Nuclear island cold end indirect air cooling device and method

Abstract

The invention provides a nuclear island cold end indirect air cooling device and method. The air cooling device comprises a first cooling mechanism and a second cooling mechanism which are arranged in series. The first cooling mechanism comprises at least one first cooling unit, and the first cooling unit adopts air forced convection cooling; the second cooling mechanism comprises at least one second cooling unit, and the second cooling unit adopts air forced convection cooling and water mist evaporative cooling; wherein the circulating water inlet pipeline is provided with a first branch flowing to the first cooling mechanism and a second branch flowing to the second cooling mechanism, and the circulating water inlet pipeline is configured to be capable of flowing through the first cooling mechanism and / or the second cooling mechanism for heat exchange and cooling; or the cooling water of the circulating water pipeline is fully bypassed.

Description

Technical Field

[0001] This invention relates to the field of indirect air cooling technology, specifically to an indirect air cooling device and method for the cold end of a nuclear island. Background Technology

[0002] Indirect air cooling technology has been widely used in thermal power plants in water-scarce areas due to its significant water-saving advantages. Its core principle is to dissipate the waste heat of the power plant into the atmosphere through non-contact heat exchange.

[0003] However, the cold end system of the nuclear island has more stringent requirements for cooling devices: not only must the outlet water temperature be strictly controlled within 40°C, but it must also meet the requirements of high reliability and large differences in heat load under different operating conditions. Conventional indirect air cooling devices often fail to meet the outlet water temperature under high-temperature conditions in summer due to low cooling efficiency, high cooling limit temperature and insufficient reliability, making it difficult to match the special operating requirements of the nuclear island side.

[0004] In existing improvement schemes, applying full-area spray cooling to the entire air-cooled unit would consume a large amount of water resources, and due to the large initial temperature difference between the cooling water and the air, it would be difficult to effectively reduce the cooling limit temperature. If multiple cooling modules are set up according to equipment or subsystems and each is subjected to further cooling measures, it would result in redundant components and complex control logic in the air-cooled unit, making it unsuitable for the simple and efficient operation requirements of the nuclear island side.

[0005] Based on this, the inventors of this application propose an indirect air-cooling device and method for the cold end of a nuclear island, in order to solve one or more of the aforementioned technical problems. Summary of the Invention

[0006] The present invention solves the above-mentioned technical problems through the following technical solution: This invention provides an indirect air-cooling device for the cold end of a nuclear island, comprising: a first cooling mechanism and a second cooling mechanism arranged in series; The first cooling mechanism includes at least one first cooling unit, which employs forced air convection cooling; the second cooling mechanism includes at least one second cooling unit, which employs both forced air convection cooling and water mist evaporation cooling; wherein... The circulating water inlet pipe is provided with a first branch flowing to the first cooling mechanism and a second branch flowing to the second cooling mechanism. The circulating water inlet pipe is configured to flow through the first cooling mechanism and / or the second cooling mechanism for heat exchange and cooling; or the cooling water of the circulating water pipe is fully bypassed.

[0007] According to one embodiment of the present invention, the first cooling mechanism includes at least two first cooling units, and the at least two first cooling units are arranged in parallel. The second cooling mechanism includes at least two second cooling units, which are arranged in parallel.

[0008] According to one embodiment of the present invention, the first cooling unit includes a first fan and two first air-cooled radiators, the two first air-cooled radiators being assembled to form a V-shaped cooling triangle; The first branch of the circulating water inlet pipe flows through the interior of the first air-cooled radiator. The first fan is used to drive air to flow through the first air-cooled radiator and carry out the heat of the circulating water in the first branch through forced air convection.

[0009] According to one embodiment of the present invention, two first air-cooled radiators are arranged symmetrically along the central axis of the first cooling unit to form a V-shaped cooling triangle with the opening facing the first fan.

[0010] According to one embodiment of the present invention, a first control valve is provided between the first branch and the branch pipe of each of the first cooling units, and the first control valve is used to control the on / off of the circulating water inlet pipe to the first cooling unit.

[0011] According to one embodiment of the present invention, the second cooling unit includes a second fan, two second air-cooled radiators, and a spray mechanism; The second branch flows through the interior of the second air-cooled radiator, and the second fan drives the air to flow through the second air-cooled radiator. The two second air-cooled radiators are assembled to form a V-shaped cooling triangle; The spray mechanism is used to spray demineralized water mist onto the second air-cooled radiator to enhance the cooling of the circulating water in the second branch.

[0012] According to one embodiment of the present invention, two second air-cooled radiators are arranged symmetrically along the central axis of the second cooling unit to form a V-shaped cooling triangle with the opening facing the second fan.

[0013] According to one embodiment of the present invention, the spraying mechanism includes a demineralized water storage tank, a spray pump, and a plurality of nozzles; the demineralized water storage tank, the spray pump, and the nozzles are connected by a spray pipeline; The nozzle faces the second air-cooled radiator, and the spray pump is used to spray the demineralized water in the demineralized water storage tank onto the surface of the second air-cooled radiator through the nozzle to cool the circulating water in the second branch.

[0014] According to one embodiment of the present invention, a plurality of the nozzles are located at the bottom end of the second air-cooled radiator and are arranged circumferentially.

[0015] The present invention also provides a method for indirect air cooling at the cold end of a nuclear island, employing the indirect air cooling device for the cold end of a nuclear island as described above, the air cooling method comprising: Step 1: Obtain the cooling water temperature under the condition of full bypass of the circulating water inlet pipe; Step 2: Adjust the connection status of the circulating water inlet pipe to the first cooling mechanism and the second cooling mechanism according to the cooling water temperature value; wherein, when the cooling water temperature is higher than the first threshold but lower than the second threshold, the circulating water inlet pipe is connected only to the first cooling mechanism; when the cooling water temperature is higher than the second threshold, the circulating water inlet pipe is connected to the first cooling mechanism and the second cooling mechanism in sequence; if the cooling water temperature is lower than the first threshold, the circulating water inlet pipe is completely bypassed.

[0016] The positive and progressive effects of this invention are as follows: This invention relates to an indirect air-cooling device for the cold end of a nuclear island. By connecting a first cooling mechanism that uses only forced air convection cooling and a second cooling mechanism that uses a combination of forced air convection and water mist evaporation cooling in series, along with a first branch, a second branch, and a full bypass design for the circulating water inlet pipeline, this invention precisely solves the pain points of conventional indirect air-cooling devices in traditional technologies, such as low cooling efficiency, high cooling limit temperature, substandard output water in summer high temperatures, large water consumption for full-area spraying, and complex control of multiple subsystems. It can meet the basic cooling requirements under normal operating conditions through the first cooling mechanism, and enhance cooling through water mist evaporation of the second cooling mechanism under extreme operating conditions such as high temperatures in summer, ensuring that the output water temperature is strictly controlled within the rated value required by the nuclear island. Simultaneously, depending on different ambient temperatures and nuclear island heat load differences, it can flexibly switch between flowing only through the first cooling mechanism, flowing through both the first and second cooling mechanisms, or a full bypass mode, to avoid the water temperature being too low under low-temperature conditions affecting system operation. This not only simplifies the control logic and improves operational flexibility, but also significantly reduces spray water consumption and lowers the risk of radiator corrosion and fouling by using water mist cooling only in the second cooling mechanism, thus significantly improving the cooling guarantee rate and operational reliability of the nuclear island cold end system. Attached Figure Description

[0017] 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: Figure 1 This is a schematic diagram of the structure of the indirect air-cooling device for the cold end of the nuclear island in this invention; Figure 2 for Figure 1 A diagram from another angle; Figure 3 This is a schematic diagram showing the arrangement of multiple nozzles; Figure 4 This is a flowchart of the indirect air-cooling method for the cold end of the nuclear island according to the present invention.

[0018] 1. First cooling mechanism; 11. First cooling unit; 12. First fan; 13. First air-cooled radiator; 2. Second cooling mechanism; 21. Second cooling unit; 22. Second fan; 23. Second air-cooled radiator; 24. Spray mechanism; 241. Demineralized water storage tank; 242. Spray pump; 243. Nozzle; 244. On / off valve; 3. Circulating water inlet pipe; 31. First branch; 311. First control valve; 32. Second branch; 321. Second control valve. Detailed Implementation

[0019] 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.

[0020] 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.

[0021] Traditional indirect air cooling technology has core pain points in nuclear island cold end applications, such as low cooling efficiency, high cooling limit temperature, large water consumption and complex control of multiple subsystems. In addition, the nuclear island cold end system has strict requirements for outlet water temperature (not exceeding 40℃), high guarantee rate and heat load adaptability under different operating conditions.

[0022] Please refer to Figures 1 to 3 This application proposes an indirect air-cooling device for the cold end of a nuclear island, specifically including a first cooling mechanism 1 and a second cooling mechanism 2 arranged in series. The first cooling mechanism 1 includes at least one first cooling unit 11, which employs forced air convection cooling; the second cooling mechanism 2 includes at least one second cooling unit 21, which employs forced air convection cooling and water mist evaporation cooling. The circulating water inlet pipe 3 is provided with a first branch 31 flowing to the first cooling mechanism 1 and a second branch 32 flowing to the second cooling mechanism 2. The circulating water inlet pipe 3 is configured to allow heat exchange and cooling through the first cooling mechanism 1 and / or the second cooling mechanism 2; or the cooling water in the circulating water pipe is fully bypassed.

[0023] like Figure 1 As shown, the function of the circulating water inlet pipe 3 is to transport the medium to be cooled. The first cooling mechanism 1 is connected to the circulating water inlet pipe 3 through the first branch 31, and the second cooling mechanism 2 is connected to the circulating water inlet pipe 3 through the second branch 32.

[0024] In practical applications, the circulating water inlet pipe 3 can be selected to supply water only to the first cooling mechanism 1, or only to the second cooling mechanism 2, or sequentially to the first cooling mechanism 1 and the second cooling mechanism 2, or completely bypass the first cooling mechanism 1 and the second cooling mechanism 2.

[0025] This application, through the series design of the first cooling mechanism 1 and the second cooling mechanism 2, can adapt to both normal operating conditions and high-temperature extreme operating conditions. That is, the first cooling mechanism 1 can meet the basic cooling requirements, while the second cooling mechanism 2 can achieve enhanced cooling by utilizing the synergistic effect of forced air convection and water mist evaporation, which can effectively solve the pain points of low cooling efficiency and substandard water output in high-temperature summers of conventional indirect air-cooled devices.

[0026] Meanwhile, through the switching of the first branch 31 and the second branch 32 and the full bypass design process, the operating mode can be flexibly adjusted according to the ambient temperature and the heat load of the nuclear island. This can avoid the impact of excessively low water temperature on system operation under low temperature conditions and simplify the complex control logic brought about by the splitting of multiple subsystems.

[0027] like Figure 1 and Figure 2 As shown, the first cooling mechanism 1 includes at least two first cooling units 11, which are arranged in parallel; the second cooling mechanism 2 includes at least two second cooling units 21, which are arranged in parallel.

[0028] Specifically, the number of first cooling units 11 connected to the first branch 31 can be flexibly selected according to the heat load of the nuclear island. Similarly, the number of second cooling units 21 connected to the second branch 32 can also be flexibly selected according to the heat load of the nuclear island.

[0029] That is, by arranging the first cooling unit 11 and the second cooling unit 21 of the first cooling mechanism 1 and the second cooling mechanism 2 in parallel, the number of cooling units put into operation can be flexibly adjusted according to the size of the nuclear island heat load. Taking the first cooling unit 11 as an example, when the heat load is small, only part of the first cooling unit 11 can be started to reduce energy consumption.

[0030] Meanwhile, multiple first cooling units 11 and multiple second cooling units 21 are connected in parallel, each with redundant backup function. The failure of a single first cooling unit 11 or second cooling unit 21 will not affect the normal operation of the overall air-cooling device, which significantly improves the operational reliability and fault tolerance of the air-cooling device.

[0031] Please refer to Figure 2 The first cooling unit 11 includes a first fan 12 and two first air-cooled radiators 13, which are assembled to form a V-shaped cooling triangle. The first branch 31 of the circulating water inlet pipe 3 flows through the interior of the first air-cooled radiator 13. The first fan 12 is used to drive air to flow through the first air-cooled radiator 13 and carry out the heat of the circulating water in the first branch 31 through forced air convection.

[0032] The first air-cooled radiator 13 adopts a V-shaped cooling triangle structure, which increases the heat dissipation area of ​​the first air-cooled radiator 13 within a limited space, improving the contact efficiency between the air and the radiator 13. Combined with the forced convection design of the first fan 12, the heat exchange efficiency of the first air-cooled radiator 13 is significantly improved compared to natural convection cooling, thereby quickly reducing the circulating water temperature to the range required under normal operating conditions. Furthermore, the V-shaped arrangement results in a more compact structural design, thus adapting to the limited space available in nuclear power plants. The pure air cooling mode also requires no additional water consumption, continuing the water-saving advantages of indirect air cooling.

[0033] Specifically, the two first air-cooled radiators 13 are arranged symmetrically along the central axis of the first cooling unit 11, forming a V-shaped cooling triangle with the opening facing the first fan 12.

[0034] like Figure 2 As shown, the V-shaped cooling triangles symmetrically arranged along the central axis, with their openings facing the first fan 12, allow the airflow driven by the first fan 12 to pass evenly across the surfaces of the two first air-cooled radiators 13, avoiding uneven heat dissipation caused by localized airflow dead zones. Furthermore, the symmetrical arrangement of the two first air-cooled radiators 13 ensures a balanced flow distribution of circulating water within them, further improving the stability of the cooling effect and guaranteeing the consistency of the output water temperature of the first cooling mechanism 1.

[0035] It should be noted that a first control valve 311 is provided between the first branch 31 and the branch pipe of each first cooling unit 11. The first control valve 311 is used to control the opening and closing of the circulating water inlet pipe 3 to the first cooling unit 11; a second control valve 321 is provided between the second branch 32 and the branch pipe of each second cooling unit 21. The second control valve 321 is used to control the opening and closing of the circulating water inlet pipe 3 to the second cooling unit 21.

[0036] By installing a first control valve 311 on the branch pipe of each first cooling unit 11, precise start-up and shutdown control of a single first cooling unit 11 can be achieved. This allows for flexible adjustment of the number of operating first cooling units 11 based on changes in nuclear island heat load and equipment maintenance needs, avoiding unnecessary energy consumption. Furthermore, when a single first cooling unit 11 requires maintenance, isolation can be achieved by closing the corresponding first control valve 311, without stopping the operation of the entire first cooling mechanism 1, thus improving the ease of maintenance and continuous operation capability of the air-cooled unit. The control principle of the second control valve 321 is the same as that of the first control valve 311; the second control valve 321 is used to precisely control the start-up and shutdown of a single second cooling unit 21.

[0037] For the second cooling unit 21, please refer to Figure 2 and Figure 3 The second cooling unit 21 includes a second fan 22, two second air-cooled radiators 23, and a spray mechanism 24; the second branch 32 flows through the interior of the second air-cooled radiator 23, and the second fan 22 drives air to flow through the second air-cooled radiator 23; the two second air-cooled radiators 23 are assembled to form a V-shaped cooling triangle; the spray mechanism 24 is used to spray demineralized water mist onto the second air-cooled radiator 23 to enhance the cooling of the circulating water in the second branch 32.

[0038] By adding a spray mechanism 24 to the V-shaped cooling triangle and forced convection, the cooling efficiency under extreme high temperature conditions is greatly improved through the synergistic effect of forced air convection and desalinated water mist evaporation and heat absorption, effectively reducing the cooling limit temperature and solving the core pain point of conventional indirect air cooling devices failing to meet high temperature output standards.

[0039] Because the spray mechanism 24 is only set for the second cooling unit 21, it greatly reduces the consumption of demineralized water compared to full-area spraying, while avoiding the rust and fouling problems caused by spraying in the first cooling unit 11, thus balancing the cooling effect and the service life of the equipment.

[0040] like Figure 3 As shown, the two second air-cooled radiators 23 are arranged symmetrically along the central axis of the second cooling unit 21, forming a V-shaped cooling triangle with the opening facing the second fan 22.

[0041] The arrangement of the second air-cooled radiator 23 is the same as that of the first air-cooled radiator 13. That is, the symmetrical arrangement of the V-shaped cooling triangles and the design of the opening facing the second fan 22 can make the airflow evenly cover the surface of the second air-cooled radiator 23, providing a stable diffusion channel for the sprayed water mist.

[0042] Moreover, the symmetrical structure of the second air-cooled radiator 23 ensures that the water mist adheres evenly to the surfaces of the two radiators, avoiding uneven cooling caused by excessive or insufficient local spraying, further enhancing the synergistic heat exchange effect of airflow and water mist, and ensuring that the second cooling unit 21 can stably output low-temperature cooling water that meets the requirements.

[0043] Please continue to refer to Figures 1 to 3 The spray mechanism 24 includes a demineralized water storage tank 241, a spray pump 242, and multiple nozzles 243. The demineralized water storage tank 241, the spray pump 242, and the nozzles 243 are connected by a spray pipeline. The nozzles 243 face the second air-cooled radiator 23. The spray pump 242 is used to spray the demineralized water in the demineralized water storage tank 241 onto the surface of the second air-cooled radiator 23 through the nozzles 243 to cool the circulating water in the second branch 32.

[0044] Using demineralized water as the spray medium effectively avoids the scaling and corrosion problems of radiators caused by ordinary water spray, thus helping to extend the equipment maintenance cycle and service life. The spray pump 242 can flexibly adjust the spray volume according to the ambient temperature and the outlet water temperature, thereby achieving precise and enhanced cooling.

[0045] Furthermore, multiple nozzles 243 are located at the bottom of the second air-cooled radiator 23 and arranged circumferentially. The pipes corresponding to the multiple nozzles 243 are connected in parallel and each is equipped with an on / off valve 244, thereby allowing different numbers of nozzles 243 to be opened as needed.

[0046] like Figure 2 and Figure 3 As shown, taking three nozzles 243 as an example, one nozzle 243 is located directly below the second air-cooled radiator 23, and the other two are located on both sides, with the spray direction of all three nozzles 243 pointing towards the second air-cooled radiator 23. The three nozzles 243 are arranged circumferentially at the bottom of the second air-cooled radiator 23, enabling the spraying of water mist onto the radiator surface from multiple angles. This achieves comprehensive coverage of the V-shaped cooling triangle, avoiding spray dead zones. Furthermore, the bottom-positioned nozzles 243 allow the water mist to mix thoroughly with the rising airflow driven by the fan under gravity, extending the contact time between the water mist and the second air-cooled radiator 23, improving evaporation heat absorption efficiency, ensuring uniform cooling across all areas of the second air-cooled radiator 23, and further guaranteeing the stability and reliability of the cooling effect under extreme high-temperature conditions.

[0047] Regarding the number of nozzles 243, the above example uses three, but does not limit the specific number.

[0048] Please refer to Figure 4 This application also proposes a method for indirect air cooling at the cold end of a nuclear island, employing the above-mentioned indirect air cooling device for the cold end of a nuclear island. The air cooling method includes: S1. Obtain the cooling water temperature under the condition of full bypass of the circulating water inlet pipe; S2. Adjust the connection status of the circulating water inlet pipe to the first cooling mechanism and the second cooling mechanism according to the cooling water temperature value; wherein, when the cooling water temperature is higher than the first threshold but lower than the second threshold, the circulating water inlet pipe is connected only to the first cooling mechanism; when the cooling water temperature is higher than the second threshold, the circulating water inlet pipe is connected to the first cooling mechanism and the second cooling mechanism in sequence; if the cooling water temperature is lower than the first threshold, the circulating water inlet pipe is completely bypassed.

[0049] For example, the first threshold can be 40℃, and the second threshold is at least higher than 40℃, such as 50℃ or 60℃, without limitation. When the temperature exceeds the second threshold, it means the temperature exceeds the cooling capacity of the first cooling mechanism, such as in summer. In this case, both the first and second cooling mechanisms can be used simultaneously for cooling. When the temperature is below the first threshold, it means no cooling is needed, so the circulating water inlet pipe can be completely bypassed. It is clear that 40℃ is only an example and does not impose a specific value limitation.

[0050] The air-cooling method described above automatically switches operating modes based on cooling water temperature thresholds, eliminating the need for frequent manual intervention and improving the automation level of the air-cooling unit. By precisely matching the cooling requirements under different temperature conditions, it ensures that the circulating water temperature is always controlled within the range required by the nuclear island, avoiding the impact of excessively low water temperature on system operation under low-temperature conditions and solving the problem of insufficient cooling under high-temperature conditions.

[0051] 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.

[0052] 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.

[0053] 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 nuclear island cold-end indirect air-cooling device, characterized in that, include: A first cooling mechanism and a second cooling mechanism are connected in series; The first cooling mechanism includes at least one first cooling unit, which employs forced air convection cooling; the second cooling mechanism includes at least one second cooling unit, which employs both forced air convection cooling and water mist evaporation cooling; wherein... The circulating water inlet pipe is provided with a first branch flowing to the first cooling mechanism and a second branch flowing to the second cooling mechanism. The circulating water inlet pipe is configured to flow through the first cooling mechanism and / or the second cooling mechanism for heat exchange and cooling; or the cooling water of the circulating water pipe is fully bypassed.

2. The indirect air-cooling device for the cold end of the nuclear island according to claim 1, characterized in that, The first cooling mechanism includes at least two first cooling units, and the at least two first cooling units are arranged in parallel. The second cooling mechanism includes at least two second cooling units, which are arranged in parallel.

3. The indirect air-cooling device for the cold end of the nuclear island according to claim 1, characterized in that, The first cooling unit includes a first fan and two first air-cooled radiators, the two first air-cooled radiators being assembled to form a V-shaped cooling triangle; The first branch of the circulating water inlet pipe flows through the interior of the first air-cooled radiator. The first fan is used to drive air to flow through the first air-cooled radiator and carry out the heat of the circulating water in the first branch through forced air convection.

4. The indirect air-cooling device for the cold end of the nuclear island according to claim 3, characterized in that, The two first air-cooled radiators are arranged symmetrically along the central axis of the first cooling unit, forming a V-shaped cooling triangle with the opening facing the first fan.

5. The indirect air-cooling device for the cold end of the nuclear island according to claim 3, characterized in that, A first control valve is provided between the first branch and each branch pipe of the first cooling unit. The first control valve is used to control the on / off of the circulating water inlet pipe to the first cooling unit. A second control valve is provided between the second branch and each branch pipe of the second cooling unit. The second control valve is used to control the on / off of the circulating water inlet pipe to the second cooling unit.

6. The indirect air-cooling device for the cold end of the nuclear island according to claim 1, characterized in that, The second cooling unit includes a second fan, two second air-cooled radiators, and a spray mechanism; The second branch flows through the interior of the second air-cooled radiator, and the second fan drives the air to flow through the second air-cooled radiator. The two second air-cooled radiators are assembled to form a V-shaped cooling triangle; The spray mechanism is used to spray demineralized water mist onto the second air-cooled radiator to enhance the cooling of the circulating water in the second branch.

7. The indirect air-cooling device for the cold end of the nuclear island according to claim 6, characterized in that, The two second air-cooled radiators are arranged symmetrically along the central axis of the second cooling unit, forming a V-shaped cooling triangle with the opening facing the second fan.

8. The indirect air-cooling device for the cold end of the nuclear island according to claim 6, characterized in that, The spraying mechanism includes a demineralized water storage tank, a spray pump, and multiple nozzles; the demineralized water storage tank, the spray pump, and the nozzles are connected by spray pipelines; The nozzle faces the second air-cooled radiator, and the spray pump is used to spray the demineralized water in the demineralized water storage tank onto the surface of the second air-cooled radiator through the nozzle to cool the circulating water in the second branch.

9. The indirect air-cooling device for the cold end of the nuclear island according to claim 8, characterized in that, The plurality of nozzles are located at the bottom of the second air-cooled radiator and are arranged circumferentially.

10. A method for indirect air cooling at the cold end of a nuclear island, characterized in that, The air cooling method using the indirect air-cooling device for the cold end of the nuclear island as described in any one of claims 1-9 includes: Step 1: Obtain the cooling water temperature under the condition of full bypass of the circulating water inlet pipe; Step 2: Adjust the connection status of the circulating water inlet pipe to the first cooling mechanism and the second cooling mechanism according to the cooling water temperature value; wherein, when the cooling water temperature is higher than the first threshold but lower than the second threshold, the circulating water inlet pipe is connected only to the first cooling mechanism; when the cooling water temperature is higher than the second threshold, the circulating water inlet pipe is connected to the first cooling mechanism and the second cooling mechanism in sequence; if the cooling water temperature is lower than the first threshold, the circulating water inlet pipe is completely bypassed.

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