Dynamic pressure reduction device for liquid-filled containers and method for dynamic pressure reduction for liquid-filled containers

Abstract

This enables the absorption of dynamic pressure fluctuations acting on a liquid-filled container whose static pressure changes when an external vibration load is applied. [Solution] A dynamic pressure reduction device for a liquid-filled container comprising a container for storing liquid, a cylindrical portion extending horizontally in part or over the vertical direction of the container, and a disc-shaped portion closing the end of the cylindrical portion, characterized in that it comprises a variable-volume air chamber near the disc-shaped portion within the cylindrical portion, an intake pipe connecting the air chamber from a position in the upper part of the container where the liquid does not reach, a pump disposed in the intake pipe for pressurizing the air chamber by supplying air, a discharge pipe connecting to the container from a lower position of the air chamber, a valve for closing the discharge pipe, and a control device for controlling the valve and the pump to maintain the volume of the air chamber in a predetermined state.

Description

Technical Field

[0001] The present invention relates to a dynamic pressure reduction device for a liquid-containing container and a method for reducing the dynamic pressure of a liquid-containing container.

Background Art

[0002] When a vibration load is applied to a tank (container) storing a liquid, a dynamic pressure load acts on the tank wall surface, generating stress in the tank. As a device for reducing a similar pressure load, for example, there is a water hammer reduction device for water pipes described in Patent Document 1 and Patent Document 2. Conventional water hammer reduction devices prevent water column vibration in pipes and protect devices such as valves from pressure fluctuations by absorbing dynamic pressure caused by sudden operations such as valves using a gas or rubber having a higher compressibility than the liquid.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, the volume-variable air chamber (bellows) for absorbing dynamic pressure caused by sudden operations such as valves is sealed, and when the static pressure (vapor pressure caused by temperature or hydrostatic pressure caused by water depth) changes greatly, the deformation becomes excessive. In Patent Document 2, it is installed outside.

[0005] There is a need for a tank structure protection and stress reduction method during design for a tank storing a liquid to which a vibration load is applied.

[0006] The object of the present invention is to provide a dynamic pressure reduction device for a liquid-filled container and a dynamic pressure reduction method for a liquid-filled container that can absorb dynamic pressure fluctuations acting on a liquid-filled container whose static pressure changes when an external vibration load is applied. [Means for solving the problem]

[0007] The present invention provides a dynamic pressure reduction device for a liquid-filled container, comprising a container for storing liquid, a cylindrical portion extending horizontally in part or over the vertical direction of the container, and a disc-shaped portion closing the end of the cylindrical portion, wherein the device further comprises a variable-volume air chamber near the disc-shaped portion within the cylindrical portion, an intake pipe connecting the air chamber from a position in the upper part of the container where the liquid does not reach, a pump disposed in the intake pipe for pressurizing the air chamber by supplying air, a discharge pipe connecting to the container from a lower position in the air chamber, a valve for closing the discharge pipe, and a control device for controlling the valve and the pump to maintain the volume of the air chamber in a predetermined state.

[0008] Alternatively, the present invention relates to a method for dynamically reducing the pressure of a liquid-filled container, comprising a container for storing liquid, a cylindrical portion extending horizontally in part or over the vertical direction of the container, and a disc-shaped portion closing the end of the cylindrical portion, characterized in that when an external vibration load acts on the container and the internal pressure or hydrostatic pressure of the container changes, the pressure is adjusted to maintain the volume of a variable-volume air chamber located near the disc-shaped portion within the cylindrical portion at a predetermined volume. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a dynamic pressure reduction device for a liquid-filled container and a dynamic pressure reduction method for a liquid-filled container that can absorb dynamic pressure fluctuations acting on a liquid-filled container whose static pressure changes when a vibration load is applied from the outside.

[0010] Other issues, configurations, and effects not mentioned above will be clarified by the following description of the embodiments. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram of the dynamic pressure reduction device for a liquid-filled container according to Example 1. [Figure 2] This is an enlarged view of the dynamic pressure reduction device configuration according to Example 1. [Figure 3] This is a schematic diagram of the dynamic pressure reduction device for a liquid-filled container according to Example 4. [Figure 4] This is an enlarged view of the dynamic pressure reduction device configuration according to Example 4. [Modes for carrying out the invention]

[0012] This embodiment focuses on a dynamic pressure reduction device installed on the end plate of a container that stores liquids ranging from room temperature and negative pressure to high temperature and high pressure. When the container is filled with liquid up to a level where the end plate is completely below the liquid surface, and an acceleration load due to an earthquake is applied, dynamic pressure may act on the end plate. In particular, this embodiment assumes a container in which a cylindrical structure is horizontally connected to the main part of the container, and the end of this structure is closed off by an end plate. In a container of this shape, the horizontally connected part resembles a tube, and dynamic pressure may act on the end plate during an earthquake. A device that reduces this dynamic pressure contributes to improving the seismic resistance performance of the container.

[0013] One possible structure to reduce the dynamic pressure acting on a liquid-filled end plate is to set up a variable-volume air chamber near the end plate, containing a fluid with a higher compressibility than the liquid inside, so that the dynamic pressure is absorbed by the deformation of the variable-volume air chamber. This is because, when dynamic pressure acts, the highly compressible part deforms first, and a pressure exceeding the pressure inside the highly compressible air chamber cannot act on the end plate. In addition, in the case of alternating dynamic pressure, if the time it takes for the acceleration to alternate is faster than the time it takes to compress the air chamber to the same pressure as the dynamic pressure acting without the dynamic pressure reduction device, the maximum value of the dynamic pressure can be reduced by the effect of the dynamic pressure reduction device.

[0014] However, since the internal pressure and temperature of the container targeted in this embodiment change from a normal temperature negative pressure state to a high temperature high pressure state, it is desirable to make the pressure of the variable-volume air chamber follow the changes in the static pressure (water vapor pressure and hydrostatic pressure) of the target container. For this purpose, an intake pipe equipped with an intake pump and valve, with an intake port that opens before the liquid level at the top of the container reaches it, and a discharge pipe with the other end open near the end plate and equipped with a valve are connected to the variable-volume air chamber. When an earthquake is detected or an earthquake early warning is received, these valves and pump close to absorb the dynamic pressure. When no earthquake is detected, and the pressure or liquid level of the container changes, the valves open and the pump starts, filling the variable-volume air chamber with gas at the same internal pressure + hydrostatic pressure as the inside of the container.

[0015] According to this embodiment, compared to conventional containers, even when external vibrations (e.g., seismic motion) act on the end plates while they are submerged below the water surface, high stress is not generated at the joints of the end plates, thereby improving the seismic resistance of the container.

[0016] An embodiment of the dynamic pressure reduction device for liquid storage containers of the present invention will be described below with reference to the drawings. Note that the analysis methods, set values, and other specific configurations shown in this embodiment are not limited to the embodiments and examples presented here, and can be appropriately combined or improved without altering the gist of the invention. Furthermore, elements not directly related to the present invention are omitted from the drawings. In addition, in the drawings used herein, identical or corresponding components are denoted by the same or similar reference numerals, and repeated explanations of these components may be omitted. [Examples]

[0017] Figure 1 is a schematic diagram of the dynamic pressure reduction device for a liquid-filled container according to Example 1. Figure 2 is an enlarged view of the dynamic pressure reduction device configuration according to Example 1. In this embodiment, the case in which the dynamic pressure reduction device 1 is applied to the reactor body foundation 2 will be described. Note that the dynamic pressure reduction device 1 is not limited to the reactor body foundation 2, but can be applied to other devices and systems as well.

[0018] The liquid-containing container includes a reactor vessel foundation 2 that stores liquid, an access tunnel 3 that is a cylindrical portion extending horizontally in part or in whole in the vertical direction of the reactor vessel foundation 2, and a head plate 4 that is a plate-like portion closing the end of the access tunnel 3.

[0019] An access tunnel 3 extending horizontally in part or in whole in the vertical direction is provided in the reactor vessel foundation 2. Normally, the access tunnel 3 is in the air, and equipment and personnel pass through it for maintenance. However, assuming all situations, the access tunnel 3 may be submerged underwater. At this time, the head plate 4 of the access tunnel 3 is also located below the water surface 5, and when seismic acceleration acts in this state, dynamic pressure may act on the head plate 4 of the access tunnel 3. For example, it is the vibration in the X direction and X' direction shown in FIG. 1 etc. In the normal state, there is air 6 inside, and when designing assuming that there is water 7 inside for a structure where the possibility of dynamic pressure acting is small, demerits due to weight increase also occur.

[0020] In the seismic evaluation assuming that there is water 7 inside, one of the factors for the large stress generated in the head plate 4 of the access tunnel 3 is considered as follows. The access tunnel 3 is regarded as a pipe, and the seismic evaluation is carried out in a state where the mass of the water existing in the access tunnel 3 is added as a dead weight to the head plate 4 of the access tunnel 3. On the other hand, in order to accurately estimate the pressure actually acting on the head plate 4 of the access tunnel 3 by applying fluid-structure coupled analysis etc. and perform seismic evaluation, it is necessary to construct a seismic evaluation method based on analysis, and there are many problems to be solved.

[0021] To solve such problems, the dynamic pressure reduction device 1 in this embodiment installs a variable-volume air chamber 8 near the thrust bearing 4 in the access tunnel 3 in order to reduce the added mass considered in the seismic evaluation as a dead weight. Then, the structure is changed so that air 6, which is a fluid with a high compressibility, abuts against the thrust bearing 4 of the access tunnel 3. By reducing the load generated by the dynamic pressure, the dead weight is reduced according to the ratio of the area where the variable-volume air chamber 8 is installed, thereby improving the seismic performance.

[0022] The thrust bearing 4 is, for example, a plate having a shape such as a semi-circular or elliptical shape that closes the end of a cylindrical pressure vessel such as a high-pressure gas tank or nuclear reactor equipment.

[0023] As shown in FIGS. 1 and 2, the variable-volume air chamber 8 is configured using, for example, a U bellows. In this embodiment, in the inner chamber 81 of the access tunnel, two air chambers 8 are arranged on the inner surface of the thrust bearing 4. Air 6 is individually sucked into the air chamber 8 from the intake pipe 11. An example of flowing a fluid in parallel through a plurality of air chambers 8 is shown.

[0024] The intake pipe 11 connects the air chamber 8 from a position where liquid does not reach at the upper part of the container. In the intake pipe 11, a valve 9I and a pump 12 for pumping and pressurizing air into the air chamber 8 are arranged in the path from the intake port 11A to the air chamber 8. By these intake systems, air can flow into the air chamber 8.

[0025] Also, a discharge pipe 10 is installed at a lower position of the air chamber 8 to discharge the fluid in the air chamber 8. A valve 9E is installed in the discharge pipe 10. By these exhaust systems, air can be discharged from the air chamber 8.

[0026] Valve 9 is preferably a type that can be completely closed and opened and closed with low power, such as a globe valve. Both valves are fixed to the end plates 4 of the access tunnel 3, and a flexible hose 10A is extended below the air chamber 8 as needed to adjust the position of the intake port 10B of the discharge pipe 10 to preferentially discharge the liquid. The intake pipe 11 is installed so that the discharge port 11B is located on the end face on the end plate side, eliminating the influence of the intake pipe 11 on volume changes in the variable-volume air chamber 8. The intake pipe 11 is made of a rigid pipe such as a steel pipe and is piped so that the intake port 11A is always above the water surface. The pump 12 is preferably a screw compressor or a scroll compressor.

[0027] A water detection sensor 14, such as a water level gauge, is installed in the variable-volume air chamber 8 to detect water ingress, and a displacement gauge 15 is installed to measure the position of the free end 8A to detect the volume of the air chamber. The containment vessel water level gauge 16 determines the state of submersion of the access tunnel 3. In standby mode, the valve 9I installed in the intake pipe 11 is open. When the displacement gauge 15 detects the compression displacement of the free end 8A, the dynamic pressure reduction device 1 begins to function. If there is no water ingress in the air chamber 8, the valve 9E installed in the discharge pipe 10 is closed and the pump 12 is started to pressurize the variable-volume air chamber 8 so that the position of the free end 8A maintains its initial position.

[0028] When the water detection sensor 14 detects that the internal water level has risen, valve 9E is opened and the pump 12 is activated to discharge the water with the discharge pipe 10 connected to the check valve. At this time, all valves 9 are open, and the fluid flows in the following order: intake pipe 11, pump 12, air chamber 8, check valve, and discharge pipe 10. Once the drainage of the air chamber 8 is complete, valve 9E on the discharge pipe 10 is closed.

[0029] Once the free end 8A reaches its initial position, the valve 9I installed in the intake pipe 11 is closed to seal the air chamber 8.

[0030] When the water level in the containment vessel drops and an expansion displacement of the free end 8A is detected, the valve 9E is opened to depressurize the variable-volume air chamber 8 so that the position of the free end 8A maintains its initial position.

[0031] In addition, in this embodiment, a gas generator device 12B that generates gas such as carbon dioxide by a chemical reaction is installed in all of the air chambers 8, thereby ensuring redundancy by maintaining the internal pressure of the air chambers 8 in the event of a pump failure 12.

[0032] The dynamic pressure reduction device 1 includes a control device 17 that sets a threshold value that takes into account a margin for determining whether to pressurize or depressurize from a sealed state, and performs appropriate control to prevent repeated pressurization and depressurization, controlling the valve 9, pump 12, and device 12B. The control device 17 controls the valve 9 and pump 12 to maintain the volume of the air chamber 8 in a predetermined state. In this embodiment, the predetermined state is the initial state in which the end plate 4 is not submerged below the water surface, no external vibrations (e.g., seismic motion) act on it, and there is no change in the internal pressure of the tank.

[0033] Once the water level in the reactor body foundation 2 has dropped sufficiently, valve 9I is opened, and the dynamic pressure reduction device 1 ceases its function.

[0034] Furthermore, the variable-volume air chamber 8 maintains a predetermined volume in a static state regardless of the internal pressure of the tank, and is configured so that its volume changes when a vibration load is applied to the tank and the connected piping is closed by a valve.

[0035] When an external vibration load acts on the reactor body foundation 2, causing a change in the internal pressure or hydrostatic pressure of the reactor body foundation 2, the seismic performance is improved by adjusting the pressure to maintain the volume of the variable-volume air chamber 8, located near the end plate 4 in the access tunnel 3, at its initial volume. The pressure adjustment is performed, for example, by controlling a pump that pressurizes the air chamber 8 by supplying air to it, and a valve that opens and closes the exhaust system that discharges air from the air chamber 8, in order to maintain the volume of the air chamber 8 at its initial state.

[0036] According to this embodiment, even when external vibrations (e.g., seismic motion) act on the end plate 4 while it is submerged below the water surface, high stress is not generated at the joint of the end plate 4, thereby improving the seismic performance of the container. Dynamic pressure (load) changes can be suppressed by the volume change of the variable-volume air chamber 8. In this way, when an external vibration load acts, the air chamber 8 deforms in advance before pressure is applied to the end plate-shaped portion and changes, thereby preventing high stress from being generated at the joint of the end plate 4 and improving the seismic performance of the container. [Examples]

[0037] In this embodiment, one or more of the variable-volume air chambers 8 are configured as a piston-cylinder type, and this piston is driven by a linear actuator to also function as a pump 12. Furthermore, some or all of the variable-volume air chambers 8 can be installed not directly on the end plate 4, but on a more robust outer wall or internal structure of the tunnel. When the free end side 8A of an air chamber other than the one used as a pump reaches its initial position, the gas generating device 12B, which was installed in Embodiment 1 to ensure redundancy, is used to pressurize the air chamber 8 so that the free end side 8A also reaches its initial position. The diagram is omitted as it is the same as Embodiment 1 except that the pump 12 also serves as one of the air chambers 8.

[0038] By driving the air chamber 8 with a piston-cylinder type linear actuator, it can function as a pump, which reduces the number of parts. [Examples]

[0039] In this embodiment, the variable-volume air chamber 8 of Example 1 functions as a dynamic vibration absorber. The spring constant of the bellows is adjusted, and the mass of the free end 8A is adjusted to bring the natural frequency of the air chamber 8 to be close to the natural frequency of, for example, the out-of-plane vibration mode of the end plate 4 in the submerged state, within the range of 80% to 120%. This makes the air chamber 8 function as a dynamic vibration absorber. The optimal spring constant and mass can be determined experimentally, but other methods such as fluid-structure interaction analysis can also be used. If there are multiple modes, if there are constraints on the installation location, or if the natural frequencies are unclear, variations in the natural frequencies of multiple air chambers 8 can be provided.

[0040] According to this embodiment, by bringing the natural frequency of, for example, the out-of-plane vibration mode of the end plate 4 in a submerged state to a range of 80% to 120% of the natural frequency of the air chamber 8, the air chamber 8 can be made to function as a dynamic vibration absorber. [Examples]

[0041] Example 1 shows an example where fluid is flowed in parallel through multiple air chambers 8, but it is also possible to pump the fluid in series through multiple air chambers 8.

[0042] Figure 3 is a schematic diagram of the dynamic pressure reduction device for a liquid-filled container according to Example 4. Figure 4 is an enlarged view of the dynamic pressure reduction device configuration according to Example 4.

[0043] The exhaust pipe 10 of air chamber 8 is connected to air chamber 8. The two air chambers 8 are connected in series by the intake and exhaust systems. Air 6 is supplied to the upper air chamber 8 via the intake pipe 11, valve 9I, and pump 12. Air is discharged to the exhaust pipe 10 from hose 10A inside the upper air chamber 8. A valve 9E is provided in the exhaust pipe 10 and is connected to the lower air chamber 8, supplying air to the lower air chamber 8. Piping and valve 9E are installed to discharge air from the lower air chamber 8.

[0044] In this embodiment, the intake and exhaust systems for the two air chambers 8 are combined into one, thus simplifying the mechanisms of the intake and exhaust systems.

[0045] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are included. The embodiments described above are explained in detail to make the present invention easier to understand, and are not necessarily limited to those having all the configurations described. Furthermore, it is possible to replace parts of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add configurations from other embodiments to the configuration of one embodiment. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment with other configurations.

[0046] For example, it is possible to use a piston-cylinder type pump instead of a screw compressor. [Explanation of Symbols]

[0047] 1...Dynamic pressure reduction device, 2...Reactor body foundation, 3...Access tunnel, 4...End plate, 5...Water surface, 6...Air, 7...Water, 8...Air chamber, 81...Inside chamber of access tunnel, 8A...Free end side, 9...Valve, 9I...Intake valve, 9E...Discharge valve, 10...Discharge pipe, 10A...Hose, 10B...Intake port, 11...Intake pipe, 11A...Intake port, 11B...Discharge port, 12...Pump, 14...Water detection sensor, 17...Control device.

Claims

1. A container for storing liquid, A cylindrical portion extending horizontally in part or in whole in the vertical direction of the container, A dynamic pressure reduction device for a liquid-filled container, comprising a disc-shaped portion that closes the end of the cylindrical portion, A variable-volume air chamber is provided near the end plate-shaped portion within the cylindrical portion, An intake pipe connecting the air chamber from a position at the top of the container where the liquid does not reach, A pump is placed in the intake pipe and pressurizes the air chamber by supplying air under pressure, A discharge pipe connecting to the container from a lower position in the air chamber, A valve for closing the aforementioned discharge pipe, A dynamic pressure reduction device for a liquid-filled container, characterized by comprising a control device that controls the valve and the pump to maintain the volume of the air chamber in a predetermined state.

2. In the dynamic pressure reduction device for a liquid-filled container according to claim 1, A dynamic pressure reduction device for a liquid-filled container, characterized in that the control device controls the valve and the pump to maintain the volume of the air chamber in an initial state.

3. In the dynamic pressure reduction device for a liquid-filled container according to claim 1, A dynamic pressure reduction device for a liquid-filled container, characterized in that the air chamber deforms before the end plate-shaped portion when an external vibration load is applied to the container.

4. In the dynamic pressure reduction device for a liquid-filled container according to claim 1, A dynamic pressure reduction device for a liquid-filled container, characterized by having a plurality of air chambers, at least one of which has a pump function.

5. In the dynamic pressure reduction device for a liquid-filled container according to claim 1, A dynamic pressure reduction device for a liquid-filled container, characterized in that the air chamber is equipped with a gas generator for pressurizing the air chamber.

6. In the dynamic pressure reduction device for a liquid-filled container according to claim 1, A dynamic pressure reduction device for a liquid-filled container, characterized in that the natural frequency of the air chamber is 80 to 120% of the natural frequency of the end-plate-shaped portion.

7. A container for storing liquid, A cylindrical portion extending horizontally in part or in whole in the vertical direction of the container, A method for dynamically reducing the pressure of a liquid-filled container, comprising a cylindrical portion and a disc-shaped portion that closes the end of the cylindrical portion, A method for reducing the dynamic pressure of a liquid-filled container, characterized by adjusting the pressure to maintain the volume of a variable-volume air chamber located near the end plate-shaped portion within the cylindrical portion at a predetermined volume when an external vibration load acts on the container and the internal pressure or hydrostatic pressure of the container changes.

8. In the method for reducing the dynamic pressure of a liquid-filled container according to claim 7, A method for dynamically reducing the pressure of a liquid-filled container, characterized by controlling a pump that pressurizes the air chamber by supplying air to it, and a valve that opens and closes a discharge system that discharges air from the air chamber, in order to maintain the volume of the air chamber in its initial state.

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