JPH1047077A - Gas turbine cycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To arbitrarily select efficiency intensified operation and output intensified operation. SOLUTION: A gas turbine cycle is formed such that air is compressed by a compressor C and fed to a combustor COB, fuel is mixed in compressed air by the combustion COB to effect combustion, combustion gas is introduced to a gas turbine T for expansion, and through rotation of the turbine T, a mechanical output is generated. In this case, a steam generating means E to generate steam by means of the exhaust heat of a turbine T is provided. A route 263A through which steam generated by the steam generating means E is injected in the compressor C so that intermediate cooling is practicable, and a route 263B through which the steam on the same condition as the aforesaid is injected in the turbine T are provided. Switching means 271A and 271B to switch a branch ratio of the steam on the same condition are arranged in the two routes 263A and 263B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a gas turbine cycle.

[0002]

2. Description of the Related Art In a gas turbine cycle, the temperature of exhaust gas discharged from a turbine to the atmosphere is 500 to 500.
Since the temperature is as high as 600 ° C., thermal efficiency is improved by recovering this heat.

[0003] Conventionally, the exhaust gas of a turbine is passed through a heat exchanger (regenerator), and the heat of the exhaust gas is given to air exiting a compressor and entering a combustor, thereby saving fuel injected by the combustor. In order to improve the thermal efficiency, the exhaust heat of the exhaust gas is used to generate steam, and the steam is used to turn a steam turbine to generate power, thereby improving the thermal efficiency. In addition, utilizing the fact that the specific heat of the constant pressure of the steam is about twice the specific heat of the constant pressure of the air as the working fluid, the steam is directly injected immediately before the combustor and into the turbine,
A method for increasing the output has also been proposed.

[0004]

However, the method of recovering heat by a regenerator has a problem that a heat exchanger is required and the heat recovery efficiency is low. In addition, the method of generating electricity by rotating a steam turbine has a problem that it is difficult to improve the efficiency because the steam temperature is not so high, and that equipment costs for a condenser, a steam turbine, and the like also increase. Further, the method of directly injecting steam into the turbine immediately before the combustor or into the turbine has a problem that, although an increase in output can be expected, it does not contribute much to an improvement in efficiency.

The present invention has been made in view of the above circumstances and provides a gas turbine cycle capable of arbitrarily selecting and executing an efficiency-oriented operation and an output-oriented operation while minimizing new equipment costs. Aim.

[0006]

According to a first aspect of the present invention, there is provided a gas turbine cycle, wherein air is compressed by a compressor and sent to a combustor, and the combustor mixes fuel with the compressed air to perform combustion. In a gas turbine cycle in which the combustion gas is introduced into a turbine and expanded to obtain a mechanical output from the rotation of the turbine, steam generation means for generating steam by exhaust heat of the turbine is provided, and the steam generated by the steam generation means is provided. A path for injecting steam under the condition into the compressor so that intermediate cooling is possible, and a path for injecting the steam into the turbine are provided, and both paths or a branch point to both paths, A switching means for switching and adjusting the branching ratio of steam is provided.

According to a second aspect of the present invention, in the first aspect, the low-pressure steam generated by the steam generating means can be injected into the low-pressure portion of the compressor and the turbine through the path.
Higher-pressure steam can be injected into the high-pressure section of the turbine, and higher-pressure steam can be injected immediately before the combustor.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a system diagram of a gas turbine cycle according to an embodiment of the present invention. This gas turbine cycle includes a gas turbine GT, a multi-stage exhaust heat boiler (steam generating means) E that generates steam using exhaust heat of the gas turbine GT, and the generated steam to various parts of the gas turbine GT. And a piping system PS for distribution. The gas turbine GT includes a compressor C for compressing air sucked from the atmosphere through an inlet cooler EVA, a combustor COB for mixing fuel with compressed air to perform combustion, and introducing and expanding combustion gas. And a turbine T that generates a rotational output.

Each of the compressor C and the turbine T has a multi-stage configuration. The compressor C includes a low-pressure compressor LPC, a medium-pressure compressor MPC, and a high-pressure compressor HPC. The turbine T includes a low-pressure turbine LPT and a medium-pressure turbine. It comprises an MPT, a high-pressure turbine HPT, and a power turbine PWT. Compressors LPC, MPC, HPC of each pressure are turbine LPT, MP of each pressure.
T and HPT are directly connected to each other by independent shafts. The output turbine PWT is a turbine LPT of each pressure,
It is independent of MPT and HPT and is directly connected to generator GEN. The compressed air passes through the low-pressure compressor LPC, the medium-pressure compressor MPC, and the high-pressure HPC in this order, and is sent to the combustor COB. be introduced. The exhaust gas emitted from the power turbine PWT passes through an exhaust gas passage 200 in the exhaust heat boiler E.
Released from the chimney 201 into the atmosphere.

In the exhaust heat boiler E, the high-pressure boilers HPE, in order from the upstream side to the downstream side of the exhaust gas passage 200,
Medium pressure boiler MPE, low medium pressure boiler IPE, low pressure boiler L
PEs are provided in four stages (three or more stages), and a economizer ECO is provided in the most downstream part. At the entrance of the economizer ECO,
The water supply pipe 251 from the raw water storage tank 250 is connected, and the outlet pipe 252 of the economizer ECO is connected to the boiler HP of each pressure.
It is connected to the entrance of E, MPE, IPE, LPE.
And the boiler HP of each pressure which comprises the piping system PS
E, MPE, IPE, LPE steam piping (outlet piping) 2
61, 262, 263, 264 are connected to various parts of the gas turbine GT.

Here, each pressure boiler HPE, MPE, I
PE and LPE are designed to generate steam at the following pressure. High-pressure boiler HPE = 8.5 MPa (megapascal) Medium-pressure boiler MPE = 5.0 MPa Low-medium-pressure boiler IPE = 2.7 MPa Low-pressure boiler LPE = 1.35 MPa

The high-pressure boiler HPE 8.5 MPa
Is injected immediately before the combustor COB, 5.0 MPa steam of the medium pressure boiler MPE is injected into the outlet of the high pressure turbine HPT, and 1.35 MPa steam of the low pressure boiler LPE is injected before the output turbine PWT. At this point, the steam is directly mixed into the working fluid. In addition, the steam of 2.7 MPa of the low- and medium-pressure boiler IPE is supplied to the outlet of the medium-pressure turbine MPT via the branch pipe (path) 263A or between the medium-pressure compressor MPC and the high-pressure compressor HPC via the branch pipe 263B. (Low pressure section).

In this case, a switching means 27 comprising a shutoff valve and a flow control valve is provided in the middle of the branch pipes 263A and 263B.
1A and 271B are provided, and the control unit 275 controls both the switching units 271A and 271B.
The branch ratio of steam to both branch pipes 263A and 263B is
Switching can be freely adjusted between 0: 100 and 100: 0. The switching means is a branch pipe 263A,
263B may be provided collectively at a branch point. Water from the raw water storage tank 250 is directly injected between the low-pressure compressor LPC and the medium-pressure compressor MPC via the pure storage tank 270.

Next, the operation will be described. First, the case of operation with an emphasis on thermal efficiency will be described. In that case, the switching means 263A and 263B are switched by the control means 275 so that all of the low-to-medium-pressure steam is introduced into the compressor C. In this state, air is supplied from the atmosphere to the low-pressure compressor LPC via the inlet cooler EVA.
At the outlet of the low-pressure compressor LPC, evaporatively cooled, and introduced into the medium-pressure compressor MPC. At the outlet of the medium pressure compressor MPC, steam is injected,
Both effects of increasing the flow rate and intercooling are obtained. High pressure compressor HP
The compressed air that has passed through the outlet of C receives a large amount of steam injection immediately before the combustor COB, is mixed with fuel in the combustor COB, burns, and becomes hot. In each part of the turbine T, the combustion gas expands while receiving the steam injection, so that the turbine HPT, MPT, LPT and the output turbine P of each pressure are generated.
The WT is rotated to lower the temperature to the inlet of the exhaust heat boiler E, and is discharged to the exhaust gas passage 200. Then, by the rotation of the output turbine PWT, the generator GEN rotates to generate electric power, and the exhaust heat boiler E generates steam having four types of pressures.

[0015] Since the steam generated by the exhaust heat boiler E is completely injected into various parts of the gas turbine GT, all the steam is used as the working fluid of the Brayton cycle, thereby improving the thermal efficiency of the cycle. Become. In particular, in the compressor C, in addition to the intermediate cooling by water injection at the low and medium pressure stages, the steam performs an intermediate cooling effect while suppressing the thermal shock at the medium and high pressure stages, so that the required power of the compressor C is reduced. Heat distribution efficiency is improved. Further, immediately before the combustor COB and in the turbine T, an effect of increasing the output by the energy of the steam can be obtained, so that the thermal efficiency can be further improved.

Further, by injecting steam into the compressor C, the flow balance of the entire gas turbine can be optimized, so that the number of revolutions of the compressor C does not increase so much, and the output and efficiency can be increased. . Therefore, combustor C
Unlike the method in which steam is injected just before the OB or only to the turbine T, the present invention can be directly applied to an existing gas turbine or an existing gas turbine by optimizing the flow rate balance while improving efficiency. Furthermore, since the exhaust heat of the exhaust gas is absorbed in multiple stages to generate steam at different pressures, the exhaust heat recovery efficiency is improved. Further, structurally, only the exhaust heat boiler E is provided, and the generated steam is simply injected into various parts of the gas turbine GT. Therefore, equipment such as a heat exchanger and a condenser is unnecessary, and the equipment cost is minimized. Can be minimized.

Table 1 shows an example of the material balance at each location of the gas turbine cycle during the efficiency-oriented operation.

[0018]

[Table 1]

Each pressure boiler HPE, MPE, IPE, LP
The steam pressures at the outlets 91, 93, 95, 97 of E are as described above. In addition, since all the low and medium pressure steam is introduced into the compressor C and not into the turbine T, the steam flow between the medium pressure compressor MPC and the high pressure compressor HPC (27) is “4.3”, Pressure turbine MPT and low pressure turbine L
The steam flow rate during (47) during PT is “0”. The output at this time was 154.5 MW at the gas turbine end, and the thermal efficiency was 56.9% at the gas turbine end.

If, for example, the need for output-oriented operation arises in response to a sudden increase in power demand in summer, the control means 275
To convert all low and medium pressure steam into medium and low pressure turbines MPT and LP
The switching means 263A and 263B are switched so as to be introduced between T. In such a case, the effect of the intermediate cooling of the compressor C cannot be expected, but the output is improved because there is an increase in fluid energy between the intermediate pressure turbine MPT and the low pressure turbine LPT (47) due to steam mixing.

Table 2 shows an example of the material balance at each point of the gas turbine cycle during the power-oriented operation.

[0022]

[Table 2]

In this case, all the low and medium pressure steam is introduced between the medium pressure turbine MPT and the low pressure turbine LPT, and the compressor C
, The medium-pressure compressor MPC and the high-pressure compressor H
The steam flow between PC (27) is “0”, and the steam flow between medium pressure turbine MPT and low pressure turbine LPT (47) is “4.8”. The output at this time was 159.0 MW at the gas turbine end, and the thermal efficiency was 5 at the gas turbine end.
It was 5.9%.

The low and medium pressure steam is supplied to the compressor C and the turbine T
The ratio of branching to one is 0,
Instead of setting the other as 100, an appropriate ratio between them may be set. Further, the ratio may be automatically adjusted while checking the operation details.

In the gas turbine cycle of the first embodiment, water is injected between the low-pressure compressor LPC and the medium-pressure compressor MPC. However, the steam generated by the low-pressure boiler LPE is supplied to the low-pressure compressor LPC. And the medium pressure compressor MPC. Also, instead of steam, the heating water generated by the economizer ECO is supplied to the low-pressure compressor LPC and the medium-pressure compressor MP.
It may be injected during C. The number of stages of the compressor C and the turbine T, the number of stages of the exhaust heat boiler E, and the like may be set arbitrarily.

[0026]

As described above, according to the first aspect of the present invention, the steam generated by the exhaust heat of the turbine can be selectively injected as necessary to the compressor or the turbine. . For example, when steam is injected into the compressor, the compressed air of the compressor can be intercooled by the steam, so that the required power of the compressor can be reduced while suppressing thermal shock to the compressor. Therefore, the heat efficiency can be improved accordingly. In addition, by injecting steam into the compressor, it is possible to optimize the flow balance of the entire gas turbine. It can be applied to an existing gas turbine as it is. Further, when steam is injected into the turbine, the output of the turbine can be improved because the fluid energy of the turbine increases due to the increase in steam. Therefore, efficiency-oriented operation and output-oriented operation can be arbitrarily selected. Further, structurally, the steam generation means is provided and the steam is simply injected into various places, and only the Brayton cycle, which is the basic cycle of the gas turbine, is enriched, thereby minimizing equipment costs. be able to.

According to the second aspect of the present invention, in addition to selectively injecting low-pressure steam to the low-pressure section of the compressor and the turbine, higher-pressure steam is injected to the high-pressure section of the turbine,
Further, since higher-pressure steam is injected immediately before the combustor, it is possible to further improve efficiency and output.

[Brief description of the drawings]

FIG. 1 is a system diagram of a first embodiment of the present invention.

[Explanation of symbols]

 C Compressor LPC Low pressure compressor MPC Medium pressure compressor HPC High pressure compressor COB Combustor T turbine LPT Low pressure turbine MPT Medium pressure turbine HPT High pressure turbine PWT Output turbine E Boiler (steam generating means) HPE High pressure boiler MPE Medium pressure boiler IPE Low Medium pressure boiler LPE Low pressure boiler 263A, 263B Branch pipe (path) 271A, 271B Switching means

Claims (2)

[Claims] 1. A compressor compresses air and sends it to a combustor. The combustor mixes fuel with the compressed air to cause combustion. The combustion gas is introduced into a turbine to expand it, and the rotation of the turbine is increased. In a gas turbine cycle for obtaining a more mechanical output, steam generating means for generating steam by exhaust heat of the turbine is provided, and steam under the same conditions generated by the steam generating means can be intercooled in the compressor. A path for injecting the steam into the turbine and a path for injecting the steam into the turbine, and a switching means for switching and adjusting the branch ratio of the steam under the same condition to both the paths at the two paths or at a branch point to the two paths. Characteristic gas turbine cycle. 2. A low-pressure steam generated by a steam generating means can be injected to a low-pressure portion of a compressor and a turbine through the path, and a higher-pressure steam can be injected to a high-pressure portion of the turbine. The gas turbine cycle according to claim 1, wherein higher pressure steam can be injected immediately before the combustor.