JP2004353604A - Steam turbine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steam turbine in which turbine components of a low-pressure turbine can secure a high level of strength guarantee coping with ultrahigh temperature main steam or reheated steam. <P>SOLUTION: The steam turbine is configured by combining a condensation system 2 and a water supply system 3 with a turbine system 1. A cooling medium supply system 27 for supplying cooling medium from the water supply system 3 is provided to a connecting part of a medium-pressure turbine 6 and a low-pressure turbine 7 in the turbine system 1. Control means 29, 30, 31a, 31b for controlling the cooling medium supplied to the connecting part are provided to the cooling medium supply system 27 when medium-pressure turbine exhaust supplied from the medium-pressure turbine 6 to the low-pressure turbine 7 is in a dry steam region. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a steam turbine, and more particularly to a steam turbine in which the components of a low-pressure turbine maintain high strength even when the temperature of steam supplied to a high-pressure turbine or an intermediate-pressure turbine is increased.
[0002]
[Prior art]
In recent steam turbines, raising the temperature of main steam or reheated steam is being studied as part of a strengthening review of improvements in plant thermal efficiency.
[0003]
Increasing the temperature of the main steam or reheated steam takes advantage of the characteristics of the Rankine cycle, and it is said that the higher the steam temperature, the more the output and thermal efficiency of the plant can be further improved. I have.
[0004]
For this reason, the steam turbine is almost establishing the respective temperatures of the main steam and the reheated steam at 538 ° C./566° C. or 538 ° C./538° C. due to the relatively low temperature and low pressure steam conditions. .
[0005]
However, recently, global warming phenomena and environmental destruction due to polluting compounds such as CO ₂ and NOx have been highlighted on a global scale. Research and development to increase the plant thermal efficiency with the increase in capacity are being promoted. One of them is to increase the temperature of the main steam supplied to the high-pressure turbine to 700 ° C or higher, or the temperature of the reheated steam supplied to the medium-pressure turbine. Is set to 700 ° C. or higher.
[0006]
In the technology of supplying reheat steam at a temperature of 700 ° C. or higher to the intermediate pressure turbine, the intermediate pressure turbine is divided into a first intermediate pressure turbine and a second intermediate pressure turbine, and the divided first intermediate pressure turbine is arranged as a top turbine. Then, the second intermediate-pressure turbine is incorporated in a conventional conventional steam turbine in which the second intermediate-pressure turbine is disposed as a bottom turbine (see Patent Document 1).
[0007]
When the first intermediate-pressure turbine is arranged as the top turbine, according to trial calculations, the plant thermal efficiency is 50% or more, and the production cost is relatively low in proportion to the supply of ultra-high-temperature reheat steam. The results are expected.
[0008]
[Patent Document 1]
Japanese Patent Application No. 2003-125672
[Problems to be solved by the invention]
Conventionally, thermal power plants use improved heat-resistant materials for turbine components, especially high-temperature components such as turbine rotors, turbine nozzles, and turbine blades, while the main steam temperature or reheat steam temperature is 538 ° C. to 566 ° C. To maintain high strength.
[0010]
However, when the temperature of the main steam or the reheat steam exceeds 700 ° C., it is becoming difficult to maintain high strength guarantee with the improved heat-resistant material.
[0011]
In addition, if the temperature of the main steam or the reheat steam alone is raised to an ultra-high temperature without changing the pressure ratio between the inlet pressure and the outlet pressure in both the high-pressure turbine and the medium-pressure turbine, load (output) fluctuations Depending on the operation, there is a problem that the outlet side of the low-pressure turbine fluctuates between a wet steam area and a dry steam area, and changes in steam state adversely affect the strength of turbine high-temperature parts.
[0012]
For this reason, a steam turbine is required to realize a new technology capable of maintaining a high strength assurance of a turbine component, and adoption of cooling by steam is being promoted as a solution thereto.
[0013]
However, the use of steam cooling is an undeveloped field for steam turbines, and has been repeated through trial and error.
[0014]
The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a steam turbine that copes with ultra-high-temperature main steam or reheat steam and maintains a high strength guarantee for turbine components of a low-pressure turbine. Aim.
[0015]
[Means for Solving the Problems]
The steam turbine according to the present invention, in order to achieve the above-described object, as described in claim 1, in a steam turbine in which a condensing system and a water supply system are combined with a turbine system, wherein the turbine system is a medium-pressure turbine. A cooling medium supply system for supplying a cooling medium from the water supply system is provided at a connection portion with the low pressure turbine, and the medium pressure turbine exhaust supplied from the medium pressure turbine to the low pressure turbine is dried in the cooling medium supply system. In the case of a steam region, the device has a control means for controlling the cooling medium supplied to the connection portion.
[0016]
In order to achieve the above object, a steam turbine according to the present invention is a steam turbine in which a condensing system and a water supply system are combined with a turbine system. A cooling medium supply system for supplying a cooling medium from the condensing system is provided at a connection portion between the turbine and the low-pressure turbine, and a medium-pressure turbine exhaust system for supplying the medium from the medium-pressure turbine to the low-pressure turbine is provided in the cooling medium supply system. A control means for controlling the cooling medium supplied to the connection portion when the temperature is in a dry steam region.
[0017]
Further, in the steam turbine according to the present invention, in order to achieve the above object, as described in claim 3, the cooling medium supply system connects the cooling medium outlet to the deaerator outlet side of the water supply system. This is a configuration in which
[0018]
Further, in the steam turbine according to the present invention, in order to achieve the above-described object, as described in claim 4, the cooling medium supply system is configured such that the outlet of the cooling medium is provided on the outlet side of the first water supply pump of the water supply system. It is configured to be connected.
[0019]
Further, in the steam turbine according to the present invention, in order to achieve the above-described object, as described in claim 5, the cooling medium supply system is configured such that the outlet of the cooling medium is provided on the outlet side of the second water supply pump of the water supply system. It is configured to be connected.
[0020]
In the steam turbine according to the present invention, in order to achieve the above object, as described in claim 6, the cooling medium supply system is configured such that an outlet of the cooling medium is provided on the outlet side of the fourth high-pressure water pump of the water supply system. It is configured to be connected to.
[0021]
Further, in the steam turbine according to the present invention, in order to achieve the above object, as described in claim 7, the cooling medium supply system connects an outlet of the cooling medium to a condensate pump outlet side of the condensate system. This is a configuration in which
[0022]
Further, in the steam turbine according to the present invention, in order to achieve the above-described object, as described in claim 8, the cooling medium supply system includes a spray nozzle.
[0023]
Further, in the steam turbine according to the present invention, in order to achieve the above object, as described in claim 9, a connecting portion between the intermediate pressure turbine and the low pressure turbine is a connecting pipe. It is.
[0024]
Further, in the steam turbine according to the present invention, in order to achieve the above object, as described in claim 10, a connection portion between the intermediate pressure turbine and the low pressure turbine is an outlet of the intermediate pressure turbine. It is a feature.
[0025]
Further, in the steam turbine according to the present invention, in order to achieve the above object, as described in claim 11, a connection portion between the intermediate pressure turbine and the low pressure turbine is provided at an outlet of a final stage of the intermediate pressure turbine. It is characterized by having.
[0026]
Further, in the steam turbine according to the present invention, in order to achieve the above object, as set forth in claim 12, the control means includes detection means provided on each of the inlet side and the outlet side of the low pressure turbine of the turbine system. When the signal from the heater exceeds a predetermined set value, the valve opening / closing operation signal is supplied to the regulating valve provided in the cooling medium supply system based on the deviation, and the operation to supply a cooling medium supply command to the communication pipe is performed. It has a control unit.
[0027]
Further, in the steam turbine according to the present invention, in order to achieve the above object, as described in claim 13, the detector includes a medium-pressure turbine exhaust flowing into a low-pressure turbine of a turbine system and exiting from the low-pressure turbine. It detects any one of the pressure, temperature, and wetness of the low-pressure turbine exhaust.
[0028]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a steam turbine according to the present invention will be described with reference to the drawings and reference numerals attached to the drawings.
[0029]
The steam turbine according to the present embodiment has a configuration in which a condensing system 2 and a water supply system 3 are combined with a turbine system 1.
[0030]
The turbine system 1 includes a boiler 4, a high-pressure turbine 5, an intermediate-pressure turbine 6, a low-pressure turbine 7, and a generator 8 which are axially connected to each other, and supplies main steam (drive steam) generated from the boiler 4 to a main steam pipe 9. To the high-pressure turbine 5, where the expansion work is performed to generate power, and the high-pressure turbine exhaust that has completed the expansion work is supplied to the reheater 11 in the boiler 4 via the low-temperature reheat pipe 10. The reheater 11 reheats the main steam that has lost the heat energy, and supplies the reheated steam to the intermediate-pressure turbine 6 through the high-temperature reheat pipe 12.
[0031]
Further, the turbine system 1 causes the reheated steam supplied to the intermediate pressure turbine 6 to perform expansion work to generate power, and the intermediate pressure turbine exhaust having completed the expansion work is connected to a communication pipe 13 such as a crossover pipe. The power is supplied to the low-pressure turbine 7 through the expansion work to generate power, and the power is used to drive the generator 8. During this time, the low-pressure turbine exhaust that has completed the expansion work is supplied to the condensing system 2. .
[0032]
On the other hand, the condensing system 2 includes a condenser 14, a condensing pump 15, a first low-pressure feed water heater 16, a second low-pressure feed water heater 17, a third low-pressure feed water heater 18, A fourth low-pressure feed water heater 19 is provided, and the low-pressure turbine exhaust from the low-pressure turbine 7 is condensed by the condenser 14 to be condensed, and the condensed water is pumped by the condensate pump 15, and the first to fourth low-pressure feed water The heaters 16, 17, 18, and 19 sequentially preheat (regenerate) the low-pressure turbine bleed air from the low-pressure turbine 7 as a heat source.
[0033]
The water supply system 3 includes a deaerator 20, a first water supply pump 21, a second water supply pump 22, a first high-pressure water heater 23, a second high-pressure water heater 24, and a third A high-pressure feed water heater 25 and a fourth high-pressure feed water heater 26 are provided. The deaerator 20 supplies condensate supplied from the fourth low-pressure feed water heater 19 of the condensing system 2 to a medium-pressure turbine bleed from the medium-pressure turbine 6. Is heated and degassed as a heat source to supply water, the pressure of the supplied water is increased by a first water supply pump 21 and a second water supply pump 22, and the intermediate-pressure turbine 6 is heated by first to fourth high-pressure water heaters 23, 24, 25, 26. After being preheated (regenerated) as a heat source, the medium pressure turbine bleed air from the high pressure turbine 5 and the low temperature reheat pipe 10 are sequentially preheated (regenerated), and then returned to the boiler 4.
[0034]
Further, the water supply system 3 includes a cooling water supply system 27 that branches from the outlet side of the deaerator 20 and connects the medium-pressure turbine 6 and the low-pressure turbine 7 to each other, for example, to a communication pipe 13 such as a crossover pipe. The deaerator 20 is configured to spray the supply water obtained by heating and degassing the condensate from the condensate system 2 to the medium-pressure turbine exhaust flowing through the communication pipe 13 from the cooling water supply system 27 via the spray nozzle 28. ing. The cooling water supply system 27 is not limited to the connecting pipe 13 and may be connected to the outlet of the intermediate-pressure turbine 6 or the outlet of the final stage of the intermediate-pressure turbine 6.
[0035]
The cooling water supply system 27 includes a regulating valve 29, an arithmetic and control unit 30, and detectors 31a and 31b provided on the inlet side and the outlet side of the low-pressure turbine 7, respectively, and the medium-pressure turbine detected by the detectors 31a and 31b. Any one of the pressure, temperature, and wetness of the exhaust gas and the low-pressure turbine exhaust that has completed the expansion work in the low-pressure turbine 7 is sent to the arithmetic and control unit 30 to exceed the predetermined value. (Dry steam range), the valve opening / closing signal is calculated based on the deviation, and the calculated signal is given to the regulating valve 29 to open and close the valve. When the intermediate-pressure turbine exhaust is in the dry steam range, the spraying is performed. The structure is such that water is sprayed from the nozzle 28 and changed to a wet steam region.
[0036]
FIG. 3 is a cooling medium supply diagram showing the flow rate of supplying supply water as cooling water to the connecting pipe 13 on the vertical axis and the outlet temperature of the low-pressure turbine 7 on the horizontal axis. In this cooling medium supply diagram, when the temperature of the low-pressure turbine exhaust of the low-pressure turbine 7 exceeds the predetermined temperature T and the low-pressure turbine exhaust enters the dry steam region, the temperature of the low-pressure turbine exhaust from the spray nozzle 28 of the cooling water supply system 27 increases. Water is supplied to the connecting pipe 13, and the medium pressure turbine exhaust flowing through the connecting pipe 13 is changed from a dry steam area to a wet steam area.
[0037]
In the present embodiment, when changing the intermediate-pressure turbine exhaust from a dry steam area to a wet steam area, water supply or condensate is used as cooling water, but steam may be used instead of water supply or condensate. When steam is used, as shown in FIG. 3, the flow rate is increased, but it is advantageous in that the particle size of bubbles contained in the steam is not controlled.
[0038]
When the feed water or the condensate is used as the cooling water, the feed water or the condensate may contain a gas having a relatively large particle size such as a bubble. When the water is supplied to the connecting pipe 13 through the spray nozzle 28, the spray nozzle 28 is provided with a mechanism for finely crushing the particle diameter of the bubble to the size of the bubble particle indicated by oblique lines as shown in FIG. There is no need to worry about erosion or the like that occurs with the burst of bubbles.
[0039]
As described above, in the present embodiment, the cooling water supply system 27 branches from the outlet side of the deaerator 20 of the water supply system 2 and is connected to the communication pipe 13 that connects the medium-pressure turbine 6 and the low-pressure turbine 7 to each other. In addition, when the intermediate-pressure turbine exhaust of the intermediate-pressure turbine 6 is in a dry steam region, the control valve 29 of the cooling-water supply system 27 is controlled to open and close to supply cooling water to the intermediate-pressure turbine exhaust flowing through the communication pipe 13. The operation control section 30 for changing the main steam supplied to the high-pressure turbine 5 or the reheated steam supplied to the intermediate-pressure turbine 6 to an ultra-high temperature is used as the low-pressure turbine while maintaining the dry steam area. 7, the strength of the components of the low-pressure turbine 7 can be kept high.
[0040]
In this embodiment, when the intermediate-pressure turbine exhaust of the intermediate-pressure turbine 6 is in the dry steam region, the cooling water to be changed to the wet steam region is taken out from the outlet side of the deaerator 20 of the water supply system 3. Not limited to the example, for example, as shown in FIG. 4, a cooling water supply system 27 may be provided by branching from the outlet side of the condensate pump 15 of the condensate system 2. As shown, a cooling water supply system 27 may be provided by branching from the outlet side of the first water supply pump 21 of the water supply system 3 or from the outlet side of the second water supply pump 22. Further, as shown in FIG. A cooling water supply system 27 may be provided branching from the outlet side of the fourth high pressure feed water heater 26 of the water supply system 30.
[0041]
【The invention's effect】
As described above, in the steam turbine according to the present invention, the cooling medium from any one of the water supply system and the condensing system is supplied to the final stage outlet of the intermediate pressure turbine, the outlet of the intermediate pressure turbine and the intermediate pressure turbine and the low pressure. A cooling medium supply system for supplying a cooling medium to one of the communication pipes for connecting the turbine and the turbine, and when the medium-pressure turbine exhaust of the medium-pressure turbine is in a dry steam region, the cooling medium supply system is provided. Control means for opening and closing the control valve of the system to supply cooling medium to the medium-pressure turbine exhaust flowing through the connecting pipe to change to a wet steam area. Even if the reheated steam is heated to an extremely high temperature, it is not supplied to the low-pressure turbine as a dry steam region, and the strength guarantee of the components of the low-pressure turbine can be maintained high. .
[Brief description of the drawings]
FIG. 1 is a schematic system diagram showing a first embodiment of a steam turbine according to the present invention.
FIG. 2 is a diagram showing the relationship between the particle size of bubbles contained in the cooling medium and the flow velocity when the cooling medium is supplied to the intermediate-pressure turbine exhaust in the steam turbine according to the present invention.
FIG. 3 is a cooling medium supply diagram for supplying a cooling medium to medium-pressure turbine exhaust gas in the steam turbine according to the present invention.
FIG. 4 is a schematic system diagram showing a second embodiment of the steam turbine according to the present invention.
FIG. 5 is a schematic system diagram showing a third embodiment of the steam turbine according to the present invention.
FIG. 6 is a schematic system diagram showing a fourth embodiment of the steam turbine according to the present invention.
FIG. 7 is a schematic system diagram showing a fifth embodiment of the steam turbine according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Turbine system 2 Condenser system 3 Water supply system 4 Boiler 5 High pressure turbine 6 Medium pressure turbine 7 Low pressure turbine 8 Generator 9 Main steam pipe 10 Low temperature reheat pipe 11 Reheater 12 High temperature reheat pipe 13 Communication pipe 14 Condenser 15 Condensate Pump 16 First low-pressure feedwater heater 17 Second low-pressure feedwater heater 18 Third low-pressure feedwater heater 19 Fourth low-pressure feedwater heater 20 Deaerator 21 First feedwater pump 22 Second feedwater pump 23 First high-pressure feedwater heater 24 Second high pressure feed water heater 25 Third high pressure feed water heater 26 Fourth high pressure feed water heater 27 Cooling water supply system 28 Spray nozzle 29 Adjusting valve 30 Operation control units 31a, 31b Detector

Claims (13)

In a turbine system, a steam turbine combining a condensing system and a water supply system, a cooling medium supply system for supplying a cooling medium from the water supply system is provided at a connection portion between the intermediate pressure turbine and the low pressure turbine of the turbine system, The cooling medium supply system further includes control means for controlling the cooling medium supplied to the connection portion when the intermediate-pressure turbine exhaust supplied from the intermediate-pressure turbine to the low-pressure turbine is in a dry steam region. And steam turbine. In the turbine system, in a steam turbine combining a condensing system and a water supply system, a connecting portion between the intermediate pressure turbine and the low pressure turbine of the turbine system is provided with a cooling medium supply system for supplying a cooling medium from the condensing system, The cooling medium supply system further includes control means for controlling the cooling medium supplied to the connection portion when the intermediate-pressure turbine exhaust supplied from the intermediate-pressure turbine to the low-pressure turbine is in a dry steam region. And steam turbine. The steam turbine according to claim 1, wherein the cooling medium supply system is configured to connect an outlet of the cooling medium to a deaerator outlet side of the water supply system. 2. The steam turbine according to claim 1, wherein the cooling medium supply system is configured to connect an outlet of the cooling medium to a first water supply pump outlet side of the water supply system. 3. 2. The steam turbine according to claim 1, wherein the cooling medium supply system is configured to connect an outlet of the cooling medium to a second water supply pump outlet side of the water supply system. 3. 2. The steam turbine according to claim 1, wherein the cooling medium supply system is configured to connect an outlet of the cooling medium to a fourth high-pressure water supply pump outlet side of the water supply system. 3. 3. The steam turbine according to claim 2, wherein the cooling medium supply system is configured to connect an outlet of the cooling medium to a condensate pump outlet side of the condensate system. The steam turbine according to claim 1, wherein the cooling medium supply system includes a spray nozzle. The steam turbine according to claim 1, wherein a connecting portion between the intermediate pressure turbine and the low pressure turbine is a connecting pipe. The steam turbine according to claim 1, wherein a connection portion between the intermediate pressure turbine and the low pressure turbine is an outlet of the intermediate pressure turbine. The steam turbine according to claim 1, wherein a connecting portion between the intermediate pressure turbine and the low pressure turbine is an outlet of a final stage of the intermediate pressure turbine. When a signal from a detector provided on each of the inlet side and the outlet side of the low pressure turbine of the turbine system exceeds a predetermined set value, the control means is provided in the cooling medium supply system based on the deviation. The steam turbine according to claim 1, further comprising a calculation control unit that supplies a valve opening / closing calculation signal to the adjustment valve and issues a cooling medium supply command to the communication pipe. 13. The detector according to claim 12, wherein the detector detects any one of pressure, temperature, and wetness of the intermediate-pressure turbine exhaust flowing into the low-pressure turbine of the turbine system and the low-pressure turbine exhaust flowing out of the low-pressure turbine. Steam turbine.

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