JP2004156517A - Steam turbine plant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steam turbine plant capable of avoiding carrying of corrosion factor component into the system due to leakage of cooling water, and realizing flash deaeration. <P>SOLUTION: The steam turbine plant is provided with a non-contact type cooling pipe 24 which the cooling water flows inside the pipe, and cools the steam outside the pipe on a condenser 22. The plant is equipped with an air cooling device 27 which cools the condensed water to be cooled and condensed with the non-contact type cooling pipe 24 by the air, and a condensed water circulation line 30 which supplies the condensed water to be cooled with the air cooling device 27 into the non-contact type cooling pipe 24 as the cooling water. The cooling water in the non-contact type cooling pipe 24 is returned as feed water of a boiler 20. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a steam turbine plant, and particularly to a configuration of a condenser.
[0002]
[Prior art]
5 and 6 show an example of a condenser of a conventional power generation plant (steam turbine plant). FIG. 5 is a front view, and FIG. 6 is a plan view. In the figure, 1 is a steam inlet, 2 is a tube group, 3 is a hot well, 4 is a condensate outlet pipe, 5 is a condensate pump, 6 is a ground condenser, 7 is a valve, 8 is a recirculation line, and 9 is a degasser. Aspirator, 10 is a recirculating water inlet pipe, 11 is a seawater inlet, 12 is a seawater outlet, 13 is a vacuum pump, and 14 is an air extraction pipe. (A seawater cooling type is generally used, but a cooling medium is used for a cooling tower. Circulating cooling water (fresh water) or air cooling).
[0003]
The steam exiting the steam turbine (not shown) enters the condenser through the steam inlet 1, is cooled and condensed while passing through the tube group 2, becomes condensed water, and accumulates in the hot well 3. Thereafter, the water is supplied from a condensing outlet pipe 4 to a boiler (not shown) via a condensing pump 5, a ground condenser 6, a valve 7, and the like.
[0004]
On the other hand, the cooling seawater introduced from the seawater inlet 11 flows through the heat transfer tubes constituting the tube group 2, cools and condenses the steam outside the tubes, and is then discharged from the seawater outlet 12. The non-condensable gas such as air contained in the steam is discharged from the center of the tube group by the vacuum pump 13 through the air extraction tube 14.
[0005]
When starting up the plant, it is necessary to keep the dissolved oxygen concentration of the condensate flowing through the boiler low. Therefore, at the time of startup, the valve 7 is fully closed, and the condensate flowing out of the ground condenser 6 passes through the recirculation line 8 and is deaerated by the deaerator 9, while being condensed again from the recirculation water inlet pipe 10. Will be returned within.
The deaerator installed in the condensate circulation line is called a starting deaerator, and is rarely installed. Generally, it is installed in a water supply system, and water is supplied in an oxygen-rich state when the unit is started.
[0006]
[Patent Document 1]
Published Japanese Utility Model Application No. Hei 7-32371
[Problems to be solved by the invention]
However, in the above-mentioned conventional condenser, since steam is cooled using seawater flowing in the tube group 2, a pinhole may be generated in the tube group 2 and seawater may be mixed into the condensate water. There is. Therefore, it is necessary to provide water quality monitoring equipment to prevent and monitor seawater leaks, and chemical injection equipment to remove corrosion factors in the event of leaks.
[0008]
In order to prevent impurities from being mixed, an air-cooling type can be adopted as a means for cooling the steam. However, in the air-cooled type, the cooling rate is low and the flash deaeration effect cannot be expected much. Therefore, in the HRSG (heat recovery steam generator), since the condenser itself is evacuated, degassing is performed without providing a deaerator. Therefore, in recent years, there has been a tendency not to provide a deaerator (the condenser is evacuated without distinction between HRSG and conventional). However, since the flash deaeration effect can hardly be expected in the air-cooled type as described above, there is a problem that a new deaerator must be provided in order to adopt the air-cooled type for HRSG.
[0009]
The present invention has been made in view of the above circumstances, and provides a steam turbine plant that can avoid bringing in a corrosion factor component due to a cooling water leak into a system and can realize flash deaeration. The purpose is to:
[0010]
[Means for Solving the Problems]
The invention described in claim 1 is a boiler that receives supply water to generate steam, a steam turbine that uses steam from the boiler, and cooling water that is exhausted by a vacuum pump and sent from the steam turbine by cooling water. A condenser for cooling and condensing, wherein the condenser is provided with a non-contact cooling pipe for cooling water flowing in the pipe to cool steam outside the pipe, and the non-contact cooling pipe is provided in the condenser. An air cooling device that cools the condensed water cooled and condensed by the cooling pipe with air, and a condensate circulation line that supplies the condensed water cooled by the air cooling device as cooling water into the non-contact cooling pipe, The cooling water in the non-contact cooling pipe is returned as water for the boiler.
[0011]
In the present invention, the steam discharged from the boiler is introduced into a steam turbine. The steam discharged from the steam turbine flows into the condenser. In the condenser, the steam is cooled by the cooling water in the non-contact cooling pipe and condenses. Since the condenser is evacuated by a vacuum pump, when the steam touches the wall of the non-contact type cooling pipe and condenses, the steam is rapidly cooled, and a flash degassing effect can be obtained. it can.
The condensed condensate is cooled by an air cooling device. The condensed water cooled in the air cooling device is sent to a non-contact cooling pipe as cooling water via a condensed water circulation line. Therefore, in the non-contact cooling pipe, the steam is cooled by its own condensate. The condensed water that has exited the non-contact cooling pipe is supplied again to the boiler, becomes steam, and is introduced into the steam turbine.
[0012]
According to a second aspect of the present invention, in the steam turbine plant according to the first aspect, a flow rate of steam from the steam turbine, a temperature of the steam, and condensate condensed by being cooled by the non-contact cooling pipe. Temperature, the temperature of the condensed water cooled by the air cooling device, and at least one of the temperature of the air taken into the air cooling device, the air cooling device operation control device that adjusts the cooling output of the air cooling device. It is characterized by having.
[0013]
In some cases, such as when the amount of steam decreases due to a change in the operating load, or when there is a change in the outside temperature, the cooling capacity of the air cooling device may be reduced. In the present invention, more economical operation can be performed by controlling the output of the air cooling device by the air cooling device operation control device.
When the air-cooling device includes a plurality of fans, the air-cooling capability may be controlled by changing the number of operating fans, or the air-cooling capability may be controlled by changing the rotation output of the fan.
[0014]
According to a third aspect of the present invention, in the steam turbine plant according to the first or second aspect, a dissolved oxygen meter that detects a concentration of dissolved oxygen contained in water sent from the condenser to the air cooling device; And a spray valve controller for controlling the opening of the spray valve based on the dissolved oxygen concentration detected by the dissolved oxygen meter. And
[0015]
When supplying make-up water to the condenser, when the make-up water rate of the condenser is high, and when the make-up water contains a large amount of dissolved oxygen, the dissolved oxygen concentration in the condensate also becomes high. There is. For this reason, when the dissolved oxygen concentration in the condensate becomes higher (dissolved oxygen concentration> 7 ppb) by taking the dissolved oxygen concentration into the spray valve controller by the dissolved oxygen meter, the spray valve controller controls the spray valve, Spray a part of the condensate again into the condenser. Since the condenser is evacuated by the vacuum pump, the condensate is sprayed into the condenser to obtain a vacuum degassing effect, and oxygen is degassed.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a power plant as a first embodiment of the steam turbine plant of the present invention.
In the figure, reference numeral 20 denotes a boiler, 21 denotes a steam turbine that uses steam from the boiler 20, and 22 denotes a condenser that cools and condenses steam from the steam turbine 21 with cooling water. The condenser 22 is evacuated by a vacuum pump 23. A non-contact cooling pipe 24 is provided inside the condenser 22 for cooling water flowing inside the pipe to cool water vapor outside the pipe. Reference numeral 25 denotes a primary condensate condensed in the condenser 22.
Reference numeral 26 denotes a condensate pump for taking out the primary condensate 25 from the condenser 22. The primary condensate 25 taken out by the condensate pump 26 is introduced into the air cooling device 27. The air cooling device 27 includes a heat exchanger 28 to which the primary condensate 25 is supplied, and an air cooling fan 29 that blows air to the heat exchanger 28.
Reference numeral 30 denotes a condensate circulation line for supplying condensed water cooled through the heat exchanger 28 to the non-contact cooling pipe 24 as cooling water.
Condensate supplied as cooling water to the non-contact cooling pipe 24 is supplied to the boiler 20 again through the condenser 22.
[0017]
Next, the operation of the power plant configured as described above will be described.
Steam discharged from the boiler 20 is introduced into a steam turbine 21. The steam discharged from the steam turbine 21 flows into the condenser 22. In the condenser 22, the steam is cooled by the cooling water in the non-contact cooling pipe 24 and condensed. Since the condenser 22 is evacuated by the vacuum pump 23, when the steam touches the wall of the non-contact type cooling pipe 24 and condenses, the steam is rapidly cooled, so that the flash degassing effect is obtained. Obtainable.
The condensed water accumulates at the bottom of the condenser 22 as a primary condensate 25. The primary condensate 25 is taken out by a condensate pump 26 and subsequently supplied to an air cooling device 27. The primary condensate 25 is supplied to the heat exchanger 28, and the heat exchanger 28 is blown by the air-cooling fan 29 to cool the condensate in the pipe when the cooling air flows around the pipe of the heat exchanger 28. The cooled condensate is sent to the non-contact cooling pipe 24 as cooling water through the condensate circulation line 30. In the non-contact cooling pipe 24, the steam is cooled by its own condensate.
The condensed water that has exited the non-contact cooling pipe 24 is supplied to the boiler 20 again, turned into steam, and introduced into the steam turbine 21.
[0018]
In the present embodiment configured as described above, the following effects can be obtained.
Air cooling of the condensate alone does not provide a sufficient deaeration effect due to the slow cooling rate. However, by introducing the condensed water after air cooling to the condenser 22 and cooling the steam by the condensed water as in the present embodiment, the steam is rapidly cooled and flash degassing can be performed. Therefore, a high deaeration effect can be obtained.
In addition, since the condensate itself containing no impurities is used as the cooling water, even if the non-contact type cooling pipe 24 has a pinhole and the cooling water is mixed in the condensate, the cooling water is used. Unlike the case where seawater is used, it is possible to prevent the corrosion factor component from being brought into the system, and to maintain the condensate at a high purity. Therefore, it is possible to simplify the water quality management, for example, by reducing the water quality monitoring equipment and the chemical injection equipment conventionally provided for countermeasures against seawater leaks.
As described above, since the power plant of the present embodiment does not require seawater, it is an effective means in inland and mountainous areas other than along the coast, or in areas along the coast where seawater cooling cannot be adopted. sell.
[0019]
Next, a second embodiment of the present invention will be described.
FIG. 2 shows a power plant according to the present embodiment. Since the schematic configuration is the same as that of the first embodiment, the same components are denoted by the same reference numerals and description thereof will be omitted.
In the figure, reference numeral 32 is operation data indicating a steam flow rate and a steam temperature in the steam turbine 21. Reference numeral 33 denotes a thermometer for detecting the temperature of the primary condensate 25 cooled and condensed by the non-contact cooling pipe 24, and reference numeral 34 denotes a condensate temperature cooled by the heat exchanger 28 (hereinafter, referred to as a heat exchanger outlet temperature). ) Is a thermometer for detecting the temperature of the air taken into the air-cooling fan 29 (hereinafter, referred to as cooling air temperature).
Reference numeral 36 denotes an air-cooling fan operation control panel (air-cooling device operation control device) to which the above-mentioned operation data 32, primary condensate temperature, heat exchanger outlet temperature, and cooling air temperature detected by the thermometers 33, 34, 35 are taken. ). In the present embodiment, a plurality of air-cooling fans 29 are provided, and the air-cooling fan operation control panel 34 controls the number of operating air-cooling fans 29 according to each of the data taken.
Reference numeral 37 denotes a recirculation amount control valve.
[0020]
Next, the operation of the present embodiment will be described.
The air-cooling fan operation control panel 36 captures plant operation data (flow rate and temperature of steam) 32 and captures temperatures detected by thermometers 33, 34, and 35 provided at various locations. The number of operating air cooling fans 29 is controlled based on the flow rate and temperature of these steams and the temperatures at various locations (primary condensate temperature, heat exchanger outlet temperature, cooling air temperature).
The air-cooling fan operation control panel 36 controls the number of operating air-cooling fans 29, specifically, as follows.
As shown in FIG. 3, when the steam flow rate, the temperature, the primary condensate temperature, the heat exchanger outlet temperature, and the cooling air temperature decrease, the condensate can be kept sufficiently low even if the number of operating air cooling fans 29 is reduced. Can be cooled. Therefore, some of the air cooling fans 29 are stopped. When the steam flow rate, temperature, primary condensate temperature, heat exchanger outlet temperature, and cooling air temperature increase, the number of operating air cooling fans 29 is increased to promote cooling of condensate.
For example, when the operation load of the unit decreases, the amount of steam decreases, so that the air-cooling fan operation control panel 36 reduces the number of operating air-cooling fans 29. Further, when the temperature of the cooling air decreases due to the temperature difference between the season and day and night, it is not necessary to operate a large number of cooling fans 29, so that a part of the cooling fans 29 can be stopped.
[0021]
As described above, in this embodiment, in addition to the effects of the first embodiment, the air-cooling fan 29 can be appropriately stopped, so that more economical operation can be realized.
Note that, in addition to changing the operation number of the plurality of air-cooling fans 29, control for changing the rotation output of the fans 29 may be performed. The point is that the cooling capacity for the heat exchanger 28 can be changed.
In the present embodiment, the air-cooling fan operation control panel 36 controls the operation of the air-cooling fan 29 using all of the steam flow rate, steam temperature, primary condensing temperature, heat exchanger outlet temperature, and cooling air temperature as elements. However, the selection of these elements may be changed as appropriate.
[0022]
Next, a third embodiment of the present invention will be described.
FIG. 4 shows a power plant according to the present embodiment. Since the schematic configuration is the same as that of the first embodiment, the same components are denoted by the same reference numerals and description thereof will be omitted.
Reference numeral 40 denotes replenishing water supplied to the condenser 22. Reference numeral 41 denotes a dissolved oxygen meter that detects the concentration of dissolved oxygen contained in the primary condensate 25 taken out of the condenser 22 by the condensate pump 26.
Part of the primary condensate 25 taken out of the condenser 22 by the condensate pump 26 is partially branched between the condensate pump 26 and the heat exchanger 28, and is again injected into the condenser 22 by the spray valve 42. It is intended to be sprayed.
Reference numeral 43 denotes a spray valve controller which receives the dissolved oxygen concentration detected by the dissolved oxygen meter 41 and controls the opening of the spray valve 42 based on the dissolved oxygen concentration.
[0023]
In the power plant of the present embodiment configured as described above, it is particularly effective to apply the present invention to a unit having a high make-up water rate or a start-up in which the dissolved oxygen concentration needs to be reduced.
When the replenishment water rate of the condenser 22 is high, the concentration of dissolved oxygen in the condensate water may increase because a large amount of dissolved oxygen is contained in the replenishment water. Therefore, the dissolved oxygen concentration is taken into the spray valve controller 43 by the dissolved oxygen meter 41 provided at the outlet of the condensate pump 26. When the dissolved oxygen concentration in the condensate increases (dissolved oxygen concentration> 7 ppb), the spray valve 42 is controlled by the spray valve controller 43, and a part of the condensate is sprayed again into the condenser. Since the condenser 22 is evacuated by the vacuum pump 23, the condensate is sprayed into the condenser 22 to obtain a vacuum degassing effect, and oxygen is degassed.
[0024]
As described above, in this embodiment, in addition to the effect of the first embodiment, oxygen can be degassed, so that the oxygen concentration in the condensed water is suppressed to a reference value or less without providing a deaerator. Can be.
[0025]
【The invention's effect】
As described above, the following effects can be obtained in the steam turbine plant of the present invention.
According to the first aspect of the invention, not only the condensed water is air-cooled, but also the flash deaeration can be performed by the non-contact cooling pipe, so that a high deaeration effect can be obtained.
Also, since the condensate itself containing no impurities is used as the cooling water, even if the non-contact type cooling pipe has pinholes and the cooling water is mixed into the condensate, the cooling water Unlike the conventional technology using seawater, it is possible to avoid bringing in a corrosion factor component into the system and maintain the condensate at a high purity. Therefore, it is possible to simplify water quality management, such as reducing the number of water quality monitoring devices and chemical injection facilities for countermeasures against seawater leaks.
As described above, since the seawater is unnecessary in the steam turbine plant of the present invention, it is an effective means in an inland area and a mountainous area other than along the coast, or in an area along the coast where the seawater cooling method cannot be adopted. sell.
[0026]
According to the second aspect of the present invention, the output of the air-cooling device can be appropriately changed, so that more economical operation can be realized.
According to the third aspect of the present invention, since oxygen can be degassed, the oxygen concentration in the condensate can be suppressed to a reference value or less, and a unit having a high make-up water rate, such as when starting the unit, This is particularly effective when the dissolved oxygen concentration needs to be reduced.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a power generation unit according to a first embodiment of the present invention.
FIG. 2 is a diagram illustrating a configuration of a power generation unit according to a second embodiment of the present invention.
FIG. 3 is a diagram showing control of the number of operating air cooling fans by an air cooling fan operation control panel in the power generation unit.
FIG. 4 is a diagram showing a configuration of a power generation unit according to a third embodiment of the present invention.
FIG. 5 is a front view showing a condenser of a conventional power plant.
FIG. 6 is a plan view showing a condenser of a conventional power plant.
[Explanation of symbols]
Reference Signs List 20 boiler 21 steam turbine 22 condenser 23 vacuum pump 24 non-contact cooling pipe 25 primary condensate 26 condensate pump 27 air cooling device 30 condensate circulation line 36 air cooling fan operation control panel (air cooling device operation control device)
41 dissolved oxygen meter 42 spray valve 43 spray valve controller

Claims (3)

A boiler that receives supply water to generate steam, a steam turbine that uses steam from the boiler, and a condenser that cools and condenses steam that is exhausted by a vacuum pump and sent from the steam turbine by cooling water. Equipped steam turbine plant,
A non-contact cooling pipe for cooling water flowing inside the pipe to cool water vapor outside the pipe is provided in the condenser, and an air cooling apparatus for cooling condensed water cooled and condensed by the non-contact cooling pipe with air. And a condensate circulation line for supplying the condensed water cooled by the air cooling device to the non-contact type cooling pipe as cooling water, further comprising cooling water in the non-contact type cooling pipe as water supply to the boiler. A steam turbine plant characterized by being returned. The steam turbine plant according to claim 1,
A flow rate of steam from the steam turbine, a temperature of the steam, a temperature of condensed water cooled and condensed by the non-contact cooling pipe, a temperature of condensed water cooled by the air cooling device, and a temperature of the air cooling device. A steam turbine plant, comprising: an air-cooling device operation control device that adjusts a cooling output of the air-cooling device based on at least one of a temperature of air taken into the steam turbine. The steam turbine plant according to claim 1 or 2,
A dissolved oxygen meter that detects the concentration of dissolved oxygen contained in the water sent from the condenser to the air cooling device, a spray valve that sprays the water into the condenser again, and the dissolved oxygen meter detects the dissolved oxygen concentration. A spray valve controller for controlling an opening degree of the spray valve based on a dissolved oxygen concentration.

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