Degassing device

Abstract

This degassing device has a degassing chamber disposed below a hot well of a single-pressure condenser. The bottom plate of the hot well is provided with a first opening for allowing the hot well and the degassing chamber to communicate with each other. Steam from a steam supply device is injected into the degassing chamber, so that degassing treatment can be performed by gas-liquid contact with condensate flowing down from the first opening. Non-condensable gas generated by performing the degassing treatment from the degassing chamber to the condensate is discharged from a vent passage. The condensate on which the degassing treatment has been performed is discharged from a condensate outlet part.

Description

Degassing device

[0001] This application claims priority to Japanese Patent Application No. 2024-019091, filed with the Japan Patent Office on February 13, 2024, the contents of which are incorporated herein by reference.

[0002] In a steam turbine used in a plant facility, steam that has completed its work by driving the turbine is cooled and condensed in a condenser to produce condensate. The condensate produced in the condenser is heated appropriately and then used to generate steam in a steam generator. The condensate produced in the condenser contains dissolved oxygen and other substances, and if used as is, it will corrode plant components and piping in a high-temperature, high-pressure environment. Therefore, the condensate produced in the condenser must be degassed in a deaerator to remove contained gases. For example, Patent Document 1 discloses an apparatus configuration in which a degassing device installed above the condenser's hot well can degas the condensate produced in the condenser.

[0003] Japanese Patent Application Laid-Open No. 2000-18846

[0004] In a turbine plant for a pressurized water reactor (PWR) among nuclear power plants, steam generated in a steam generator drives a steam turbine, and the steam that has completed its work in the steam turbine is generally degassed by a degasser as described above. On the other hand, in a turbine plant for a small modular reactor (SMR), such a degasser may not be installed to simplify the system. In this case, degassing is possible by maintaining a vacuum in the condenser during normal plant operation, but when the plant starts up, it takes a considerable amount of time for the condenser to reach a sufficient vacuum, and therefore it takes a long time before degassing can be performed.

[0005] At least one embodiment of the present disclosure has been made in consideration of the above circumstances, and an object of the present disclosure is to provide a degassing device that can suitably perform degassing treatment even during plant startup.

[0006] In order to solve the above problems, a degassing device according to at least one embodiment of the present disclosure comprises: a degassing chamber arranged below a hot well of a single-pressure condenser; a first opening provided in a bottom plate of the hot well so as to communicate the hot well with the degassing chamber; a steam injection unit for injecting steam from a steam supply unit into the degassing chamber; a vent passage for discharging non-condensable gases generated by performing a degassing process on the condensate from the degassing chamber; and a condensate outlet unit provided in the degassing chamber for discharging the condensate after the degassing process.

[0007] According to at least one embodiment of the present disclosure, it is possible to provide a degassing device that can preferably perform degassing treatment even during plant startup.

[0008] It is an overall configuration diagram of a plant facility according to one embodiment. It is a schematic diagram showing the internal configuration of the degassing device of Figure 1 together with the peripheral configuration. It is a modified example of Figure 2. It is another modified example of Figure 2. It is another modified example of Figure 2.

[0009] Hereinafter, several embodiments of the present invention will be described with reference to the accompanying drawings. However, the configurations described as the embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present invention.

[0010] 1 is an overall configuration diagram of a plant facility 1 according to one embodiment. The plant facility 1 includes a steam generator 2, a steam turbine 4, a condenser 6, a deaerator 8, a steam supply device 10, a condensate tank 12, and a condensate pump 14.

[0011] The steam generator 2 is configured to generate steam from feedwater (condensate). The steam generator 2 is configured, for example, as a heat exchanger capable of generating high-temperature, high-pressure steam by exchanging heat between a heat medium heated by a heat source (not shown) and the feedwater (condensate). If the plant facility 1 is a nuclear plant, the heat source is a nuclear reactor, and steam is generated by a heat medium heated by nuclear energy. The nuclear reactor is, for example, a small modular reactor (SMR).

[0012] The steam turbine 4 is driven by steam supplied from the steam generator 2. When the plant facility 1 is a power generation plant, a generator (not shown) connected to an output shaft of the steam turbine 4 is rotationally driven to generate electrical energy.

[0013] The condenser 6 is a single-pressure condenser capable of generating condensed water by cooling and condensing steam that has completed its work in the steam turbine 4. The condenser 6 includes a cooling pipe group 9 (see FIG. 2 ) for reducing pressure to cool and condense the steam. The cooling pipe group 9 includes a plurality of cooling pipes through which a cooling medium, such as seawater or cooling tower water, flows. The steam supplied from the steam turbine 4 to the condenser 6 condenses on the outer surface of the cooling pipe group 9 by heat exchange with the cooling medium flowing therethrough, generating condensed water and reducing the pressure inside the condenser 6. The condensed water generated in the condenser 6 is temporarily stored in the hot well 22 and then supplied to the deaerator 8. The cooling pipe group 9 is positioned so that a space of 300 mm or more is secured between its bottom (the lowest point of the plurality of cooling pipes included in the cooling pipe group 9) and the maximum water level of the condensed water stored in the hot well 22.

[0014] In addition, non-condensable gases such as oxygen and ammonia contained in the steam supplied from the steam turbine 4 to the condenser 6 are discharged via a discharge line 17 disposed near the cooling tube group 9 and connected to a vacuum pump 16.

[0015] The degassing device 8 is configured to perform a degassing treatment on the condensate generated in the condenser 6. The condensate generated in the condenser 6 contains a considerable amount of dissolved non-condensable gases such as the above-mentioned oxygen and ammonia, and if used as is, there is a risk of corroding plant components and piping in a high-temperature, high-pressure environment. Therefore, the condensate generated in the condenser 6 is subjected to a degassing treatment by the degassing device 8, thereby removing the non-condensable gases contained in the condensate.

[0016] The detailed configuration of the degassing device 8 will be described later, but in order to perform degassing treatment in the degassing device 8 when the plant is started up, a steam supply device 10 separate from the steam generator 2 is connected to the degassing device 8. The steam supply device 10 is, for example, an auxiliary boiler.

[0017] The condensate that has been deaerated by the deaerator 8 is stored in a condensate tank 12. The condensate stored in the condensate tank 12 is supplied to the steam generator 2 by a condensate pump 14 as needed.

[0018] Next, a specific configuration of the degassing device 8 will be described. Figure 2 is a schematic diagram showing the internal configuration of the degassing device 8 of Figure 1 together with the peripheral configuration.

[0019] The degassing device 8 has a degassing chamber 20 in which degassing treatment is carried out. The degassing chamber 20 is arranged adjacent to the condenser 6, which is the supply source of condensate. In particular, the degassing chamber 20 is arranged below the hot well 22 of the condenser 6. The hot well 22 has a bottom, and the cooling pipe group 9 is arranged therein as described above. In the condenser 6, the steam introduced into the condenser 6 is depressurized by the cooling pipe group 9, thereby generating condensate, which is stored in the hot well 22.

[0020] The bottomed hot well 22 has a bottom plate 24 that is disposed between the condenser 6 and the degassing device 8 to separate them. The bottom plate 24 is provided with a first opening 26 that connects the hot well 22 to the degassing chamber 20. A plurality of first openings 26 are provided along the surface direction of the bottom plate 24, and the bottom plate 24 is configured as a perforated plate. The condensate stored in the hot well 22 flows down through the first openings 26 into the degassing chamber 20. The condensate that flows down through the first openings 26 is received by a tray 28 disposed in the degassing chamber 20.

[0021] The degassing chamber 20 is also provided with a steam injection unit 30 for injecting steam S from the steam supply device 10. The injection of steam S by the steam injection unit 30 is performed when the plant is started up, and the steam S is brought into gas-liquid contact with the condensate flowing down from the hot well 22 through the first opening 26, thereby performing a degassing process on the condensate.

[0022] Furthermore, the steam injection section 30 may be located at a position where the steam S injected from the steam injection section 30 can come into gas-liquid contact with the condensate flowing down through the first opening 26 (i.e., the condensate before being received by the tray 28), or may be located at a position where the steam S can come into gas-liquid contact with the condensate flowing further down from the tray 28.

[0023] The degassing chamber 20 is also provided with a vent passage 32 for discharging non-condensable gases separated from the condensate by the degassing process. In this embodiment, the vent passage 32 is connected to a vacuum pump 34, thereby enabling the non-condensable gases generated in the degassing chamber 20 to be discharged to the outside. The condensate that has been degassed in the degassing chamber 20 is discharged from a condensate outlet 35. The condensate discharged from the condensate outlet 35 is stored in a condensate tank located downstream (see FIG. 1).

[0024] During normal operation of the plant facility 1, the condensate can be degassed by maintaining a vacuum in the condenser 6, but when the plant is started up, it takes a considerable amount of time for the condenser to reach a sufficient vacuum state, and so it takes time before the degassing process can be performed. Therefore, in this embodiment, when the plant is started up, steam S is injected from the steam injection unit 30, causing gas-liquid contact with the condensate that has flowed down from the hot well 22 through the first opening 26 into the degassing chamber 20, thereby performing the degassing process. This allows the condensate to be degassed appropriately from the time the plant is started up.

[0025] The steam injection by the steam injection unit 30 may be performed manually or automatically by a controller (not shown). In this case, the controller may be configured with an arithmetic processing device such as a computer, and the operation may be realized by executing a program pre-installed for realizing the operation.

[0026] Furthermore, injection of steam S by the steam injection unit 30 is stopped during normal plant operation when degassing is possible by maintaining a vacuum in the condenser 6. By not performing unnecessary steam injection in this way, excess energy consumption can be avoided and plant efficiency can be suitably improved.

[0027] Figure 3 shows a modification of Figure 2. In this modification, the discharge line 17 and the vent passage 32 join together and are connected to a common vacuum pump 16. That is, while the embodiment of Figure 2 uses two vacuum pumps 16 and 34, in this modification, these are integrated into a single vacuum pump 16, thereby simplifying the device configuration. As a result, in this modification, the vacuum pump 16 discharges non-condensable gases from the condenser 6 via the discharge line 17 and discharges non-condensable gases generated in the degassing chamber 20 to the outside via the vent passage 32.

[0028] FIG. 4 shows another modification of FIG. 2 . In this modification, the bottom plate 24 of the hot well 22 includes a first region R1 in which a first opening 26 is formed, and a second region R2 that is positioned higher than the first region R1. In particular, in the example of FIG. 4 , the first region R1 is configured substantially horizontally, while the second region R2 is configured in a tapered shape with a predetermined inclination. A second opening that functions as a vent passage 32 is formed in the second region R2. That is, in this modification, the vent passage 32 is configured as an opening formed in the bottom plate 24, similar to the first opening 26. The vent passage 32 formed as the second opening is provided at a position higher than the height of the condensate stored in the first region R1.

[0029] In this way, the vent passage 32 of this modified example is configured as a second opening provided in the bottom plate 24 at a higher position than the first opening 26. As a result, the second opening functioning as the vent passage 32 can be configured integrally with the bottom plate 24, which is configured as a perforated plate, together with the first opening 26, which allows condensate to flow down from the hot well 22 to the degassing chamber 20, and the device configuration can be more effectively simplified.

[0030] 4, the vacuum pump 16 for discharging non-condensable gases in the condenser 6 applies negative pressure to the degassing chamber 20 via the vent passage 32, thereby discharging the non-condensable gases generated in the degassing chamber 20. As a result, similar to the modification described above with reference to FIG. 3, the single vacuum pump 16 can be used to discharge non-condensable gases in the condenser 6 and from the degassing chamber 20, thereby simplifying the device configuration.

[0031] 5 shows another modification of FIG. 2. In this modification, the vent passage 32 is configured as a tubular member arranged to penetrate the bottom plate 24. The end of the vent passage 32 on the hot well side is located 300 mm above the bottom of the cooling pipe group 9 of the condenser 6. This configuration ensures that the end of the vent passage 32 on the hot well 22 side is higher than the condensate stored in the hot well 22. As a result, the bottom plate 24, configured as a perforated plate, can have a simple flat shape, allowing the present invention to be preferably realized with a simpler configuration.

[0032] The vent passage 32 formed as a pipe member has an orifice formed therein, so that the flow resistance when the non-condensable gas passes through the vent passage 32 can be adjusted appropriately.

[0033] As described above, according to each of the above embodiments, the first opening 26 is provided in the bottom plate 24 of the hot well 22 of the single-pressure condenser, so that the condensate in the hot well 22 flows down into the degassing chamber 20 through the first opening 26. The condensate that flows down into the degassing chamber 20 is brought into gas-liquid contact with steam injected from the steam injection unit 30 at the time of plant startup, so that degassing treatment can be carried out appropriately even at the time of plant startup.

[0034] In addition, within the scope of the present disclosure, the components in the above-described embodiments may be replaced with well-known components as appropriate, and the above-described embodiments may be combined as appropriate.

[0035] The contents described in each of the above embodiments can be understood, for example, as follows.

[0036] (1) A degassing device according to one embodiment includes a degassing chamber arranged below a hot well of a single-pressure condenser; a first opening provided in a bottom plate of the hot well to communicate the hot well with the degassing chamber; a steam injection unit for injecting steam from a steam supply unit into the degassing chamber; a vent passage for discharging non-condensable gases generated by performing a degassing process on the condensate from the degassing chamber; and a condensate outlet unit provided in the degassing chamber for discharging the condensate after the degassing process.

[0037] According to the above aspect (1), a first opening is provided in the bottom plate of the hot well of the single-pressure condenser, and the condensate stored in the hot well flows down into the degassing chamber through the first opening. The condensate that flows down into the degassing chamber is degassed by gas-liquid contact with steam injected from the steam injection unit. This makes it possible to appropriately perform degassing even during plant startup, when degassing is difficult with a single-pressure condenser.

[0038] (2) In another aspect, in the aspect (1) above, the steam injection unit is configured to inject the steam when the plant is started up, so that the steam is brought into gas-liquid contact with the condensate that has flowed down from the hot well into the degassing chamber through the first opening in the degassing chamber.

[0039] According to the above aspect (2), when the plant is started up, the degassing process can be carried out suitably by bringing the steam injected from the steam injection section into gas-liquid contact with the condensate flowing down into the degassing chamber through the first opening.

[0040] (3) In another aspect, in the aspect (2), the steam injection unit stops injecting the steam during normal plant operation.

[0041] According to the above aspect (3), during normal plant operation, degassing treatment can be performed using a single-pressure condenser, and therefore, by stopping the injection of steam into the degassing chamber by the steam injection unit, unnecessary energy consumption can be avoided and plant efficiency can be suitably improved.

[0042] (4) In another aspect, in any one of the above aspects (1) to (3), the bottom plate is configured as a perforated plate having the first opening.

[0043] According to the above aspect (4), by configuring the bottom plate of the hot well as a perforated plate, it is possible to preferably realize a configuration for causing condensate to flow down from the hot well to the degassing chamber.

[0044] (5) In another aspect, in any one of the above aspects (1) to (4), the degassing chamber has a tray for receiving the condensate flowing down from the first opening.

[0045] According to the above aspect (5), the condensate that flows down from the hot well through the first opening into the degassing chamber is received by a tray provided in the degassing chamber, whereby, at the time of plant startup, the condensate received by the tray is brought into gas-liquid contact with steam injected from the steam injection unit, thereby enabling the degassing process to be carried out suitably.

[0046] (6) In another aspect, in any one of the above aspects (1) to (5), the vent passage is connected to a vacuum pump provided outside the degassing chamber.

[0047] According to the above aspect (6), the degassing chamber is connected to an external vacuum pump via a vent passage, whereby non-condensable gases generated by the degassing process in the degassing chamber can be suitably discharged using the external vacuum pump.

[0048] (7) In another aspect, in any one of the above aspects (1) to (5), the vent passage communicates with a vacuum pump for discharging non-condensable gases from within the single-pressure condenser.

[0049] According to the above aspect (7), the degassing chamber is connected to a vacuum pump for discharging non-condensable gases from the single-pressure condenser via a vent passage, whereby the non-condensable gases generated by the degassing treatment in the degassing chamber can be suitably discharged using the vacuum pump for discharging non-condensable gases from the single-pressure condenser.

[0050] (8) In another aspect, in any one of the above aspects (1) to (7), the vent passage is configured as a second opening provided in the bottom plate at a position higher than the first opening.

[0051] According to the above aspect (8), the vent passage is configured as a second opening provided in the bottom plate. This allows the second opening functioning as the vent passage to be provided integrally in the bottom plate with a similar configuration to the first opening for allowing condensate to flow down from the hot well to the degassing chamber, thereby enabling the present device to be realized with a simpler device configuration.

[0052] (9) In another aspect, in any one of the above aspects (1) to (8), the vent passage is configured as a pipe member arranged to penetrate the bottom plate.

[0053] According to the above configuration (9), the vent passage is configured as a pipe member disposed so as to penetrate the bottom plate, which simplifies the shape of the bottom plate itself, thereby enabling the present invention to be preferably realized with a simpler configuration.

[0054] (10) In another aspect, in the aspect (9), the pipe member has an orifice therein.

[0055] According to the above aspect (10), an orifice is provided inside the pipe member that constitutes the vent passage, so that the flow resistance when passing through the vent passage can be suitably adjusted.

[0056] (11) In another aspect, in any one of the above aspects (1) to (10), the end of the vent passage on the hot well side is positioned above a height of 300 mm below the bottom of the cooling pipe group of the single-pressure condenser.

[0057] According to the above aspect (11), by configuring the end of the vent passage on the hot well side to be positioned above a height of 300 mm below the bottom of the cooling pipe group of the single-pressure condenser, condensate is stored in the hot well, and a portion of it is allowed to flow appropriately from the hot well to the degassing chamber through the first opening, while non-condensable gases generated in the degassing chamber can be suitably discharged to the condenser side through the vent passage.

[0058] (12) In another aspect, in any one of the above aspects (1) to (11), the condensate discharged from the condensate outlet is introduced into a condensate pump.

[0059] According to the above aspect (12), by introducing the condensate that has been deaerated by the deaerator into the condensate pump, corrosion of the plant components and piping including the condensate pump can be suitably suppressed.

[0060] (13) In another aspect, in any one of the above aspects (1) to (12), the single-pressure condenser generates the condensate from steam that is generated using a nuclear reactor as a heat source and has completed work in a steam turbine.

[0061] According to the above aspect (13), the steam turbine is driven by steam generated using a heat source from the nuclear reactor, and condensate is produced in the single-pressure condenser from the steam that has completed its work in the steam turbine. When a plant equipped with such a single-pressure condenser is started up, steam is injected from the steam injection unit, and gas-liquid contact with the condensate flowing down from the first opening allows the condensate to be degassed in an appropriate manner.

[0062] (14) In another aspect, in the aspect (13), the nuclear reactor is a small modular reactor.

[0063] According to the above aspect (14), when the plant is started up, degassing treatment can be suitably carried out by injecting steam from the steam injection unit onto the condensate generated from steam generated using a heat source from a nuclear reactor that is a small modular reactor.

[0064] REFERENCE SIGNS LIST 1 Plant equipment 2 Steam generator 4 Steam turbine 6 Condenser 8 Deaerator 10 Steam supply device 12 Condensate tank 14 Condensate pump 16 Vacuum pump 17 Discharge line 20 Deaerator chamber 22 Hot well 24 Bottom plate 26 First opening 28 Tray 30 Steam injection section 32 Vent passage 34 Vacuum pump

Claims

1. A degassing device comprising: a degassing chamber located below a hot well of a single-pressure condenser; a first opening provided in a bottom plate of the hot well so as to communicate between the hot well and the degassing chamber; a steam injection unit for injecting steam from a steam supply device into the degassing chamber; a vent passage for discharging non-condensable gases generated by degassing the condensate from the degassing chamber; and a condensate outlet provided in the degassing chamber for discharging the condensate after the degassing treatment.

2. The degassing device according to claim 1, wherein the steam injection section is configured to inject the steam when the plant is started up, thereby bringing the steam into gas-liquid contact with the condensate that has flowed down from the hot well into the degassing chamber through the first opening in the degassing chamber.

3. The degassing device according to claim 2, wherein the steam injection section stops injecting the steam during normal plant operation.

4. A degassing device according to claim 1 or 2, wherein the bottom plate is configured as a perforated plate having the first opening.

5. A degassing device as described in claim 1 or 2, wherein the degassing chamber has a tray for receiving the condensate flowing down from the first opening.

6. A degassing device according to claim 1 or 2, wherein the vent passage is connected to a vacuum pump provided outside the degassing chamber.

7. A degassing device according to claim 1 or 2, wherein the vent passage communicates with a vacuum pump for discharging non-condensable gases from the single-pressure condenser.

8. A degassing device as described in claim 1 or 2, wherein the vent passage is configured as a second opening provided in the bottom plate at a position higher than the first opening.

9. A degassing device according to claim 1 or 2, wherein the vent passage is configured as a pipe member arranged to pass through the bottom plate.

10. A degasser according to claim 9, wherein said tubular member has an orifice therein.

11. A degassing device as described in claim 1 or 2, wherein the end of the vent passage on the hot well side is positioned above a height of 300 mm below the bottom of the cooling pipe group of the single-pressure condenser.

12. A degassing device according to claim 1 or 2, wherein the condensate discharged from the condensate outlet is introduced into a condensate pump.

13. A degassing device according to claim 1 or 2, wherein the single-pressure condenser generates the condensate from steam that is generated using a nuclear reactor as a heat source and has completed work in a steam turbine.

14. The degassing apparatus of claim 13, wherein the reactor is a small modular reactor.

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