A forced separation type passive system steam condensation induced water hammer elimination device

Abstract

The present invention discloses a forced separation type passive system steam condensation induced water hammer elimination device, which relates to the technical fields of fluid mechanics and heat transfer, and solves the problems that the existing water hammer suppression and elimination methods have poor effects and will increase the system flow resistance, resulting in inapplicability to passive natural circulation systems. One end of the cold pipe section of the present invention is connected to seawater, and the other end is connected to the heating section; one end of the heat pipe section is connected to the heating section, and the other end is closed; a forced separation type device is arranged on the heat pipe section, and the forced separation type device is connected to seawater; by utilizing the principle of the density difference between steam and water, in the forced separation type device, steam enters the steam storage header through the steam riser pipe and is discharged into the atmosphere in the steam storage header. Due to the action of gravity, the liquid enters the liquid water outflow pipe through the liquid water downcomer and is discharged into seawater in the liquid water outflow pipe, realizing steam-water separation and fundamentally avoiding violent condensation.

Description

Technical Field

[0001] The present invention relates to the technical fields of fluid mechanics and heat transfer, and specifically to a forced separation type passive system steam condensation induced water hammer elimination device. Background Art

[0002] Floating nuclear power plants combine ship design and nuclear power technology, and can provide stable energy support for activities such as ocean development. In such nuclear power plants, when an accident occurs, a passive residual heat removal system (such as a natural circulation system) will discharge the residual heat of the reactor core into the ocean to ensure the safety of the reactor core. However, in the initial stage of the accident, due to the relatively strong residual heat of the reactor core, the heat exchanger in the seawater natural circulation loop may boil, and then generate saturated steam hydrates. When these steam hydrates come into contact with the cooling seawater, a violent condensation reaction will occur, which may cause the seawater to flow backward into the heat pipe and form a steam plug. As the steam is surrounded by the cooling seawater and quickly condenses, violent collisions will occur at both ends of the liquid column, generating a water hammer phenomenon. The water hammer phenomenon will trigger pressure pulses up to the megapascal level, which may cause pipeline vibration, increased noise, and even lead to system failures. Therefore, the water hammer phenomenon poses a major threat to the operation of the passive safety system and limits its scope of practical application.

[0003] Currently, there have been some technical methods to attempt to suppress and eliminate the water hammer phenomenon. For the water hammer caused by steam condensation, the existing solutions include in-pipe water hammer suppression technology and heat exchanger isolation technology. Through the heat exchanger isolation technology, it is possible to avoid direct contact between the steam and the low-temperature seawater, thereby reducing the occurrence of water hammer. However, this method requires a large heat transfer area, resulting in high costs and complex maintenance. In addition, since the water temperature in the heat exchanger heat transfer tubes is higher than the seawater temperature, the density difference required to form a natural circulation will be significantly reduced, thereby reducing the natural circulation capacity.

[0004] For the suppression of in-pipe water hammer, common technologies include partitioned pipes and porous pipes. The partitioned pipes reduce the occurrence of water hammer by dividing the pipeline into multiple flow channels, but do not fundamentally solve the steam condensation problem, only reducing the possibility of water hammer in each flow channel. The porous pipe suppression method is usually only effective under specific steam pressures and will increase the flow resistance, thereby reducing the system efficiency. Although these methods reduce the water hammer by changing the geometry of the pipeline, the increased flow resistance will affect the system flow characteristics. Especially in a passive natural circulation system, the resistance change may cause changes in the flow characteristics, thereby affecting the system adaptability. It should be noted that in the case of high steam flow rates, the in-pipe water hammer elimination measures may not be able to completely condense the steam, resulting in the re-aggregation of small bubbles to form large bubbles, and these large bubbles may still trigger the water hammer phenomenon after entering the low-temperature water environment.

[0005] In summary, although some existing technical methods can suppress the water hammer phenomenon to a certain extent, they usually have drawbacks such as affecting flow characteristics, increasing system resistance, or being costly, which limit their wide application. Further research and technological innovation are needed to make up for the deficiencies of existing solutions and ensure the safe and efficient operation of floating nuclear power plants. Summary of the Invention

[0006] In order to solve the problems mentioned above that the existing water hammer suppression and elimination methods have poor effects and will increase the system flow resistance, making them inapplicable to passive natural circulation systems, the present invention hereby proposes a forced separation type passive system steam condensation induced water hammer elimination device. The present invention utilizes the principle of the density difference between steam and water. Under the action of gravity, steam rises and liquid descends, thereby achieving steam-water separation and fundamentally avoiding violent condensation.

[0007] The present invention proposes a forced separation type passive system steam condensation induced water hammer elimination device, which specifically includes a cold pipe section, a heating section, a heat pipe section, a storage wall, and a forced separation device. One end of the cold pipe section passes through the storage wall and is connected to seawater, and the other end is connected to the lower end of the heating section; the upper end of the heating section is connected to one end of the heat pipe section, and the other end of the heat pipe section is closed; a forced separation device is provided on the heat pipe section, and the lower end of the forced separation device passes through the storage wall and is connected to seawater; the forced separation device includes a steam storage header, a plurality of steam rising pipes, a plurality of liquid water descending pipes, and a liquid water outflow pipe. The steam storage header is arranged above the heat pipe section and is connected through a plurality of steam rising pipes; the liquid water outflow pipe is arranged below the heat pipe section and is connected through a plurality of liquid water descending pipes; a steam storage header outlet is provided on the steam storage header; the liquid water outflow pipe is connected to seawater.

[0008] Furthermore, the heat pipe section, the liquid water descending pipes, and the liquid water outflow pipe are below the sea level.

[0009] Furthermore, the steam storage header is above the sea level.

[0010] Furthermore, the steam rising pipes and the liquid water descending pipes are arranged at equal intervals and have the same spacing.

[0011] Furthermore, the steam rising pipes and the liquid water descending pipes are vertically aligned.

[0012] Furthermore, the steam rising pipes and the liquid water descending pipes have the same pipe diameter.

[0013] Furthermore, the length of the steam rising pipes is four times or more the length of the liquid water descending pipes.

[0014] Furthermore, the pipe diameter of the liquid water outflow pipe is two times or more the pipe diameter of the steam rising pipes and the liquid water descending pipes.

[0015] The beneficial effects of the forced separation type passive system steam condensation induced water hammer elimination device described in the present invention are as follows:

[0016] (1) The forced separation type passive system steam condensation induced water hammer elimination device described in the present invention solves the problems that the existing water hammer suppression and elimination methods have poor effects and will increase the system flow resistance, resulting in inapplicability to the passive natural circulation system. The present invention utilizes the principle of the density difference between steam and water, and ensures the separation of steam from liquid through the influence of gravity factors. The purpose of this is to enable the steam-water mixture generated in the heating section to enter the steam storage header through the steam riser pipe and then be discharged into the atmosphere when flowing through the steam-water separation device, while the remaining liquid enters the liquid water outflow pipe through the liquid downcomer and is then discharged into the sea to achieve steam-water separation and fundamentally avoid violent condensation.

[0017] (2) The forced separation type passive system steam condensation induced water hammer elimination device described in the present invention can strengthen the turbulence of the steam-water mixture and break large air bubbles into small air bubbles when the steam-water mixture collides with the wall surface by closing the end of the heat pipe section, further accelerating the separation of steam from liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0019] In the drawings:

[0020] Figure 1 is a schematic structural diagram of the forced separation type passive system steam condensation induced water hammer elimination device described in the present invention;

[0021] Figure 2 is a side view of the forced separation type device of the forced separation type passive system steam condensation induced water hammer elimination device described in the present invention;

[0022] Figure 3 is a front view of the forced separation type device of the forced separation type passive system steam condensation induced water hammer elimination device described in the present invention;

[0023] Wherein: 1 - cold pipe section, 2 - heating section, 3 - heat pipe section, 4 - storage wall, 5 - forced separation type device, 5-1 - steam storage header outlet, 5-2 - steam storage header, 5-3 - steam riser pipe, 5-4 - liquid water downcomer, 5-5 - liquid water outflow pipe, 6 - seawater. DETAILED DESCRIPTION OF THE INVENTION

[0024] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0025] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0026] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0028] Specific Embodiment 1: Refer to Figures 1-3 Specifically illustrate this embodiment. The forced separation type passive system steam condensation induced water hammer elimination device described in this embodiment specifically includes a cold pipe section 1, a heating section 2, a heat pipe section 3, a storage wall 4, and a forced separation device 5. One end of the cold pipe section 1 passes through the storage wall 4 and is connected to seawater 6, and the other end is connected to the lower end of the heating section 2; the upper end of the heating section 2 is connected to one end of the heat pipe section 3, and the other end of the heat pipe section 3 is closed, which can strengthen the turbulence of the steam-water mixture and break large bubbles into small bubbles when the steam-water mixture collides with the wall surface, further accelerating the separation of steam and liquid; a forced separation device 5 is arranged on the heat pipe section 3, and the lower end of the forced separation device 5 passes through the storage wall 4 and is connected to seawater 6;

[0029] The forced separation device 5 includes a steam storage header 5-2, a plurality of steam riser pipes 5-3, a plurality of liquid water downcomer pipes 5-4, and a liquid water outlet pipe 5-5. The steam storage header 5-2 is arranged directly above the heat pipe section 3 and is connected to the heat pipe section 3 through a plurality of steam riser pipes 5-3. The liquid water outlet pipe 5-5 is arranged directly below the heat pipe section 3 and is connected to the heat pipe section 3 through a plurality of liquid water downcomer pipes 5-4. A steam storage header outlet 5-1 is provided on the steam storage header 5-2. The liquid water outlet pipe 5-5 is connected to the seawater 6.

[0030] The heat pipe section 3, the liquid water downcomer pipe 5-4, and the liquid water outlet pipe 5-5 are below the plane of the seawater 6. The steam storage header 5-2 is above the plane of the seawater 6.

[0031] The steam riser pipes 5-3 are arranged at equal intervals between the steam storage header 5-2 and the heat pipe section 3, and the liquid water downcomer pipes 5-4 are arranged at equal intervals between the liquid water outlet pipe 5-5 and the heat pipe section 3. The arrangement intervals of the steam riser pipes 5-3 and the liquid water downcomer pipes 5-4 are the same. Moreover, in the vertical direction, the steam riser pipes 5-3 and the liquid water downcomer pipes 5-4 are vertically aligned.

[0032] The steam riser pipes 5-3 and the liquid water downcomer pipes 5-4 have the same pipe diameter. The length of the steam riser pipes 5-3 is four times or more the length of the liquid water downcomer pipes 5-4. The pipe diameter of the liquid water outlet pipe 5-5 is two times or more the pipe diameter of the steam riser pipes 5-3 and the liquid water downcomer pipes 5-4.

[0033] The specific operation process of the passive system steam condensation-induced water hammer elimination device with forced separation according to the present invention is as follows:

[0034] When the system operates, the seawater in the cold pipe section 1 flows through the heating section 2 and is heated and raised in temperature. Driven by the density difference of the seawater in the cold pipe section 1 and the seawater 6, the natural circulation is started, and the heat generated in the heating section 2 is discharged into the seawater 6 after being separated into steam and water through the heat pipe section 3. When the heat load of the heating section 2 increases, saturated steam-water mixture or superheated steam is generated at its outlet. The saturated steam-water mixture or superheated steam first enters the heat pipe section 3. When the saturated steam-water mixture flows through the heat pipe section 3, the steam, due to its relatively small density, will flow into the steam storage header 5-2 through the steam riser pipes 5-3 and is discharged into the atmosphere through the steam storage tank outlet 5-1 in the steam storage header 5-2. The liquid, due to its large density, will flow into the liquid water outlet pipe 5-5 through the liquid water downcomer pipes 5-4 and flow into the seawater 6 through the liquid water outlet pipe 5-5. Through the above process, the separation of the steam-water mixture is realized, fundamentally avoiding violent condensation, preventing high-subcooled seawater from contacting and condensing with steam in the heat pipe section, and effectively alleviating the harm of water hammer.

[0035] Summarizing the above embodiments, an active system steam condensation-induced water hammer elimination device with forced separation according to the present invention solves the problems that the existing water hammer suppression and elimination methods have poor effects and will increase the system flow resistance, making them inapplicable to passive natural circulation systems. The present invention utilizes the principle of the density difference between steam and water, and ensures the separation of steam from liquid through the influence of gravity factors. The purpose of this is to enable the steam-water mixture generated in the heating section 2 to flow through the steam-water separation device, where the steam in the steam-water mixture enters the steam storage header 5-2 through the steam riser 5-3 and is then discharged into the atmosphere, while the remaining liquid enters the liquid outlet pipe 5-5 through the liquid downcomer 5-4 and is then discharged into the sea to achieve steam-water separation and fundamentally avoid violent condensation. An active system steam condensation-induced water hammer elimination device with forced separation according to the present invention can strengthen the turbulence of the steam-water mixture and break large air bubbles into small bubbles when the steam-water mixture collides with the wall surface by closing the end of the heat pipe section 3, further accelerating the separation of steam from liquid.

[0036] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the invention. It can also be a reasonable combination of the features described in the above embodiments. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A passive system steam condensation-induced water hammer elimination device with forced separation, characterized in that: It includes a cold pipe section (1), a heating section (2), a heat pipe section (3), a silo wall (4), and a forced separation device (5). One end of the cold pipe section (1) passes through the silo wall (4) and is connected to seawater (6), and the other end is connected to the lower end of the heating section (2). The upper end of the heating section (2) is connected to one end of the heat pipe section (3), and the other end of the heat pipe section (3) is closed. A forced separation device (5) is provided on the heat pipe section (3), and the lower end of the forced separation device (5) passes through the silo wall (4) and is connected to seawater (6). The forced separation device (5) includes a steam storage header (5-2), a number of steam rising pipes (5-3), a number of liquid water descending pipes (5-4), and a liquid water outflow pipe (5-5). The steam storage header (5-2) is arranged above the heat pipe section (3) and is connected through a number of steam rising pipes (5-3). The liquid water outflow pipe (5-5) is arranged below the heat pipe section (3) and is connected through a number of liquid water descending pipes (5-4). A steam storage header outlet (5-1) is provided on the steam storage header (5-2). The liquid water outflow pipe (5-5) is connected to seawater (6). The heat pipe section (3), the liquid water descending pipes (5-4), and the liquid water outflow pipe (5-5) are below the seawater (6) level. The steam storage header (5-2) is above the seawater (6) level.

2. The forced separation type passive system steam condensation induced water hammer elimination device according to claim 1, characterized in that: The steam rising pipes (5-3) and the liquid water descending pipes (5-4) are arranged at equal intervals and have the same spacing.

3. The forced separation type passive system steam condensation induced water hammer elimination device according to claim 2, characterized in that: The steam rising pipes (5-3) and the liquid water descending pipes (5-4) are vertically aligned.

4. The forced separation type passive system steam condensation induced water hammer elimination device according to claim 2, characterized in that: The steam rising pipes (5-3) and the liquid water descending pipes (5-4) have the same pipe diameter.

5. The forced separation type passive system steam condensation induced water hammer elimination device according to claim 2, characterized in that: The length of the steam rising pipes (5-3) is four times or more the length of the liquid water descending pipes (5-4).

6. The forced separation type passive system steam condensation induced water hammer elimination device according to claim 4, characterized in that: The pipe diameter of the liquid water outflow pipe (5-5) is two times or more the pipe diameter of the steam rising pipes (5-3) and the liquid water descending pipes (5-4).

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