Reverse flow stabilizing device and important service water system

Abstract

The invention discloses a reverse flow stabilizing device and an important service water system. The reverse flow stabilizing device comprises a main body pipe part and a control baffle plate, the main body pipe part is provided with a pipe cavity extending in the axial direction, the two ends of the pipe cavity are provided with a first pipe opening and a second pipe opening respectively, the first pipe opening and the second pipe opening are both communicated with the water inlet main pipe, water in the water inlet main pipe flows through the pipe cavity, and the forward flow direction of the water flows from the first pipe opening to the second pipe opening. The control baffle is installed in a pipe cavity of the main body pipe part and is in a circular ring shape, and the central axis of the control baffle and the central axis of the main body pipe part are located on the same extension line. The two ends of the control baffle are provided with a first end and a second end respectively, the first end is close to the first pipe opening, the second end is close to the second pipe opening, the control baffle is obliquely arranged, the first end is located on the outer side of the second end, and the control baffle is used for generating blocking water flow in the direction opposite to the reverse flow direction when reverse flow occurs. Therefore, reverse flow is hindered.

Description

Technical Field

[0001] The present invention specifically relates to a reverse flow stabilizing device and an important component service water system. Background Art

[0002] As a nuclear safety class system of a nuclear power plant, pressure fluctuations often occur in the pipelines of the important component service water system. The reasons for the pressure fluctuations include: the large water conveyance volume of the important component service water system, the high pipeline flow velocity; the single and double pump switching operation conditions are numerous and complex; the medium is seawater, the change range of the external sea tide level is large, the pressure pipeline is long and has a large height difference, etc.

[0003] The pressure fluctuations may cause water hammer phenomenon in the pipeline, and even lead to accidents such as interruption of system water supply, damage to water pumps, valves and pipelines. Therefore, how to reduce the pressure fluctuations in the important component service water system has become an urgent technical problem to be solved. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a reverse flow stabilizing device, an important component service water system and a method, aiming at the above deficiencies in the prior art. The reverse flow stabilizing device can effectively reduce the pressure fluctuations in the important component service water system.

[0005] According to an embodiment of the first aspect of the present invention, a reverse flow stabilizing device is provided, including: a main pipe portion and a control baffle;

[0006] The main pipe portion has a lumen extending along the axial direction. The two ends of the lumen are respectively provided with a first pipe orifice and a second pipe orifice. Both the first pipe orifice and the second pipe orifice communicate with the inlet header pipe. The water flow in the inlet header pipe flows through the lumen, and the positive flow direction of the water flow is from the first pipe orifice to the second pipe orifice. The control baffle is installed in the lumen of the main pipe portion. The control baffle is annular, and the central axis of the control baffle is on the same extension line as the central axis of the main pipe portion. The two ends of the control baffle are respectively provided with a first end portion and a second end portion. The first end portion is the end close to the first pipe orifice, and the second end portion is the end close to the second pipe orifice. The control baffle is inclined so that the first end portion is located outside the second end portion. The control baffle is used to generate a water flow that hinders the reverse flow in the opposite direction when the reverse flow occurs, so as to hinder the reverse flow.

[0007] Preferably, the thickness of the control baffle gradually decreases from the first end portion to the second end portion.

[0008] Preferably, the number of the control baffles is multiple, and the multiple control baffles are arranged along the central axis of the main pipe portion.

[0009] Preferably, the first end of the control baffle is spaced from the inner side wall of the main tube, the inner side wall of the control baffle encloses a first flow channel, and the outer side wall of the control baffle and the inner side wall of the main tube form a second flow channel. There is a confluence channel between two adjacent control baffles, the confluence channel is inclined to the first flow channel and the second flow channel, one end of the confluence channel is connected to the first flow channel, and the other end is connected to the second flow channel. The confluence channel is used to make the water flow in the second flow channel converge to the first flow channel when water backflow occurs in the water inlet main pipe, so as to form a water flow obstruction in the opposite direction of the backflow, thereby obstructing the backflow.

[0010] According to an embodiment of the second aspect of the present invention, there is provided an important plant water system, comprising a water inlet main pipe, a water pump, a heat exchanger and the above-mentioned reverse flow stabilizing device, wherein the water pump is connected to the heat exchanger via the water inlet main pipe, and is used to deliver cooling water to the heat exchanger; the reverse flow stabilizing device is connected to the water inlet main pipe, and is located between the water pump and the heat exchanger, and is used to reduce pressure fluctuations in the water inlet main pipe.

[0011] Preferably, the system also includes a pressure stabilizing branch unit, which is connected to the water inlet main pipe and is located between the water pump and the reverse flow stabilizing device; the pressure stabilizing branch unit includes a pressure stabilizing tank, which is connected to the water inlet main pipe, and the pressure stabilizing tank is used to receive the backflow when the backflow is generated in the water inlet main pipe, thereby unloading the pressure fluctuation caused by the backflow.

[0012] Preferably, the pressure stabilizing branch unit also includes a branch gate valve, which is located between the pressure stabilizing tank and the water inlet main pipe and is used to control the connection / isolation between the pressure stabilizing tank and the water inlet main pipe when there is reverse flow / normal flow in the water inlet main pipe.

[0013] Preferably, the system further comprises a receiving pool, which is located downstream of the heat exchanger and is connected to the cooling water outlet of the heat exchanger, and is used to receive the cooling water after heat exchange. An overflow weir is provided at the upper edge of one side wall of the receiving pool, and the cooling water after heat exchange can overflow from the overflow weir.

[0014] Preferably, the system further comprises an airbag dam, which is installed in the overflow weir and can be extended and retracted in the vertical direction. When the airbag dam is extended upward in the vertical direction, it can block the overflow gap, thereby increasing the overflow water level in the receiving tank (15).

[0015] Preferably, the system further comprises an air pump; the air pump (16) is connected to the airbag dam (18) and is used to inflate the airbag dam (18) so that the airbag dam (18) expands and extends upward to block the overflow weir.

[0016] In the reverse flow stabilizing device of the present invention, the control baffle is inclined in the direction opposite to the countercurrent (i.e., inclined from the first pipe orifice to the second pipe orifice). Specifically, the first end of the control baffle is the end close to the first pipe orifice, the second end is the end close to the second pipe orifice, and the first end is located outside the second end.

[0017] When the pump in the important service water system stops, a water hammer effect will occur, that is, the water flow will cause a countercurrent due to inertia and impact the pump, resulting in a sharp increase in pressure and vibration in the system. When there is a reverse water flow (the water flow flows from the second pipe orifice to the first pipe orifice), that is, when there is a water hammer pressure fluctuation, the direction of the water flow is opposite to the inclination direction of the control baffle, and the outer wall of the control baffle will play a role in blocking and dispersing the countercurrent. Moreover, the control baffle can also generate a water flow that hinders the countercurrent in the opposite direction when there is a countercurrent, further weakening the countercurrent.

[0018] In summary, the reverse flow stabilizing device can effectively disperse and weaken the countercurrent, thereby reducing the pressure fluctuation in the important service water system. Description of the Drawings

[0019] Figure 1 is a schematic structural diagram of the important water use system in some embodiments of the present invention;

[0020] Figure 2 is a schematic diagram of the forward flow of the reverse flow stabilizing device in some embodiments of the present invention;

[0021] Figure 3 is a schematic diagram of the countercurrent of the reverse flow stabilizing device in some embodiments of the present invention;

[0022] Figure 4 is a schematic structural diagram when the overflow weir retracts in some embodiments of the present invention;

[0023] Figure 5 is a schematic structural diagram when the overflow weir extends in some embodiments of the present invention.

[0024] In the figure: 1 - inlet header pipe, 2 - water pump, 3 - check valve, 4 - pressure stabilizing branch unit, 5 - branch gate valve, 6 - pressure stabilizing tank, 7 - exhaust valve, 8 - liquid part, 9 - gas part, 10 - reverse flow stabilizing device, 11 - main pipe part, 12 - control baffle, 13 - shellfish trap, 14 - heat exchanger, 15 - receiving pool, 16 - air inflation pump, 17 - air inflation pipeline, 18 - airbag dam, 19 - airbag dam limiting wall. Detailed Embodiments

[0025] The technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of the present invention.

[0026] In the description of the present invention, it should be noted that the terms "upper", "lower", "upstream", "downstream", etc. indicating the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings. It is only for the convenience and simplification of description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.

[0027] In the description of the present invention, the terms "first" and "second" are only used for descriptive purposes and should not 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 defined, the terms "connected", "set", "installed", "fixed", etc. should be understood in a broad sense. For example, it can be a fixed connection or a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] First of all, it should be noted that the essential service water system, as a nuclear safety class system of a nuclear power plant, has the following specific technological process: the essential service water pump does work, takes water filtered by the rotary screen of the circulating water filtration system located in the combined pump house, passes through the essential service water intake gallery, and the shellfish trap provides cooling water to the plate heat exchanger located in the nuclear island building, and is discharged into the essential service water drainage pipeline through the essential service water system receiving pool outside the nuclear island building, then converges to the siphon well and finally discharges into the sea.

[0030] The essential service water system has the following characteristics: a nuclear safety seismic class system, large water delivery volume, high pipeline flow velocity; there are many and complex single and double pump switching operation conditions, the medium is seawater, the change range of the external tide level is large, the pressure pipeline is long and has a large height difference. Therefore, pressure fluctuations are likely to occur in the pipelines of the essential service water system, resulting in water hammer phenomena that may occur during various hydraulic transient processes, and even leading to accidents such as system water supply interruption, damage to pumps, valves and pipelines.

[0031] At present, the main measures taken to address the pressure fluctuation phenomenon are to install one-stage or two-stage check valves behind the pump, but the effect of a single check valve protection scheme in eliminating and weakening the pressure fluctuation phenomenon is limited.

[0032] Example 1

[0033] Please refer to Figure 1 、 Figure 2 and Figure 3 As shown in FIGS.

[0034] The present invention discloses a reverse flow stabilizing device 10, including: a main pipe portion 11 and a control baffle 12. The main pipe portion 11 is in a straight cylindrical tubular shape, and both ends of the main pipe portion 11 are respectively provided with a first pipe orifice and a second pipe orifice. Both the first pipe orifice and the second pipe orifice communicate with a water inlet main pipe 1. The water flow in the water inlet main pipe 1 flows through the main pipe portion 11, and the positive flow direction of the water flow is from the first pipe orifice to the second pipe orifice. The control baffle 12 is installed in the lumen of the main pipe portion 11. The control baffle 12 is in an annular shape, and the central axis of the control baffle 12 and the central axis of the main pipe portion 11 are on the same extension line. Both ends of the control baffle 12 are respectively provided with a first end portion and a second end portion. The first end portion is the end close to the first pipe orifice, and the second end portion is the end close to the second pipe orifice. The control baffle 12 is inclined such that the first end portion is located outside the second end portion. The control baffle 12 is used to generate a flow resistance opposite to the reverse flow direction when a reverse flow occurs, thereby hindering the reverse flow.

[0035] It should be noted that by inclining the control baffle 12 in the direction opposite to the reverse flow (i.e., inclining from the first pipe orifice to the second pipe orifice), the control baffle 12 can play a role in blocking the flow. Specifically, when the water flow is from the second pipe orifice to the first pipe orifice, the flow direction of the water is opposite to the inclination direction of the control baffle 12, and the outer wall of the control baffle 12 will play a role in blocking and dispersing the reverse flow.

[0036] When the water pump 2 is suddenly shut down, a water hammer effect will occur, that is, the water flow impacts the water pump 2 due to inertia, resulting in a sharp increase in pressure and vibration. Specifically, when the water pump 2 is operating normally, it will supply water flow to the system through the pipeline and maintain a certain pressure. However, when the water pump 2 suddenly stops, the water flow originally pushed by the water pump 2 loses its forward driving force. Under the action of inertia, the water flow will continue to flow in the original direction, resulting in a partial vacuum between the water pump 2 and the water flow. The suction force generated by the vacuum causes the water flow to reverse and impact the water pump 2. In this application, the inclined design of the control baffle 12 can alleviate this effect to a certain extent because the control baffle 12 causes the water flow to gradually decelerate and disperse when flowing reversely through the control baffle 12, thereby weakening the water hammer effect.

[0037] The present reverse flow stabilizing device 10 can be applied to any scenario where it is necessary to eliminate the impact of pressure fluctuations and water hammer effects caused by reverse flow in the water inlet main pipe 1, and is particularly suitable for application in the important service water system in a nuclear power plant.

[0038] Because, compared with ordinary water systems, in the important component cooling water system of a nuclear power plant, seawater is used as the cooling water. Although it is filtered, there are still many impurities in the seawater. This will cause greater impacts on the pipe wall of the inlet header 1 and the water pump 2 when reverse flow and water hammer effects occur (that is, the destructive force of the water hammer effect is stronger). The traditional check valve 3 can only achieve hard contact with the water hammer impact, and the effect of weakening the water hammer is limited.

[0039] However, the reverse flow stabilizing device 10 in this application does not directly contact the water hammer shock wave hard, but gradually weakens the water hammer fluctuation and reduces the reverse rotation of the water pump 2 by setting a control baffle 12 in the direction opposite to the reverse flow direction. Specifically, the control baffle 12 causes the water flow to gradually decelerate and disperse when passing through the control baffle 12, rather than being suddenly blocked.

[0040] More importantly, the reverse flow stabilizing device 10 in this embodiment can increase the number, thereby increasing the effect of weakening the water hammer fluctuation. Exemplarily, by setting multiple reverse flow stabilizing devices 10 on one inlet header 1, it can be ensured that each time the reverse flow (water hammer) passes through one level of the reverse flow stabilizing device 10, it will achieve a deceleration and dispersion, and finally achieve the ideal effect of weakening the water hammer fluctuation. However, the traditional check valve 3 does not have such an effect. The reason is that no matter how many check valves 3 are connected in series on the inlet header 1, the first check valve 3 in the reverse flow direction is always in contact with the reverse flow water hammer. This hard partition protection method makes the check valve 3 quickly damaged and needs to be disassembled and replaced, which is not conducive to the continuous operation of the important component cooling water system of the nuclear power plant.

[0041] In this embodiment, the control baffle 12 can be composed of a whole ring, or can be formed by enclosing a ring with multiple arc plates. For example: the control baffle 12 can be composed of an upper baffle and a lower baffle. The upper and lower baffles are arranged oppositely, and both the upper and lower baffles are semi-circular arcs, and the upper and lower baffles enclose to form a complete circular baffle.

[0042] Further, as Figure 2 and Figure 3 shown, the number of the control baffles 12 is multiple, and the multiple control baffles 12 are arranged along the central axis of the main pipe part 11. The number of the control baffles 12 is 3, 4 or 5. Exemplarily, the number of the control baffles 12 is 3, and the three control baffles 12 are all arranged along the central axis of the main pipe part 11. Each control baffle 12 can achieve the effect of dispersing the reverse flow and weakening the water hammer pressure once. Therefore, by increasing the number of the control baffles 12, the effect of dispersing the reverse flow and weakening the water hammer pressure can be further improved.

[0043] In this embodiment, there is a gap between the first end of the control baffle 12 and the inner wall of the main pipe portion 11. Specifically, the control baffle 12 can be welded to the inner wall of the main pipe portion 11 through a bracket, so that a gap is formed between the first end and the inner wall of the main pipe portion 11. The inner wall of the control baffle 12 encloses to form a first flow channel, and a second flow channel is formed between the outer wall of the control baffle 12 and the inner wall of the main pipe portion 11.

[0044] There is a confluence channel between two adjacent control baffles 12. The confluence channel is inclined to the first flow channel and the second flow channel. One end of the confluence channel is communicated with the first flow channel, and the other end is communicated with the second flow channel. The confluence channel is used to make the water flow in the second flow channel converge into the first flow channel when a water flow countercurrent occurs in the inlet header pipe 1, so as to form a blocking water flow opposite to the countercurrent direction, thereby hindering the countercurrent.

[0045] There is a confluence channel between two adjacent control baffles 12. The confluence channel is inclined to the first flow channel and the second flow channel. One end of the confluence channel is communicated with the first flow channel, and the other end is communicated with the second flow channel. The confluence channel is used to make the water flow in the second flow channel converge into the first flow channel when a water flow countercurrent occurs in the inlet header pipe 1, so as to form a blocking water flow opposite to the countercurrent direction, thereby hindering the countercurrent.

[0046] As Figure 2 shown, when the system is operating normally, the water flow direction is the same as the inclination direction of the flow control baffle 12. At this time, most of the water flows along the position in the center of the device, and a small part of the water flows through the gap outside the baffle. The flow direction of this part of the water flow is the same as the main flow, and due to the smaller flow area, it has a higher flow velocity and will not affect the main flow velocity or even promote the forward flow.

[0047] As Figure 3 shown, when the system is shut down (that is, when the water pump 2 is suddenly closed and the water flow generates a countercurrent due to inertia, forming a water hammer), the water flow direction is opposite to the inclination direction of the flow control baffle 12. At this time, a part of the water flows along the position in the center of the device, and another part of the water flows through the gap outside the baffle. The flow direction of this part of the water flow when converging is opposite to the main flow, hindering the flow of the countercurrent main flow and weakening the energy of the countercurrent water flow, and the water hammer pressure fluctuation is further weakened.

[0048] Specifically, Figure 3For the case of system shutdown, at this time, the flow control baffle 12 functions under the action of the reverse flow stabilizing device 10. When the incoming water flows from the outlet of the reverse flow stabilizing device 10 to the inlet, that is, the liquid flow flows from the trailing edge of the flow control baffle 12 to the leading edge. The countercurrent will be divided into two parts. One part flows out from the middle flow channel of the main pipeline part of the device (i.e., the main pipe part 11), and the other part will flow through the outer gap formed between the flow control baffle 12 and the inner wall of the main pipeline part of the device to form a backflow. This is because the outer gap is a wedge-shaped contraction section, and the flow velocity of the backflow liquid flowing through this position will be much higher than the main part of the countercurrent. Therefore, when the backflow converges with the main part of the countercurrent, it will hinder the flow of the main part of the countercurrent and weaken the energy of the countercurrent water flow, so that the water hammer pressure fluctuation will be further weakened.

[0049] In some other embodiments, the first end of the control baffle 12 can also be directly welded to the inner side wall of the main pipe part 11, so that a flow blocking space can be formed between the control baffle 12 and the inner side wall of the main pipe part 11. A part of the countercurrent flows through the first flow channel (i.e., the main flow channel) of the control baffle 12, and another part of the countercurrent enters the flow blocking space. Since there is no outlet in the flow blocking space, this part of the water flow can only flow along the inner side wall of the main pipeline and the outer side wall of the control baffle 12, and finally forms a blocking water flow in the opposite direction to the countercurrent. The flow direction of the blocking water flow when converging is opposite to the main flow, hindering the flow of the main part of the countercurrent and weakening the energy of the countercurrent water flow, and the water hammer pressure fluctuation is further weakened.

[0050] As Figure 2 and Figure 3 shown, in this embodiment, the control baffle 12 is wedge-shaped. The thickness of the control baffle 12 gradually decreases from the first end to the second end. Specifically, due to the gradual decrease in thickness, the control baffle 12 forms a more sharp or compact blocking surface at the end near the second pipe orifice (i.e., the inlet end when the countercurrent appears). This design makes the countercurrent encounter greater resistance and pressure when trying to pass through, thus more effectively preventing the occurrence of the countercurrent.

[0051] Moreover, the gradual change design of the thickness of the control baffle 12 helps to optimize the dynamic performance of the fluid when passing through. When the forward water flow (from the first pipe orifice to the second pipe orifice), the gradually thinning baffle can reduce the obstruction to the water flow, reduce the energy loss, and improve the water flow efficiency. At the same time, when the countercurrent occurs, the thicker first end can more effectively block the countercurrent, while the gradually thinning second end helps to disperse the countercurrent and guide the countercurrent to flow into the second flow channel, thereby weakening the pressure of the countercurrent.

[0052] In summary, the reverse flow stabilizing device 10 in this embodiment can effectively disperse the countercurrent and weaken the water hammer pressure fluctuation, that is, it can effectively reduce the pressure fluctuation in the important plant service water system.

[0053] Embodiment 2

[0054] Please refer to Figure 1 , the present invention discloses an important plant water system to solve the problem that the current single check valve 3 protection measure in the important plant water system has limited effect in eliminating pressure fluctuation phenomena. The system includes an inlet header 1, a water pump 2, a heat exchanger 14, and a reverse flow stabilizing device 10 in Embodiment 1.

[0055] Among them, the water pump 2 is connected to the heat exchanger 14 through the inlet header 1 and is used to transport cooling water to the heat exchanger 14. The reverse flow stabilizing device 10 is connected to the inlet header 1 and is located between the water pump 2 and the heat exchanger 14, and is used to stabilize the flow of the inlet header 1 when a reverse flow occurs in the inlet header 1.

[0056] This system may include multiple safety trains (pipelines) containing important plant water pumps 2 and heat exchangers 14, for example: 2, 3, or 4 safety trains (pipelines). Taking the important plant water system with 2 safety train pipelines as an example for illustration:

[0057] This important plant water system includes two safety trains containing important plant water pumps 2 and heat exchangers 14. The important plant water system is a nuclear safety class system, with two identical trains set, that is, two safety trains. The two safety trains are in standby with each other, and only one train is operating during normal operation. Each train is provided with the same pumps, heat exchangers, valves and other equipment, as well as pipelines of the same specification and material.

[0058] Each safety train is provided with a pressure stabilizing tank branch (i.e., a pressure stabilizing branch unit 4) after the check valve 3, and one or more reverse flow stabilizing devices 10 are provided on the horizontal pipe section after the pressure stabilizing tank branch. An adjustable height airbag dam 18 overflow weir is provided at the receiving pool 15. When a pressure fluctuation phenomenon occurs, the air chamber of the buffer tank deforms to absorb the pressure fluctuation energy. The reverse flow stabilizing device 10 weakens the energy of the reverse flow fluid. The adjustable height airbag dam 18 overflow weir raises the liquid level of the receiving pool 15, reduces the maximum negative pressure of the system, and further weakens the pressure fluctuation. Through the combined action of multiple measures, the pressure fluctuation phenomenon of the important plant water system is more effectively controlled.

[0059] Specifically, a reverse flow stabilizing device 10 is provided on each safety train pipeline. The reverse flow stabilizing device 10 is connected to the inlet header 1 and is located between the water pump 2 and the heat exchanger 14. The reverse flow stabilizing device 10 includes a main pipeline part and a flow control baffle 12. When the important plant water system is operating normally, the seawater flows forward, and the internal flow of the device does not affect the fluid flow; when the system is shut down, the seawater flows backward, and the internal fluids of the device block each other (the reverse flow and the blocked water flow cancel each other out), consuming the fluid energy and weakening the pressure fluctuation. By setting the reverse flow stabilizing device 10, the pressure fluctuation in the important plant water system can be effectively reduced, and the safety of the inlet header 1 and the water pump 2 can be ensured.

[0060] In this embodiment, the number of reverse flow stabilizing devices 10 included in each safety series is 1, 2 or 3. Figure 1 As shown, the number of the reverse flow stabilizing device 10 is one, and the reverse flow is first dispersed and weakened by the reverse flow stabilizing device, and then cooperates with the check valve 3 to achieve more effective protection for the water pump 2. The reverse flow stabilizing device 10 has the function of slowing down the reverse flow velocity, and can reduce the reverse flow velocity, weaken the water hammer fluctuation, and reduce the reversal of the water pump 2 when the pump stops water hammer.

[0061] This important plant water system also includes a pressure stabilizing branch unit 4, which is connected to the water inlet main pipe 1 and is located between the reverse flow stabilizing device 10 and the reverse stabilizing device. The pressure stabilizing branch unit 4 includes a pressure stabilizing tank 6, which is connected to the water inlet main pipe 1 through a branch pipeline. The pressure stabilizing tank 6 is used to receive the backflow when a backflow occurs in the water inlet main pipe 1, thereby unloading the pressure fluctuation caused by the backflow. Further, the pressure stabilizing branch unit 4 also includes a branch gate valve 5, which is installed on the branch pipeline. The branch gate valve 5 is located between the pressure stabilizing tank 6 and the water inlet main pipe 1, and is used to control the connection / isolation between the pressure stabilizing tank 6 and the water inlet main pipe 1 when there is a backflow / positive flow in the water inlet main pipe 1.

[0062] In other words, a surge tank branch gate valve 5 is provided on the surge tank pipeline (i.e., the branch pipeline), and the pipeline after the branch gate valve 5 is finally connected to the surge tank 6, and the surge tank 6 is provided with an exhaust valve 7, and the tank interior includes a liquid part 8 and a gas part 9. Furthermore, after the system is started, the branch gate valve 5 is opened, and part of the water in the main pipeline flows into the surge tank 6 to form a liquid part 8 in the tank, and the liquid level in the tank begins to rise. When the liquid level in the tank reaches a predetermined position and the pressure stabilizes, the branch gate valve 5 is closed, and the system starts to operate normally. When the system needs to stop the pump operation, the gate valve is opened in advance. At this time, the system stops the pump, and the backflowing water flows into the surge tank 6. Due to the compressibility of the gas in the tank and the existence of the exhaust valve 7, the fluid energy is released and buffered, and the water hammer pressure fluctuation is weakened. A reverse flow stabilizing device 10 is provided on the main pipeline of the important plant water system behind the branch pipeline of the pressure-stabilizing tank. The main pipeline part of the device is connected to the pipeline of the important plant water system through a flange. The nominal diameters of the two are the same. The device mainly includes a main pipeline part and a dynamic control baffle 12.

[0063] Furthermore, when the system is running, the branch gate valve 5 is opened to fill the pressure-suppressing tank 6 with water. There is a certain volume of water in the tank, and it also contains gas. The change in the volume of the gas has a stabilizing effect. When the pump stops and water hammer occurs, the pressure-suppressing tank 6 absorbs fluid energy, buffers flow rate changes, and reduces pressure fluctuations. The pressure-suppressing tank 6 includes two parts, gas and liquid. When the system stops, the gas in the tank has a buffering effect. When the pressure reaches the threshold of the exhaust valve 7, the exhaust valve 7 opens to further buffer the pressure fluctuations.

[0064] After the countercurrent flow is dispersed and weakened by the reverse flow stabilizing device, the water hammer pressure fluctuation in the inlet header pipe 1 is further weakened through the pressure stabilizing tank branch (i.e., the pressure stabilizing branch unit 4), and finally, in cooperation with the check valve 3, more effective protection for the water pump 2 can be achieved, and the water hammer pressure fluctuation in the inlet header pipe 1 can be greatly weakened, prolonging the service life of the water pump 2 and the check valve 3.

[0065] In this embodiment, a shellfish trap 13 is provided on the main pipeline behind the reverse flow stabilizing device 10, that is, between the reverse flow stabilizing device 10 and the heat exchanger 14. It should be noted that seawater is mainly used as the cooling water in this system, and there are a large number of impurities such as marine organisms and sand and gravel in the seawater. The shellfish trap 13 is mainly used to filter out the fine impurities that are not filtered by the front-end filtering equipment to avoid damage to the pipes in the heat exchanger 14.

[0066] It can be seen from the above description that the inlet header pipe 1 of each safety train is sequentially connected to a water pump 2, a check valve 3, a pressure stabilizing tank branch, a reverse flow stabilizing device 10, a shellfish trap 13, and a heat exchanger 14. The main pipeline after passing through the heat exchanger 14 finally falls into the receiving pool 15, and an air inflation pump 16, an air inflation pipeline 17, an airbag dam 18, and an airbag dam limiting wall 19 are provided on the weir body part of the receiving pool 15.

[0067] Please refer to Figure 4 and Figure 5 , and the receiving pool will be specifically described below:

[0068] The receiving pool 15 of this important service water system is located downstream of the heat exchanger 14 and is connected to the cooling water outlet of the heat exchanger 14. The receiving pool 15 is used to receive the cooled cooling water. The number of receiving pools 15 is the same as the number of safety trains, and each receiving pool 15 corresponds to a safety train pipeline. The cooling water outlets of the heat exchangers 14 in multiple safety train pipelines are respectively connected to multiple receiving pools 15.

[0069] In this embodiment, an overflow weir is provided at the upper edge of one side wall of the receiving pool 15, and the cooled cooling water can overflow from the overflow weir. In other words, the overflow weir is a notch provided on one side wall of the receiving pool 15.

[0070] The system further includes an airbag dam 18, which is installed in the overflow weir. The airbag dam 18 can expand and contract in the vertical direction. When the airbag dam 18 extends upward in the vertical direction, it can block the overflow gap, thereby increasing the overflow water level in the receiving pool 15. Specifically, due to the relatively high height of the high-point pipeline of the system and the large height difference with the liquid level in the receiving pool 15, there is a relatively large negative pressure in the pipeline height. When the pump in the system stops, the rapid change in flow rate causes a rapid change in pressure. The negative pressure at the high point of the system reaches a vacuum, forming a flow-breaking cavity and triggering a more harmful flow-breaking closing water hammer, which has an adverse impact on the operation of the important plant water system. Therefore, before the pump in the system stops (the pump stop in the system will cause reverse flow and water hammer effects), it is necessary to control the overflow weir to extend upward in the vertical direction, so that the upper edge height of the overflow weir rises, the water level that can be accommodated in the receiving pool 15 increases, the liquid level difference with the high point of the system decreases, and the maximum negative pressure of the system decreases. This can reduce the possibility of generating a flow-breaking cavity when the pump stops, and the pressure fluctuation situation is weakened again.

[0071] Specifically, as Figure 4 and Figure 5 shown, the system further includes an air inflation pump 16. The airbag dam 18 is installed in the overflow gap (i.e., the overflow weir). The air inflation pump 16 is connected to the airbag dam 18 and is used to inflate the airbag dam 18, so that the airbag dam 18 expands and extends upward to block the overflow weir. Before the pump in the system stops, the air inflation pump 16 is operated, and gas enters the airbag dam 18 from the outside through the air inflation pipeline 17. The airbag dam 18 inflates and expands, and expands upward due to the existence of the airbag dam limiting wall 19. At this time, the upper edge height of the overflow weir (i.e., the airbag dam 18) is increased, and the water level in the receiving pool 15 rises, so that the liquid level difference between the accumulated liquid in the receiving pool 15 and the high point of the system decreases. Of course, the overflow weir can also be implemented by using other existing structures. For example, a plate-shaped dam body is used, and the dam body is driven to lift and lower in the vertical direction by a driving motor.

[0072] In other words, the adjustable-height airbag dam 18 overflow weir at the receiving pool 15 includes an air inflation pump 16, an air inflation pipeline 17, an airbag dam 18, and an airbag dam limiting wall 19. The airbag dam 18 can expand in the vertical direction after being inflated. The airbag dam 18 can be inflated and deflated through the air inflation pump 16, and expand or contract upward to achieve the function of controlling the height of the overflow weir. Before the pump stops, by increasing the liquid level in the receiving pool 15, the negative pressure at the highest point of the system is reduced, and the possibility of generating closing water hammer is reduced, and the pressure fluctuation is weakened again. Further, the air inflation pump 16 inflates the airbag dam 18 at the overflow weir through the air inflation pipeline 17 to achieve the control of the height of the overflow weir. Before the occurrence of water hammer pressure fluctuations such as pump stop in the system, by adjusting the height of the weir, the severity of the water hammer pressure fluctuation can be affected, and the pressure fluctuation phenomenon is further weakened.

[0073] The working process of the important plant water system in this embodiment will be further described below:

[0074] like Figure 1 As shown, the important plant water system of the nuclear power plant includes pipelines (water inlet main pipe 1), important plant water pumps 2, check valves 3, pressure stabilizing tanks, reverse flow stabilizing devices 10, shellfish traps 13, plate heat exchangers 14, and adjustable overflow weir height receiving tanks 15.

[0075] The water inlet main pipe 1 of the important plant water system of the nuclear power plant is connected to the important plant water pump 2 in the pump room. A check valve 3 is provided on the outlet side of the important plant water pump 2 to prevent water backflow. The check valve 3 can be a butterfly type or a swing type, and the closing speed can be one stage or two stages. On the pipeline behind the check valve 3, a surge tank branch pipeline (i.e., branch pipeline) is provided. A surge tank branch gate valve 5 is provided on the surge tank branch pipeline. The branch pipeline after the branch gate valve 5 is finally connected to the surge tank 6. The surge tank 6 is provided with an exhaust valve 7. The tank includes a liquid part 8 and a gas part 9. After the system is started, the branch gate valve 5 is opened, and part of the water in the main pipeline flows into the surge tank 6 to form a liquid part 8 in the tank. The liquid level in the tank begins to rise. When the liquid level in the tank reaches the predetermined position and the pressure stabilizes, the branch gate valve 5 is closed, and the system starts to operate normally. When the system needs to stop the pump, the gate valve is opened in advance. At this time, the system stops the pump, and the backflow water flows into the pressure-stabilizing tank 6. Due to the compressibility of the gas in the tank and the existence of the exhaust valve 7, the fluid energy is released and buffered, and the water hammer pressure fluctuation is weakened. A reverse flow stabilization device 10 is provided on the main pipeline of the important plant water system after the pressure-stabilizing branch unit. The main pipeline part of the device is connected to the important plant water system pipeline through a flange. The nominal diameters of the two are the same. The device mainly includes the main pipeline part and the flow control baffle 12. On the rear main pipeline of the reverse flow stabilization device 10, there are shellfish catchers 13 and heat exchangers 14 in sequence. The main pipeline after the heat exchanger 14 finally falls into the receiving pool 15. The weir part of the receiving pool 15 is also provided with an air pump 16, an air pipeline 17, an air bag dam 18 and an air bag dam limit wall 19.

[0076] Figure 2 and Figure 3They are respectively the schematic diagrams of the forward flow and reverse flow of the liquid flow in the reverse flow stabilizing device 10. When the system is operating normally, the water flow direction is the same as the inclination direction of the flow control baffle 12. At this time, most of the water flows along the position in the center of the device, and a small part of the water flows through the gap outside the baffle. The flow direction of this part of the water flow is the same as the main flow, and due to the smaller flow area, it has a higher flow velocity, which will not affect the main flow velocity and even promotes the forward flow. When the system is shut down, the water flow direction is opposite to the inclination direction of the flow control baffle 12. At this time, a part of the water flows along the position in the center of the device, and another part of the water flows through the gap outside the baffle. The flow direction of this part of the water flow when converging is opposite to the main flow, hindering the flow of the reverse flow main stream and weakening the energy of the reverse water flow, and the water hammer pressure fluctuation is further weakened.

[0077] Figure 4 and Figure 5 They are respectively the structural schematic diagrams when the overflow weir extends and retracts. When the system is operating normally, the air inflation pump 16 does not operate, the airbag dam 18 does not act, and the height of the receiving pool 15 remains fixed, performing the normal function of the receiving pool 15. Ensure that the water flows out of the overflow weir smoothly. Due to the relatively high height of the pipeline at the high point of the system and the relatively large height difference with the liquid level in the receiving pool 15, there is a relatively large negative pressure in the pipeline height. When the pump in the system is stopped, the rapid change in flow velocity causes a rapid change in pressure. The negative pressure at the high point of the system reaches a vacuum, forming a broken flow cavity, and triggering a more harmful broken flow closure water hammer, which has an adverse impact on the operation of the important service water system. Therefore, before the pump in the system is stopped, the air inflation pump 16 is operated, and gas enters the airbag dam 18 from the outside through the air inflation pipeline 17. The airbag dam 18 inflates and expands, and due to the existence of the airbag dam limiting wall 19, it expands upward. At this time, the height of the overflow weir is increased, the water level in the receiving pool 15 rises, the liquid level difference with the high point of the system decreases, and the maximum negative pressure of the system decreases. When the pump is stopped, the possibility of generating a broken flow cavity is reduced, and the pressure fluctuation situation is weakened again.

[0078] The beneficial effects of the important service water system in this embodiment are as follows:

[0079] In order to solve the problem that the current single check valve 3 protection measure in the important service water system has limited effect in eliminating pressure fluctuation phenomena, a pressure stabilizing tank branch is provided behind the check valve 3. One or more reverse flow stabilizing devices 10 are provided on the horizontal pipe section behind the pressure stabilizing tank branch. An adjustable height airbag dam 18 overflow weir is provided at the receiving pool 15. When pressure fluctuation phenomena occur, the air cavity of the buffer tank deforms to absorb the pressure fluctuation energy; the reverse flow stabilizing device 10 weakens the energy of the reverse impact fluid; the adjustable height airbag dam 18 overflow weir raises the liquid level of the receiving pool 15, reduces the maximum negative pressure of the system, and further weakens the pressure fluctuation. Through the combined action of multiple measures, the pressure fluctuation phenomena in the important service water system are more effectively controlled.

[0080] In other words, by adding the check valve 3 and the branch pressure stabilizing tank 6, the air chamber in the tank absorbs the fluid energy flowing backward when the water hammer pressure fluctuation occurs, weakening part of the pressure fluctuation. The reverse flow stabilizing device 10 is arranged in the main pipeline part behind the check valve 3, further buffering the fluid energy flowing backward. At the receiving pool 15, the height of the overflow weir is adjusted by an air pump, and different overflow weir heights can be adjusted corresponding to different operating conditions, so that the pressure fluctuation is relieved again. This important service water system can weaken the pressure fluctuation through multiple devices, and finally cooperate with the check valve 3 to complete the protection of the water pump 2, avoid the reverse rotation of the water pump 2, and thus extend the service life of the check valve 3 and the water pump 2.

[0081] Embodiment 3

[0082] This embodiment discloses the operation process of the important service water system in Embodiment 2. The specific operation process is as follows:

[0083] Before the important service water system is started, the staff conducts the start-up preparation work of the important service water system. First, ensure that the water pump 2 in the pipeline is in a stopped state; ensure that the branch gate valve 5 and the exhaust valve 7 in the pipeline are in a closed state, and drain all the liquid in the pressure stabilizing tank 6 in the pipeline, and then fill it with gas (the air pressure in the pressure stabilizing tank 6 needs to reach 0.15 MPa. It should be noted that the parameter values in the embodiment are only for a certain engineering case, and this value will change with the specific project. For the pressure stabilizing tank, it is necessary to ensure that the gas pressure in the tank is less than the water pressure in the main pipeline at this place under any working conditions). At this time, a closed and gas-filled pressure stabilizing tank 6 is obtained; ensure that the airbag dam 18 in the pipeline is in a contracted state.

[0084] Under normal start-up conditions, the staff sends a start-up instruction to the controller through the instruction sending end, and the controller starts the water pump 2 according to the start-up instruction. After the water pump 2 is started, cooling water (i.e., seawater) is conveyed to the heat exchanger 14 through the inlet main pipe 1, so that the heat exchanger 14 can work normally.

[0085] At the same time, control the branch gate valve 5 in the pipeline to open, and part of the seawater in the inlet main pipe 1 flows into the pressure stabilizing tank 6 to form the liquid part 8 in the tank. A pressure monitoring unit is arranged in the pressure stabilizing tank 6, and the pressure monitoring unit is used to monitor the air pressure in the pressure stabilizing tank 6. When the liquid level in the tank reaches the predetermined position and the pressure is stable (the pressure in the tank needs to be maintained at 0.2 MPa), the pressure monitoring unit sends a gate closing signal to the controller, and the controller closes the branch gate valve 5 according to the gate closing signal.

[0086] When the pump stops, the staff sends a valve closing instruction to the controller through the instruction sending end. The controller controls the branch gate valve 5 of the safety series to open according to the valve closing instruction. A first feedback unit is provided at the branch gate valve 5, and the first feedback unit is used to feedback a first electrical signal to the controller after the branch gate valve 5 opens. Moreover, the controller controls the air inflation pump 16 of the safety series to operate and inflate the airbag dam 18 according to the valve closing instruction. A second feedback unit is provided at the airbag dam 18, and the second feedback unit is used to feedback a second electrical signal to the controller when the airbag dam 18 reaches the preset height. When the controller receives the first electrical signal and the second electrical signal, it controls the water pump 2 to close.

[0087] After the system stops the pump, a water hammer pressure fluctuation with reverse flow is generated. Inside the reverse flow stabilizing device 10 in an important water use system, it can generate a resistance to the water flow, and the resistance to the water flow and the reverse flow fluid block and offset each other, effectively consuming the fluid energy and weakening the pressure fluctuation.

[0088] At the same time, after the reverse flowing water flows into the pressure stabilizing tank 6, due to the compressibility of the gas in the tank, the fluid energy is released and buffered, and the water hammer pressure fluctuation is weakened. Moreover, the pressure monitoring unit in the pressure stabilizing tank 6 is also used to send an exhaust valve 7 opening signal to the controller after the air pressure in the pressure stabilizing tank 6 reaches the threshold value of the exhaust valve 7 (the threshold value of the exhaust valve 7 is 0.3 MPa). The controller controls the exhaust valve 7 to open according to the exhaust valve 7 opening signal to further buffer the pressure fluctuation.

[0089] In addition, after the airbag dam 18 inflates and expands, the position of the upper edge of the overflow weir is raised at this time, and the water level that can be accommodated in the receiving pool 15 rises. As the water level in the receiving pool 15 rises, the liquid level difference between the water level in the receiving pool 15 and the high point of the system decreases, and the maximum negative pressure of the system decreases. When the pump stops, the possibility of generating a broken flow cavity decreases, and the pressure fluctuation situation is weakened again.

[0090] It can be understood that the above embodiments are merely exemplary embodiments adopted to illustrate the principle of the present invention. However, the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also regarded as the protection scope of the present invention.

Claims

1. A reverse flow stabilization device, characterized in that: include: A main body tube (11) and a control baffle (12); The main tube part (11) has a tube cavity extending in the axial direction, and a first tube opening and a second tube opening are respectively provided at both ends of the tube cavity. When water flows through the tube cavity, the normal flow direction of the water flow is from the first tube opening to the second tube opening. The control baffle (12) is installed in the tube cavity of the main tube portion (11), the control baffle (12) is in a conical ring shape, and the central axis of the control baffle (12) and the central axis of the main tube portion (11) are on the same extension line; The control baffle (12) is provided with a first end and a second end at both ends, the first end is located at an end close to the first pipe opening, and the second end is located at an end close to the second pipe opening. The control baffle (12) is tilted so that the first end is located outside the second end. The control baffle (12) is used to generate an obstructing water flow in the opposite direction to the reverse flow when reverse flow occurs, thereby obstructing the reverse flow.

2. The reverse flow stabilization device according to claim 1, characterized in that: The thickness of the control baffle (12) gradually decreases from the first end to the second end.

3. The reverse flow stabilization device according to claim 2, characterized in that: There are a plurality of control baffles (12), and the plurality of control baffles (12) are arranged along the central axial direction of the main body tube portion (11).

4. The reverse flow stabilizing device according to claim 3, characterized in that: The first end of the control baffle (12) is spaced apart from the inner side wall of the main tube portion (11); the inner side wall of the control baffle (12) encloses a first flow channel, and the outer side wall of the control baffle (12) and the inner side wall of the main tube portion (11) form a second flow channel; There is a confluence channel between two adjacent control baffles (12), the confluence channel is inclined to the first flow channel and the second flow channel, one end of the confluence channel is connected to the first flow channel, and the other end of the confluence channel is connected to the second flow channel; The confluence channel is used to make the water flow in the second flow channel converge to the first flow channel when water backflow occurs in the water inlet main pipe (1), so as to form a blocking water flow in the opposite direction to the backflow direction, thereby blocking the backflow.

5. An important plant water system, characterized in that: It comprises a water inlet main pipe (1), a water pump (2), a heat exchanger (14) and a reverse flow stabilizing device (10) according to any one of claims 1 to 4, The water pump (2) is connected to the heat exchanger (14) through the water inlet main pipe (1) and is used to transport cooling water to the heat exchanger (14); The reverse flow stabilizing device (10) is in communication with the water inlet main pipe (1) and is located between the water pump (2) and the heat exchanger (14), and is used to reduce pressure fluctuations in the water inlet main pipe (1).

6. The important plant water system according to claim 5, characterized in that: It also includes a pressure stabilizing branch unit (4), which is in communication with the water inlet main pipe (1) and is located between the water pump (2) and the reverse flow stabilizing device (10); The pressure stabilizing branch unit (4) comprises a pressure stabilizing tank (6), the pressure stabilizing tank (6) being in communication with the water inlet main pipe (1), and the pressure stabilizing tank (6) being used to receive the backflow when a backflow is generated in the water inlet main pipe (1), thereby relieving the pressure fluctuation generated by the backflow.

7. The important plant water system according to claim 6, characterized in that: The pressure stabilizing branch unit (4) further comprises a branch gate valve (5), wherein the branch gate valve (5) is located between the pressure stabilizing tank (6) and the water inlet main pipe (1), and is used to control the connection / disconnection between the pressure stabilizing tank (6) and the water inlet main pipe (1) when there is reverse flow / normal flow in the water inlet main pipe (1).

8. The important plant water system according to claim 5, characterized in that: It also includes a receiving pool (15), the receiving pool (15) is located downstream of the heat exchanger (14) and is connected to the cooling water outlet of the heat exchanger (14), and the receiving pool (15) is used to receive the cooling water after heat exchange; An overflow weir is provided at the upper edge of one side wall of the receiving tank (15), and the cooling water after heat exchange can overflow from the overflow weir.

9. The important plant water system according to claim 8, characterized in that: It also includes an airbag dam (18), which is installed in the overflow weir and can be retracted in the vertical direction. When the airbag dam (18) is extended upward in the vertical direction, it can block the overflow gap, thereby increasing the overflow water level in the receiving pool (15).

10. The important plant water system according to claim 9, characterized in that: Also includes an air pump (16); The air pump (16) is connected to the airbag dam (18) and is used to inflate the airbag dam (18) so that the airbag dam (18) expands and extends upward to block the overflow weir.

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