Pressure stabilization system for nuclear power plant reactor coolant system gas venting

Abstract

The application provides a pressure stabilizing system for gas discharge of a reactor coolant system of a nuclear power plant, comprising a stabilizer and a gas treatment mechanism, the stabilizer is provided with at least one accident discharge pipeline, each of the accident discharge pipelines is sequentially provided with a flow limiting unit and an accident discharge valve along a medium flow direction; the gas treatment mechanism comprises a gas receiving pipeline and a receiving container, one end of the gas receiving pipeline is connected to an outlet end of the flow limiting unit, the other end is connected to the receiving container, and a pressure reducing valve is arranged on the gas receiving pipeline; wherein the receiving container maintains a constant temperature and pressure state during the process of discharging gas by the gas receiving pipeline.

Description

Technical Field

[0001] This invention relates to the field of reactor pressure stabilization technology, and more specifically to a pressure stabilization system for gas emissions from a nuclear power plant reactor coolant system. Background Technology

[0002] During the operation of a nuclear power plant reactor coolant system, hydrogen needs to be injected into the system to maintain the reducing state of the coolant and prevent oxidation and corrosion of metal components. During this process, some hydrogen will escape from the coolant and accumulate in the pressurizer steam space. Therefore, at the end of each fuel cycle and before reactor shutdown, the mixture of steam and hydrogen must be discharged through the pressurizer steam space to remove hydrogen.

[0003] In the existing technology, the mixed gas is usually directly discharged into a low-temperature and low-pressure venting container. However, due to the high temperature, high pressure and radioactivity of the discharged gas, it will quickly heat the venting container and cause its internal pressure to rise sharply. In order to prevent the container from overpressure, the discharge needs to be stopped frequently and restarted after the container returns to normal. This intermittent discharge mode is time-consuming and seriously reduces the availability of nuclear power plants, which has a significant adverse impact on the economics of operation.

[0004] Based on this, the inventors of this application propose a pressure stabilization system for gas emissions from a nuclear power plant reactor coolant system, in order to solve one or more of the aforementioned technical problems. Summary of the Invention

[0005] The present invention solves the above-mentioned technical problems through the following technical solution:

[0006] This invention provides a pressure stabilization system for gas emissions from a nuclear power plant reactor coolant system, comprising:

[0007] The voltage regulator is provided with at least one emergency discharge line, and each of the emergency discharge lines is provided with a flow limiting unit and an emergency discharge valve in sequence along the medium flow direction;

[0008] A gas handling mechanism includes a gas receiving pipeline and a receiving container. One end of the gas receiving pipeline is connected to the outlet of the flow-limiting unit, and the other end is connected to the receiving container. A pressure-reducing valve is provided on the gas receiving pipeline.

[0009] The receiving container maintains a constant temperature and pressure state during the gas discharge process of the gas receiving pipeline.

[0010] According to one embodiment of the present invention, the current limiting unit is a current limiter.

[0011] According to one embodiment of the present invention, the gas receiving pipeline is provided with a control valve upstream of the pressure reducing valve, and the control valve is used to control the on / off state of the gas receiving pipeline.

[0012] According to one embodiment of the present invention, the gas receiving pipeline is further provided with a gas isolation valve upstream of the control valve.

[0013] According to one embodiment of the present invention, the voltage regulator is provided with at least two parallel emergency discharge lines;

[0014] The gas receiving pipeline is provided with at least two branch pipelines upstream of the control valve. One end of each branch pipeline is connected to the outlet end of the flow limiting unit of the emergency discharge pipeline, and the other end flows into the control valve.

[0015] The gas isolation valves are installed one-to-one on each of the branch pipelines.

[0016] According to one embodiment of the present invention, the branch pipeline is connected to the emergency discharge pipeline downstream of the gas isolation valve via a diversion branch pipe.

[0017] According to one embodiment of the present invention, the receiving container is provided with coolant, and one end of the gas receiving pipe extends into the coolant;

[0018] The receiving container is equipped with a heat exchanger located below the coolant level. The heat exchanger continuously exchanges heat with the coolant through an external cooling medium to maintain a stable coolant temperature.

[0019] According to one embodiment of the present invention, the receiving container is further provided with a gas outlet pipe at the top, the gas outlet pipe being used to export cooled hydrogen and connect it to a gas processing system.

[0020] According to one embodiment of the present invention, the coolant is cooling water or cooling oil.

[0021] According to one embodiment of the present invention, the medium in the emergency discharge pipeline is a mixture of water vapor and hydrogen gas.

[0022] The positive and progressive effects of this invention are as follows:

[0023] This invention relates to a pressure stabilization system for gas emissions from reactor coolant systems in nuclear power plants. By installing a flow-limiting unit on the emergency discharge line of the pressurizer and a pressure-reducing valve on the gas receiving line, and by maintaining a constant temperature and pressure in the receiving container during gas emission, a synergistic mechanism of throttling, pressure reduction, and constant temperature and pressure reception is formed. This effectively solves the problem in existing technologies where direct emission of high-temperature and high-pressure mixed gases leads to a sudden pressure surge in the receiving container and requires repeated start-ups and shutdowns for emission. It achieves continuous and stable emission of gas from the reactor coolant system, significantly shortens the hydrogen removal operation time before major overhauls of nuclear power plants, and significantly improves the availability and operational economy of nuclear power plants. Attached Figure Description

[0024] The above and other features, properties and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings and embodiments, wherein:

[0025] Figure 1 This is a schematic diagram of the pressure stabilization system for gas emissions from a nuclear power plant reactor coolant system, as described in this invention.

[0026] 1. Voltage regulator; 11. Emergency discharge pipeline; 12. Flow limiting unit; 13. Emergency discharge valve;

[0027] 2. Gas handling mechanism; 21. Gas receiving pipeline; 22. Receiving container; 23. Pressure reducing valve; 24. Control valve; 25. Gas isolation valve; 26. Branch pipeline; 27. Diversion branch pipe; 28. Heat exchanger; 29. ​​Gas outlet pipe;

[0028] 3. Gas handling system. Detailed Implementation

[0029] The present invention will be further described below with reference to specific embodiments and accompanying drawings. More details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention can obviously be implemented in many other ways different from those described herein. Those skilled in the art can make similar extensions and derivations based on actual application situations without departing from the spirit of the present invention. Therefore, the scope of protection of the present invention should not be limited by the content of this specific embodiment.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0031] Currently, during the hydrogen removal process of the reactor coolant system in nuclear power plants, the direct discharge of high-temperature and high-pressure mixed gas presents technical challenges, including a sudden increase in the pressure of the receiving container and the need for repeated start-ups and shutdowns for discharge.

[0032] Based on this, please refer to Figure 1This application proposes a pressure stabilization system for gas emissions from a nuclear power plant reactor coolant system, comprising a pressurizer 1 and a gas handling mechanism 2. The pressurizer 1 is provided with at least one emergency discharge pipeline 11, and each emergency discharge pipeline 11 is provided with a flow limiting unit 12 and an emergency discharge valve 13 in sequence along the medium flow direction. The gas handling mechanism 2 includes a gas receiving pipeline 21 and a receiving container 22. One end of the gas receiving pipeline 21 is connected to the outlet end of the flow limiting unit 12, and the other end is connected to the receiving container 22. A pressure reducing valve 23 is provided on the gas receiving pipeline 21. The receiving container 22 maintains a constant temperature and pressure state during the gas emission process of the gas receiving pipeline 21.

[0033] This application forms a coordinated pressure reduction and stabilization mechanism by using the flow limiting unit 12 for initial throttling and the pressure reducing valve 23 for precise pressure regulation, combined with the constant temperature and pressure state maintained by the receiving container 22. This completely solves the drawback of intermittent discharge in the existing technology, thereby enabling the continuous and safe discharge of the mixed gas and significantly shortening the hydrogen removal time before the overhaul of the nuclear power plant.

[0034] Because hydrogen gas accumulates in the top space of the pressure regulator 1, one end of the emergency discharge pipe 11 is connected to the top of the pressure regulator 1. The connection method between the emergency discharge pipe 11 and the pressure regulator 1 can be socketing, welding, etc., and is not limited here.

[0035] Because the gas emitted by the nuclear power plant reactor system is a mixture of high-temperature and high-pressure water vapor and hydrogen, at least one flow-limiting unit 12 is installed on each emergency discharge pipeline 11. The flow-limiting unit 12 can initially throttle the mixed gas, reduce the gas flow rate and pressure, lay the foundation for the precise pressure regulation of the downstream pressure reducing valve 23, avoid the high-pressure gas from directly impacting the downstream pipelines and components, and ensure the stability of the system pressure regulation.

[0036] Moreover, when downstream valves (such as gas isolation valve 25 and control valve 24) are accidentally opened or leak, the flow limiting unit 12 can reduce the loss of coolant and gas in the pressurizer 1 by limiting the flow orifice or adjusting the throttling degree, maintain the pressure in the pressurizer 1 within a safe range, avoid the normal operation of the reactor coolant system due to sudden pressure drop, and at the same time enhance the protection effect of the reactor coolant pressure boundary, adapting to the high safety standards of nuclear power plants.

[0037] Optionally, the flow limiting unit 12 can be a flow restrictor. In some other alternative embodiments, the flow limiting unit 12 can also be a throttling orifice plate, a throttling valve, a venturi throttling device, or a multi-hole flow restrictor, etc., which are not limited here.

[0038] Emergency discharge valve 13 is used to control the opening and closing of emergency discharge pipeline 11. One emergency discharge valve 13 can be installed on each emergency discharge pipeline 11, or two or three valves can be installed. Figure 1Two examples are used for illustration, but the specific number is not limited here. Under normal system conditions, the emergency discharge valve 13 is in the closed state, which can isolate the emergency discharge pipeline 11 from the downstream pipeline and ensure the pressure boundary integrity of the reactor coolant system.

[0039] The gas receiving pipeline 21 is connected at one end to the outlet end of the flow limiting unit 12, so it is used to receive the high temperature and high pressure mixed gas after being throttled by the flow limiting unit 12 and transport it to the receiving container 22.

[0040] By further installing a pressure reducing valve 23 on the gas receiving pipeline 21, the gas pressure delivered to the receiving container 22 can be adjusted to a suitable range, preventing high-pressure gas from directly entering the receiving container 22 and causing a sudden pressure increase. Moreover, the pressure reducing valve 23 can stabilize the pressure inside the gas receiving pipeline 21, preventing sudden changes in gas flow or volume caused by pressure fluctuations in the gas receiving pipeline 21, ensuring that the mixed gas can be continuously and evenly delivered to the receiving container 22, thus enabling continuous hydrogen removal in conjunction with the receiving container 22.

[0041] Furthermore, a control valve 24 is provided on the gas receiving pipeline 21, which is used to control the opening and closing of the gas receiving pipeline 21.

[0042] The number of emergency discharge pipes 11 can be one, two, three, or more, and there is no limitation here. If the number of emergency discharge pipes 11 is at least two, then the at least two emergency discharge pipes 11 shall be arranged in parallel.

[0043] When there is only one emergency discharge line 11, the gas receiving line 21 is an independent pipeline. However, when there are at least two gas receiving lines 21, at least two branch lines 26 are provided upstream of the control valve 24 for the gas receiving line 21, and all the branch lines 26 converge at one end and are respectively connected to the outlet end of the flow limiting unit 12 of the corresponding emergency discharge line.

[0044] Optionally, each branch pipe 26 is equipped with a control gas isolation valve 25, which is located upstream of the control valve 24. The control gas isolation valve 25 is used to control the on / off state of the corresponding branch pipe 26.

[0045] As can be seen, under normal system operation, both the control gas isolation valve 25 and the control valve 24 are closed, forming a double isolation structure. This effectively isolates the reactor coolant system from the gas receiving pipeline 21, preventing radioactive gas leakage and ensuring the integrity of the pressure boundary. Under gas emission conditions, both valves can be opened separately according to hydrogen removal requirements, providing a safe flow path for the mixed gas after throttling by the flow limiting unit 12.

[0046] In one embodiment, branch line 26 is connected to emergency discharge line 11 downstream of control gas isolation valve 25 via diversion branch line 27.

[0047] like Figure 1 As shown, for safety redundancy, two emergency discharge valves 13 are provided on the emergency discharge pipeline 11. One end of the branch pipe 27 is connected to the pipe section between the two emergency discharge valves 13, and the other end is connected to the branch pipe 26 downstream of the control gas isolation valve 25.

[0048] By setting up the branch pipe 27, the mixed gas in the pressurizer 1 can either be throttled by the flow limiting unit 12 before entering the branch pipe 26, or it can directly enter the branch pipe 26 without throttling. Thus, when the flow limiting unit 12 fails, the mixed gas can be transported to the receiving container 22 through the branch pipe 27, avoiding emission interruption due to a single throttling path failure and meeting the safety requirements of nuclear power plants for multiple redundancy and fault tolerance. Furthermore, because there are two emergency emission valves 13 on the emergency emission pipeline 11, when the mixed gas is transported using the branch pipe 27, the upstream emergency emission valve 13 is open, while the downstream emergency emission valve 13 is closed.

[0049] Please continue to refer to Figure 1 The receiving container 22 is filled with coolant, and one end of the gas receiving pipe 21 extends into the coolant. The receiving container 22 is equipped with a heat exchanger 28 located below the coolant level. The heat exchanger 28 continuously exchanges heat with the coolant through an external cooling medium to maintain a stable coolant temperature.

[0050] The coolant in the receiving container 22 can quickly condense the water vapor in the mixed gas, reducing the gas volume and temperature, and initially stabilizing the container pressure. The heat exchanger 28 below the liquid level continuously exchanges heat through the external cooling medium, which can maintain the coolant temperature stably, thereby avoiding pressure fluctuations caused by the coolant temperature rise and achieving long-term maintenance of the constant temperature and pressure state of the receiving container 22.

[0051] Furthermore, the top of the receiving container 22 is also provided with a gas outlet pipe 29, which is used to export the cooled hydrogen and connect it to the gas processing system 3.

[0052] The cooled hydrogen gas can be promptly discharged to the dedicated gas treatment system 3 through the gas outlet pipe 29 at the top of the receiving container 22, preventing the hydrogen gas from accumulating in the container and causing the pressure to exceed the limit, and ensuring the stable constant temperature and pressure state of the receiving container 22.

[0053] It can also achieve effective separation of hydrogen and condensate, which facilitates subsequent purification, recovery or compliant emission of hydrogen, meets the environmental protection and safety standards for radioactive gas treatment in nuclear power plants, and improves the integrity and compliance of the system.

[0054] Alternatively, the coolant may be cooling water or cooling oil.

[0055] Cooling water or cooling oil are both widely available, inexpensive, heat-resistant, and chemically stable media, making them suitable for the high-temperature, high-pressure, and radioactive environments of nuclear power plants. Cooling water or cooling oil can efficiently condense water vapor in the gas mixture and, in conjunction with heat exchanger 28, achieve continuous cooling, thus ensuring stable and reliable cooling performance.

[0056] In summary, compared with the prior art, this application has at least the following beneficial effects:

[0057] This application constructs a collaborative gas emission path through a flow-limiting unit 12, a control gas isolation valve 25, a control valve 24, a pressure-reducing valve 23, and a receiving container 22 with a heat exchanger 28. It adopts an integrated design of successive throttling, precise pressure regulation, and continuous cooling. The flow-limiting unit 12 achieves initial throttling of high-temperature and high-pressure steam and pressure protection of the pressure regulator 1 in case of accidental opening of downstream valves. The pressure-reducing valve 23 stabilizes the outlet pressure to ensure continuous gas flow. Combined with the condensation effect of the coolant in the receiving container 22 and the continuous cooling of the heat exchanger 28, it effectively solves the problem in the prior art of high-temperature and high-pressure mixed gas emission causing a sudden pressure rise in the receiving container 22 and requiring repeated start-stop emission. It realizes continuous and safe emission of gas from the reactor coolant system, significantly shortens the hydrogen removal time before nuclear power plant overhaul, and significantly improves the availability and operating economy of nuclear power plants.

[0058] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical terms such as "installation", "connection", "joining", and "fixing" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can also refer to mechanical connections. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0059] This application uses specific terms to describe embodiments of the application. Terms such as "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic associated with at least one embodiment of the application. Therefore, it should be emphasized and noted that references to "an embodiment," "one embodiment," or "an alternative embodiment" in different locations throughout this specification do not necessarily refer to the same embodiment. Furthermore, certain features, structures, or characteristics in one or more embodiments of the application can be appropriately combined.

[0060] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any variations and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the invention, fall within the protection scope defined by the claims of the present invention.

Claims

1. A pressure stabilization system for gas emissions from a reactor coolant system in a nuclear power plant, characterized in that, include: The voltage regulator is provided with at least two parallel emergency discharge lines, and each of the emergency discharge lines is provided with a flow limiting unit and an emergency discharge valve in sequence along the medium flow direction; A gas handling mechanism includes a gas receiving pipeline and a receiving container. One end of the gas receiving pipeline is connected to the outlet of the flow-limiting unit, and the other end is connected to the receiving container. A pressure-reducing valve is provided on the gas receiving pipeline. The receiving container maintains a constant temperature and pressure state during the gas discharge process in the gas receiving pipeline. The gas receiving pipeline is equipped with a control valve upstream of the pressure reducing valve, and the control valve is used to control the opening and closing of the gas receiving pipeline; The gas receiving pipeline is also equipped with a gas isolation valve upstream of the control valve; The gas receiving pipeline is provided with at least two branch pipelines upstream of the control valve. One end of each branch pipeline is connected to the outlet end of the flow limiting unit of the emergency discharge pipeline, and the other end flows to the control valve. The gas isolation valves are correspondingly provided on each of the branch pipelines. The branch pipeline is connected to the emergency discharge pipeline downstream of the gas isolation valve via a diversion branch pipe; The receiving container is pre-filled with coolant, and one end of the gas receiving pipeline extends into the coolant. The receiving container is equipped with a heat exchanger located below the coolant level. The heat exchanger continuously exchanges heat with the coolant through an external cooling medium to maintain the coolant temperature stable.

2. The pressure stabilization system for gas emissions from a nuclear power plant reactor coolant system according to claim 1, characterized in that, The current limiting unit is a current limiter.

3. The pressure stabilization system for gas emissions from a nuclear power plant reactor coolant system according to claim 1, characterized in that, The receiving container is also equipped with a gas outlet pipe at the top, which is used to export the cooled hydrogen gas and connect it to the gas processing system.

4. The pressure stabilization system for gas emissions from a nuclear power plant reactor coolant system according to claim 1, characterized in that, The coolant is either cooling water or cooling oil.

5. The pressure stabilization system for gas emissions from a nuclear power plant reactor coolant system according to claim 1, characterized in that, The medium in the accident discharge pipeline is a mixture of water vapor and hydrogen gas.

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