Emergency shaft seal system for main supply pump of nuclear power station

Abstract

The invention discloses a nuclear power station supply main pump emergency shaft seal system which comprises a first steam generator which is communicated with the high-temperature side of a nuclear island coolant and enters the steam generator through external replenished water, and the water is gasified to form water vapor to absorb heat of the nuclear island coolant; a double-channel countercurrent design is adopted in the second steam generator, and a steam flow channel is completely isolated from an organic working medium flow channel; steam enters from the first end of the second steam generator, flows to the second end, becomes low-temperature steam after gradually releasing heat, and is discharged from the second end; the liquid organic working medium enters from the second end of the second steam generator, flows towards the first end, becomes a gasified organic working medium after absorbing heat released by steam, and is discharged from the first end. The steam turbine is driven by gasified organic working media, the output end of the steam turbine is connected with a standby shaft seal pump, and water is supplied to the main pump shaft seal through the standby shaft seal pump to form sealing.

Description

Technical Field

[0001] The invention relates to the field of main pump shaft seals, in particular to an emergency shaft seal system for a main pump in a nuclear power plant. Background Art

[0002] In existing nuclear power plants, shaft seals for the main pumps are supplied primarily by emergency shaft seal pumps driven by SBO emergency diesel engines, requiring a complex system. Emergency diesel pumps typically require a period of startup. Delayed startup of the diesel pumps can prevent the shaft seals from being adequately cooled and lubricated immediately during the initial power outage, increasing the risk of seal damage. This startup delay can also slow the equipment's response time in emergencies.

[0003] When the entire plant loses power, the charging pump supplying the main pump shaft seal loses power and cannot supply the shaft seal, while the reactor coolant system is still in a high-pressure state. The shaft seal system still needs to provide a certain sealing water pressure to maintain the sealing of the shaft seal to prevent high-pressure coolant containing radioactive substances from leaking into the environment through the shaft seal, threatening the safety of workers and the surrounding environment; in the event of a power outage, the main pump shaft seal also needs to maintain its temperature and lubrication status through a backup system or emergency water supply to avoid rapid damage or failure of the shaft seal due to high temperature or dry friction. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is: how to ensure that the main shaft bearing is in a sealed state when the power is off?

[0005] The above technical problems are solved by the following technical solution: The present invention proposes an emergency shaft seal system for a main pump of a nuclear power plant, which includes a first steam generator, which is connected to the high-temperature side of the nuclear island coolant. Water is supplied from the outside to the first steam generator, and the water is vaporized to form water vapor to absorb the heat of the nuclear island coolant;

[0006] The second steam generator adopts a dual-channel countercurrent design internally, and the steam flow channel is completely isolated from the organic working fluid flow channel; steam enters from the first end of the second steam generator, flows to the second end, gradually releases heat and becomes low-temperature steam, and is discharged from the second end; liquid organic working fluid enters from the second end of the second steam generator, flows to the first end, absorbs the heat released by the steam and becomes vaporized organic working fluid, and is discharged from the first end.

[0007] A steam turbine driven by a gasified organic working medium, wherein the output end of the steam turbine is connected to a spare shaft seal pump, through which water is supplied to the main pump shaft seal to form a seal;

[0008] The backup shaft seal pump driven by the steam turbine can supply water to the main pump shaft seal to form a seal, thereby ensuring that the nuclear island reactor will not leak.

[0009] In a preferred embodiment of the nuclear power plant main pump emergency shaft seal system of the present invention: the second steam generator is provided with a water collection port on one side near the first end thereof, and the water collection port is connected to the first steam generator through a water inlet pipe;

[0010] A water inlet gate, a water inlet thermometer, a water inlet flowmeter and a check valve are sequentially provided between the water collecting port and the first steam generator;

[0011] The amount of water supplied to the first steam generator can be effectively controlled by providing a water inlet gate, a water inlet thermometer, a water inlet flowmeter and a check valve.

[0012] In a preferred embodiment of the emergency shaft seal system for the main pump of a nuclear power plant according to the present invention: a gas collecting port is provided on a side of the second steam generator close to the second end, and the gas collecting port is connected to the first steam generator via a steam pipe;

[0013] A steam outlet door and a steam outlet thermometer are respectively provided between the first steam generator and the gas collecting port;

[0014] The steam outlet door and steam thermometer make it easy for workers to understand the steam temperature and control the steam to enter the steam flow channel through the gas collecting port.

[0015] In a preferred embodiment of the nuclear power plant main pump emergency shaft seal system of the present invention: the steam flow channel is a bent closed pipe structure, and the two ends of the pipe are respectively connected to the gas collection port and the water collection port;

[0016] Steam enters the interior of the second steam generator through the gas collecting port, the organic working medium exchanges heat with the steam, and the gasified organic working medium flows from the first end of the second steam generator to the steam turbine;

[0017] After the steam cools down, it flows back to the first steam generator through the water collecting port;

[0018] The steam flow channel and the organic working medium flow channel are completely separated to effectively avoid mixing of the two, and the steam and organic working medium flow directions are set in opposite directions to ensure that the two can fully exchange heat.

[0019] In a preferred embodiment of the emergency shaft seal system for the main pump of a nuclear power plant according to the present invention: a turbine inlet valve is provided between the second steam generator and the steam turbine, and the gasified organic working medium enters the interior of the steam turbine through the turbine inlet valve and drives the turbine to rotate;

[0020] The steam turbine output end is connected to the organic working fluid condensate pump, and the steam turbine and the organic working fluid condensate pump are coaxially arranged;

[0021] The outlet of the steam turbine gasified organic working medium is connected to a cooler

[0022] The gasified organic working medium is discharged from the interior of the steam turbine and enters the interior of the cooler; the cooler cools the gasified organic working medium into a liquid state;

[0023] The vaporized organic working medium can drive the steam turbine to rotate, and the steam turbine synchronously drives the organic working medium condensation pump to work, thereby transporting the liquid organic working medium to the inside of the second steam generator and vaporizing the liquid organic working medium.

[0024] In a preferred embodiment of the emergency shaft seal system for the main pump of a nuclear power plant according to the present invention: the organic working medium condensation pump is capable of conveying the liquid organic working medium to the second end of the second steam generator and into the interior of the organic working medium flow channel;

[0025] A condensate pump outlet door and a condensate pump outlet pressure gauge are sequentially arranged between the organic working medium condensate pump and the second steam generator;

[0026] The condensation pump outlet gate and the condensation pump outlet pressure gauge are provided to effectively control the flow of liquid organic working medium and the pressure inside the transmission pipeline.

[0027] In a preferred embodiment of the nuclear power plant main pump emergency shaft seal system of the present invention: the condensate pump outlet door is connected to a branch pipeline of the organic working fluid condensate pump, the branch pipeline is connected to the cooler, and a first circulation door is installed on the branch pipeline;

[0028] The pressure and flow rate of the organic working medium entering the first steam generator can be adjusted through the first circulation gate.

[0029] In a preferred embodiment of the emergency shaft seal system for the main pump of a nuclear power plant according to the present invention: the steam turbine and the standby shaft seal pump are connected via a transmission;

[0030] The pumping end of the standby shaft seal pump is connected to the water tank, a return pipe is provided between the standby shaft seal pump and the water tank, and a second circulation door is installed on the return pipe;

[0031] The water supply pressure of the standby shaft seal pump can be effectively adjusted through the second circulation door to ensure that the main pump shaft seal is well sealed.

[0032] The beneficial effect of the present invention is that external water enters the first evaporator, absorbs the temperature of the nuclear island coolant and vaporizes to form steam, the steam enters the second evaporator to exchange heat with the liquid organic working medium, and then the vaporized organic working medium enters the steam turbine, drives the steam turbine to drive the standby shaft seal pump to work, thereby completing the sealing of the main pump shaft seal. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings of the embodiments of the present invention. Obviously, the drawings described below only relate to some embodiments of the present invention, and are not intended to limit the present invention.

[0034] Figure 1 Shows a schematic structural diagram of the cooling end of the emergency shaft seal system;

[0035] Figure 2 A schematic structural diagram of the sealing end of the emergency shaft sealing system is shown. DETAILED DESCRIPTION

[0036] In order to enable those skilled in the art to better understand the present invention, the present invention is further described in detail below with reference to specific embodiments and the accompanying drawings.

[0037] The terms used in the present invention are those commonly used in the art in view of the functions of the present invention, but these terms may vary according to the intentions of those skilled in the art, precedents, or new technologies in the art. In addition, specific terms may be selected by the applicant, and in such cases, their detailed meanings will be described in the detailed description of the present invention. Therefore, the terms used in the specification should not be understood as simple names, but rather as the meanings of the terms and the overall description of the present invention.

[0038] Reference Figures 1 and 2 This embodiment provides an emergency shaft seal system for a main pump of a nuclear power plant, including a second steam generator 11. In this example, the second steam generator 11 is arranged in a vertical direction, and a steam flow channel is formed inside the second steam generator 11. The steam inlet of the steam flow channel is located at the top of the second steam generator 11. After the steam heat exchange is completed, it is discharged from the bottom pipe and re-enters the pipeline loop inside the first steam generator 7.

[0039] The steam then enters the first evaporator 7 through the connecting pipe. External water replenishment ensures that there is sufficient low-temperature medium inside the first evaporator 7 to exchange heat with the high temperature of the nuclear island coolant, thereby effectively reducing the temperature of the coolant; the steam generated by the first steam generator 7 flows back to the gas collecting port 10, and then enters the steam flow channel set inside the second steam generator 11; and then exchanges heat with the organic working medium.

[0040] Furthermore, an organic working medium flow channel is provided inside the second steam generator 11, and the organic working medium enters the organic working medium flow channel from the bottom of the second steam generator 11, and is discharged from the top side wall of the second steam generator 11 after heat exchange with steam; then the vaporized organic working medium enters the steam turbine 15, and the vaporized organic working medium drives the steam turbine 15 to rotate, and the steam turbine 15 drives the standby shaft seal pump 21 to work, thereby supplying water to the main pump shaft seal to form a seal.

[0041] It should be noted that after the vaporized organic working fluid enters the steam turbine 15 and performs work, it flows out of the steam turbine 15 and enters the cooler 16 along a specific pipeline. The organic working fluid passing through the cooler 16 is converted into liquid organic working fluid, and then pumped into the organic working fluid flow channel inside the second steam generator 11, and undergoes heat exchange with the steam to form a vaporized organic working fluid that flows into the steam turbine 15, serving as a power source to drive the steam turbine 15 to drive the standby shaft seal pump 21 to perform work and supply water to the main pump shaft seal.

[0042] In one embodiment provided in the present application, a water inlet gate 3 is included, which controls the water entering the first steam generator 7. A water inlet thermometer 4 is provided along the flow direction from the water collection port 1 to the first steam generator 7. The water inlet thermometer 4 can effectively detect the water temperature, making it convenient for staff to make corresponding adjustments according to the conditions of the equipment.

[0043] Then, the amount of water inside the water replenishment system can be effectively calculated through the water inlet flow meter 5, and the amount of water replenishment can be well controlled through the water inlet flow meter 5, thereby ensuring that there is enough water inside the system to meet the needs of normal operation of the equipment.

[0044] The check valve 6 can effectively prevent steam from passing through the pipe near the water collection port 1, ensuring that the temperature at the water collection port 1 is not affected by the steam; the backflow through the connecting pipe affects the temperature of the make-up water, thereby ensuring the heat exchange efficiency between the organic working medium and the steam.

[0045] In some embodiments, a gas collecting port 10 is provided on the side wall of one end of the second steam generator 11 away from the water collecting port 1, and the gas collecting port 10 is the entrance position for steam to enter the steam flow channel; the gas collecting port 10 and the water collecting port 1 are located at two relatively far ends of the second steam generator 11, and the steam enters the steam flow channel through the gas collecting port 10, and after heat exchange with the organic working medium, it flows back from the water collecting port 1 to the inside of the first steam generator 7 to absorb heat and vaporize again.

[0046] It should be noted that the flow direction of steam is opposite to that of the organic working medium. Steam flows from high to low along the steam flow channel, and the organic working medium enters the organic working medium flow channel from low. After the organic working medium exchanges heat with the steam, the steam is liquefied into water and flows back to the water collection port 1 under the action of gravity. After the organic working medium reacts with the steam, it changes from liquid to gas. The vaporized organic working medium flows to the upper position of the second steam generator 11, and then enters the interior of the steam turbine 15 through the upper position of the organic solute channel to drive the steam turbine 15 to rotate.

[0047] In one embodiment provided in the present application, a turbine air inlet valve 14 is installed on the outside of the pipeline through which the gasified organic working medium enters the interior of the steam turbine 15. The turbine air inlet valve 14 can effectively control the amount of the gasified organic working medium entering the interior of the steam turbine 15, thereby ensuring that there is sufficient gasified organic working medium to drive the steam turbine 15 to do work.

[0048] Furthermore, the output ends of the steam turbine 15 are respectively connected to the organic working fluid condensate pump 17, and the rotation of the main shaft of the steam turbine 15 drives the organic working fluid condensate pump 17 to rotate; the steam turbine 15 can drive the organic working fluid condensate pump 17 to liquefy the gasified organic working fluid flowing through the interior of the steam turbine 15 again.

[0049] It should be noted that the vaporized organic working medium drives the turbine 15 to rotate the shaft and flows out from the inside of the turbine 15, and then the vaporized organic working medium enters the cooler 16. A curved serpentine pipe is provided inside the cooler 16, and the cooler 16 is a hollow water pool filled with sufficient cooling water. The cooling water and the vaporized organic working medium exchange heat, thereby liquefying the vaporized organic working medium. In order to ensure a constant temperature of the cooling water, heat exchange is performed between the cooling water and the flowing air to quickly absorb the heat of the cooling water to ensure that the cooling water is always at a temperature that can liquefy the vaporized organic working medium.

[0050] While the steam turbine 15 drives the organic working medium condensate pump 17 to rotate, the organic working medium condensate pump 17 transports the liquefied organic working medium to the organic working medium flow channel set inside the second steam generator 11; in order to ensure the normal transportation of the organic working medium by the organic working medium condensate pump 17, the outer wall of the pipeline for transporting the liquid organic working medium is also provided with a condensate pump outlet door 18 and a condensate pump outlet pressure gauge 19; the condensate pump outlet door 18 can better control the flow of the organic working medium entering the second steam generator 11; the condensate pump outlet pressure gauge 19 can reflect the pressure inside the transportation pipeline, and the pressure value fed back by the condensate pump outlet pressure gauge 19 facilitates the staff to make corresponding adjustments in time.

[0051] Furthermore, in order to avoid excessive pressure in the pipeline between the organic working medium condensation pump 17 and the second steam generator 11, and at the same time control the amount of organic working medium entering the organic working medium flow channel; an external reflux pipeline is located between the condensation pump outlet gate 18 and the organic working medium condensation pump 17; and a first circulation gate 26 is installed on the outside of the reflux pipeline, and the opening and closing state of the reflux pipeline can be controlled by the first circulation gate 26; when the first circulation gate 26 is opened, a part of the liquid organic working medium transported by the organic working medium condensation pump 17 enters the second steam generator 11 along the condensation pump outlet gate 18, and a part flows through the first circulation gate 26 and flows back to the cooler 16, thereby effectively reducing the organic working medium entering the second steam generator 11.

[0052] In some embodiments, another main shaft of the steam turbine 15 drives the transmission 20 to rotate, and the transmission 20 is connected to the spare shaft seal pump 21. The transmission 20 can better control the amount of shaft seal water delivered by the spare shaft seal pump 21, so that the staff can make corresponding adjustments according to the working conditions.

[0053] The backup shaft seal pump 21 is used to transport the water inside the water tank 22 to the main pump shaft seal position, and the main pump is sealed by water; in order to further avoid excessive pressure at the main pump shaft seal, a branch pipe is also provided in the middle position of the pipe through which the backup shaft seal pump 21 transports water into the main pump shaft seal, and a second circulation door 24 is installed on the outside of the branch pipe; when the liquid pressure at the main pump shaft seal is too high, a part of the water can be returned to the water tank 22 by opening the second circulation door 24, thereby effectively preventing the main pump shaft seal from being subjected to excessive pressure.

[0054] Finally, it should be pointed out that the methods and devices described in detail above are merely embodiments, and those skilled in the art can modify these embodiments in different ways without departing from the scope of the present invention.

[0055] It is important to note that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. An emergency shaft seal system for a main pump in a nuclear power plant, characterized by: include, A first steam generator (7) is connected to the high-temperature side of the nuclear island coolant, and water is supplied from the outside to the first steam generator (7), where water vaporizes to form steam that absorbs heat from the nuclear island coolant; The second steam generator (11) has a dual-channel countercurrent design, and the steam flow channel is completely isolated from the organic working medium flow channel; steam enters the second steam generator (11) from the first end, flows toward the second end, gradually releases heat and becomes low-temperature steam, and is discharged from the second end; liquid organic working medium enters the second steam generator (11) from the second end, flows toward the first end, absorbs the heat released by the steam and becomes gasified organic working medium, and is discharged from the first end; A steam turbine (15) is driven by a gasified organic working medium. The output end of the steam turbine (15) is connected to a spare shaft seal pump (21), and the spare shaft seal pump (21) supplies water to the main pump shaft seal to form a seal.

2. The emergency shaft seal system for the main pump of a nuclear power plant according to claim 1, characterized in that: The second steam generator (11) is provided with a water collection port (1) on one side close to the first end thereof, and the water collection port (1) is connected to the first steam generator (7) via a water inlet pipe; A water inlet gate (3), a water inlet thermometer (4), a water inlet flowmeter (5) and a check valve (6) are respectively provided between the water collecting port (1) and the first steam generator (7).

3. The emergency shaft seal system for the main pump of a nuclear power plant according to claim 2, characterized in that: The second steam generator (11) is provided with a gas collecting port (10) on one side close to the second end, and the gas collecting port (10) is connected to the first steam generator (7) via a steam pipe; A steam outlet door (8) and a steam outlet thermometer (9) are respectively provided between the first steam generator (7) and the gas collecting port (10).

4. The emergency shaft seal system for the main pump of a nuclear power plant according to claim 3, characterized in that: The steam flow channel is a bent closed pipe structure, and both ends of the pipe are respectively connected to the gas collection port (10) and the water collection port (1); Steam enters the interior of the second steam generator (11) through the gas collecting port (10), the organic working medium exchanges heat with the steam, and the gasified organic working medium flows from the first end of the second steam generator (11) to the steam turbine (15); After the steam cools down, it flows back into the first steam generator (7) through the water collecting port (1).

5. The emergency shaft seal system for the main pump of a nuclear power plant according to claim 4, characterized in that: A turbine air inlet valve (14) is provided between the second steam generator (11) and the steam turbine (15), and the gasified organic working medium enters the interior of the steam turbine (15) through the steam turbine air inlet valve (14) and drives the turbine to rotate; The output end of the steam turbine (15) is connected to an organic working fluid condensation pump (17), and the steam turbine (15) and the organic working fluid condensation pump (17) are coaxially arranged; The outlet of the gasified organic working medium of the steam turbine (15) is connected to a cooler (16) The gasified organic working medium is discharged from the interior of the steam turbine (15) and enters the interior of the cooler (16); the cooler (16) cools the gasified organic working medium into a liquid state.

6. The emergency shaft seal system for the main pump of a nuclear power plant according to claim 5, characterized in that: The organic working medium condensation pump (17) is capable of transporting the liquid organic working medium to the second end of the second steam generator (11) and into the interior of the organic working medium flow channel; A condensate pump outlet door (18) and a condensate pump outlet pressure gauge (19) are sequentially arranged between the organic working medium condensate pump (17) and the second steam generator (11).

7. The emergency shaft seal system for the main pump of a nuclear power plant according to claim 6, characterized in that: The condensation pump outlet gate (18) is connected to the organic working medium condensation pump (17) via a branch pipeline, the branch pipeline is communicated with the cooler (16), and a first circulation gate (26) is installed on the branch pipeline.

8. The emergency shaft seal system for the main pump of a nuclear power plant according to claim 7, characterized in that: The steam turbine (15) and the standby shaft seal pump (21) are connected via a transmission (20); The water pumping end of the standby shaft seal pump (21) is connected to the water tank (22), a return pipe is provided between the standby shaft seal pump (21) and the water tank (22), and a second circulation door (24) is installed on the return pipe.

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