Containment suppression spray pipe based on ejection principle

Abstract

The invention discloses a containment suppression spray pipe based on an injection principle, relates to the technical field of reactor thermal hydraulic power, and solves the problem that condensate water hammer and thermal stratification caused by low-speed discharge operation of a suppression system are not considered at the same time in the prior art. The device comprises a containment, a discharge pipeline, a pressure suppression spray pipe and a pressure suppression box, wherein the containment is arranged at the upper end of the pressure suppression box; the upper end of the discharge pipeline is arranged in the containment, and the lower end is arranged in the water space of the pressure suppression box; a suppression spray pipe is arranged at the lower end of the discharge pipeline; the suppression spray pipe comprises a contraction pipe section, a straight pipe section and a diffusion pipe section, one end of the contraction pipe section is communicated with the discharge pipeline, and the other end is sequentially communicated with the straight pipe section and the diffusion pipe section; a plurality of through holes are formed in the straight pipe section. The pressure suppression spray pipe runs according to the Bernoulli principle, injection of supercooled water and gas can be achieved without external power, the pressure suppression spray pipe is simple and reliable, and the problems of condensate water hammer and thermal stratification are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of reactor thermal-hydraulics, and specifically to a containment suppression nozzle based on the ejector principle. 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 sprayed 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 steam condensation, and the upper gas space provides a retention space for non-condensable gases. The low-speed discharge of steam may cause condensate water hammer and pool thermal stratification, posing risks of damage and failure to the suppression system. Therefore, how to design a suppression nozzle has become an engineering problem.

[0003] The Chinese patent with the authorization announcement number CN105957565B discloses a suppression pool, which is installed inside the containment vessel and is annularly arranged around the reactor pit of the containment 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 communicating with both sides are opened at the bottom of the anti-slosh partitions. The Chinese patent with the authorization 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, and is respectively used for accommodating non-condensable gas and a condensing medium; the conduit passes through the first space and extends into the second space, and is used to introduce the steam-air mixture formed in the containment vessel under accident conditions into the condensing medium to condense the mixture by 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 arranged 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, and is used to open when the pressure in the first space is higher than a preset threshold. The Chinese patent with the authorization 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 communicating with both of them is vertically arranged 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 in 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. The Chinese patent with the authorization 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 arranged 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 arranged 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 Publication 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 Authorization Publication No. CN107093470B discloses a containment suppression system with enhanced cooling. The system includes a large-volume sealed water tank, a ventilation duct, a condensation return pipe, and a waste liquid pool. The large-volume sealed water tank is arranged in the containment, with a gas space left at the upper part and water filled in the lower space; the ventilation duct is arranged in the containment and passes through the large-volume sealed water tank for guiding the gas in the containment into the large-volume sealed water tank; the condensation return pipe is immersed in the water filled in the large-volume sealed water tank for connecting the ventilation duct and the internal space of the large-volume sealed water tank and for condensing and returning the gas in the containment flowing through the ventilation duct; the waste liquid pool is arranged in front of the gas outlet of the ventilation duct in the containment for receiving the condensed liquid led out through the ventilation duct. The above patents are all descriptions of the overall suppression system and the design of the suppression pool, and the partitioned pool has a certain weakening effect on the problem of pool sloshing. However, the engineering problems such as condensate water hammer and thermal stratification faced during system operation are not mentioned, and the specific structure of the suppression nozzle is not designed.

[0004] Chinese Patent Authorization Publication 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 conducts when the air pressure outside the pipe is greater than the air pressure inside the pipe. The suppression pool using this suppression pipe is a closed structure. The suppression pool is 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 in the containment, and the other end is immersed in the liquid. The gas one-way conduction component connects the gas in the pipe and the gas space in 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 the problem of thermal stratification.

[0005] The Chinese patent with the authorization announcement number CN107578826B discloses a containment suppression and water washing filtration integrated system, including a containment and a suppression pool. The upper part of the suppression pool is an air space, and the lower part is water. The containment is communicated with the lower part of the suppression pool through a spray pipe. The spray pipe includes an inlet section, a contraction section and a throat section 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 and is atomized under the action of the high-speed airflow, and the radioactive substances in the mixed steam are removed by colliding with the radioactive substances. This patent uses a Venturi spray pipe, which can improve the steam condensation efficiency, but cannot solve the problem of thermal stratification in the pool.

[0006] In summary, the existing technologies do not consider both the condensate water hammer and thermal stratification problems caused by the suppression system during low-speed discharge operation. Summary of the Invention

[0007] In order to solve the above-mentioned problems that the existing technologies do not consider both the condensate water hammer and thermal stratification problems caused by the suppression system during low-speed discharge operation, the present invention hereby provides a containment suppression spray pipe based on the ejector principle. The suppression spray pipe of the present invention operates based on Bernoulli's principle, and can achieve the ejection of subcooled water and gas without external power, which is simple and reliable, and solves the problems of condensate water hammer and thermal stratification.

[0008] The present invention provides a containment suppression spray pipe based on the ejector principle, which specifically includes a containment, a discharge pipe, a suppression spray pipe and a suppression tank. The upper end of the suppression tank is provided with the containment; the upper end of the discharge pipe is arranged inside the containment, and the lower end is arranged in the water space of the suppression tank; the lower end of the discharge pipe is provided with the suppression spray pipe; the suppression spray pipe includes a contraction pipe section, a straight pipe section and a diffusion pipe section. One end of the contraction pipe section is communicated with the discharge pipe, and the other end is sequentially communicated with the straight pipe section and the diffusion pipe section; a plurality of through holes are arranged on the straight pipe section.

[0009] Furthermore, an ejector air pipe is arranged on the straight pipe section, and the upper end of the ejector air pipe is communicated with the air space in the suppression tank.

[0010] Furthermore, the through holes are arranged on one side of the straight pipe section close to the contraction pipe section, and the ejector air pipe is arranged on one side of the straight pipe section close to the diffusion pipe section.

[0011] Furthermore, an ejector water cavity is arranged at the position corresponding to the plurality of through holes on the straight pipe section, and an ejector liquid inlet is arranged on the ejector water cavity.

[0012] Furthermore, the ejector water cavity is of an annular structure.

[0013] Furthermore, the injection liquid inlet is offset.

[0014] Furthermore, the injection liquid inlet faces the bottom of the water space.

[0015] The beneficial effects of the suppression nozzle of the containment based on the injection principle of the present invention are as follows:

[0016] (1) For the suppression nozzle of the containment based on the injection principle of the present invention, both the condensate water hammer and the thermal stratification problems caused by the low-speed discharge operation of the suppression system are considered. The suppression nozzle operates based on Bernoulli's principle, and the injection of subcooled water and gas can be achieved without external power, which is simple and reliable; the injected subcooled water is atomized, strengthening local heat transfer, reducing the temperature difference between the upper and lower parts of the water space, and improving the cooling capacity of the suppression system; the injection gas pipe reduces the gas space stratification and the intensity of condensate water hammer, and at the same time eliminates the check valve, simplifying the system.

[0017] (2) For the suppression nozzle of the containment based on the injection principle of the present invention, by offsetting the injection water inlet, a swirl flow is formed in the injection water cavity for the subcooled water. At the same time, the water flow is dispersed through several through holes provided on the straight pipe section, which is beneficial for the water flow to be atomized into droplets after entering the straight pipe section; the injection liquid inlet is close to the bottom of the water space, thereby reducing the degree of thermal stratification in the water space. 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 to the present invention.

[0019] In the drawings:

[0020] Figure 1 is a schematic structural diagram of a suppression nozzle of a containment based on the injection principle of the present invention;

[0021] Figure 2 is a front view of the suppression nozzle of a containment based on the injection principle of the present invention;

[0022] Figure 3 is a left view of the suppression nozzle of a containment based on the injection principle of the present invention;

[0023] Among them: 1 - containment; 2 - discharge pipe; 3 - suppression nozzle; 31 - contraction pipe section; 32 - straight pipe section; 33 - diffusion pipe section; 34 - injection water cavity; 35 - injection water inlet; 4 - suppression tank; 41 - water space; 42 - gas space; 5 - injection gas pipe. Detailed Embodiments

[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 to 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 defined and limited, the terms "mounted", "connected", "coupled" 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.

[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 1-3Specifically describe this embodiment. A containment suppression spray nozzle based on the ejector principle described in this embodiment specifically includes a containment 1, a discharge pipe 2, a suppression spray nozzle 3, and a suppression tank 4. The suppression tank 4 is composed of a lower water space 41 and an upper gas space 42. The water space 41 serves as a hot well to absorb the latent heat released by steam condensation, and the gas space 42 accommodates air. The upper end of the suppression tank 4 is provided with a containment 1, and the containment 1 and the suppression tank 4 are connected through a discharge pipe 2. The upper end of the discharge pipe 2 is arranged inside the containment 1, and the lower end is arranged in the water space 41 of the suppression tank 4. A suppression spray nozzle 3 is arranged at the lower end of the discharge pipe 2. The suppression spray nozzle 3 includes a converging pipe section 31, a straight pipe section 32, and a diverging pipe section 33. One end of the converging pipe section 31 is connected to the discharge pipe 2, and the other end is sequentially connected to the straight pipe section 32 and the diverging pipe section 33. A number of through holes are uniformly arranged on the circumference of the straight pipe section 32. An ejector air pipe 5 is also arranged on the straight pipe section 32. The through holes are arranged on the side of the straight pipe section 32 close to the converging pipe section 31, and the ejector air pipe 5 is arranged on the side of the straight pipe section 32 close to the diverging pipe section 33. The upper end of the ejector air pipe 5 is connected to the gas space 42 inside the suppression tank 4.

[0029] An ejector water chamber 34 is arranged at the position corresponding to a number of through holes on the straight pipe section 32. The through holes are all inside the ejector water chamber 34, and an ejector liquid inlet 35 is arranged on the ejector water chamber 34. The ejector water chamber 34 is of an annular structure. The ejector liquid inlet 35 is of a tubular structure and is offset on the ejector water chamber 34, as Figure 3 shown. The ejector liquid inlet 35 faces and is close to the bottom of the water space 41.

[0030] The specific working principle of a containment suppression spray nozzle based on the ejector principle described in the present invention is as follows:

[0031] When the air flow sequentially passes through the converging pipe section 31, the straight pipe section 32, and the diverging pipe section 33, since the flow area experiences a change of decreasing - increasing, the corresponding gas flow velocity experiences a change of increasing - decreasing. According to Bernoulli's principle, the static pressure of the air flow will experience a change of decreasing - increasing. Therefore, the static pressure of the straight pipe section 32 is less than the static pressures of the water space 41 and the gas space 42. Under the action of the pressure difference, the air flow will eject the subcooled water at the lower part and the air at the upper part. The lower subcooled water enters the air flow in the straight pipe section 32 through the ejector water inlet 35 and the ejector water chamber 34 and is atomized into water droplets, and the steam condenses on the surface of the water droplets. The ejector water inlet 35 faces and is close to the bottom of the water space 41, thereby reducing the thermal stratification degree of the water space 41. The upper air enters the air flow in the straight pipe section 32 through the ejector air pipe 5, reducing the local steam condensation rate, and bringing a gas buffering effect at the end of bubble condensation to eliminate condensate water hammer. At the same time, the ejector gas comes from the upper part of the gas space 42, which also reduces the concentration stratification and thermal stratification of the gas space 42.

[0032] After the accident ends, the pressure inside the containment 1 may be lower than the pressure in the gas space 42. The gas in the gas space 42 sequentially passes through the ejector gas pipe 5, the straight pipe section 32, the contraction pipe section 31, and the discharge pipe 2 and enters the containment 1.

[0033] Summarizing the above embodiments, a suppression nozzle for a containment based on the ejector principle according to the present invention takes into account both the condensate water hammer and thermal stratification problems caused by the low-speed discharge operation of the suppression system. The suppression nozzle operates based on Bernoulli's principle and can eject subcooled water and gas without external power, which is simple and reliable. The ejected subcooled water is atomized, enhancing local heat transfer, reducing the temperature difference between the upper and lower parts of the water space, and improving the cooling capacity of the suppression system. The ejector gas pipe 5 reduces the gas space stratification and the intensity of the condensate water hammer, and at the same time eliminates the check valve, simplifying the system. A suppression nozzle for a containment based on the ejector principle according to the present invention forms a swirl of subcooled water in the ejector water chamber 34 by offsetting the ejector water inlet 35, and at the same time disperses the water flow through a number of through holes provided on the straight pipe section 32, which is beneficial for the water flow to be atomized into droplets after entering the straight pipe section 32. The ejector liquid inlet 35 is close to the bottom of the water space, thereby reducing the degree of thermal stratification of the water space.

[0034] In the specific embodiments described above, the purpose, technical solution, and beneficial effects of the present invention have been further described in detail. 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 principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A containment pressure suppression nozzle based on the ejection principle, characterized in that: The invention comprises a containment shell (1), a discharge pipe (2), a pressure suppression nozzle (3) and a pressure suppression box (4); the containment shell (1) is arranged at the upper end of the pressure suppression box (4); the upper end of the discharge pipe (2) is arranged inside the containment shell (1), and the lower end is arranged in the water space (41) of the pressure suppression box (4); the lower end of the discharge pipe (2) is arranged with a pressure suppression nozzle (3); the pressure suppression nozzle (3) comprises a contraction pipe section (31), a straight pipe section (32) and a diffusion pipe section (33); one end of the contraction pipe section (31) is connected to the discharge pipe (2), and the other end is connected to the straight pipe section (32) and the diffusion pipe section (33) in sequence; a plurality of through holes are arranged on the straight pipe section (32).

2. The containment pressure suppression nozzle based on the ejection principle according to claim 1 is characterized in that: The straight pipe section (32) is provided with an ejection air pipe (5), and the upper end of the ejection air pipe (5) is connected to the air space (42) in the pressure suppression box (4).

3. The containment pressure suppression nozzle based on the ejection principle according to claim 2 is characterized in that: The through hole is arranged on a side of the straight pipe section (32) close to the contraction pipe section (31), and the ejection air pipe (5) is arranged on a side of the straight pipe section (32) close to the diffusion pipe section (33).

4. The containment pressure suppression nozzle based on the ejection principle according to claim 1, 2 or 3, characterized in that: An ejection water cavity (34) is arranged at positions corresponding to the plurality of through holes on the straight pipe section (32), and an ejection liquid inlet (35) is arranged on the ejection water cavity (34).

5. The containment pressure suppression nozzle based on the ejection principle according to claim 4 is characterized in that: The ejection water cavity (34) is a circular ring structure.

6. The containment pressure suppression nozzle based on the ejection principle according to claim 5 is characterized in that: The injection liquid inlet (35) is offset.

7. The containment pressure suppression nozzle based on the ejection principle according to claim 6 is characterized in that: The injection liquid inlet (35) faces the bottom of the water space (41).

Images