Distortion suppression spray pipe capable of adjusting immersion depth in self-adaptive mode

Abstract

The invention discloses a twisted pressure suppression spray pipe capable of adaptively adjusting the immersion depth, relates to the technical field of reactor thermal hydraulic power, and solves the problems of condensate water hammer and thermal stratification caused by water seal removal, pool swelling and low-speed discharge in the whole operation stage of a pressure suppression system in the prior art. The suppression spray pipe comprises a twisted inner pipe and a circular outer pipe, the twisted inner pipe is arranged at the bottom of the pressure suppression box, one end is communicated with the containment, and the other end penetrates through the water space in the pressure suppression box and is arranged above the liquid level of the water space; the upper end of the circular outer pipe is closed, and the lower end movably sleeves the twisted inner pipe; an air space in the pressure suppression box is communicated with the containment through a vacuum release valve; the twisted inner pipe is a spiral straight pipe. The pressure suppression spray pipe adopts a passive design, the immersion depth of the spray pipe is automatically adjusted by virtue of the spring, the gravity of the outer pipe and the pressure difference between the containment and the pressure suppression box, the pressure suppression spray pipe is simple and reliable, and the problems of condensate water hammer and thermal stratification are solved by virtue of a plurality of through holes formed in the limiting porous ring.

Description

Technical Field

[0001] The present invention relates to the technical field of reactor thermal-hydraulics, and particularly to a distorted suppression nozzle with an adaptive adjustment of the immersion depth. Background Art

[0002] When a large-break loss-of-coolant accident (LOCA) occurs in a pressurized water reactor, a large amount of high-temperature and high-pressure coolant will be discharged and flashed into the containment within dozens of seconds. The steam-non-condensable gas mixture in the containment will flow through the discharge pipeline into the suppression pool under the action of the pressure difference between the containment and the suppression pool. The lower water space of the suppression pool serves as a hot well to absorb the latent heat released by the condensation of steam, and the upper gas space provides a retention space for non-condensable gases. The suppression system will go through typical stages such as water seal removal, pool swelling, and low-speed discharge. The water seal removal time and pool swelling are directly determined by the immersion depth of the suppression nozzle in the pool. The smaller the immersion depth of the nozzle, the shorter the water seal removal time, the better the suppression effect of the containment, and at the same time, the smaller the load caused by pool swelling. The low-speed discharge of steam may cause condensate water hammer and pool thermal stratification. Reducing the flow area of the suppression nozzle is beneficial to eliminating condensate water hammer, and increasing the immersion depth of the suppression nozzle is beneficial to eliminating thermal stratification. Therefore, how to design the suppression nozzle has become an engineering problem.

[0003] Currently, the design of suppression systems focuses on the design of suppression pools. For example, a Chinese patent with the authorized announcement number CN105957565B discloses a suppression pool installed inside the containment vessel and annularly arranged around the reactor pit of the vessel. The suppression pool includes a water space and a gas space. A number of anti-slosh partitions are provided in the water space, and communication holes connecting both sides are opened at the bottom of the anti-slosh partitions. A Chinese patent with the authorized announcement number CN116246804B discloses a suppression pool and a safety system for a floating nuclear power plant on water. The suppression pool is arranged outside the containment vessel of the floating nuclear power plant on water and is connected to the containment vessel through a conduit. The suppression pool includes a housing, which is internally divided into a first space located above and a second space located below, for accommodating non-condensable gas and condensing medium respectively. The conduit passes through the first space and extends into the second space for introducing the steam-air mixture formed inside the containment vessel under accident conditions into the condensing medium to condense the mixture using the condensing medium. The inside of the suppression pool is separated by baffles arranged horizontally and vertically, and through holes and flow guiding tapered pipes connecting the through holes are provided between the baffles for accelerating the flow and circumferential flow guiding. A pressure relief valve is connected to the housing and communicates with the first space for opening when the pressure in the first space is higher than a preset threshold. A Chinese patent with the authorized announcement number CN106098111B discloses a containment vessel with a suppression pool structure. An suppression pool and a dry well located above the suppression pool and isolated from the suppression pool are provided inside the containment vessel. The suppression pool has a water space and a gas space. A gas-liquid circulation pipe connecting the two vertically is provided between the water space and the dry well. A vacuum breaker is provided between the gas space and the dry well. A first isolation hole is provided inside the suppression pool. The first isolation hole is isolated from the suppression pool and communicates with the dry well. The first isolation hole houses the reactor pressure vessel. The water space surrounds the first isolation hole so that the water in the water space surrounds the reactor pressure vessel. A Chinese patent with the authorized announcement number CN107293336B discloses a suppression system for a containment vessel of an offshore nuclear power plant, including a suppression pool provided inside the containment vessel. The suppression pool includes a water space and a gas space. The water space is provided at the bottom of the containment vessel and surrounds the reactor core. The water space communicates with the dry well of the containment vessel. The gas space is provided above the water space and surrounds the main equipment. The gas space cavity is directly connected to the water space.When a LOCA occurs in a nuclear power plant, the gas, steam, and water mixture in the dry well of the containment is introduced into the water space and quickly condensed by the cooling water therein, thereby alleviating the pressure increase effect of the containment; Chinese Patent No. CN108346475A discloses a passive suppression system for a small reactor containment, which includes a containment, a suppression pool, and a suppression pool cooling device; the containment and the suppression pool are connected by a vertical communication pipe, and a horizontal discharge pipe is connected to the vertical communication pipe, and the horizontal discharge pipe is used to guide the gas, steam, and liquid mixture in the containment into the suppression pool for condensation; both ends of the suppression pool cooling device are connected to the suppression pool through pipelines to form a circulation loop, and the suppression pool cooling device is used to cool the suppression pool water passing through the circulation loop to cool the suppression pool to control the temperature range of the suppression pool water temperature. Chinese Patent No. CN107093470B discloses a containment suppression system with enhanced cooling. The system includes a large-volume closed water tank, a ventilation pipe, a condensation return pipe, and a waste liquid pool. The large-volume closed water tank is arranged inside the containment, with a gas space left at the upper part and water filled in the lower space; the ventilation pipe is arranged inside the containment and passes through the large-volume closed water tank for guiding the gas inside the containment into the large-volume closed water tank; the condensation return pipe is immersed in the water filled in the large-volume closed water tank for connecting the ventilation pipe and the internal space of the large-volume closed water tank and for condensing and returning the gas inside the containment flowing through the ventilation pipe; the waste liquid pool is arranged in front of the gas outlet of the ventilation pipe inside the containment for receiving the condensed liquid led out through the ventilation pipe.

[0004] Chinese Patent Nos. CN111599492B, CN111599493B, and CN111599494B disclose a suppression pipe and a suppression pool using the suppression pipe. At least one gas one-way conduction component is arranged on the suppression pipe, and the conduction direction is from the outside of the pipe into the inside of the pipe, and it is conducted when the air pressure outside the pipe is greater than the air pressure inside the pipe. The suppression pool using this suppression pipe is of a closed structure. The suppression pool is internally filled with a liquid for condensation, and an incondensable gas space is above the liquid. The ventilated pipe body passes through the pool and extends below the liquid level and is fixedly connected to the suppression pool. One end of the ventilated pipe body is connected to the gas space inside the containment, and the other end is immersed in the liquid. The gas one-way conduction component connects the gas inside the pipe and the gas space inside the suppression pool. Although this patent can effectively suppress the pressure oscillation in the suppression pool during the low-speed steam discharge stage through the enclosure component and the bubble cutting component, it cannot solve problems such as pool swelling and thermal stratification.

[0005] The Chinese patent with the authorization announcement number CN107578826B discloses a containment suppression and water washing filtration integrated system, which includes a containment and a suppression pool. The upper part of the suppression pool is an air space, and the lower part is water. The lower part of the containment is connected to the suppression pool through a spray pipe. The spray pipe includes an inlet section, a contraction section, and a throat section that are connected in sequence. The diameter of the throat section is smaller than that of the inlet section, and the diameter of the contraction section gradually shrinks. A cooling water inlet is provided above the throat section; when a break accident occurs, the mixed steam containing radioactive substances enters the suppression pool through the spray pipe to achieve rapid pressure relief of the containment; the cooling water in the suppression pool enters the throat section through the cooling water inlet, is atomized under the action of high-speed air flow, and collides with the radioactive substances in the mixed steam to remove the radioactive substances. This patent uses a Venturi spray pipe, which can improve the steam condensation efficiency, but cannot solve problems such as pool swelling and thermal stratification.

[0006] In summary, the existing technologies do not comprehensively consider the problems of water seal removal, pool swelling, condensate water hammer and thermal stratification caused by low-speed discharge faced during the entire operation stage of the suppression system. Summary of the Invention

[0007] In order to solve the problems mentioned above that the existing technologies do not comprehensively consider the problems of water seal removal, pool swelling, condensate water hammer and thermal stratification caused by low-speed discharge faced during the entire operation stage of the suppression system, the present invention hereby provides a twisted suppression spray pipe with an adaptive adjustment of the immersion depth. The suppression spray pipe of the present invention adopts a passive design, automatically adjusts the immersion depth of the spray pipe relying on the spring, the gravity of the outer pipe and the pressure difference between the containment and the suppression tank, which is simple and reliable, and a number of through holes are provided on the limiting porous ring, solving the problems of water seal removal, pool swelling, condensate water hammer and thermal stratification caused by low-speed discharge.

[0008] The present invention provides a twisted suppression spray pipe with an adaptive adjustment of the immersion depth, which specifically includes a suppression spray pipe, a suppression tank and a containment. The suppression spray pipe includes a twisted inner pipe and a circular outer pipe; the twisted inner pipe is arranged at the bottom of the suppression tank, one end is connected to the containment, and the other end passes through the water space inside the suppression tank and is arranged above the liquid level of the water space; the upper end of the circular outer pipe is closed, and the lower end is movably sleeved outside the twisted inner pipe; the air space inside the suppression tank is connected to the inside of the containment through a vacuum release valve; the twisted inner pipe is a spiral straight pipe.

[0009] Furthermore, the top of the twisted inner pipe is connected to the circular outer pipe through a spring.

[0010] Furthermore, a limiting porous ring is arranged at the lower part of the twisted inner pipe, and a number of through holes are provided on the limiting porous ring.

[0011] Furthermore, the outer diameter of the limiting porous ring is larger than the outer diameter of the circular outer pipe.

[0012] Furthermore, the suppression tank is arranged outside the containment vessel; a vacuum release pipe is provided at the upper end of the suppression tank and is communicated with the containment vessel through the vacuum release pipe; a vacuum release valve is provided on the vacuum release pipe; the lower end of the twisted inner pipe is communicated with the containment vessel through a discharge pipe.

[0013] Furthermore, the suppression tank is arranged inside the containment vessel, and the vacuum release valve is arranged at the upper end of the circular outer pipe.

[0014] The beneficial effects of the twisted suppression spray nozzle with self - adaptive adjustment of immersion depth according to the present invention are as follows:

[0015] (1) The twisted suppression spray nozzle with self - adaptive adjustment of immersion depth according to the present invention comprehensively considers different stages of the suppression system operation, solves problems such as water seal removal, pool swelling, and condensate water hammer and thermal stratification caused by low - speed discharge. The suppression spray nozzle adopts a passive design and automatically adjusts the immersion depth of the suppression spray nozzle by relying on the spring, the gravity of the outer pipe, and the pressure difference between the containment vessel and the suppression tank, which is simple and reliable; the size of steam bubbles is reduced by several through - holes provided on the limiting porous ring, improving the steam condensation heat transfer coefficient, which is beneficial to eliminating condensate water hammer and fluid oscillation.

[0016] (2) The twisted suppression spray nozzle with self - adaptive adjustment of immersion depth according to the present invention effectively reduces the vibration and noise caused during system operation through the spring arranged between the twisted inner pipe and the circular outer pipe, reducing the probability of equipment operation wear and fatigue damage.

[0017] (3) The twisted suppression spray nozzle with self - adaptive adjustment of immersion depth according to the present invention, the twisted inner pipe is a spiral straight pipe, and the horizontal translation of the circular outer pipe during up - and - down movement is restricted by the threaded structure on the twisted inner pipe. While simplifying the support structure between the twisted inner pipe and the circular outer pipe, it creates a swirling flow to enhance steam condensation heat transfer. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings forming 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 to the present invention.

[0019] In the drawings:

[0020] Figure 1 is a schematic structural diagram of the first specific embodiment of the twisted suppression spray nozzle with self - adaptive adjustment of immersion depth according to the present invention;

[0021] Figure 2 is a cross - sectional view of the twisted inner pipe and the circular outer pipe of the twisted suppression spray nozzle with self - adaptive adjustment of immersion depth according to the present invention;

[0022] Figure 3It is a three-dimensional structural schematic diagram of the twisted inner tube of a twisted suppression nozzle with self-adaptive adjustment of immersion depth according to the present invention;

[0023] Figure 4 It is a structural schematic diagram of the limit porous ring of a twisted suppression nozzle with self-adaptive adjustment of immersion depth according to the present invention;

[0024] Figure 5 It is a structural schematic diagram of the second specific implementation manner of a twisted suppression nozzle with self-adaptive adjustment of immersion depth according to the present invention;

[0025] Wherein: 1 - twisted inner tube; 2 - spring; 3 - circular outer tube; 4 - limit porous ring; 5 - water space; 6 - gas space; 7 - suppression box; 8 - vacuum release valve; 9 - vacuum release pipeline 10 - containment; 11 - discharge pipeline. Specific implementation manner

[0026] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. 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.

[0027] 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, and 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 therefore 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.

[0028] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, 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 situations.

[0029] 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.

[0030] Specific Embodiment 1: Refer to Figures 1-4 This specific embodiment will be described in detail. The self - adaptive immersion - depth - adjusting twisted suppression nozzle described in this embodiment specifically includes a suppression nozzle, a suppression tank 7, and a containment 10. The suppression tank 7 is arranged outside the containment 10. The suppression tank 7 is composed of a lower water space 5 and an upper gas space 6. The water space 5 serves as a hot well to absorb the latent heat released by steam condensation, and the gas space 6 accommodates air. The suppression nozzle includes a twisted inner pipe 1 and a circular outer pipe 3. The twisted inner pipe 1 is a spiral straight pipe. As Figure 3 shown, the threaded structure on the twisted inner pipe 1 restricts the horizontal translation of the circular outer pipe 3 during up - and - down movement, simplifies the support structure between the twisted inner pipe 1 and the circular outer pipe 3, and creates a swirling flow to enhance steam condensation heat transfer. The twisted inner pipe 1 is vertically fixed at the bottom of the suppression tank 7. One end is connected to the containment 10 through a discharge pipe 11, and the other end passes through the water space 5 inside the suppression tank 7 and is arranged above the liquid level of the water space 5. The upper end of the circular outer pipe 3 is closed, and the lower end is movably sleeved outside the twisted inner pipe 1. The outer diameter of the twisted inner pipe 1 is slightly smaller than the inner diameter of the circular outer pipe 3 that can move up and down. The gap between the twisted inner pipe 1 and the circular outer pipe 3 forms a gas flow path and restricts the lateral movement of the circular outer pipe 3. A vacuum release pipe 9 is arranged at the upper end of the suppression tank 7 and is connected to the containment 10 through the vacuum release pipe 9. A vacuum release valve 8 is arranged on the vacuum release pipe 9.

[0031] The top of the twisted inner pipe 1 is connected to the circular outer pipe 3 through a spring 2, which is used to balance the gravity of the circular outer pipe 3 and restrict the up - and - down displacement of the circular outer pipe 3.

[0032] A limiting porous ring 4 is arranged at the lower part of the twisted inner pipe 1, and a number of through - holes are arranged on the limiting porous ring 4. The outer diameter of the limiting porous ring 4 is larger than the outer diameter of the circular outer pipe 3.

[0033] In the initial stage of the accident, the large pressure difference between the containment 10 and the suppression tank 7 causes the circular outer pipe 3 to move upward, reducing the immersion depth of the circular outer pipe 3, effectively reducing the water seal clearance time and the degree of pool swelling. In the stage of low - velocity steam discharge, the small pressure difference between the containment 10 and the suppression tank 7 causes the circular outer pipe 3 to move downward. At this time, the circular outer pipe 3 has sufficient immersion depth to eliminate thermal stratification. As Figure 3 shown, the porous structure arranged on the limiting porous ring 4 can effectively eliminate condensate water hammer.

[0034] After the accident ends, the pressure in the containment 10 may be lower than the atmospheric pressure, posing a risk of negative - pressure breakage. A one - way vacuum release valve 8 is arranged at the upper part of the suppression tank 7. When the vacuum release valve 8 is opened, the air in the gas space 6 of the suppression tank 7 returns to the containment 10 through the discharge pipe 11.

[0035] Specific Embodiment 2: Refer to Figures 2-5Specifically describe this embodiment. For a twisted pressure suppression nozzle with adaptive adjustment of the immersion depth described in this embodiment, its pressure suppression tank 7 is arranged inside the containment 10, and the vacuum relief valve 8 is arranged at the upper end of the circular outer pipe 3; the pressure suppression discharge pipe 11 and the vacuum relief pipe 13 are omitted, increasing the compactness of the containment pressure suppression system and reducing the weight and volume of the pressure suppression system. The other components and connection relationships in this embodiment are the same as those in the first specific embodiment.

[0036] In the initial stage of the accident, the large pressure difference between the containment 10 and the pressure suppression tank 7 causes the circular outer pipe 3 to move upward, reducing the immersion depth of the circular outer pipe 3, effectively reducing the water seal clearance time and the degree of pool swelling; in the low steam flow rate discharge stage, the small pressure difference between the containment 10 and the pressure suppression tank 7 causes the circular outer pipe 3 to move downward, and at this time, the circular outer pipe 3 has sufficient immersion depth to eliminate thermal stratification. As Figure 3 shown, the porous structure provided on the limit porous ring 4 can effectively eliminate condensate water hammer.

[0037] After the accident ends, the pressure in the containment 10 may be lower than the atmospheric pressure, posing a risk of negative pressure breakage. A one-way vacuum relief valve 8 is arranged on the upper part of the pressure suppression tank 7. When the vacuum relief valve 8 is opened, the air in the gas space 6 in the pressure suppression tank 7 returns to the containment 10 through the discharge pipe 11.

[0038] Summarize the above embodiments. A twisted pressure suppression nozzle with adaptive adjustment of the immersion depth described in the present invention comprehensively considers different stages of the operation of the pressure suppression system, solves the problems of water seal clearance, pool swelling, and condensate water hammer and thermal stratification caused by low-speed discharge. The pressure suppression nozzle adopts a passive design and relies on the spring 2, the gravity of the circular outer pipe 3, and the pressure difference between the containment 10 and the pressure suppression tank 7 to automatically adjust the immersion depth of the pressure suppression nozzle, which is simple and reliable; by setting a number of through holes on the limit porous ring 4, the steam bubble size is reduced, and the steam condensation heat transfer coefficient is increased, which is beneficial to eliminating condensate water hammer and fluid oscillation. A twisted pressure suppression nozzle with adaptive adjustment of the immersion depth described in the present invention effectively reduces the vibration and noise caused during the operation of the system through the spring 2 arranged between the twisted inner pipe 1 and the circular outer pipe 3, reducing the probability of equipment operation wear and fatigue damage. A twisted pressure suppression nozzle with adaptive adjustment of the immersion depth described in the present invention has a spiral straight twisted inner pipe 1, which simplifies the support structure between the twisted inner pipe 1 and the circular outer pipe 3 while creating a swirling flow to enhance steam condensation heat transfer.

[0039] The above specific embodiments 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 twisted pressure suppression nozzle with adaptive immersion depth adjustment, characterized in that: The invention comprises a pressure suppression nozzle, a pressure suppression box (7) and a containment shell (10), wherein the pressure suppression nozzle comprises a twisted inner tube (1) and a circular outer tube (3); the twisted inner tube (1) is arranged at the bottom of the pressure suppression box (7), one end of the twisted inner tube (1) is connected to the containment shell (10), and the other end of the twisted inner tube (1) passes through a water space (5) inside the pressure suppression box (7) and is arranged above the liquid level of the water space (5); the upper end of the circular outer tube (3) is closed, and the lower end is movably sleeved outside the twisted inner tube (1); the gas space (6) inside the pressure suppression box (7) is connected to the inside of the containment shell (10) through a vacuum release valve (8); and the twisted inner tube (1) is a spiral straight tube.

2. The twisted pressure suppression nozzle with adaptive immersion depth adjustment according to claim 1, characterized in that: The top of the twisted inner tube (1) is connected to the circular outer tube (3) via a spring (2).

3. The twisted pressure suppression nozzle with adaptive immersion depth adjustment according to claim 2, characterized in that: A limiting porous ring (4) is arranged at the lower part of the twisted inner tube (1), and a plurality of through holes are arranged on the limiting porous ring (4).

4. The twisted pressure suppression nozzle with adaptive immersion depth adjustment according to claim 3, characterized in that: The outer diameter of the limiting porous ring (4) is greater than the outer diameter of the circular outer tube (3).

5. The twisted pressure suppression nozzle with adaptive immersion depth adjustment according to any one of claims 1 to 4, characterized in that: The pressure suppression box (7) is arranged outside the containment shell (10); a vacuum release pipe (9) is arranged at the upper end of the pressure suppression box (7), and the pressure suppression box (7) is connected to the containment shell (10) through the vacuum release pipe (9); a vacuum release valve (8) is arranged on the vacuum release pipe (9); and the lower end of the twisted inner tube (1) is connected to the containment shell (10) through a discharge pipe (11).

6. The twisted pressure suppression nozzle with adaptive immersion depth adjustment according to any one of claims 1 to 4, characterized in that: The pressure suppression box (7) is arranged inside the containment shell (10), and the vacuum release valve (8) is arranged at the upper end of the circular outer tube (3).

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