JPH074211A - Gas turbine combined power generation equipment - Google Patents

Abstract

PURPOSE:To decrease heat loss due to dry gas in an exhaust heat boiler so as to enhance efficiency of equipment as a whole. CONSTITUTION:A part of boiler exhaust gas 15 exhausted from an exhaust heat boiler 10 is fed together with atmosphere 4 to a compressor 2 to be compressed, obtained compressed gas 24 is fed to a combustor 7 to serve for combustion of fuel 8, a gas turbine 1 is driven by obtained combustion gas 9, and a generator 6 and the compressor 2 are driven by the gas turbine 1. Turbine exhaust gas 12 exhausted from the gas turbine 1 is fed to the exhaust heat boiler 10 to generate steam 13 by means of heat of the turbine exhaust gas 12, and a steam turbine 16 is driven by the steam 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas turbine combined power generation facility.

[0002]

2. Description of the Related Art In recent years, in order to improve thermal efficiency, turbine exhaust gas after driving a generator and a compressor is fed to an exhaust heat boiler, and steam generated by being heated by the turbine exhaust gas in the exhaust heat boiler is generated. A gas turbine combined cycle power generation facility has been proposed in which it is fed to a steam turbine to drive a generator.

An example of such a gas turbine combined cycle power generation facility is shown in FIG. 3, in which 1 is a gas turbine, 2 is a gas turbine 1 driven by a gas turbine 1, and an atmosphere 4 blown through a pipe 3 is compressed. A compressor that can be discharged as compressed air 5, 6 is a generator that is driven by the gas turbine 1, and 7 is a mixture of compressed air 5 from the compressor 2 and fuel 8 introduced from another system. It is a combustor configured to be combusted by the above and to be able to send the obtained combustion gas 9 to the gas turbine 1.

Reference numeral 10 denotes a turbine exhaust gas 1 sent from a gas turbine 1 and having a heat transfer section 11 such as an evaporator and a superheater.
An exhaust heat boiler that applies the heat of 2 to the fluid to generate steam 13 is a chimney for discharging the boiler exhaust gas 15 discharged from the exhaust heat boiler 10 to the atmosphere.

A steam turbine 16 is driven by the steam 13 from the exhaust heat boiler 10 and also drives a generator 17, and 18 is a steam turbine which cools the steam 13 extracted from the steam turbine 16 and returns it to water 19. Water bottle, 20 is condenser 1
The heat transfer part 11 of the exhaust heat boiler 10 by pressurizing the water 19 from 8
It is a water supply pump that can supply water to.

In the above gas turbine combined cycle power generation facility, the atmosphere 4 is sucked into the compressor 2 driven by the gas turbine 1 through the pipe 3 and compressed into compressed air 5, which is discharged from the compressor 2. 5 is sent to the combustor 7, and the fuel 8 sent from another system and the compressed air 5 are mixed in the combustor 7 to burn the fuel 8, whereby the combustion gas 9
Is generated, and the generated combustion gas 9 is sent to the gas turbine 1 to drive the gas turbine 1.
Thus, the compressor 2 and the generator 6 are driven.

Turbine exhaust gas 12 discharged from the gas turbine 1 after driving the gas turbine 1 is a waste heat boiler 10.
The fluid introduced into the heat transfer section 11 is heated, and the fluid is discharged from the exhaust heat boiler 10 as the boiler exhaust gas 15 and discharged into the atmosphere through the chimney 14.

The steam 13 produced in the heat transfer section 11 of the exhaust heat boiler 10 is introduced into the steam turbine 16 to drive the steam turbine 16, and the steam turbine 16 drives the generator 17.

The steam 13 discharged from the steam turbine 16 after driving the steam turbine 16 is cooled by the condenser 18 and returned to the water 19, and is pressurized by the water supply pump 20 to generate the water 19.
And is pressurized by the water supply pump 20 to be discharged into the heat exhaust boiler 10
Water is supplied to the heat transfer section 11 of the.

In the above gas turbine combined cycle power generation facility, the temperature of the combustion gas 9 is set to a maximum of about 1300 ° C. in order to protect the liner lining the combustor 7 and the blades of the gas turbine 1 from the heat of the combustion gas 9. Must be
For this reason, the combustor 7 increases the inflow amount of the compressed air 5 per unit time to perform excess air combustion. That is, the relationship between the air ratio (weight flow rate of air / weight flow rate of fuel) λ and the combustion gas temperature Tb is shown in FIG. 4, and the air ratio λ =
The combustion gas temperature Tb is highest near 0.9 (about 2000
℃). Therefore, as in normal combustion, the air ratio λ ≒
When the fuel 8 is burned at 1.0 to 1.2, the temperature of the obtained combustion gas 9 becomes high, which may damage the liner of the combustor 7 and the blade of the gas turbine 1. However, when the fuel 8 is burned with the air ratio λ of about 2 to 3, the temperature of the combustion gas 9 becomes about 1300 ° C., and the liner of the combustor 7 and the blade of the gas turbine 1 are prevented from being damaged by heat. it can.

[0011]

However, when the combustor 7 performs excess air combustion with λ = 2 to 3, the oxygen concentration in the turbine exhaust gas 12 discharged from the gas turbine 1 and introduced into the exhaust heat boiler 10 is increased. Is about 12 to 17%,
There is a problem that dry gas loss (loss due to exhaust heat amount determined by the dry gas amount and the temperature of the gas) in the boiler loss becomes high and it becomes difficult to improve the efficiency of the entire equipment.

The present invention has been made in view of the above circumstances and has an object to improve the efficiency of the entire equipment by reducing the dry gas loss.

[0013]

SUMMARY OF THE INVENTION The present invention is directed to a combustor which mixes and combusts a compressed gas containing air obtained by being compressed by a compressor and a fuel, and driven by the combustion gas from the combustor. A gas turbine configured to drive the first generator and the compressor, an exhaust heat boiler configured to generate steam by heat of turbine exhaust gas discharged from the gas turbine, and an exhaust heat boiler generated. Steam turbine driven by the steam and driving the second generator, a line for feeding the atmosphere to the compressor, and a part of the boiler exhaust gas discharged from the exhaust heat boiler. A line is provided for circulation to the compressor.

[0014]

In the combustor, the fuel is mixed with the compressed gas containing the atmosphere and a part of the boiler exhaust gas and burned to generate the combustion gas. The combustion gas is fed to the gas turbine to drive the gas turbine, The first generator and the compressor are driven by the gas turbine, the turbine exhaust gas discharged from the gas turbine is sent to the exhaust heat boiler to generate steam, and the steam is sent to the steam turbine to send the steam turbine. Are driven, and the second generator is driven by the steam turbine.
In this case, the oxygen concentration of the turbine exhaust gas sent to the exhaust heat boiler is low, and even though the heat quantity of the dry gas after heat recovery in the exhaust heat boiler is equal to that of the conventional means, the heat quantity discharged to the stack is only Since the exhaust gas of the part is recirculated and used, it is significantly suppressed as compared with the conventional means. That is, when viewed as a whole equipment, the dry gas loss is reduced and the flame temperature due to exhaust gas mixing is suppressed in the combustor of the gas turbine, so that not only NOx at the combustor outlet is suppressed but also the temperature of the combustor is increased. The low temperature has the effect of not requiring excess air for cooling the liner.

[0015]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an embodiment of the present invention, the basic structure of which is the same as that of the conventional equipment shown in FIG. 3, but in this embodiment, the boiler exhaust gas 15 discharged from the exhaust heat boiler 10 is used.
Is circulated so that it can be introduced into the compressor 2 together with the atmosphere 4.

In the figure, 21 is a damper installed in the pipeline 3 for adjusting the flow rate of the atmosphere 4 introduced into the compressor 2 through the pipeline 3, and 22 is one end from the exhaust heat boiler 10 to the chimney 14
Is connected to an intermediate part of the conduit leading to and the other end is connected to an intermediate part of the conduit 3, and 23 is a compressor 2 via the conduit 22.
The damper 24 installed in the pipe line 22 for adjusting the flow rate of the boiler exhaust gas 15 introduced into the compressor 24 is a compressed gas discharged from the compressor 2 after the atmosphere 4 and the boiler exhaust gas 15 are mixed and compressed. The same parts as those shown in FIG. 3 are designated by the same reference numerals.

In the gas turbine combined cycle power generation facility according to this embodiment, the oxygen concentration in the compressed gas 24 is about 2 to 3%.
Before starting the operation, the opening degrees of the dampers 21 and 23 are adjusted in advance by a trial operation or the like so that the degree of operation becomes appropriate.

Thus, in the gas turbine combined cycle power generation facility of the present invention, part of the boiler exhaust gas 15 discharged from the atmosphere 4 and the exhaust heat boiler 10 is piped to the compressor 2 driven by the gas turbine 1. 3 and the pipes 22 and 3, compressed by the compressor 2 and sent to the combustor 7 as the compressed gas 24. In the combustor 7, the fuel 8 and the compressed gas 24 sent from another system. Are mixed and the fuel 8 is burned to generate combustion gas 9, and the generated combustion gas 9 is fed to the gas turbine 1 to drive the gas turbine 1, and the gas turbine 1 drives the compressor 2 and The generator 6 is driven.

Turbine exhaust gas 12 discharged from the gas turbine 1 after driving the gas turbine 1 is a waste heat boiler 10.
Is introduced into the heat transfer section 11 to heat the fluid, and is discharged from the exhaust heat boiler 10 as the boiler exhaust gas 15. Some of the boiler exhaust gas 15 is discharged from the chimney 14 to the atmosphere, while the remaining boiler exhaust gas 15 is It circulates, passes through the pipe line 22, and is introduced into the compressor 2 together with the atmosphere 4 fed from the pipe line 3.

The behavior of the steam 13 generated in the heat transfer section 11 of the exhaust heat boiler 10 is exactly the same as that in the case of FIG.

As described above, the compressed gas 24 introduced into the combustor 7 contains the boiler exhaust gas 15 in addition to the atmosphere 4, and the oxygen concentration can be set to about 2 to 3%. Can suppress excessive air combustion. That is, when the ratio of the boiler exhaust gas 15 in the compressed gas 24 is increased at the same air ratio λ, the temperature (combustion gas temperature) Tb of the combustion gas 9 obtained in the combustor 7 is gradually increased as shown in FIG. And the ratio becomes about 50%, the air ratio λ = 1.0
The temperature reaches about 1300 ° C. in the vicinity of about 1.2.

Thus, as described above, by mixing the boiler exhaust gas 15 into the compressed gas 24, the oxygen concentration of the turbine exhaust gas 12 introduced into the exhaust heat boiler 10 can be reduced, so that the boiler loss is lost. Dry gas loss is reduced, and the efficiency of the entire equipment can be improved.

Further, since the ratio of oxygen in the compressed gas 24 can be suppressed to a low level, the temperature of the combustion gas 9 in the combustor 7 can be suppressed and NOx in the boiler exhaust gas 15 can be suppressed.

In the embodiment of the present invention, the opening of the dampers 21 and 23 is determined in advance by a trial run or the like. However, an oxygen concentration detector is provided in the conduit 22 to detect the detected oxygen concentration. Dampers 21 and 2 based on
Needless to say, the opening degree of 3 may be adjusted, and other various changes may be made without departing from the scope of the invention.

[0026]

According to the gas turbine combined cycle power generation facility of the present invention, the dry gas loss of the exhaust heat boiler can be reduced, so that the efficiency of the entire facility can be improved, and the combustion gas obtained by the combustor can be improved. Since the temperature lowers, various excellent effects such as NOx reduction can be achieved.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an embodiment of a gas turbine combined cycle power generation facility of the present invention.

2 is a graph showing the relationship between the air ratio and the combustion gas temperature when the ratio of the boiler exhaust gas in the compressed gas sent to the combustor of FIG. 1 is changed.

FIG. 3 is a schematic diagram of an example of a conventional gas turbine combined cycle power generation facility.

FIG. 4 is a graph showing a relationship between an air ratio of compressed air supplied to the combustor of FIG. 3 and a combustion gas temperature.

[Explanation of Codes] 1 gas turbine 2 compressor 3 pipe (line) 4 atmosphere (air) 6 generator (first generator) 7 combustor 8 fuel 9 combustion gas 10 exhaust heat boiler 12 turbine exhaust gas 13 steam 15 Boiler exhaust gas 16 Steam turbine 17 Generator (second generator) 22 Pipeline (line) 24 Compressed gas

Claims (1)

[Claims] 1. A combustor that mixes and combusts a compressed gas containing air obtained by compressing with a compressor and a fuel, a first generator driven by the combustion gas from the combustor, and the compressor. A gas turbine configured to drive the machine, an exhaust heat boiler configured to generate steam by heat of the turbine exhaust gas discharged from the gas turbine, and a steam driven by the exhaust heat boiler, and a second A steam turbine for driving the generator, a line for feeding the atmosphere to the compressor, and a line for circulating a part of the boiler exhaust gas discharged from the exhaust heat boiler to the compressor. A gas turbine combined cycle power generation facility characterized by being provided with.