Online removal system and removal method for dissolved nitrogen in primary loop of nuclear power plant

Abstract

The invention provides a nuclear power plant primary loop dissolved nitrogen online removal system and removal method, and relates to the technical field of nuclear power plant emission purification. Comprising a carrier gas supply unit, a gas-liquid mixing device, a gas separator, a first pipeline, an exhaust pipeline and a gas supply pipeline. The carrier gas supply unit supplies carrier gas into the online dissolved nitrogen removal system; the gas-liquid mixing device comprises a liquid inlet, a gas inlet and a mixed outlet; the gas separator is connected with a mixing outlet of the gas-liquid mixing device and is used for separating carrier gas and a coolant in a gas-liquid mixture; the first pipeline is connected with the gas phase space and a gas inlet of the gas-liquid mixing device, so that the gas phase space supplies carrier gas into the gas-liquid mixing device; the exhaust pipeline is connected with the gas phase space so as to exhaust the carrier gas mixed with nitrogen when a preset threshold value is reached; and the gas supply pipeline is connected with the carrier gas supply unit, so that the carrier gas supply unit supplies the carrier gas. The coolant flow is obviously larger than the exhaust flow of the pressure stabilizer, and the removal effect of dissolved nitrogen is improved.

Description

An online dissolved nitrogen removal system and method for the primary loop of a nuclear power plant Technical Field

[0001] This application relates to the field of nuclear power plant emission purification technology, and in particular to an online dissolved nitrogen removal system and method for the primary loop of a nuclear power plant. Background Technology

[0002] Nuclear power plant operation generates the radioactive isotope C-14, a long-lived radioactive isotope with a half-life of up to 5730 years. As nuclear power plants expand, their environmental impact accumulates. Strict requirements govern C-14 emissions from nuclear power plants, with clear control limits on C-14 emissions from single-reactor effluents and total effluents from multiple reactor sites. With the widespread construction of multiple reactor sites, controlling C-14 emissions has become an increasingly important and critical aspect of site environmental impact assessments.

[0003] The main source of C-14 in reactor coolant is the activation of N-14 and O-17 atoms in the coolant by neutrons, which then produce C-14 with a certain probability. Currently, there are no effective engineering measures to control the abundance of O-17 in the coolant. Therefore, to solve this problem and optimize the design value of C-14 emissions, the control process of dissolved nitrogen concentration in the primary loop has become a key technology.

[0004] Some nuclear power plants have a continuous venting line installed above the pressurizer of the reactor coolant system (RCP). Dissolved nitrogen from the primary loop is precipitated in the gas phase of the pressurizer during spraying and discharged along with water vapor through the continuous venting line. The pressurizer continuous venting line is located on the pressure boundary of the primary loop, where the pressure and temperature are very high during normal operation. Its design requirements are high and the design is difficult. Moreover, its venting flow rate is generally small, and its effect on removing dissolved nitrogen from the primary loop is limited. Summary of the Invention

[0005] This application provides an online dissolved nitrogen removal system and method for the primary loop of a nuclear power plant to solve the technical problem of poor dissolved nitrogen removal effect in existing primary loops.

[0006] The first aspect of this application provides an online dissolved nitrogen removal system for the primary loop of a nuclear power plant, the online dissolved nitrogen removal system for the primary loop of a nuclear power plant includes a carrier gas supply unit, a gas-liquid mixing device, a gas separator, a first pipeline, an exhaust pipeline and a gas supply pipeline. A carrier gas supply unit supplies carrier gas to the dissolved nitrogen online removal system; a gas-liquid mixing device includes a liquid inlet, a gas inlet, and a mixing outlet. The liquid inlet is configured to connect to the coolant in the reactor coolant system, and the gas inlet is configured to connect to the carrier gas. The gas-liquid mixing device is configured to mix the carrier gas and coolant to form a gas-liquid mixture, thereby precipitating dissolved nitrogen from the coolant into the carrier gas; a gas separator is connected to the mixing outlet of the gas-liquid mixing device. The gas separator includes a gas phase space and a liquid phase space to separate the carrier gas from the coolant in the gas-liquid mixture; a first pipeline connects the gas phase space to the gas inlet of the gas-liquid mixing device, so that the gas phase space supplies carrier gas to the gas-liquid mixing device; an exhaust pipeline is connected to the gas phase space to discharge the carrier gas mixed with nitrogen when a preset threshold is reached; and a gas supply pipeline is connected to the carrier gas supply unit, so that the carrier gas supply unit supplies carrier gas.

[0007] The removal system can be installed in the drain line of the reactor cooling system. Compared with the process of removing dissolved nitrogen from the primary loop through the continuous exhaust line of the pressurizer, the component of this application maintains lower pressure and temperature during normal operation, with lower design requirements and less design difficulty. Moreover, the coolant flow rate of the drain line is significantly greater than that of the pressurizer exhaust flow rate, which not only improves the removal effect of dissolved nitrogen but also effectively reduces costs, showing significant advantages in terms of economy and effectiveness.

[0008] In an exemplary embodiment of this application, a gas supply pipeline connects a carrier gas supply unit to a gas phase space, so that the carrier gas supply unit supplies carrier gas to the gas phase space.

[0009] The carrier gas supply unit supplies carrier gas directly into the gas phase space through the gas supply pipeline. When the carrier gas in the carrier gas circulation system needs to be discharged and replaced, the carrier gas supply unit injects carrier gas into the gas phase space, which can replace and discharge the carrier gas in the gas phase space as much as possible, thereby improving the efficiency and effect of carrier gas renewal.

[0010] In an exemplary embodiment of this application, the gas-liquid mixing device includes a plurality of mixing elements arranged along the flow channel of the gas-liquid mixing device.

[0011] By incorporating multiple mixing elements, the gas-liquid mixture is thoroughly mixed, improving the mixing effect. As the carrier gas and coolant flow along the flow channel of the gas-liquid mixing device, they pass through multiple mixing elements. On one hand, the mixing elements break down the carrier gas into tiny bubbles, increasing the gas-liquid contact area. Dissolved nitrogen in the coolant precipitates into these tiny bubbles, thereby reducing the dissolved nitrogen content in the coolant. On the other hand, the mixing elements can change the flow direction of the coolant and carrier gas, ensuring thorough mixing and effectively precipitating dissolved nitrogen from the coolant.

[0012] In an exemplary embodiment of this application, the mixing element includes at least one first mixing element and at least one second mixing element, with the first mixing element and the second mixing element being alternately arranged.

[0013] In an exemplary embodiment of this application, the hybrid element is composed of a plurality of corrugated sheets stacked together, with the crests and troughs of the cross sections of adjacent corrugated sheets corresponding one-to-one, so as to form a channel between adjacent corrugated sheets.

[0014] The narrow, curved channels formed between adjacent corrugated sheets can break down the carrier gas into tiny bubbles and allow the tiny bubbles to mix thoroughly with the coolant.

[0015] In an exemplary embodiment of this application, the plane on which the corrugated sheet of the first hybrid element is located is perpendicular to the plane on which the corrugated sheet of the second hybrid element is located.

[0016] For example, the plane where the corrugated sheet of the first mixing element is located is perpendicular to the horizontal plane, and the plane where the corrugated sheet of the second mixing element is located is parallel to the horizontal plane. The first mixing element can not only break the carrier gas into tiny bubbles, but also guide the bubbles to the bottom of the gas-liquid mixing device, making the gas-liquid mixing more uniform.

[0017] In an exemplary embodiment of this application, the first pipeline includes a suction pump to pump the carrier gas in the gas phase space to the gas-liquid mixing device.

[0018] In an exemplary embodiment of this application, the gas phase space is located above the liquid phase space, and the first pipeline is connected to the upper part of the gas phase space.

[0019] In an exemplary embodiment of this application, an exhaust pipe is connected to a first pipe, and an exhaust regulating valve and an exhaust isolation valve are provided on the exhaust pipe. The exhaust regulating valve and the exhaust isolation valve open when a preset threshold is reached.

[0020] When the preset threshold is reached, the carrier gas in the removal system can be discharged by opening the exhaust isolation valve and the exhaust regulating valve to replace it with a purer carrier gas, thus ensuring the precipitation effect of dissolved nitrogen in the coolant.

[0021] In an exemplary embodiment of this application, the preset threshold includes a preset time threshold and / or a preset nitrogen content threshold in the carrier gas.

[0022] The preset threshold can be a preset time threshold or a preset nitrogen content threshold in the carrier gas. The preset threshold can also include both the preset time threshold and the preset nitrogen content threshold in the carrier gas. The venting operation is based on whichever comes first, thereby effectively ensuring the carrier gas's effect on the precipitation of dissolved nitrogen in the coolant, reducing the concentration of dissolved nitrogen, reducing the probability of activation and generation of radioactive nuclide C-14, ensuring safe emission, and improving environmental safety.

[0023] In an exemplary embodiment of this application, the outlet of the liquid phase space is connected to the reactor coolant system to inject coolant that has released dissolved nitrogen into the reactor coolant system.

[0024] In an exemplary embodiment of this application, the carrier gas includes one or more of hydrogen, helium, and argon.

[0025] In an exemplary embodiment of this application, the gas supply pipeline includes a supply regulating valve and a supply isolation valve; when the carrier gas includes hydrogen, the supply regulating valve maintains a preset opening degree.

[0026] When hydrogen is mixed with the coolant as a carrier gas, on the one hand, the tiny bubbles of hydrogen can precipitate dissolved nitrogen from the coolant, allowing the dissolved nitrogen to separate from the coolant along with the hydrogen; on the other hand, some hydrogen will mix into the coolant as a dissolved gas, resulting in hydrogen consumption. Maintaining a preset opening degree by the supply regulating valve allows for continuous replenishment of hydrogen, ensuring sufficient carrier gas and guaranteeing its denitrification effect on the coolant.

[0027] The second aspect of this application provides an online method for removing dissolved nitrogen in the primary loop of a nuclear power plant. The method includes: mixing carrier gas with coolant from the reactor coolant system through a gas-liquid mixing device to form a gas-liquid mixture; separating the carrier gas and coolant from the gas-liquid mixture into a gas phase space and a liquid phase space, respectively, through a gas separator; re-injecting the carrier gas from the gas phase space into the gas-liquid mixing device; and discharging the coolant from the liquid phase space into the reactor coolant system.

[0028] The gas-liquid mixing device can break down the carrier gas into tiny bubbles, increasing the gas-liquid contact area between the carrier gas and the coolant. On the other hand, the gas-liquid mixing device ensures that the carrier gas and coolant are fully mixed, allowing dissolved nitrogen in the coolant to precipitate into the tiny bubbles of the carrier gas. This reduces the dissolved nitrogen in the coolant, lowers the nitrogen concentration in the primary loop, reduces the emission of radioactive nuclide C-14 generated by its activation, improves emission safety, and is beneficial to ecological and environmental safety.

[0029] In an exemplary embodiment of this application, the carrier gas includes hydrogen, and the method includes: continuously injecting carrier gas into the gas phase space through a carrier gas supply unit.

[0030] When hydrogen is mixed with the coolant as a carrier gas, on the one hand, the tiny bubbles of hydrogen can precipitate dissolved nitrogen from the coolant, allowing the dissolved nitrogen to separate from the coolant along with the hydrogen; on the other hand, some hydrogen will mix into the coolant as a dissolved gas, resulting in hydrogen consumption. Maintaining a preset opening degree by the supply regulating valve allows for continuous replenishment of hydrogen, ensuring sufficient carrier gas and guaranteeing its denitrification effect on the coolant.

[0031] In an exemplary embodiment of this application, a carrier gas mixed with nitrogen is discharged from the gas phase space when a preset threshold is reached. The preset threshold includes a preset time threshold and / or a nitrogen content threshold in the carrier gas.

[0032] The preset threshold can be a preset time threshold. For example, the exhaust isolation valve and exhaust regulating valve on the exhaust pipeline open after the removal system has been running for a certain period of time to discharge the carrier gas containing more nitrogen.

[0033] During normal power operation of a nuclear power plant, the dissolved nitrogen concentration in the reactor coolant is low, resulting in a small amount of nitrogen being released through the removal system described in this application. The gas phase of the gas separator requires a relatively long time to accumulate a certain percentage of nitrogen. The exhaust regulating valve and exhaust isolation valve on the exhaust pipeline are manually opened periodically by the operator based on operational experience, for example, once a week, once every two weeks, or once a month. Specific preset time thresholds can be determined or calculated based on operational experience. By opening the exhaust regulating valve and exhaust isolation valve, nitrogen in the carrier gas is discharged, thereby reducing the dissolved nitrogen concentration in the primary loop. After venting is completed, the carrier gas supply unit automatically replenishes new carrier gas based on the liquid level in the liquid phase space of the gas separator, initiating the next cycle of dissolved nitrogen release and accumulation.

[0034] During nuclear power plant startup, there is a significant amount of residual gas in the reactor coolant. Considering the large flow rate of the released coolant, this removal system can quickly remove the dissolved gases. At this time, the opening frequency of the exhaust regulating valve and exhaust isolation valve in the exhaust pipeline can be adjusted to increase the number of exhausts, for example, once every 1-2 hours. This rapidly removes residual nitrogen from the reactor coolant, reducing the dissolved nitrogen concentration in the primary loop and significantly decreasing the probability of its activation and generation of radioactive nuclide C-14. Under certain circumstances, the exhaust regulating valve can also be preset to a certain opening for continuous exhaust to ensure continuous renewal of the carrier gas and reduce the nitrogen content in the carrier gas.

[0035] During the primary circuit water replacement or makeup water process in a nuclear power plant, considering the dissolved nitrogen introduced into the makeup water, an venting operation can be added after makeup water to ensure that the dissolved nitrogen in the reactor coolant can be discharged in a timely manner, thereby reducing the concentration of dissolved nitrogen in the primary circuit and significantly reducing the probability of its activation and generation of radioactive nuclide C-14.

[0036] The preset threshold can also be a preset threshold for nitrogen content in the carrier gas, such as a preset nitrogen content of 5% to 10%. When the nitrogen content in the carrier gas reaches the preset threshold, the exhaust regulating valve and exhaust isolation valve on the exhaust pipeline will open, thereby realizing the renewal of the carrier gas, ensuring that residual nitrogen in the reactor coolant can be released, reducing the dissolved nitrogen concentration in the primary loop, and thus greatly reducing the probability of its activation to produce radioactive nuclide C-14.

[0037] Of course, in some embodiments, the preset threshold may also include a preset time threshold and a preset nitrogen content threshold in the carrier gas. The first of the preset time threshold and the preset nitrogen content threshold in the carrier gas shall be used for exhaust operation, thereby effectively ensuring the effect of the carrier gas on the precipitation of dissolved nitrogen in the coolant, reducing the concentration of dissolved nitrogen, reducing the probability of activation and generation of radioactive nuclide C-14, ensuring safe emission, and improving environmental safety.

[0038] The opening and closing of the exhaust isolation valve and the exhaust regulating valve can be done manually by the operator or automatically by the system control.

[0039] The advantages of this application, based on existing technologies, are as follows: Existing nuclear power plant reactor coolant systems discharge nitrogen along with steam via continuous exhaust lines; however, this results in low exhaust flow, complex design, and limited removal of dissolved nitrogen. The dissolved nitrogen online removal system of this application, under the action of a gas-liquid mixing device, breaks down the carrier gas into microbubbles, significantly increasing the gas-liquid contact area, thereby causing dissolved nitrogen in the coolant to precipitate into the carrier gas bubbles. A gas separator separates the nitrogen-containing carrier gas into the gas phase space, and the carrier gas in the gas phase space is then transported back to the gas-liquid mixing device, achieving carrier gas reuse.

[0040] The dissolved nitrogen online removal system of this application is installed on the drain line of the reactor coolant system, where the coolant flow rate is significantly greater than the pressurizer exhaust flow rate, resulting in a significant improvement in dissolved nitrogen removal efficiency. During normal operation, the system operates at lower pressure and temperature compared to the pressurizer system, requiring less design effort and reducing costs, thus demonstrating significant advantages in both economy and effectiveness. Attached Figure Description

[0041] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0042] In the accompanying drawings: Figure 1 is a schematic diagram of the principle of an online dissolved nitrogen removal system for the primary loop of a nuclear power plant provided in an embodiment of this application; Figure 2 is a schematic diagram of an online dissolved nitrogen removal method for the primary loop of a nuclear power plant provided in an embodiment of this application.

[0043] The reference numerals in the attached drawings are as follows: 100, gas-liquid mixing device; 200, gas separator; 300, first pipeline; 310, suction pump; 400, exhaust pipeline; 500, gas supply pipeline. Detailed Implementation

[0044] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0045] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. The drawings only show the components related to this application and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0046] In the following description, numerous details are explored to provide a more thorough explanation of embodiments of the present application. However, it will be apparent to those skilled in the art that embodiments of the present application may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the present application.

[0047] It should be noted that the terms such as "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity of description and are not intended to limit the scope of this application. Any changes or adjustments to their relative relationships, without substantially altering the technical content, shall also be considered as part of the scope of this application.

[0048] In existing nuclear power plant reactor coolant systems, a continuous venting line is installed on the upper part of the pressurizer. Dissolved nitrogen in the primary loop is precipitated in the gas phase of the pressurizer during spraying and discharged along with water vapor through the continuous venting line. However, the pressurizer continuous venting line is located on the pressure boundary of the primary loop, and the pressure and temperature are very high during normal operation. Its design requirements are high and the design is difficult. Moreover, its venting flow rate is generally small, and its removal effect on dissolved nitrogen in the primary loop is limited (see Figure 1). In view of this, the first aspect of this application provides an online dissolved nitrogen removal system for the primary loop of a nuclear power plant. The online dissolved nitrogen removal system for the primary loop of a nuclear power plant includes a carrier gas supply unit, a gas-liquid mixing device 100, a gas separator 200, a first pipeline 300, an venting pipeline 400, and a gas supply pipeline 500.

[0049] The carrier gas supply unit supplies carrier gas to the dissolved nitrogen online removal system. Dissolved nitrogen in the coolant can precipitate into the bubbles of the carrier gas, and thus the dissolved nitrogen in the coolant is separated by the carrier gas and nitrogen together. The carrier gas supply unit can directly supply carrier gas to the gas-liquid mixing device 100, or it can first supply carrier gas to the gas phase space of the gas separator 200, and then supply carrier gas to the gas-liquid mixing device 100 through the gas phase space of the gas separator 200. Of course, the carrier gas supply unit can also be connected to other locations in the removal system to supply carrier gas to the gas-liquid mixing device 100 or the gas separator 200.

[0050] The gas-liquid mixing device 100 is used to mix the carrier gas and coolant to form a gas-liquid mixture. Through sufficient contact between the carrier gas and coolant, dissolved nitrogen is precipitated into the bubbles formed by the carrier gas. The gas-liquid mixing device 100 includes a liquid inlet, a gas inlet, and a mixing outlet. The liquid inlet is used to connect the coolant to the reactor coolant system, and the gas inlet is used to connect the carrier gas. After the coolant and carrier gas enter the gas-liquid mixing device 100, they are dispersed and mixed by the device, achieving sufficient contact between the coolant and the carrier gas.

[0051] For example, the liquid inlet and the gas inlet can be provided on the body of the gas-liquid mixing device 100, or they can be provided on the extension pipeline of the gas-liquid mixing device 100. In other words, the coolant and the carrier gas are injected into the body of the gas-liquid mixing device 100 after initial mixing in the extension pipeline.

[0052] For example, the liquid inlet is connected to the drain pipe of the reactor cooling system via a connecting flange. The liquid inlet can also be connected to the drain pipe of the reactor cooling system via other connection methods so that the coolant in the reactor cooling system can be injected into the gas-liquid mixing device 100.

[0053] For example, the gas inlet is connected to the gas supply line 500 of the gas-liquid mixing device 100 via a connecting flange. The gas inlet can also be connected to the gas supply line 500 via other connection methods to supply carrier gas into the gas-liquid mixing device 100.

[0054] In some embodiments, the gas inlet extends into the inner cavity of the gas-liquid mixing device 100 and bends along the flow channel of the gas-liquid mixing device 100 to facilitate the flow of the carrier gas along the flow channel of the gas-liquid mixing device 100, which is beneficial to the thorough mixing of the carrier gas and the coolant.

[0055] In other embodiments, the gas inlet is inserted obliquely into the gas-liquid mixing device 100, and the gas inlet is inclined downwards towards the flow channel of the gas-liquid mixing device 100. The carrier gas enters the gas-liquid mixing device 100 at an angle downwards, which on the one hand allows the carrier gas to move along the flow channel of the gas-liquid mixing device 100, and on the other hand allows the carrier gas to quickly fill the longitudinal space of the gas-liquid mixing device 100. At the same time, the inclined arrangement of the gas inlet can also meet different layout requirements.

[0056] The mixing outlet is used to discharge the gas-liquid mixture of carrier gas and coolant in the gas-liquid mixing device 100. The gas-liquid mixture flows into the gas separator 200 to separate the carrier gas from the coolant, thereby separating dissolved nitrogen in the coolant and reducing the dissolved nitrogen content in the coolant.

[0057] The gas separator 200 is connected to the mixing outlet of the gas-liquid mixing device 100. The gas separator 200 and the gas-liquid mixing device 100 can be connected by a flange or by other connection structures to achieve communication between the gas separator 200 and the gas-liquid mixing device 100. The gas separator 200 receives the gas-liquid mixture of carrier gas and coolant flowing out of the gas-liquid mixing device 100.

[0058] The gas separator 200 includes a gas phase space and a liquid phase space to separate the carrier gas from the coolant phase in the gas-liquid mixture. The gas phase space is used to contain the carrier gas, which is repeatedly injected into the gas-liquid mixing unit 100 via the gas phase space to remove dissolved nitrogen from the coolant. The liquid phase space is used to contain the coolant, and the coolant with reduced dissolved nitrogen content is reinjected into the reactor coolant system.

[0059] For example, the gas separator 200 can be a two-phase separator, which can be a horizontal or vertical pressure vessel, wherein the gas phase space is located above the liquid phase space, so that the carrier gas floats above the coolant.

[0060] Of course, the gas separator 200 can also be other separators that can separate the carrier gas from the coolant, thereby reducing the dissolved nitrogen content in the coolant.

[0061] The first pipeline 300 connects the gas phase space to the gas inlet of the gas-liquid mixing device 100, so that the gas phase space supplies carrier gas into the gas-liquid mixing device 100.

[0062] The first pipeline 300 includes the necessary pipes and interfaces that need to be set up as required to meet the layout of different sites.

[0063] The gas supply line 500 is connected to the carrier gas supply unit so that the carrier gas supply unit supplies carrier gas. One end of the gas supply line 500 is connected to the carrier gas supply unit, and the other end is connected to the carrier gas in the circulation loop of the removal system so that the carrier gas supply unit supplies gas to the circulation loop of the removal system.

[0064] For example, the other end of the supply line can be connected to the first line 300 to inject carrier gas into the gas-liquid mixing device 100 using the first line 300; the other end of the supply line can also be connected to the gas phase space of the gas separator 200 to inject carrier gas into the circulation loop of the carrier gas.

[0065] The online dissolved nitrogen removal system for the primary loop of a nuclear power plant disclosed in this application can be installed in the drain line of the reactor cooling system. Compared with the process of removing dissolved nitrogen from the primary loop through the continuous exhaust line of the pressurizer, the components of this application maintain lower pressure and temperature values ​​during normal operation, have lower design requirements and less design difficulty, and the coolant flow rate of the drain line is significantly greater than that of the pressurizer exhaust flow rate, which not only improves the dissolved nitrogen removal effect but also effectively reduces costs, showing significant advantages in terms of economy and effectiveness.

[0066] In some embodiments, the gas supply line 500 connects the carrier gas supply unit to the gas phase space, so that the carrier gas supply unit supplies carrier gas into the gas phase space.

[0067] The carrier gas supply unit supplies carrier gas directly into the gas phase space through the gas supply pipeline 500. When the carrier gas in the carrier gas circulation system needs to be discharged and replaced, the carrier gas supply unit injects carrier gas into the gas phase space, which can replace and discharge the carrier gas in the gas phase space as much as possible, thereby improving the efficiency and effect of carrier gas renewal.

[0068] Of course, as an alternative, the supply line can also be connected to other locations in the carrier gas circulation system to replenish the carrier gas in the system.

[0069] For example, the carrier gas supplied by the carrier gas supply unit can be hydrogen, argon, helium, etc. The carrier gas can be a single gas, such as one of hydrogen, argon, and helium; the carrier gas can also be a mixture of multiple gases, such as two or more of hydrogen, argon, and helium.

[0070] In some embodiments, the gas supply line 500 includes a supply regulating valve and a supply isolation valve. The supply regulating valve and the supply isolation valve are used to adjust the amount of carrier gas supplied to the dissolved nitrogen removal system.

[0071] When hydrogen is included as the carrier gas, the supply regulating valve is maintained at a preset opening. When hydrogen is mixed with the coolant as the carrier gas, on the one hand, the tiny bubbles in the hydrogen can precipitate dissolved nitrogen from the coolant, allowing the dissolved nitrogen to separate from the coolant along with the hydrogen; on the other hand, some hydrogen will mix into the coolant as a dissolved gas, leading to hydrogen consumption. Maintaining the preset opening of the supply regulating valve allows for continuous replenishment of hydrogen, ensuring sufficient carrier gas and guaranteeing the carrier gas's denitrification effect on the coolant.

[0072] The preset opening degree of the supply regulating valve is determined based on the amount of hydrogen consumed. The amount of hydrogen consumed is positively correlated with the flow rate of the coolant. The preset opening degree of the supply regulating valve can be obtained through calculation or experimentation.

[0073] The supply isolation valve remains open to ensure the supply of hydrogen. When maintenance or special circumstances require the supply to be stopped, the supply isolation valve is closed.

[0074] Of course, as an alternative, when hydrogen is used as the carrier gas, the supply regulating valve can also be kept closed. When the total flow rate of the coolant reaches the threshold or the carrier gas usage time reaches the threshold, the supply regulating valve will open to supplement hydrogen, so as to ensure that hydrogen is used as a carrier to remove dissolved nitrogen from the coolant.

[0075] As some alternatives, when the carrier gas does not include hydrogen, the supply regulating valve and the supply isolation valve can be kept normally closed and opened as needed; the supply regulating valve can also be kept at a certain opening degree according to the amount of loss.

[0076] In some embodiments, the first line 300 includes a suction pump 310, which provides power to the first line 300 to pump carrier gas in the gas phase space to the gas-liquid mixing device 100.

[0077] For example, the first pipe 300 is connected to the gas phase space of the gas separator 200 via a flange. The first pipe 300 can be connected to the top of the gas separator 200 so that the carrier gas enters the first pipe 300 while reducing the risk of coolant entering the first pipe 300.

[0078] For example, the first pipeline 300 is connected to the gas inlet of the gas-liquid mixing device 100 via a flange.

[0079] The exhaust pipe 400 connects to the gas phase space to discharge the carrier gas mixed with nitrogen when a preset threshold is reached. After the carrier gas is reused for a period of time or after a certain amount of dissolved nitrogen has been released, the increased nitrogen content in the carrier gas affects its ability to release dissolved nitrogen. By discharging the carrier gas from the gas phase space through the exhaust pipe 400 and replacing it with pure carrier gas, the carrier gas's ability to release dissolved nitrogen is ensured, reducing the dissolved nitrogen content of the coolant, lowering carbon-14 emissions, meeting emission requirements, and reducing environmental impact.

[0080] In some embodiments, the gas phase space is located above the liquid phase space, and the first conduit 300 is connected to the upper part of the gas phase space.

[0081] The density of the gas phase is much smaller than that of the liquid phase, and the gas phase space being located above the liquid phase space is more conducive to the separation of the gas and liquid phases. The first pipeline 300 being connected to the upper part of the gas phase space is more conducive to the flow of carrier gas into the first pipeline 300.

[0082] In some embodiments, the gas-liquid mixing device 100 includes a plurality of mixing elements arranged along the flow channel of the gas-liquid mixing device 100.

[0083] The gas-liquid mixing device 100 includes multiple mixing elements, which are fixedly installed in the flow channel of the gas-liquid mixing device 100. The fixing methods include, but are not limited to, snap-fit ​​connection, welding connection, and bolt connection.

[0084] The outer side of the mixing element is in contact with the inner wall of the flow channel of the gas-liquid mixing device 100, or there is a small gap between the outer side of the mixing element and the inner wall of the gas-liquid mixing device 100, so as to ensure that the coolant and the carrier gas can pass through the mixing element and improve the situation where the mixing effect is poor when the coolant and the carrier gas flow in the gap between the mixing element and the inner wall of the gas-liquid mixing device 100.

[0085] The cross-sectional shape of the mixing element is consistent with the cross-sectional shape of the gas-liquid mixing device 100. For example, the cross-sectional shapes of both the mixing element and the gas-liquid mixing device 100 are rectangular, circular, elliptical, or similar shapes.

[0086] By setting up multiple mixing elements, the gas and liquid are thoroughly mixed, thereby improving the mixing effect.

[0087] When the carrier gas and coolant flow along the flow channel of the gas-liquid mixing device 100, they pass through multiple mixing elements. On the one hand, the mixing elements break down the carrier gas into tiny bubbles, increasing the gas-liquid contact area. Dissolved nitrogen in the coolant will precipitate into the tiny bubbles of the carrier gas, thereby reducing the dissolved nitrogen content in the coolant. On the other hand, the mixing elements can change the flow direction of the coolant and the carrier gas, so that the coolant and the carrier gas are fully mixed, thereby effectively precipitating dissolved nitrogen in the coolant.

[0088] For example, the mixing element may be composed of several corrugated sheets stacked together, with the crests and troughs of the cross-sections of adjacent corrugated sheets connected one-to-one to form channels between adjacent corrugated sheets. The narrow, tortuous channels formed between adjacent corrugated sheets can, on the one hand, break down the carrier gas into tiny bubbles, and on the other hand, allow the tiny bubbles to mix thoroughly with the coolant.

[0089] In some embodiments, adjacent corrugated sheets are connected by connecting pieces, and the corrugated sheets and connecting pieces are stacked alternately, forming a channel between the corrugated sheets and connecting pieces for the passage of carrier gas and coolant.

[0090] When the carrier gas passes through the mixing element, it is broken down into tiny bubbles and comes into full contact with the coolant. This allows dissolved nitrogen in the coolant to precipitate into the tiny bubbles until the coolant and the dissolved nitrogen in the tiny bubbles reach equilibrium, thereby reducing the dissolved nitrogen content in the coolant.

[0091] In some embodiments, the mixing element includes at least one first mixing element and at least one second mixing element, with the first mixing element and the second mixing element being alternately arranged.

[0092] The mixing element includes a first mixing element and a second mixing element. The two mixing elements have different structures or arrangements, which in turn change the flow direction and flow rate of the coolant and the carrier gas, so that the coolant and the carrier gas can be fully mixed.

[0093] In some embodiments, the first mixing element and the second mixing element have the same shape, structure, and size, but are arranged in different directions within the gas-liquid mixing device 100. For example, the plane containing the corrugated sheet of the first mixing element is perpendicular to the plane containing the corrugated sheet of the second mixing element, allowing the gas and liquid to mix in opposite longitudinal and transverse directions. Preferably, the plane containing the corrugated sheet of the first mixing element is perpendicular to the horizontal plane, and the plane containing the corrugated sheet of the second mixing element is parallel to the horizontal plane. The first mixing element not only breaks the carrier gas into microbubbles but also guides the bubbles to the bottom of the gas-liquid mixing device 100, resulting in more uniform gas-liquid mixing.

[0094] Of course, as some alternatives, the first mixing element and the second mixing element can also be mixing elements with different shapes and structures. The corrugated sheets of the first mixing element and the second mixing element can be perpendicular to each other or at a certain angle that is not parallel. The channels of the first mixing element and the channels of the second mixing element are staggered to change the flow direction and flow rate of the coolant and the carrier gas, so as to break down the carrier gas into tiny bubbles and make the tiny bubbles of the coolant and the carrier gas fully blend together.

[0095] In some embodiments, the exhaust pipe 400 is connected to the first pipe 300, and the exhaust pipe 400 is provided with an exhaust regulating valve and an exhaust isolation valve, which open when a preset threshold is reached.

[0096] When the preset threshold is reached, the carrier gas in the removal system can be discharged by opening the exhaust isolation valve and the exhaust regulating valve to replace it with a purer carrier gas, thus ensuring the precipitation effect of dissolved nitrogen in the coolant.

[0097] In some embodiments, the preset threshold includes a preset time threshold and / or a preset nitrogen content threshold in the carrier gas.

[0098] The preset threshold can be a preset time threshold. For example, the exhaust isolation valve and exhaust regulating valve on the exhaust pipe 400 will open after the removal system has been running for a certain period of time to discharge the carrier gas containing more nitrogen.

[0099] During normal power operation of a nuclear power plant, the dissolved nitrogen concentration in the reactor coolant is low, resulting in a small amount of nitrogen being released through the removal system described in this application. The gas phase of the gas separator 200 requires a relatively long time to accumulate a certain percentage of nitrogen. The exhaust regulating valve and exhaust isolation valve on the exhaust pipeline 400 are manually opened periodically by the operator based on operational experience, for example, once a week, once every two weeks, or once a month. Specific preset time thresholds can be determined or calculated based on operational experience. By opening the exhaust regulating valve and exhaust isolation valve, nitrogen in the carrier gas is discharged, thereby reducing the dissolved nitrogen concentration in the primary loop. After venting is completed, the carrier gas supply unit automatically replenishes new carrier gas based on the liquid level in the liquid phase space of the gas separator 200, initiating the next cycle of dissolved nitrogen release and accumulation.

[0100] During nuclear power plant startup, there is a significant amount of residual gas in the reactor coolant. Considering the large flow rate of the released coolant, this removal system can quickly remove the dissolved gases. At this time, the opening frequency of the exhaust regulating valve and exhaust isolation valve in the exhaust pipeline 400 can be adjusted to increase the number of exhausts, for example, once every 1-2 hours. This rapidly removes residual nitrogen from the reactor coolant, reducing the dissolved nitrogen concentration in the primary loop and significantly decreasing the probability of its activation and generation of radioactive nuclide C-14. Under certain circumstances, the exhaust regulating valve can also be preset to a certain opening for continuous exhaust to ensure continuous carrier gas renewal and reduce the nitrogen content in the carrier gas.

[0101] During the primary circuit water replacement or makeup water process in a nuclear power plant, considering the dissolved nitrogen introduced into the makeup water, an venting operation can be added after makeup water to ensure that the dissolved nitrogen in the reactor coolant can be discharged in a timely manner, thereby reducing the concentration of dissolved nitrogen in the primary circuit and significantly reducing the probability of its activation and generation of radioactive nuclide C-14.

[0102] The preset threshold can also be a preset nitrogen content threshold in the carrier gas, such as a preset nitrogen content of 5% to 10%. The preset nitrogen content threshold in the carrier gas can be any value between 5% and 10%, such as 5%, 8%, or 10%. When the nitrogen content in the carrier gas reaches the preset threshold, the exhaust regulating valve and exhaust isolation valve on the exhaust pipe 400 are opened, thereby realizing the renewal of the carrier gas, ensuring that residual nitrogen in the reactor coolant can be released, reducing the dissolved nitrogen concentration in the primary loop, and thus greatly reducing the probability of its activation to produce radioactive nuclide C-14.

[0103] Of course, in some embodiments, the preset threshold may also include a preset time threshold and a preset nitrogen content threshold in the carrier gas. The first of the preset time threshold and the preset nitrogen content threshold in the carrier gas shall be used for exhaust operation, thereby effectively ensuring the effect of the carrier gas on the precipitation of dissolved nitrogen in the coolant, reducing the concentration of dissolved nitrogen, reducing the probability of activation and generation of radioactive nuclide C-14, ensuring safe emission, and improving environmental safety.

[0104] The opening and closing of the exhaust isolation valve and the exhaust regulating valve can be done manually by the operator or automatically by the system control.

[0105] Of course, as an option, the exhaust pipe 400 can also be directly connected to the gas phase space of the gas separator 200, which is beneficial for the rapid venting and replacement of the carrier gas.

[0106] In some embodiments, the outlet of the liquid phase space is connected to the reactor coolant system to inject coolant that has released dissolved nitrogen into the reactor coolant system.

[0107] The coolant that releases dissolved nitrogen is reinjected into the reactor coolant system, reducing the nitrogen concentration in the primary loop, decreasing the emission of radioactive nuclide C-14 generated by its activation, improving emission safety, and contributing to ecological and environmental safety.

[0108] The dissolved nitrogen online removal system for the primary loop of a nuclear power plant disclosed in this application, under the action of the gas-liquid mixing device 100, breaks down the carrier gas into tiny bubbles, significantly increasing the gas-liquid contact area, thereby causing dissolved nitrogen in the coolant to precipitate into the carrier gas bubbles. The carrier gas mixed with nitrogen is separated into the gas phase space by the gas separator 200, and the carrier gas in the gas phase space is then transported back to the gas-liquid mixing device 100, realizing the reuse of the carrier gas.

[0109] The dissolved nitrogen online removal system of this application is installed on the drain line of the reactor coolant system, where the coolant flow rate is significantly greater than the pressurizer exhaust flow rate, resulting in a significant improvement in dissolved nitrogen removal efficiency. During normal operation, the system operates at lower pressure and temperature compared to the pressurizer system, requiring less design effort and reducing costs, thus demonstrating significant advantages in both economy and effectiveness.

[0110] Please refer to Figure 2. The second aspect of this application provides an online method for removing dissolved nitrogen in the primary loop of a nuclear power plant. The removal method includes: step S210, mixing the carrier gas with the coolant of the reactor coolant system into a gas-liquid mixture using a gas-liquid mixing device 100.

[0111] The gas-liquid mixing device 100 can break down the carrier gas into tiny bubbles, increasing the gas-liquid contact area between the carrier gas and the coolant. On the other hand, the gas-liquid mixing device 100 ensures that the carrier gas and the coolant are fully mixed, allowing dissolved nitrogen in the coolant to precipitate into the tiny bubbles of the carrier gas. This reduces the dissolved nitrogen in the coolant, lowers the nitrogen concentration in the primary loop, reduces the emission of radioactive nuclide C-14 generated by its activation, improves emission safety, and is beneficial to ecological and environmental safety.

[0112] Step S220: The carrier gas and coolant of the gas-liquid mixture are separated into the gas phase space and the liquid phase space respectively by the gas separator 200.

[0113] Dissolved nitrogen in the coolant is released into the carrier gas, and the gas phase is separated from the liquid phase by the gas separator 200. The carrier gas carries nitrogen to the gas phase space, while the coolant flows into the liquid phase space, thereby realizing the release and separation of dissolved nitrogen in the coolant, reducing the dissolved nitrogen content in the coolant, and reducing C-14 emissions.

[0114] Step S230: The carrier gas in the gas phase space is repeatedly injected into the gas-liquid mixing device 100, and the coolant in the liquid phase space is discharged into the reactor coolant system.

[0115] During normal operation, nuclear power plants have low dissolved nitrogen in the coolant and low nitrogen content in the carrier gas. The carrier gas is recycled by repeatedly injecting it into the gas-liquid mixing device 100 from the gas phase space, which reduces carrier gas consumption and lowers costs.

[0116] In some embodiments, a carrier gas mixed with nitrogen is discharged from the gas phase space when a preset threshold is reached. The preset threshold includes a preset time threshold and / or a nitrogen content threshold in the carrier gas.

[0117] The preset threshold can be a preset time threshold. For example, the exhaust isolation valve and exhaust regulating valve on the exhaust pipe 400 will open after the removal system has been running for a certain period of time to discharge the carrier gas containing more nitrogen.

[0118] During normal power operation of a nuclear power plant, the dissolved nitrogen concentration in the reactor coolant is low, resulting in a small amount of nitrogen being released through the removal system described in this application. The gas phase of the gas separator 200 requires a relatively long time to accumulate a certain percentage of nitrogen. The exhaust regulating valve and exhaust isolation valve on the exhaust pipeline 400 are manually opened periodically by the operator based on operational experience, for example, once a week, once every two weeks, or once a month. Specific preset time thresholds can be determined or calculated based on operational experience. By opening the exhaust regulating valve and exhaust isolation valve, nitrogen in the carrier gas is discharged, thereby reducing the dissolved nitrogen concentration in the primary loop. After venting is completed, the carrier gas supply unit automatically replenishes new carrier gas based on the liquid level in the liquid phase space of the gas separator 200, initiating the next cycle of dissolved nitrogen release and accumulation.

[0119] During nuclear power plant startup, there is a significant amount of residual gas in the reactor coolant. Considering the large flow rate of the released coolant, this removal system can quickly remove the dissolved gases. At this time, the opening frequency of the exhaust regulating valve and exhaust isolation valve in the exhaust pipeline 400 can be adjusted to increase the number of exhausts, for example, once every 1-2 hours. This rapidly removes residual nitrogen from the reactor coolant, reducing the dissolved nitrogen concentration in the primary loop and significantly decreasing the probability of its activation and generation of radioactive nuclide C-14. Under certain circumstances, the exhaust regulating valve can also be preset to a certain opening for continuous exhaust to ensure continuous carrier gas renewal and reduce the nitrogen content in the carrier gas.

[0120] During the primary circuit water replacement or makeup water process in a nuclear power plant, considering the dissolved nitrogen introduced into the makeup water, an venting operation can be added after makeup water to ensure that the dissolved nitrogen in the reactor coolant can be discharged in a timely manner, thereby reducing the concentration of dissolved nitrogen in the primary circuit and significantly reducing the probability of its activation and generation of radioactive nuclide C-14.

[0121] The preset threshold can also be a preset threshold for nitrogen content in the carrier gas, such as a preset nitrogen content of 5% to 10%. When the nitrogen content in the carrier gas reaches the preset threshold, the exhaust regulating valve and exhaust isolation valve on the exhaust pipe 400 are opened, thereby realizing the renewal of the carrier gas, ensuring that residual nitrogen in the reactor coolant can be released, reducing the dissolved nitrogen concentration in the primary loop, and thus greatly reducing the probability of its activation to produce radioactive nuclide C-14.

[0122] Of course, in some embodiments, the preset threshold may also include a preset time threshold and a preset nitrogen content threshold in the carrier gas. The first of the preset time threshold and the preset nitrogen content threshold in the carrier gas shall be used for exhaust operation, thereby effectively ensuring the effect of the carrier gas on the precipitation of dissolved nitrogen in the coolant, reducing the concentration of dissolved nitrogen, reducing the probability of activation and generation of radioactive nuclide C-14, ensuring safe emission, and improving environmental safety.

[0123] The opening and closing of the exhaust isolation valve and the exhaust regulating valve can be done manually by the operator or automatically by the system control.

[0124] In some embodiments, the carrier gas includes hydrogen, which is continuously injected into the gas phase space through a carrier gas supply unit.

[0125] When hydrogen is mixed with the coolant as a carrier gas, on the one hand, the tiny bubbles of hydrogen can precipitate dissolved nitrogen from the coolant, allowing the dissolved nitrogen to separate from the coolant along with the hydrogen; on the other hand, some hydrogen will mix into the coolant as a dissolved gas, resulting in hydrogen consumption. Maintaining a preset opening degree by the supply regulating valve allows for continuous replenishment of hydrogen, ensuring sufficient carrier gas and guaranteeing its denitrification effect on the coolant.

[0126] The dissolved nitrogen online removal system and method of this application, under the action of the gas-liquid mixing device 100, breaks down the carrier gas into microbubbles, significantly increasing the gas-liquid contact area, thereby causing dissolved nitrogen in the coolant to precipitate into the carrier gas bubbles. The carrier gas mixed with nitrogen is separated into the gas phase space by the gas separator 200, and the carrier gas in the gas phase space is then transported back to the gas-liquid mixing device 100, realizing the reuse of the carrier gas.

[0127] The dissolved nitrogen online removal system of this application is installed on the drain line of the reactor coolant system, where the coolant flow rate is significantly greater than the pressurizer exhaust flow rate, resulting in a significant improvement in dissolved nitrogen removal efficiency. During normal operation, the system operates at lower pressure and temperature compared to the pressurizer system, requiring less design expertise and complexity, effectively reducing costs and demonstrating significant advantages in both economy and effectiveness. Therefore, this application effectively overcomes some practical problems in the prior art, thus possessing high utilization value and practical significance.

[0128] The above embodiments are merely illustrative of the principles and effects of this application and are not intended to limit this application. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this application should still be covered by the claims of this application.

Claims

1. An online dissolved nitrogen removal system for the primary loop of a nuclear power plant, characterized in that, include: The carrier gas supply unit supplies carrier gas into the dissolved nitrogen online removal system; A gas-liquid mixing device includes a liquid inlet, a gas inlet, and a mixing outlet. The liquid inlet is configured to connect to the coolant in a reactor coolant system, and the gas inlet is configured to connect to the carrier gas. The gas-liquid mixing device is configured to mix the carrier gas and the coolant to form a gas-liquid mixture, thereby precipitating dissolved nitrogen from the coolant into the carrier gas. A gas separator is connected to the mixing outlet of the gas-liquid mixing device. The gas separator includes a gas phase space and a liquid phase space to separate the carrier gas from the coolant in the gas-liquid mixture. A first pipeline connects the gas phase space to the gas inlet of the gas-liquid mixing device, so that the gas phase space supplies the carrier gas into the gas-liquid mixing device; An exhaust pipe is connected to the gas phase space to discharge the carrier gas mixed with nitrogen when a preset threshold is reached; A gas supply line is connected to the carrier gas supply unit so that the carrier gas supply unit supplies the carrier gas.

2. The online dissolved nitrogen removal system for the primary loop of a nuclear power plant according to claim 1, characterized in that, The gas supply line connects the carrier gas supply unit to the gas phase space, so that the carrier gas supply unit supplies the carrier gas into the gas phase space.

3. The online dissolved nitrogen removal system for the primary loop of a nuclear power plant according to claim 1, characterized in that, The gas-liquid mixing device includes multiple mixing elements arranged along the flow channel of the gas-liquid mixing device.

4. The online dissolved nitrogen removal system for the primary loop of a nuclear power plant according to claim 2, characterized in that, The mixing element includes at least one first mixing element and at least one second mixing element, with the first mixing element and the second mixing element being alternately arranged.

5. The online dissolved nitrogen removal system for the primary loop of a nuclear power plant according to claim 4, characterized in that, The hybrid element is composed of several corrugated sheets stacked together, with the crests and troughs of the cross sections of adjacent corrugated sheets corresponding one-to-one to form channels between adjacent corrugated sheets.

6. The online dissolved nitrogen removal system for the primary loop of a nuclear power plant according to claim 5, characterized in that, The plane containing the corrugated sheet of the first mixing element is perpendicular to the plane containing the corrugated sheet of the second mixing element.

7. The online dissolved nitrogen removal system for the primary loop of a nuclear power plant according to claim 1, characterized in that, The first pipeline includes an air pump to pump the carrier gas in the gas phase space to the gas-liquid mixing device.

8. The online dissolved nitrogen removal system for the primary loop of a nuclear power plant according to claim 7, characterized in that, The gas phase space is located above the liquid phase space, and the first pipeline is connected to the upper part of the gas phase space.

9. The online dissolved nitrogen removal system for the primary loop of a nuclear power plant according to claim 7, characterized in that, The exhaust pipe is connected to the first pipe, and the exhaust pipe is equipped with an exhaust regulating valve and an exhaust isolation valve. The exhaust regulating valve and the exhaust isolation valve open when a preset threshold is reached.

10. The online dissolved nitrogen removal system for the primary loop of a nuclear power plant according to claim 7, characterized in that, The preset thresholds include a preset time threshold and / or a preset nitrogen content threshold in the carrier gas.

11. The online dissolved nitrogen removal system for the primary loop of a nuclear power plant according to claim 1, characterized in that, The outlet of the liquid phase space is connected to the reactor coolant system to inject the coolant containing dissolved nitrogen into the reactor coolant system.

12. The online dissolved nitrogen removal system for the primary loop of a nuclear power plant according to claim 1, characterized in that, The carrier gas includes one or more of hydrogen, helium, and argon.

13. The online dissolved nitrogen removal system for the primary loop of a nuclear power plant according to claim 12, characterized in that, The gas supply pipeline includes a supply regulating valve and a supply isolation valve; when the carrier gas includes hydrogen, the supply regulating valve maintains a preset opening.

14. A method for online removal of dissolved nitrogen in the primary loop of a nuclear power plant, characterized in that, The removal method includes: mixing carrier gas with coolant from the reactor coolant system using a gas-liquid mixing device to form a gas-liquid mixture; separating the carrier gas and coolant from the gas-liquid mixture into a gas phase space and a liquid phase space respectively using a gas separator; re-injecting the carrier gas from the gas phase space into the gas-liquid mixing device; and discharging the coolant from the liquid phase space into the reactor coolant system.

15. The method for online removal of dissolved nitrogen in the primary loop of a nuclear power plant according to claim 14, characterized in that, The carrier gas includes hydrogen, and the method includes: continuously injecting the carrier gas into the gas phase space through a carrier gas supply unit.

16. The method for online removal of dissolved nitrogen in the primary loop of a nuclear power plant according to claim 14, characterized in that, When a preset threshold is reached, the carrier gas containing nitrogen mixed in the gas phase space is discharged. The preset threshold includes a preset time threshold and / or a nitrogen content threshold in the carrier gas.

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