Heat exchange device, waste heat removal system and use method

Abstract

The invention relates to the technical field of nuclear reactor safety, in particular to a heat exchange device, a waste heat removal system and a use method. A heat exchange device comprises a first cooling water tank, a second cooling water tank and a heat exchanger, a heat exchanger is suitable for being arranged in the first cooling water tank, the first cooling water tank is suitable for being connected with a containment, and cooling liquid flows in the first cooling water tank; the second cooling water tank is suitable for being connected with the containment vessel, and cooling liquid flows in the second cooling water tank; and the first cooling water tank and the second cooling water tank are communicated through the pipeline assembly. The invention provides a heat exchange device, a waste heat removal system and a using method, and aims to solve the problems that a cooling water tank of an existing waste heat removal system is usually designed to be a tank body, so that the flowability of cooling liquid in partial space in the cooling water tank is insufficient, and the cooling liquid does not participate in heat exchange.

Description

Technical Field

[0001] The present invention relates to the field of nuclear reactor safety technology, and in particular to a heat exchange device, a waste heat removal system and a use method thereof. Background Art

[0002] The residual heat removal system is also called the shutdown cooling system. After a reactor that has been operating at a certain power level for a period of time is shut down, the decay power generated by the decay of fission fragments and neutron capture products will slowly decrease and continue for a long time. Therefore, a nuclear power plant must be equipped with a system for removing residual heat from the core. The system must be able to remove the residual heat of the core from the primary or secondary loop system at a certain rate, as well as the residual heat of the fluid and equipment in the primary loop and the residual heat removal system, and the heat applied to the primary loop by the operation of the main pump. And when the whole plant is powered off, the residual heat removal system can only take away the above heat through natural circulation, which is the so-called residual heat removal system. Internationally, it is recognized that the residual heat removal system is one of the main differences between the second-generation and third-generation reactors, which greatly improves the safety of the reactor.

[0003] The heat transfer process of the heat exchanger water tank used in the existing third-generation reactor waste heat removal system is mainly to exchange heat between the heat exchanger and the larger heat exchanger water tank to remove the waste heat in the secondary side. The cooling water tank of the existing waste heat removal system is often designed as a box body, resulting in insufficient coolant flow in some spaces in the cooling water tank and not participating in heat exchange. The volume of a water tank is large, which makes the installation and production of the cooling water tank difficult. Summary of the invention

[0004] In view of this, the present invention provides a heat exchange device, a waste heat removal system and a method of use to solve the problem that the cooling water tank of the existing waste heat removal system is often designed as a box body, resulting in insufficient coolant fluidity in some spaces in the cooling water tank and the problem of not participating in heat exchange.

[0005] In a first aspect, the present invention provides a heat exchange device, comprising:

[0006] a first cooling water tank, wherein a heat exchanger is arranged in the first cooling water tank, the first cooling water tank is adapted to be connected to the containment shell, and a coolant flows in the first cooling water tank;

[0007] a second cooling water tank, the second cooling water tank being adapted to be connected to the containment shell, and having a coolant flowing in the second cooling water tank;

[0008] A pipeline assembly, the first cooling water tank and the second cooling water tank are connected through the pipeline assembly.

[0009] There is a heat exchanger in the first cooling water tank. The temperature of the coolant in the first cooling water tank is higher than that of the coolant in the second cooling water tank. The coolant at the outlet near the heat exchanger in the first cooling water tank undergoes a phase change to produce a two-phase fluid. The density difference between the coolant in the first cooling water tank and the second cooling water tank generates a natural circulation. The pipe assembly transports the coolant in the first cooling water tank to the second cooling water tank, and then transports the coolant in the second cooling water tank to the first cooling water tank by gravity, so as to realize the circulation of the coolant in the first cooling water tank and the second cooling water tank. The fluidity of the coolant is improved through the cooling pipe, so that the coolant circulates in the first cooling water tank and the second cooling water tank, effectively improving the fluidity of the coolant and improving the heat exchange efficiency. Compared with the setting of one cooling water tank, the setting of the first cooling water tank and the second cooling water tank reduces the difficulty of installation and production.

[0010] In an optional embodiment, the first cooling water tank is arranged on the outer peripheral surface of the containment shell, and the second cooling water tank is arranged on the top of the containment shell.

[0011] In an optional embodiment, the first cooling water tank is arranged in the containment shell, and the second cooling water tank is arranged on the outer peripheral surface of the containment shell. An auxiliary building is suitable for being arranged outside the containment shell, and the second cooling water tank is arranged on the top of the auxiliary building. The height of the auxiliary building is lower than the height of the containment shell.

[0012] In an optional embodiment, the pipe assembly includes at least two pipes, and the at least two pipes include a first pipe and a second pipe. The top of the first cooling water tank and the top of the second cooling water tank are connected through the first pipe, and the bottom of the side wall of the first cooling water tank and the bottom of the second cooling water tank are connected through the second pipe.

[0013] By arranging the first pipe and the second pipe, sufficient flow of water in the first cooling water tank and the second cooling water tank is achieved, so that the coolant flows from the top of the first cooling water tank to the top of the second cooling water tank, and then flows from the bottom of the second cooling water tank to the bottom of the side of the first cooling water tank. The coolant in the first cooling water tank must flow from the bottom of the side to the top, and the coolant must also flow from the top to the bottom in the second cooling water tank, thereby achieving sufficient flow of the coolant in the first cooling water tank and the second cooling water tank respectively.

[0014] In an optional embodiment, a first control valve is provided in the first pipeline, a second control valve is provided in the second pipeline, a first circulation pump is provided in the first pipeline and / or a second circulation pump is provided in the second pipeline.

[0015] In an optional embodiment, the heat exchanger is suitable for being connected to a main steam pipe, in which saturated steam flows, and the temperature of the saturated steam is higher than the temperature of the cooling liquid.

[0016] In an optional implementation, the bottom elevation of the second cooling water tank is higher than the top elevation of the first cooling water tank.

[0017] In an optional embodiment, the volume of the first cooling water tank is smaller than the volume of the second cooling water tank; or, the volume of the first cooling water tank is equal to the volume of the second cooling water tank.

[0018] In a second aspect, the present invention further provides a waste heat removal system, comprising at least two of the above-mentioned heat exchange devices.

[0019] In the third aspect, the present invention also provides a method for using a heat exchange device, wherein a heat exchanger is arranged in a first cooling water tank, the temperature of the coolant in the first cooling water tank is higher than the temperature of the coolant in the second cooling water tank, the coolant at the outlet near the heat exchanger in the first cooling water tank undergoes a phase change to produce a two-phase fluid, and a natural circulation is generated by the density difference of the coolant in the first cooling water tank and the second cooling water tank. The pipe assembly transports the coolant in the first cooling water tank to the second cooling water tank, and then transports the coolant in the second cooling water tank to the first cooling water tank by gravity, so as to realize the circulation of the coolant in the first cooling water tank and the second cooling water tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 A schematic diagram of the connection between a heat exchange device, a containment vessel and an auxiliary plant building according to an embodiment of the present invention;

[0022] Figure 2 A schematic diagram of another heat exchange device, a containment vessel and an auxiliary plant building connected in accordance with an embodiment of the present invention;

[0023] Figure 3 is a schematic diagram of a waste heat removal system according to an embodiment of the present invention;

[0024] Figure 4 It is a schematic plan view of a waste heat removal system according to an embodiment of the present invention.

[0025] Explanation of the reference numerals: 1. first cooling water tank; 2. heat exchanger; 3. second cooling water tank; 4. containment vessel; 5. auxiliary plant building; 6. pipeline assembly; 601. first pipeline; 602. second pipeline. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0027] Example 1

[0028] Combine the following Figures 1 to 4 , describing an embodiment of the present invention.

[0029] According to an embodiment of the present invention, on the one hand, a heat exchange device is provided, including: a first cooling water tank 1, wherein a heat exchanger 2 is suitable for being arranged in the first cooling water tank 1, the first cooling water tank 1 is suitable for being connected to a containment shell 4, and coolant flows in the first cooling water tank 1; a second cooling water tank 3, wherein the second cooling water tank 3 is suitable for being connected to the containment shell 4, and coolant flows in the second cooling water tank 3; and a pipeline assembly 6, wherein the first cooling water tank 1 and the second cooling water tank 3 are connected via the pipeline assembly 6.

[0030] The heat exchanger 2 is arranged in the first cooling water tank 1. The temperature of the coolant in the first cooling water tank 1 is higher than that of the coolant in the second cooling water tank 3. The coolant in the first cooling water tank 1 undergoes a phase change at the outlet near the heat exchanger 2 to produce a two-phase fluid. The density difference between the coolant in the first cooling water tank 1 and the second cooling water tank 3 generates a natural circulation. The pipe assembly 6 transports the coolant in the first cooling water tank 1 to the second cooling water tank 3, and then transports the coolant in the second cooling water tank 3 to the first cooling water tank 1 by gravity, so as to realize the circulation of the coolant in the first cooling water tank 1 and the second cooling water tank 3. The fluidity of the coolant is improved by the cooling pipe, so that the coolant circulates in the first cooling water tank 1 and the second cooling water tank 3, effectively improving the fluidity of the coolant and improving the heat exchange efficiency. Compared with the setting of one cooling water tank, the setting of the first cooling water tank 1 and the second cooling water tank 3 reduces the difficulty of installation and production. It should be noted that the coolant in this embodiment is cooling water.

[0031] In one embodiment, Figure 1As shown, the first cooling water tank 1 is arranged on the outer peripheral surface of the containment shell 4, and the second cooling water tank 3 is arranged on the top of the containment shell 4. The first cooling water tank 1 is arranged on the outer peripheral surface of the containment shell 4 to reduce the installation cost of the first cooling water tank 1 and facilitate the disassembly and assembly of the first cooling water tank 1, and the second cooling water tank 3 is arranged on the top of the containment shell 4 to facilitate the disassembly and assembly of the second cooling water tank 3. It should be noted that the first cooling water tank 1 and the second cooling water tank 3 are both located outside the containment shell 4.

[0032] In this embodiment, if Figure 1 As shown, the second cooling water tank 3 is located at the top of the containment shell 4, and the bottom elevation of the second cooling water tank 3 is higher than the top elevation of the first cooling water tank 1, so that there is a height difference between the coolant in the first cooling water tank 1 and the coolant in the second cooling water tank 3, which facilitates the natural flow of the coolant.

[0033] In one embodiment, Figure 1 As shown, the pipe assembly 6 includes at least two pipes, and the at least two pipes include a first pipe 601 and a second pipe 602. The top of the first cooling water tank 1 and the top of the second cooling water tank 3 are connected through the first pipe 601, and the bottom of the side wall of the first cooling water tank 1 and the bottom of the second cooling water tank 3 are connected through the second pipe 602. By setting the first pipe 601 and the second pipe 602, the water flow in the first cooling water tank 1 and the second cooling water tank 3 can be fully flowed, so that the coolant flows from the top of the first cooling water tank 1 to the top of the second cooling water tank 3, and then flows from the bottom of the second cooling water tank 3 to the bottom of the side of the first cooling water tank 1, wherein the coolant in the first cooling water tank 1 should flow from the top to the bottom of the side, and the coolant should also flow from the bottom to the top in the second cooling water tank 3, so that the coolant can flow fully in the first cooling water tank 1 and the second cooling water tank 3 respectively. It should be noted that, in the whole process, the top of the first cooling water tank 1 connected to the first pipe 601 and the bottom of the side where the first cooling water tank 1 is connected to the second pipe 602 are set with an oblique line between the top and the bottom of the side, wherein the first pipe 601 is located at the top of the first cooling water tank 1 on the side where the heat exchanger 2 is provided, so that the coolant in the first cooling water tank 1 can flow fully in the tank. In addition, by providing the first pipe 601 and the second pipe 602, the fluidity of the coolant is much greater than that of the traditional water tank design, which greatly improves the flow rate of the water tank fluid near the heat exchanger 2, increases the convection heat transfer coefficient, and improves the heat exchange efficiency.

[0034] In one embodiment, the heat exchanger 2 is suitable for being connected to a main steam pipe, in which saturated steam flows, and the temperature of the saturated steam is higher than the temperature of the coolant. It should be noted that saturated steam flows in the main steam pipe, and the temperature of the saturated steam is a first temperature (316°C), which is much higher than the temperature of the coolant in the second cooling water tank 3 (4°C-50°C). In addition, the temperature of the coolant in the first cooling water tank 1 will slowly rise after heat exchange in the heat exchanger 2. After the coolant is heated for a period of time, a phase change occurs at the outlet of the first cooling water tank 1 to produce a two-phase fluid, and a two-phase natural circulation of the coolant in the first cooling water tank 1 and the second cooling water tank 3 occurs. Figure 4 As shown, when the saturated steam in the main steam pipe exchanges heat with the coolant in the first cooling water tank 1 in the heat exchanger 2, the coolant in the first cooling water tank 1 close to the heat exchanger 2 is rapidly heated up or even undergoes a phase change (the liquid turns into a gas), that is, the coolant flowing from the top of the first cooling water tank 1 into the second cooling water tank 3 is a two-phase mixture of liquid and gas, and the coolant that undergoes a phase change enters the top of the second cooling water tank 3 from the top of the first cooling water tank 1 through the first pipe 601. After being fully cooled in the second cooling water tank 3, the coolant in the second cooling water tank 3 flows into the side bottom of the first cooling water tank 1 through the second pipe 602 by gravity, so that when a power outage occurs in the nuclear reactor, the saturated steam in the main steam pipe is condensed by the coolant in the first cooling box to reduce the temperature of the saturated steam flowing in the main steam pipe.

[0035] In one embodiment, Figure 1 , Figure 2 As shown, the bottom elevation of the second cooling water tank 3 is higher than the top elevation of the first cooling water tank 1, the main steam pipe is connected to the steam generator, and the bottom elevation of the first cooling water tank 1 is higher than the top elevation of the steam generator. The liquid water formed by the saturated steam after condensation will flow under the action of gravity. The height difference between the first cooling water tank 1 and the second cooling water tank 3 facilitates the natural flow of the coolant.

[0036] In one embodiment, Figure 1 , Figure 2 As shown, the volume of the first cooling water tank 1 is smaller than that of the second cooling water tank 3 , which facilitates the coolant to flow fully in the first cooling water tank 1 and improves the utilization rate of the coolant in the first cooling water tank 1 .

[0037] In this embodiment, if Figure 1 , Figure 2As shown, the second cooling water tank 3 is an arc-shaped pipe arrangement, the first cooling water tank 1 has an arc-shaped fitting surface, the arc-shaped fitting surface is adapted to the peripheral surface of the containment shell 4, and the first pipe 601 and the second pipe 602 are respectively partially arranged to pass through the shell of the containment shell 4. It should be noted that the first cooling water tank 1 and the second cooling water tank 3 of the present application are both prefabricated in the factory, and only need to be hoisted on site to complete the installation, thereby reducing the difficulty of installation.

[0038] In this embodiment, if Figure 1 , Figure 2 As shown, it also includes an auxiliary building 5 arranged on the outer periphery of the containment shell 4, wherein the bottom elevation of the first cooling water tank 1 and the bottom elevation of the second cooling water tank 3 are respectively higher than the top elevation of the auxiliary building 5, thereby avoiding the first cooling water tank 1 or the second cooling water tank 3 from occupying additional usable space during the installation process. This installation method saves space.

[0039] A waste heat removal system, such as Figure 3 As shown, it includes three of the above-mentioned heat exchange devices, that is, three second cooling water tanks 3 are spliced ​​into a complete circle, and each heat exchange device is connected by a first cooling water tank 1 and a second cooling water tank 3 through a pipe assembly 6. In order to facilitate the full flow of the coolant, the adjacent second cooling water tanks 3 in this embodiment are connected, that is, the coolant in one second cooling water tank 3 can flow into the adjacent second cooling water tank 3 to achieve full flow of the liquid. It should be noted that each second cooling water tank 3 is not completely filled with coolant, but there is a certain gas space at the top of the second cooling water tank 3.

[0040] A method for using a heat exchange device, applied in a nuclear power plant, comprises the following steps:

[0041] 1) When a power outage occurs in the nuclear power plant, the steam generator loses water supply, and the backup power supply provides power. The saturated steam in the main steam pipe enters the heat exchanger 2, and the saturated steam in the heat exchanger 2 exchanges heat with the first cooling water tank 1 and then condenses;

[0042] 2) During the continuous heat exchange process of the first cooling water tank 1, the temperature of the coolant will continue to rise, and the first temperature sensor will feed back the temperature to the controller in real time. The coolant in the first cooling water tank 1 will heat up and even undergo a phase change, causing the coolant to flow from the top of the first cooling water tank 1 to the top of the second cooling water tank 3, and then from the bottom of the second cooling water tank 3 to the bottom of the side of the first cooling water tank 1, thereby generating a natural circulation (without any power, relying only on heat exchange) to cool the main steam pipeline.

[0043] Example 2

[0044] The first cooling water tank 1 is arranged in the containment shell 4, and the second cooling water tank 3 is arranged on the outer circumference of the containment shell 4. The first cooling water tank 1 is arranged in the containment shell 4 to protect the first cooling water tank 1, and the second cooling water tank 3 is arranged on the outer circumference of the containment shell 4 to reduce the installation cost of the second cooling water tank 3 and facilitate the disassembly and assembly of the second cooling water tank 3. The remaining devices and usage methods are exactly the same as those in Example 1.

[0045] Example 3

[0046] On the basis of the above two embodiments, in order to achieve control, a first control valve is provided in the first pipeline 601, a second control valve is provided in the second pipeline 602, and a first circulation pump is provided in the first pipeline 601. Specifically, the first control valve and the second control valve are both flow control valves. The first control valve can control the flow of the coolant in the first pipeline 601, and the second control valve can control the flow of the coolant in the second pipeline 602, so as to control the flow of the coolant according to the temperature in the first cooling box body to achieve the most optimized flow rate. In addition, the first circulation pump provides flow power for the flow of the coolant, so that the coolant flows from the bottom of the side of the first cooling water tank 1 to the bottom of the second cooling water tank 3, and then flows from the top of the second cooling water tank 3 to the top of the first cooling water tank 1.

[0047] In this embodiment, in order to measure the temperature in the cooling water tank, a first temperature sensor is provided in the first cooling water tank 1, and a second temperature sensor is provided in the second cooling water tank 3. In order to realize control, a controller is also included, and the controller is respectively connected to the first control valve, the second control valve, the third control valve, the first temperature sensor, the second temperature sensor, the first circulation pump and / or the second circulation pump. In order to provide power, a backup power supply is also included, and the backup power supply is respectively connected to the first control valve, the second control valve, the third control valve, the first circulation pump and / or the second circulation pump.

[0048] A method for using a heat exchange device, applied in a nuclear power plant, comprises the following steps:

[0049] 1) When a power outage occurs in the nuclear power plant, the steam generator loses water supply, and the backup power supply provides power. The controller starts the third control valve to allow the saturated steam in the main steam pipe to enter the heat exchanger 2. The saturated steam in the heat exchanger 2 exchanges heat with the first cooling water tank 1 and then condenses;

[0050] 2) During the continuous heat exchange process in the first cooling water tank 1, the temperature of the coolant will continue to rise, and the first temperature sensor will feed back the temperature to the controller in real time until the coolant in the first cooling water tank 1 reaches the preset temperature. The first control valve, the second control valve and the first circulation pump are opened to allow the coolant to flow from the bottom of the side of the first cooling water tank 1 to the bottom of the second cooling water tank 3, and then from the top of the second cooling water tank 3 to the top of the first cooling water tank 1, thereby generating a flow circulation to cool the main steam pipeline.

[0051] In order to control the communication between the main steam pipeline and the heat exchanger 2, a third control valve is provided at the connection between the heat exchanger 2 and the main steam pipeline. Specifically, the third control valve is a solenoid valve.

[0052] It should be noted that during normal operation of the nuclear power plant, the first control valve, the second control valve, the third control valve, the first circulation pump and the second circulation pump are all in a closed state, and the heat exchange device of the present application will not work.

[0053] The heat exchange device and waste heat removal system provided by the present application have the following advantages: (1) Compared with the traditional cooling water tank, the present application sets a first cooling water tank 1 and a second cooling water tank 3, connects the two cooling water tanks with a first pipe 601 and a second pipe 602, connects the coolant at the top of the first cooling water tank 1 with the coolant at the top of the second cooling water tank 3 and mixes them, and connects the coolant at the bottom of the second cooling water tank 3 with the coolant at the bottom of the side of the first cooling water tank 1 and mixes them, thereby improving the utilization rate of the coolant in the two cooling water tanks, avoiding the problem that the coolant at the bottom of the first cooling water tank 1 and the bottom of the second cooling water tank 3 cannot participate in the natural circulation, and improving the heat exchange efficiency; (2) The first cooling water tank 1 and the second cooling water tank 3 of the present application are connected by the first pipe 601 and the second pipe 602, and the fluidity of the entire device is much greater Compared with the traditional cooling water tank design, the coolant fluid flow rate near the heat exchanger 2 is greatly improved, the convective heat transfer coefficient is increased, and the heat transfer efficiency is improved; (3) Since a traditional cooling water tank is changed to the first cooling water tank 1 and the second cooling water tank 3 of the present application, the overall production cost is reduced, and it is convenient to install the two cooling water tanks by hoisting operations, which greatly reduces the difficulty of production and installation of the cooling water tanks; (4) Traditional cooling water tanks need to be fixed by other structures during use. In the present application, the first cooling water tank 1 or the second cooling water tank 3 is avoided from occupying additional use space during the installation process. This installation method saves space and has a relatively simple layout. The two cooling water tanks are independent parts and can be changed from on-site construction and installation to modular equipment manufactured by the factory and then transported to the site for hoisting, which greatly reduces the difficulty of on-site layout and construction.

[0054] As an alternative embodiment, the number of the pipe assemblies 6 may also be 4, 6, 8, etc., so as to fully realize the exchange of the coolant in the first cooling water tank 1 and the second cooling water tank 3 .

[0055] As an alternative embodiment, the coolant flows from the bottom of the second cooling water tank 3 to the bottom of the side of the first cooling water tank 1, and then from the top of the first cooling water tank 1 to the top of the second cooling water tank 3, wherein the coolant must flow from top to bottom in the second cooling water tank 3, and the coolant must also flow from the bottom of the side to the top in the first cooling water tank 1, thereby achieving sufficient flow of the coolant in the first cooling water tank 1 and the second cooling water tank 3 respectively.

[0056] As an alternative embodiment, a first circulation pump is provided in the first pipeline 601 and a second circulation pump is provided in the second pipeline 602; or, a second circulation pump is provided in the second pipeline 602.

[0057] As an alternative embodiment, two or more first cooling water tanks 1 in a heat exchange device can be connected to a second cooling water tank 3 through a pipe assembly 6, so as to fully utilize the coolant in the second cooling water tank 3 when the first cooling water tank 1 is small in size and the second cooling water tank 3 is large in size.

[0058] As an alternative embodiment, the volume of the first cooling water tank 1 is equal to the volume of the second cooling water tank 3 .

[0059] As an alternative implementation, the number of heat exchange devices in the waste heat removal system can also be 2, 4, 5 or even more to improve the heat exchange efficiency.

[0060] As an alternative embodiment, the coolant in the first cooling water tank 1 and the second cooling water tank 3 may also be other cooling media such as oil.

[0061] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A heat exchange device, characterized in that: Applied in nuclear power plants, including: A first cooling water tank (1), wherein the heat exchanger (2) is arranged in the first cooling water tank (1), the first cooling water tank (1) is suitable for being connected to the containment shell (4), and a coolant flows in the first cooling water tank (1); a second cooling water tank (3), the second cooling water tank (3) being suitable for being connected to the containment shell (4), and having a coolant flowing in the second cooling water tank (3); A pipeline assembly (6), wherein the first cooling water tank (1) and the second cooling water tank (3) are connected to each other through the pipeline assembly (6).

2. The heat exchange device according to claim 1, characterized in that: The first cooling water tank (1) is arranged on the outer peripheral surface of the containment shell (4), and the second cooling water tank (3) is arranged on the top of the containment shell (4).

3. The heat exchange device according to claim 1, characterized in that: The first cooling water tank (1) is arranged in the containment shell (4), the second cooling water tank (3) is arranged on the outer peripheral surface of the containment shell (4), an auxiliary building (5) is suitably arranged outside the containment shell (4), the second cooling water tank (3) is arranged on the top of the auxiliary building (5), and the height of the auxiliary building (5) is lower than the height of the containment shell (4).

4. The heat exchange device according to claim 2 or 3, characterized in that: The pipe assembly (6) comprises at least two pipes, wherein the at least two pipes comprise a first pipe (601) and a second pipe (602), wherein the top of the first cooling water tank (1) and the top of the second cooling water tank (3) are connected via the first pipe (601), and the bottom of the side wall of the first cooling water tank (1) and the bottom of the second cooling water tank (3) are connected via the second pipe (602).

5. The heat exchange device according to claim 4, characterized in that: A first control valve is provided in the first pipeline (601), a second control valve is provided in the second pipeline (602), a first circulation pump is provided in the first pipeline (601) and / or a second circulation pump is provided in the second pipeline (602).

6. The heat exchange device according to claim 4, characterized in that: The heat exchanger (2) is suitable for being connected to a main steam pipeline, in which saturated steam flows, and the temperature of the saturated steam is higher than the temperature of the coolant.

7. The heat exchange device according to claim 2 or 3, characterized in that: The bottom elevation of the second cooling water tank (3) is higher than the top elevation of the first cooling water tank (1).

8. The heat exchange device according to claim 1, characterized in that: The volume of the first cooling water tank (1) is smaller than the volume of the second cooling water tank (3); or, the volume of the first cooling water tank (1) is equal to the volume of the second cooling water tank (3).

9. A waste heat removal system, characterized in that: The heat exchange device comprises at least two heat exchange devices according to any one of claims 1 to 8.

10. A method for using a heat exchange device, for using the heat exchange device according to claim 1, characterized in that: A heat exchanger (2) is arranged in the first cooling water tank (1), the temperature of the coolant in the first cooling water tank (1) is higher than the temperature of the coolant in the second cooling water tank (3), the coolant in the first cooling water tank (1) undergoes a phase change at an outlet near the heat exchanger (2) to generate a two-phase fluid, and a natural circulation is generated by the density difference of the coolant in the first cooling water tank (1) and the second cooling water tank (3), the pipe assembly (6) transports the coolant in the first cooling water tank (1) to the second cooling water tank (3), and then transports the coolant in the second cooling water tank (3) to the first cooling water tank (1) by gravity, so as to realize the circulation of the coolant in the first cooling water tank (1) and the second cooling water tank (3).

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