up method (part 3) of the present invention.

FIG. 5 is a system diagram showing an example of a conventional combined cycle power plant.

[Explanation of symbols]

 Reference Signs List 3 Gas turbine 5 Steam turbine 9 Exhaust gas duct 10 Exhaust heat recovery boiler 15 Fuel control valve 17 Divertor 22 Exhaust gas temperature control valve 23, 29, 33, 35, 36 Control device 24, 25, 30, 31 Temperature detector 26 Temperature reducer 28 Main steam temperature control valve

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02C 7/26 F02C 7/26 D F22B 1/18 F22B 1/18 C F-term (Reference) 3G071 AB01 BA00 CA01 DA11 EA02 FA06 GA00 HA05 JA02 3G081 BA01 BA02 BA11 BB00 BC07 BD03 DA01 DA22 3L021 AA03 BA03 CA01 DA38 FA05 FA08

Claims (4)

[Claims] 1. A gas turbine unit including a compressor, a combustor, and a gas turbine, an exhaust heat recovery boiler that takes in exhaust gas from the gas turbine as a heat source medium and generates steam, and a steam from the exhaust heat recovery boiler. In the method of starting a combined cycle power plant comprising:
An air extraction pipe having an exhaust gas temperature control valve is connected to an exhaust gas duct that connects the gas turbine and the exhaust heat recovery boiler, and guides compressed air from the compressor to the exhaust gas duct by bypassing the combustor and the gas turbine. A steam path from the steam drum of the exhaust heat recovery boiler to the steam turbine is provided with a temperature reducer for injecting spray water into steam passing therethrough, and a main steam temperature control valve is provided in a spray water pipe connected to the temperature reducer. Before starting the steam cycle, the exhaust gas to the exhaust heat recovery boiler is maintained at a high temperature without controlling the exhaust gas temperature control valve before the aeration condition is satisfied. Bypassed to the condenser, after the aeration conditions are satisfied, the opening degree of the exhaust gas temperature control valve is controlled to inject low-temperature compressed air into the exhaust gas, and Combined cycle power generation that controls the opening of the steam temperature control valve and injects low-temperature spray water into the generated steam so that the main steam temperature satisfies the metal matching condition and is introduced into the steam turbine at a desired temperature. How to start the plant. 2. A gas turbine unit including a compressor, a combustor, and a gas turbine, an exhaust heat recovery boiler that generates exhaust steam by taking exhaust gas from the gas turbine as a heat source medium, and a steam from the exhaust heat recovery boiler. In the method of starting a combined cycle power plant comprising:
A bypass stack having a diverter is connected to an exhaust gas duct connecting the gas turbine and the exhaust heat recovery boiler,
In the steam path from the steam drum of the exhaust heat recovery boiler to the steam turbine, a temperature reducer for injecting spray water into steam passing therethrough is provided, and a main steam temperature control valve is provided in a spray water pipe connected to the temperature reducer. However, before starting the steam cycle, before the ventilation conditions are satisfied, the exhaust gas to the exhaust heat recovery boiler is maintained at a high temperature without controlling the diverter, and at this time, the generated steam bypasses the steam turbine and is restored. Escape to the water heater, after the aeration conditions are satisfied, control the opening degree of the diverter to guide the exhaust gas whose flow rate is adjusted to the exhaust heat recovery boiler, and further control the opening degree of the main steam temperature control valve. A combined cycle power generation pump in which low-temperature spray water is injected into the generated steam to maintain the main steam temperature at a desired temperature that satisfies the metal matching condition and is introduced into the steam turbine. Theft of how to start. 3. A gas turbine unit including a compressor, a combustor, and a gas turbine, an exhaust heat recovery boiler that takes in exhaust gas from the gas turbine as a heat source medium to generate steam, and a steam from the exhaust heat recovery boiler. In the method of starting a combined cycle power plant comprising:
Before starting the steam cycle, before the ventilation conditions are satisfied,
The fuel control valve of the gas turbine unit is controlled in accordance with a fuel demand determined from the operating conditions of the gas cycle. At this time, the steam generated from the exhaust heat recovery boiler is bypassed to the steam turbine to escape to the condenser, and After being established, the fuel control valve is controlled in accordance with a fuel demand that matches an output pattern determined based on the turbine metal temperature, so that the main steam temperature satisfies the metal matching condition and is introduced into the steam turbine while maintaining a desired temperature. To start a combined cycle power plant. 4. A gas turbine unit including a compressor, a combustor, and a gas turbine, an exhaust heat recovery boiler that takes in exhaust gas from the gas turbine as a heat source medium and generates steam, and a steam from the exhaust heat recovery boiler. In the method of starting a combined cycle power plant comprising:
Before starting the steam cycle, before the ventilation conditions are satisfied,
The fuel control valve of the gas turbine unit is controlled in accordance with a fuel demand determined from the operating conditions of the gas cycle. At this time, the steam generated from the exhaust heat recovery boiler is bypassed to the steam turbine to escape to the condenser, and After being established, the fuel control valve is controlled in accordance with a fuel demand obtained from a thermal stress calculated based on a superheater outlet steam temperature and a turbine metal temperature, and the main steam temperature is maintained at a desired temperature satisfying a metal matching condition. A method for starting a combined cycle power plant to be introduced into a turbine.