Containment heat conduction steam collecting device and containment heat removal system of nuclear power plant

Abstract

The present invention discloses a containment heat-conducting steam collecting device and a heat export system, which includes a steam collecting pipe. The steam collecting pipe includes a steam outlet, and at least one exhaust port is provided on the side wall of the steam collecting pipe. It also includes at least one sleeve, which is sleeved outside the steam collecting pipe. Under its own acting force, the sleeve moves axially along the steam collecting pipe following the change of the cooling medium liquid level, so as to open or close the exhaust port corresponding to the sleeve. When the liquid level of the cooling medium is higher than a predetermined value, the sleeve completely covers the exhaust port, and the steam-water mixture entering the steam collecting pipe is discharged from the steam outlet. When the liquid level of the cooling medium is lower than the predetermined value and is in the process of decreasing, the sleeve moves downward axially along the steam collecting pipe, so that at least one exhaust port is opened, and at least part of the steam-water mixture entering the steam collecting pipe is discharged from the exhaust port. The steam collecting device proposed by the present invention effectively eliminates the water hammer phenomenon of the cooling medium and at the same time avoids the problem of the reduction of the heat dissipation capacity due to the decrease of the liquid level.

Description

Technical Field

[0001] The present invention relates to the field of nuclear power, and more specifically, to a steam collecting device for heat conduction of a containment and a heat removal system for the containment of a nuclear power plant. Background Art

[0002] The containment is the last and most important safety barrier in a nuclear power plant. In the event of an accident in the nuclear power plant, a large amount of high-temperature and high-pressure steam enters the containment, causing the temperature and pressure inside the containment to rise rapidly. If the temperature and pressure limits that the containment can withstand are exceeded, the integrity of the containment will be damaged, and at that time, the radioactive substances in the reactor will be uncontrollably released into the external environment, posing a hazard to the public and the environment. The passive heat removal technology of the containment has become an important means to ensure nuclear power safety.

[0003] Patents CN201710285748.4 and CN201110437864.6 disclose a passive heat removal system for a containment based on the principle of open natural circulation. Neither of them involves the design of a steam collecting device, but directly inserts the riser of the natural circulation loop into the water tank. This design allows the steam at the outlet of the riser section to directly contact the subcooled water in the water tank, thereby inducing water hammer. Moreover, as the passive heat removal system of the containment operates, the water tank continuously heats up until it reaches saturated evaporation. When the water level is lower than the inlet of the riser, the driving force of the system will be greatly reduced, and even the natural circulation will stop.

[0004] The passive heat removal systems disclosed in patents CN201580075448.2 and CN202110361904.7 are provided with steam release valves or steam-water separators, and the patent application also indicates that the steam release valve / steam-water separator can eliminate water hammer, but does not disclose the specific design structure, and cannot eliminate the impact of the reduction of the water tank water level on the heat removal of the system.

[0005] Patent CN202120737834.6 discloses a passive residual heat removal system for a containment, which includes a door body assembly that will open according to the reduction of the water tank liquid level, thereby solving the problem of insufficient driving force of the system caused by the decrease in water level. However, the design of the door body assembly of this patent is too complex, including door leaves, slide rails, limit blocks, latches, lock rods, and floating bodies. The complex structure reduces the reliability of the device, and it is not convenient for installation, disassembly, and maintenance.

[0006] In view of the above technical problems, the present invention is specifically proposed. Summary of the Invention

[0007] The main purpose of the present invention is to provide a containment heat conduction steam collecting device and a nuclear power plant containment heat removal system, which can ensure the heat removal capacity of the system when the water level drops, improve the stability of the loop flow rate, and eliminate the water hammer phenomenon at the same time. The device and the system have a simple structure and high reliability.

[0008] To achieve the above object, according to one aspect of the present invention, there is provided a containment heat conduction steam collecting device, which is arranged in a cooling medium and is used for discharging a steam-water mixture into the gas phase space of a coolant tank to avoid the water hammer phenomenon. The device includes a steam collecting pipe, the steam collecting pipe includes a steam outlet, and at least one exhaust port is opened on the side wall of the steam collecting pipe. The device further includes at least one sleeve, the sleeve is sleeved outside the steam collecting pipe, and the sleeve moves axially along the steam collecting pipe by itself under its own action following the change of the cooling medium liquid level, so as to open or close the exhaust port corresponding to the sleeve.

[0009] The sleeve is arranged such that when the cooling medium liquid level is higher than a predetermined value, the sleeve completely covers the exhaust port, and the steam-water mixture entering the steam collecting pipe is discharged from the steam outlet. When the cooling medium liquid level is lower than the predetermined value and is in the process of dropping, at least one sleeve moves axially downward along the steam collecting pipe, so that at least one exhaust port is opened, and at least part of the steam-water mixture entering the steam collecting pipe is discharged from the exhaust port, so as to improve the heat removal capacity at a low liquid level.

[0010] Further, a multi-stage sleeve distributed along the height direction of the cooling medium liquid level is included. The first-stage sleeve in the multi-stage sleeve is located at the lowermost part, and the number of stages increases successively along the height of the cooling medium liquid level. Each sleeve in the multi-stage sleeve can move axially along the steam collecting pipe following the change of the cooling medium liquid level, and is arranged such that when the liquid level height of the cooling medium drops, the multi-stage sleeve moves downward successively from the higher stage to the lower stage.

[0011] Further, a multi-stage exhaust port is provided in the height direction of the steam collecting pipe, the multi-stage exhaust port is correspondingly arranged with the multi-stage sleeve, and the multi-stage sleeve moves downward successively from the higher stage to the lower stage to open the multi-stage exhaust port successively from the higher one to the lower one.

[0012] Further, the inner diameter of the upper-stage sleeve in the multi-stage sleeve is larger than the outer diameter of the lower-stage sleeve, adjacent sleeves are nested with each other, and the upper-stage sleeve can move along the outer wall of the lower-stage sleeve.

[0013] Further, an exhaust area is defined axially along the steam collecting pipe above the first positioning portion, and a reinforcing ring is provided on the outer wall of the steam collecting pipe corresponding to the exhaust area to enhance the stability of the steam collecting pipe.

[0014] Further, the maximum axial length of the multi-stage sleeve along the steam collecting pipe is not less than the axial length of the exhaust area along the steam collecting pipe, so that the multi-stage sleeve can completely cover each exhaust port within the length range of the steam collecting pipe.

[0015] Further, a non-exhaust region is defined along the axial direction of the steam collecting pipe below the first positioning portion, and the height of the first-stage sleeve is greater than the length of the non-exhaust region along the axial direction of the steam collecting pipe.

[0016] Further, each sleeve in the multi-stage sleeve encloses a hollow cavity, and the buoyancy force received by the hollow cavity in the cooling medium is greater than the gravity received by the sleeve.

[0017] Further, it includes a first positioning portion. The first positioning portion is sleeved on the outside of the steam collecting pipe. The first positioning portion defines the highest position of the multi-stage sleeve to prevent the multi-stage sleeve from detaching from the steam collecting pipe from the upper part of the steam collecting pipe.

[0018] Further, it further includes a fourth positioning portion. The fourth positioning portion is sleeved on the outside of the steam collecting pipe. The fourth positioning portion defines the lowest position of the multi-stage sleeve to prevent the multi-stage sleeve from detaching from the steam collecting pipe from the lower part of the steam collecting pipe.

[0019] Further, a second positioning portion is provided at the top of each stage of sleeve, and the second positioning portions of adjacent sleeves are in contact with each other to prevent the upper-stage sleeve from detaching from the bottom of the lower-stage sleeve.

[0020] Further, a third positioning portion is provided at the bottom of each stage of sleeve. The third positioning portion of the upper-stage sleeve is in contact with the second positioning portion of the lower-stage sleeve to prevent the upper-stage sleeve from detaching from the lower-stage sleeve when the upper-stage sleeve moves upward..

[0021] Further, the inner diameter of the second positioning portion is equal to the outer diameter of the steam collecting pipe, and the outer diameter of the second positioning portion is equal to the inner diameter of the upper-stage sleeve.

[0022] Further, the inner diameter of the third positioning portion is equal to the outer diameter of the lower-stage sleeve, and the outer diameter of the third positioning portion is the outer diameter of this stage of sleeve.

[0023] Further, the outer diameter of the first positioning portion is equal to the inner diameter of the first-stage sleeve.

[0024] Further, each sleeve in the multi-stage sleeve is independent of each other and corresponds to different liquid level heights of the cooling medium.

[0025] Further, a plurality of limiters are sleeved on the outer wall of the steam collecting pipe. The limiters axially divide the steam collecting pipe into a plurality of independent regions, and the multi-stage sleeves are respectively arranged in each independent region.

[0026] Further, the fourth positioning portion is close to the bottom of the steam collecting pipe.

[0027] Further, the second positioning portion and the third positioning portion are detachably connected to the sleeve.

[0028] Further, it further includes a flow guide cover. The flow guide cover is sleeved on the outside of the multi-stage sleeve.

[0029] Furthermore, a liquid discharge port is provided at the bottom of the fairing, and the cooling medium in the fairing is discharged through the liquid discharge port, reducing the disturbance to the liquid level of the cooling medium.

[0030] Furthermore, a steam-water separation cover is provided above the steam outlet, and the steam-water separation cover separates the steam-water mixture flowing out of the steam outlet.

[0031] Furthermore, it also includes a support column, and the support column supports the steam-water separation cover, keeping the steam-water separation cover at a predetermined distance from the fairing.

[0032] The containment heat conduction steam collecting device proposed by the present invention achieves the following technical effects:

[0033] 1. Under the action of the buoyancy and its own gravity of the sleeve in the cooling medium, it moves along the axial direction of the steam collecting pipe following the liquid level change, realizing the automatic opening and closing of the steam exhaust port, reducing the resistance of the natural circulation loop, ensuring the heat rejection capacity of the system at low liquid levels, and at the same time avoiding direct contact between the steam-water mixture and the cooling medium, preventing water hammer phenomenon;

[0034] 2. Adopting the nested mode of multiple-stage sleeves and setting multiple positioning plates to avoid the separation of multiple-stage sleeves from each other, ensuring the structural stability;

[0035] 3. The steam collecting pipe is divided into multiple independent regions by the limiters, and the multiple-stage sleeves are respectively sleeved outside the steam collecting pipes in the independent regions. The limiters limit the moving regions of each sleeve, with a simple structure, good stability, and being convenient for disassembly and assembly;

[0036] 4. By optimizing the structure of the multiple-stage sleeves, the multiple-stage sleeves completely cover the steam exhaust region, increasing the height of the rising section, thereby increasing the length of the natural circulation two-phase section and increasing the system driving force and heat rejection capacity;

[0037] 5. The containment heat conduction steam collecting device proposed in this application has a simple structure and is convenient for disassembly, assembly and maintenance.

[0038] To achieve the above object, according to another aspect of the present invention, a nuclear power plant containment heat export system is provided, including a steam collecting device, a riser pipe, a water tank and a heat exchanger. The steam collecting device is arranged inside the water tank. The steam collecting device is connected to the heat exchanger through the riser pipe. The medium in the heat exchanger absorbs the heat of the containment and enters the steam collecting device through the riser pipe, and is sent into the water tank through the steam collecting device to export the heat in the containment.

[0039] The nuclear power plant containment heat export system proposed by the present invention achieves the following technical effects:

[0040] 1. Under the action of the buoyancy and its own gravity of the sleeve of the steam collecting device adopted by the containment heat removal system of a nuclear power plant in the cooling medium, it moves along the axial direction of the steam collecting pipe following the liquid level change, realizing the automatic opening and closing of the exhaust port, ensuring the heat removal capacity and system driving force of the system under low liquid level;

[0041] 2. The steam collecting device adopted by the containment heat removal system of a nuclear power plant uses a multi-stage sleeve nesting method and is provided with multiple positioning plates to prevent the multi-stage sleeves from separating from each other, ensuring the structural stability;

[0042] 3. The structure of the containment heat removal system of a nuclear power plant is simple, facilitating disassembly, assembly and maintenance;

[0043] 4. The steam collecting device in the containment heat removal system of a nuclear power plant is arranged at the outlet of the riser pipe, increasing the length of the two-phase section of the natural circulation loop and the driving force of natural circulation, thereby improving the heat removal capacity of the system;

[0044] 5. The steam-water mixture at the outlet of the riser section in the containment heat removal system of a nuclear power plant is directly transported to the gas phase space of the water tank, avoiding the contact between steam and subcooled water, thus achieving the elimination of water hammer phenomenon. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The accompanying drawings forming a part of this invention are used to provide a further understanding of the invention. The schematic embodiments and descriptions thereof of the invention are used to explain the invention and do not constitute an improper limitation to the invention. In the drawings:

[0046] Figure 1 Showing the structural schematic diagram of the steam collecting device of Embodiment 1 of the present invention;

[0047] Figure 2 Showing the structural schematic diagram of the multi-stage sleeve of the steam collecting device of Embodiment 1 of the present invention;

[0048] Figure 3 Showing the top view of the multi-stage sleeve of the steam collecting device of Embodiment 1 of the present invention;

[0049] Figure 4 Showing the structural schematic diagram of the first positioning part and the sleeve of Embodiment 1 of the present invention;

[0050] Figure 5 Showing the structural relationship schematic diagram of the second positioning part and the third positioning part of Embodiment 1 of the present invention;

[0051] Figure 6 Showing the structural schematic diagram of the steam collecting device of Embodiment 2 of the present invention;

[0052] Figure 7 Showing the structural schematic diagram of the containment heat removal system of the nuclear power plant of the present invention.

[0053] Among them, the above-mentioned attached drawings include the following reference numerals:

[0054] 10. Steam collecting pipe; 121. Steam outlet; 160. Exhaust port; 200. Sleeve; 180. First positioning part; 190. Fourth positioning part; 222. Second positioning part; 224. Third positioning part; 170. Limiter; 110. Reinforcing ring; 50. Deflector; 520. Drain port; 60. Steam-water separation cover; 70. Support column; 4. Rising pipe; 1. Steam collecting device; 2. Water tank; 3. Heat exchanger. Detailed implementation manners

[0055] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to the attached drawings and in combination with the embodiments.

[0056] The present invention will be further described in detail below with reference to specific embodiments, and these embodiments should not be construed as limiting the scope claimed by the present invention. The term "comprising" indicates the presence of features when used, but does not exclude the presence or addition of one or more other features; the terms "transverse", "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the attached drawings, and are only for the convenience of 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 on the present invention; in addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0057] In the description, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be directly connected, or indirectly connected through an intermediate medium, and may 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 may be understood according to specific situations. In addition, in the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0058] Embodiment 1:

[0059] According to one aspect of the present invention, a containment heat-conducting steam collecting device 1 is proposed, which is arranged in a cooling medium. When the steam collecting device 1 is in the water phase, the water phase enters the cooling medium for heat exchange to export the heat of the containment; when the steam collecting device 1 is in a steam-water mixture, the steam-water mixture enters the gas phase space of the cooling medium to avoid direct contact with the cooling medium and prevent the occurrence of water hammer phenomenon. As Figure 1As shown, the steam collecting device 1 includes a steam collecting pipe 10. The steam collecting pipe 10 includes a steam outlet 121, and at least one exhaust port 160 is formed on the side wall of the steam collecting pipe 10.

[0060] In addition, in combination with Figure 1 and Figure 2 As shown, the steam collecting device 1 further includes at least one sleeve 200. The sleeve 200 is sleeved outside the steam collecting pipe 10. Under its own acting force, the sleeve 200 moves axially along the steam collecting pipe 10 following the change of the cooling medium liquid level, so as to open or close the exhaust port 160 corresponding to the sleeve 200. In this application, the self-acting force of the sleeve mainly includes the buoyancy force of the sleeve in the cooling medium and the self-gravity of the sleeve. In this application, the cooling medium includes but is not limited to water medium, and the cooling medium is arranged in a water tank.

[0061] When the liquid level of the water tank is higher than the predetermined value, due to the buoyancy force of the cooling medium received by the sleeve being greater than its own gravity, the sleeve 200 completely covers the exhaust port 160, and the steam-water mixture entering the steam collecting pipe 10 is discharged from the steam outlet 121; when the liquid level of the water tank is lower than the predetermined value and during the descending process, due to the decrease of the liquid level in the water tank, the buoyancy force received by the sleeve decreases, and its own gravity is greater than the received buoyancy force, at least one sleeve 200 moves downward axially along the steam collecting pipe 10, so that at least one exhaust port 160 is opened, and at least part of the steam-water mixture entering the steam collecting pipe 10 is discharged from the exhaust port 160.

[0062] For the steam collecting device proposed in this application, by using the change of the sleeve buoyancy with the liquid level, the sleeve is enabled to move axially along the steam collecting pipe, thereby controlling the opening and closing of the exhaust port, balancing the static pressure difference inside and outside the steam collecting device 1, increasing the system circulation driving force and heat dissipation capacity at a low liquid level height, and promoting the natural circulation of the system.

[0063] In an embodiment of this application, the steam collecting device 1 includes a multi-stage sleeve distributed along the height direction of the cooling medium liquid level. The first-stage sleeve in the multi-stage sleeve is located at the lowermost part, and the number of stages increases successively along the height of the cooling medium liquid level. Each sleeve in the multi-stage sleeve can move axially along the steam collecting pipe 10 following the change of the cooling medium liquid level, and is arranged such that when the liquid level height of the cooling medium decreases, the multi-stage sleeve moves downward successively from the higher level to the lower level.

[0064] In addition, multi-stage exhaust ports are provided in the height direction of the steam collecting pipe 10. The multi-stage exhaust ports are arranged corresponding to the multi-stage sleeves. The multi-stage sleeves move downward successively from the higher level to the lower level, causing the multi-stage exhaust ports to open successively from the higher level to the lower level.

[0065] By setting up a multi-stage sleeve and cooperating with multi-stage exhaust ports, when the evaporation of the cooling medium causes the liquid level to drop, the exhaust port at the lower position opens, prompting the steam-water mixture to enter the exhaust port to balance the static pressure difference between the inside and outside of the steam collecting device 1, increasing the system circulation driving force at a low liquid level height, thereby improving the heat rejection capacity of the system at a low liquid level and promoting the natural circulation of the system.

[0066] In this application, the number of stages of the multi-stage sleeve should not be too small. When all the cooling medium evaporates or the liquid level is extremely low, the height of the steam outlet mainly depends on the height of the first-stage sleeve. The fewer the number of stages, the higher the height of the first-stage sleeve. The higher first-stage sleeve increases the resistance of the natural circulation system. Therefore, the number of sleeves should be appropriately increased.

[0067] Furthermore, in the multi-stage sleeve of this application, the inner diameter of the upper-stage sleeve is larger than the outer diameter of the lower-stage sleeve. Adjacent sleeves are nested together, and the upper-stage sleeve can move along the outer wall of the lower-stage sleeve.

[0068] As Figure 3 shown, each sleeve 200 in the multi-stage sleeve encloses to form a hollow cavity, and the buoyancy of the hollow cavity in the cooling medium is greater than the gravity of the sleeve 200. In an embodiment of this application, the multi-stage sleeve is made of stainless steel material, and the stainless steel material can ensure the service life of the steam collecting device 1, and the stainless steel material can resist the strong oscillation brought by the natural circulation flow rate.

[0069] To ensure that the multi-stage sleeve does not break away from the steam collecting pipe, a limiting structure for the steam collecting device 1 is proposed in this application.

[0070] Specifically, as Figure 4 shown, the steam collecting device 1 includes a first positioning part 180. The first positioning part 180 is sleeved on the outside of the steam collecting pipe 10. The first positioning part 180 limits the highest position of the multi-stage sleeve to prevent the multi-stage sleeve from detaching from the upper part of the steam collecting pipe 10. In this application, the first positioning part 180 is located in the lower area of the steam collecting pipe. Preferably, the first positioning part 180 is welded to the outside of the steam collecting pipe 10, and the first positioning part 180 is an annular structure. The outer diameter of the first positioning part 180 is equal to the inner diameter of the first-stage sleeve, and the inner diameter of the first positioning part 180 is equal to the outer diameter of the steam collecting pipe 10.

[0071] In addition, as Figure 1 shown, the steam collecting device 1 further includes a fourth positioning part 190. The fourth positioning part 190 is sleeved on the outside of the steam collecting pipe 10. The fourth positioning part 190 limits the lowest position of the multi-stage sleeve to prevent the multi-stage sleeve from detaching from the lower part of the steam collecting pipe 10. In this application, the fourth positioning part 190 is a limiting flange. The fourth positioning part 190 is located at the bottom of the steam collecting pipe 10 near the inlet position and is lower than the position of the first positioning part 180.

[0072] The first positioning part 180 and the fourth positioning part 190 define a non-exhaust region along the axial direction of the steam collecting pipe 10, and the region above the first positioning part 180 defines an exhaust region along the axial direction of the steam collecting pipe 10. No exhaust ports are provided on the outer wall of the steam collecting pipe in the non-exhaust region, and exhaust ports are provided on the outer wall of the steam collecting pipe in the exhaust region.

[0073] In an embodiment of this application, the maximum axial length of the multi-stage sleeve 200 along the axial direction of the steam collecting pipe 10 is not less than the axial length of the exhaust region along the axial direction of the steam collecting pipe 10. When the water tank is at full water level, the height of the multi-stage hollow sleeve is not less than the height of the steam collecting pipe 10. The multi-stage hollow sleeve can completely block each exhaust port 160 in the exhaust region and expose the non-exhaust region. In addition, the height of the first-stage sleeve is greater than the axial length of the non-exhaust region along the axial direction of the steam collecting pipe. When there is no water level in the water tank, the first-stage sleeve can completely cover the non-exhaust region.

[0074] In addition, as Figure 2 shown, a reinforcing ring 110 is provided on the outer wall of the steam collecting pipe 10 corresponding to the exhaust region to enhance the stability of the steam collecting pipe 10.

[0075] Furthermore, in order to prevent the disconnection between the multi-stage sleeves, positioning parts are provided on each stage of the sleeve in this application. Specifically, as Figure 5 shown, a second positioning part 222 is provided at the top of each stage of the sleeve. The second positioning parts 222 of adjacent sleeves are in contact with each other to prevent the upper-stage sleeve from detaching from the bottom of the lower-stage sleeve. The second positioning part 222 is a ring structure. The inner diameter of the second positioning part 222 is equal to the outer diameter of the steam collecting pipe 10, and the outer diameter of the second positioning part 222 is equal to the inner diameter of the upper-stage sleeve 200.

[0076] A third positioning part 224 is provided at the bottom of each stage of the sleeve. The third positioning part 224 of the upper-stage sleeve is in contact with the second positioning part 222 of the lower-stage sleeve to prevent the upper-stage sleeve from detaching from the lower-stage sleeve when the upper-stage sleeve moves upward. Preferably, in this application, the third positioning part 224 is a ring structure. The inner diameter of the third positioning part 224 is equal to the outer diameter of the lower-stage sleeve 200, and the outer diameter of the third positioning part 224 is the outer diameter of this stage of the sleeve.

[0077] In this application, the second positioning part 222 and the third positioning part 224 are detachably connected to the sleeve 200. Preferably, the second positioning part 222 and the third positioning part 224 are fixed to the sleeve 200 by rivets, which is convenient for disassembly and assembly.

[0078] When the buoyancy of the upper-stage sleeve is greater than its own gravity, the upper-stage sleeve moves upward and tries to escape from the lower-stage sleeve. At this time, the second positioning part 222 of the lower-stage sleeve abuts against the third positioning part 224 of the upper-stage sleeve to prevent the upper-stage sleeve from detaching from the top of the lower-stage sleeve. The third positioning part of the lowest-stage sleeve abuts against the first positioning part 180 to prevent the multi-stage sleeve from detaching from the steam collecting pipe 10 under the action of buoyancy.

[0079] When the buoyancy of the upper-level sleeve is less than its own gravity, the upper-level sleeve moves downward and attempts to escape from the lower-level sleeve. At this time, the second positioning portion of the lower-level sleeve abuts against the second positioning portion of the upper-level sleeve, preventing the upper-level sleeve from leaving from the bottom of the lower-level sleeve. The multi-level sleeves move downward in sequence from high to low and finally fall above the fourth positioning portion 190.

[0080] In summary, the steam collecting device proposed by the present invention achieves the following technical effects:

[0081] 1. Under the action of the buoyancy and its own gravity of the sleeve in the cooling medium, it moves along the axial direction of the steam collecting pipe following the liquid level change, realizing the opening and closing of the exhaust port, and ensuring the heat dissipation capacity of the system at low liquid levels; 2. Adopting the nested manner of multi-level sleeves and setting multiple positioning plates to prevent the multi-level sleeves from separating from each other, ensuring the structural stability; 3. The containment heat conduction steam collecting device proposed in this application has a simple structure, which is convenient for disassembly, installation and maintenance; 4. By optimizing the structure of the multi-level sleeves, the multi-level sleeves completely block the exhaust area, increasing the height of the rising section, thereby increasing the length of the natural circulation two-phase section and increasing the system driving force and heat dissipation capacity.

[0082] Embodiment 2

[0083] A containment heat conduction steam collecting device 1 is arranged in the cooling medium. When the steam collecting device 1 is in the water phase, the water phase enters the cooling medium for heat exchange to export the heat of the containment. When the steam collecting device 1 is in the steam-water mixture, the steam-water mixture enters the gas phase space of the cooling medium to avoid direct contact with the cooling medium and prevent the occurrence of water hammer phenomenon. As Figure 6 shown, the steam collecting device 1 includes a steam collecting pipe 10. The steam collecting pipe 10 includes an outlet 121. At least one exhaust port 160 is opened on the side wall of the steam collecting pipe 10. In addition, the steam collecting device 1 further includes at least one sleeve 200. The sleeve 200 is sleeved outside the steam collecting pipe 10. The sleeve 200 moves along the axial direction of the steam collecting pipe 10 by itself following the change of the cooling medium liquid level under its own acting force, so that the exhaust port 160 corresponding to the sleeve 200 is opened or closed. The self-acting force of the sleeve in this application mainly includes the buoyancy of the sleeve in the cooling medium and the gravity of the sleeve itself. The cooling medium in this application includes but is not limited to water medium, and the cooling medium is arranged in a water tank.

[0084] The steam collecting device 1 proposed in this application utilizes the change of the sleeve buoyancy with the liquid level change to realize the axial movement of the sleeve along the steam collecting pipe, thereby controlling the opening and closing of the exhaust port, ensuring the heat dissipation capacity of the system at low liquid levels, and promoting the natural circulation of the system.

[0085] When the water level in the water tank is higher than the predetermined value, since the buoyancy of the cooling medium acting on the sleeve is greater than its own gravity, the sleeve 200 completely covers the steam exhaust port 160, and the steam-water mixture entering the steam collecting pipe 10 is discharged from the steam outlet 121; when the water level in the water tank is lower than the predetermined value and is in the process of dropping, due to the drop of the water level in the water tank, the buoyancy acting on the sleeve decreases, and its own gravity is greater than the buoyancy it receives, at least one sleeve 200 moves downward along the axial direction of the steam collecting pipe 10, so that at least one steam exhaust port 160 is opened, and at least part of the steam-water mixture entering the steam collecting pipe 10 is discharged from the steam exhaust port 160.

[0086] In an embodiment of this application, the steam collecting device 1 includes multiple levels of sleeves distributed in the height direction of the cooling medium level. The first-level sleeve in the multiple levels of sleeves is located at the lowermost part, and the number of levels increases successively upward along the height of the cooling medium level. Each sleeve in the multiple levels of sleeves can move along the axial direction of the steam collecting pipe 10 following the change of the cooling medium level, and is arranged such that when the level height of the cooling medium drops, the multiple levels of sleeves move downward in sequence from the higher level to the lower level.

[0087] In addition, multiple levels of steam exhaust ports are provided in the height direction of the steam collecting pipe 10. The multiple levels of steam exhaust ports are arranged corresponding to the multiple levels of sleeves. The multiple levels of sleeves move downward in sequence from the higher level to the lower level, causing the multiple levels of steam exhaust ports to open successively from high to low.

[0088] By providing multiple levels of sleeves and cooperating with multiple levels of steam exhaust ports, when the cooling medium evaporates and causes the liquid level to drop, the steam exhaust ports at the lower positions are opened, prompting the steam-water mixture to enter the steam exhaust ports, thereby improving the heat dissipation capacity and natural circulation of the system.

[0089] In this embodiment, each sleeve 200 in the multiple levels of sleeves is independent of each other and corresponds to different liquid level heights of the cooling medium. A plurality of limiters 170 are sleeved on the outer wall of the steam collecting pipe 10. The limiters 170 axially divide the steam collecting pipe 10 into multiple independent regions, and the multiple levels of sleeves are respectively arranged in each independent region. In this application, the limiter 170 is not limited to the baffle structure.

[0090] Each sleeve 200 in the multiple levels of sleeves encloses a hollow cavity, and the buoyancy of the hollow cavity in the cooling medium is greater than the gravity of the sleeve 200. In an embodiment of this application, the multiple levels of sleeves are made of stainless steel material, and the stainless steel material can ensure the service life of the steam collecting device, and the stainless steel material can resist the strong oscillation brought by the natural circulation flow rate.

[0091] In this application, the steam collecting device 1 further includes a fairing 50. The fairing 50 is sleeved outside the multi-stage sleeve, and the fairing 50 is concentrically arranged with the steam collecting pipe 10 to avoid the impact on the water tank caused by the change of the liquid level in the water tank. A drain port 520 is provided at the bottom of the fairing 50. The water in the steam-water mixture falls back into the fairing 50, and the cooling medium in the fairing 50 is discharged through the drain port 520, reducing the disturbance of the steam-water mixture to the liquid level of the water tank and ensuring the driving stability of the natural circulation of the system.

[0092] In addition, a steam-water separation cover 60 is provided above the steam outlet 121. The steam-water separation cover 60 separates the steam-water mixture flowing out of the steam outlet 121 by means of inertial impact and diversion. The separated water enters the fairing 50 to avoid excessive impact load on the water tank caused by the high-speed fluid at the steam outlet 121 and reduce the entrainment loss of steam flow to water. In this application, the steam-water separation cover 60 is of an arc structure.

[0093] Furthermore, the steam collecting device 1 further includes a support column 70. The support column 70 supports the steam-water separation cover 60 to keep a predetermined distance between the steam-water separation cover 60 and the fairing 50.

[0094] In summary, the steam collecting device proposed by the present invention achieves the following technical effects:

[0095] 1. Under the action of buoyancy and its own gravity in the cooling medium, the sleeve moves along the axial direction of the steam collecting pipe following the liquid level change, realizing the opening and closing of the exhaust port, and ensuring the heat dissipation capacity of the system at low liquid level; 2. By setting multi-stage sleeves and multi-stage exhaust ports, it is more adaptable to liquid level changes; 3. The steam collecting pipe is divided into multiple independent regions by the position limiters, and the multi-stage sleeves are respectively sleeved outside the steam collecting pipes in the independent regions. The position limiters define the moving regions of the respective sleeves, with a simple structure, good stability, and being convenient for disassembly and assembly; 4. When the water level is relatively high, the multi-stage sleeves completely block the exhaust region, increasing the height of the rising section, thereby increasing the length of the natural circulation two-phase section and increasing the system driving force and heat dissipation capacity.

[0096] To achieve the above object, according to another aspect of the present invention, a containment heat removal system for a nuclear power plant is proposed, as Figure 7 shown. The containment heat removal system for a nuclear power plant includes a steam collecting device 1, a riser 4, a water tank 2, and a heat exchanger 3. The steam collecting device 1 is arranged inside the water tank 2. The steam collecting device 1 is connected to the heat exchanger 3 through the riser 4. The medium in the heat exchanger 3 absorbs the heat of the containment, enters the steam collecting device 1 through the riser 4, and is sent into the water tank 2 through the steam collecting device 1 to export the heat in the containment.

[0097] The steam collecting device 1 is installed at the outlet of the system riser 4, which increases the rising length. Since the rising section is a flashing two-phase section, it is equivalent to increasing the length of the two-phase section of the natural circulation loop, greatly increasing the driving force of natural circulation, and thus improving the heat rejection capacity of the system. In addition, by installing the steam collecting device 1 at the outlet of the system riser 4, the steam-water mixture at the outlet of the riser 4 is directly transported to the gas phase space of the water tank 2, avoiding the contact between steam and subcooled water, and thus eliminating the water hammer phenomenon.

[0098] In summary, the containment heat removal system proposed by the present invention achieves the following technical effects:

[0099] 1. In the steam collecting device adopted by the containment heat removal system of the nuclear power plant, the sleeve moves axially along the steam collecting pipe following the liquid level change under the action of the buoyancy and its own gravity in the cooling medium, realizing the opening and closing of the steam exhaust port, and ensuring the heat rejection capacity of the system at low liquid level; 2. The steam collecting device adopted by the containment heat removal system of the nuclear power plant uses a multi-stage sleeve nesting method and is provided with multiple positioning plates to prevent the multi-stage sleeves from separating from each other, ensuring the structural stability; 3. The structure of the containment heat removal system of the nuclear power plant is simple, facilitating disassembly, assembly and maintenance; 4. The steam collecting device in the containment heat removal system of the nuclear power plant is arranged at the outlet of the riser, increasing the length of the two-phase section of the natural circulation loop, increasing the driving force of natural circulation, and thus improving the heat rejection capacity of the system; at the same time, the steam-water mixture in the riser is transported to the gas phase space of the cooling medium through the steam collecting pipe, avoiding direct contact with the cooling medium and eliminating the water hammer phenomenon.

[0100] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A containment heat-conducting steam collecting device (1), which is arranged in a cooling medium. Characterized in that, It includes a steam collecting pipe (10). The steam collecting pipe (10) includes a steam outlet (121), and at least one exhaust port (160) is formed on the side wall of the steam collecting pipe (10). It further includes at least one sleeve (200). The sleeve (200) is sleeved outside the steam collecting pipe (10). Under its own acting force, the sleeve (200) moves along the axial direction of the steam collecting pipe (10) following the change of the cooling medium liquid level, so that the exhaust port (160) corresponding to the sleeve (200) is opened or closed. The sleeve (200) is arranged such that when the cooling medium liquid level is higher than a predetermined value, the sleeve (200) completely covers the exhaust port (160), and the steam-water mixture entering the steam collecting pipe (10) is discharged from the steam outlet (121). When the cooling medium liquid level is lower than the predetermined value and is in the process of decreasing, at least one sleeve (200) moves downward along the axial direction of the steam collecting pipe (10), so that at least one exhaust port (160) is opened, and at least part of the steam-water mixture entering the steam collecting pipe (10) is discharged from the exhaust port (160), so as to improve the heat removal capacity at low liquid levels.

2. The steam collecting device (1) according to claim 1, characterized in that, It includes a multi-stage sleeve distributed along the height direction of the cooling medium liquid level. The first-stage sleeve in the multi-stage sleeve is located at the lowermost part, and the number of stages increases sequentially along the height of the cooling medium liquid level. Each sleeve in the multi-stage sleeve can move along the axial direction of the steam collecting pipe (10) following the change of the cooling medium liquid level, and is arranged such that when the liquid level height of the cooling medium decreases, the multi-stage sleeve moves downward sequentially from the higher stage to the lower stage.

3. The steam collecting device (1) according to claim 2, characterized in that Multi-stage exhaust ports are provided in the height direction of the steam collecting pipe (10). The multi-stage exhaust ports are arranged corresponding to the multi-stage sleeves. The multi-stage sleeves move downward sequentially from the higher stage to the lower stage, so that the multi-stage exhaust ports are opened sequentially from high to low.

4. The steam collecting device (1) according to claim 3, characterized in that, The inner diameter of the upper-stage sleeve in the multi-stage sleeve is larger than the outer diameter of the lower-stage sleeve. Adjacent sleeves are nested with each other, and the upper-stage sleeve can move along the outer wall of the lower-stage sleeve.

5. The steam collecting device (1) according to claim 2 or 3, characterized in that, Each sleeve (200) in the multi-stage sleeve encloses to form a hollow cavity. The buoyancy received by the hollow cavity in the cooling medium is greater than the gravity received by the sleeve (200).

6. The steam collecting device (1) according to claim 2 or 3, characterized in that, It includes a first positioning part (180). The first positioning part (180) is sleeved outside the steam collecting pipe (10). The first positioning part (180) defines the highest position of the multi-stage sleeve, and prevents the multi-stage sleeve from detaching from the upper part of the steam collecting pipe (10).

7. The steam collecting device (1) according to claim 6, characterized in that, An exhaust area is defined along the axial direction of the steam collecting pipe (10) above the first positioning part (180). A reinforcing ring (110) is provided on the outer wall of the steam collecting pipe (10) corresponding to the exhaust area to enhance the stability of the steam collecting pipe (10).

8. The steam collecting device (1) according to claim 7, characterized in that The maximum axial length of the multi-stage sleeve (200) along the steam collecting pipe (10) is not less than the axial length of the exhaust region along the steam collecting pipe (10), so that the multi-stage sleeve (200) can completely cover each of the exhaust ports (160) within the length range of the steam collecting pipe (10).

9. The steam collecting device (1) according to claim 2 or 3, characterized in that, A non-exhaust region is defined axially along the steam collecting pipe (10) below the first positioning portion (180), and the height of the first-stage sleeve is greater than the axial length of the non-exhaust region along the steam collecting pipe (10).

10. The steam collecting device (1) according to claim 2 or 3, characterized in that, It further includes a fourth positioning portion (190) sleeved outside the steam collecting pipe (10). The fourth positioning portion (190) defines the lowest position of the multi-stage sleeve to prevent the multi-stage sleeve from detaching from the lower part of the steam collecting pipe (10).

11. The steam collecting device (1) according to claim 2 or 3, characterized in that, A second positioning portion (222) is provided at the top of each stage of the sleeve. The second positioning portions (222) of adjacent sleeves are in contact with each other to prevent the upper-stage sleeve from detaching from the bottom of the lower-stage sleeve.

12. The steam collecting device (1) according to claim 11, characterized in that, A third positioning portion (224) is provided at the bottom of each stage of the sleeve. The third positioning portion (224) of the upper-stage sleeve is in contact with the second positioning portion (222) of the lower-stage sleeve to prevent the upper-stage sleeve from detaching from the lower-stage sleeve when moving upward.

13. The steam collecting device (1) according to claim 11, characterized in that, The inner diameter of the second positioning portion (222) is equal to the outer diameter of the steam collecting pipe (10), and the outer diameter of the second positioning portion (222) is equal to the inner diameter of the upper-stage sleeve (200).

14. The steam collecting device (1) according to claim 12, characterized in that, The inner diameter of the third positioning portion (224) is equal to the outer diameter of the lower-stage sleeve (200), and the outer diameter of the third positioning portion 224 is the outer diameter of this stage of the sleeve.

15. The steam collecting device (1) according to claim 6, characterized in that, The outer diameter of the first positioning portion (180) is equal to the inner diameter of the first-stage sleeve.

16. The steam collecting device (1) according to claim 2 or 3, characterized in that, Each sleeve in the multi-stage sleeve is independent of each other and corresponds to different liquid level heights of the cooling medium.

17. The steam collecting device (1) according to claim 16, characterized in that, A plurality of limiters (170) are sleeved on the outer wall of the steam collecting pipe (10). The limiters (170) axially divide the steam collecting pipe (10) into a plurality of independent regions, and the multi-stage sleeves are respectively arranged in each of the independent regions.

18. The steam collecting device (1) according to claim 10, characterized in that, The fourth positioning portion (190) is close to the bottom of the steam collecting pipe (10).

19. The steam collecting device (1) according to claim 12, characterized in that, The second positioning portion (222) and the third positioning portion (224) are detachably connected to the sleeve (200).

20. The steam collecting device (1) according to claim 2 or 3, characterized in that, It further includes a flow guiding cover (50) sleeved outside the multi-stage sleeve.

21. The steam collecting device (1) according to claim 20, characterized in that, A liquid discharge port (520) is provided at the bottom of the flow guiding cover (50). The cooling medium in the flow guiding cover (50) is discharged through the liquid discharge port (520) to reduce the disturbance to the liquid level of the cooling medium.

22. The steam collecting device (1) according to claim 21, characterized in that, A steam-water separation cover (60) is provided above the steam outlet (121). The steam-water separation cover (60) separates the steam-water mixture flowing out of the steam outlet (121).

23. The steam collecting device (1) according to claim 22, characterized in that, It further includes a support column (70) that supports the steam-water separation cover (60) to keep the steam-water separation cover (60) at a predetermined distance from the flow guiding cover (50).

24. A containment heat removal system for a nuclear power plant, characterized in that, Comprising the steam collecting device (1) according to any one of claims 1-23, the riser pipe (4), the water tank (2) and the heat exchanger (3), wherein the steam collecting device (1) is arranged inside the water tank (2), the steam collecting device (1) is connected to the heat exchanger (3) through the riser pipe (4), the medium in the heat exchanger (3) absorbs the heat of the containment and then enters the steam collecting device (1) through the riser pipe (4), and is sent into the water tank (2) through the steam collecting device (1), so as to conduct the heat in the containment out.

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