JPH02242778A - Liquid surface splashing preventive apparatus - Google Patents

Abstract

PURPOSE:To make controllable the splashing of the surface of a liquid due to the sloshing and revolving motion of the liquid at any liquid level by providing a hollow cylindrical inner body wherein a plurality of holes is so arranged as to be always located near the surface of the liquid concentrically with the outer body of a tank and in such manner that the upper part of the inner body projects beyond the liquid surface. CONSTITUTION:A cylindrical vertical liquid storage tank is provided in its interior with a hollow cylindrical inner body 3 concentric with an outer body 2 of the tank and projecting beyond the liquid surface 4. A plurality of holes 5 formed in the side wall of the inner body 3 is so arranged as to be always located near the liquid surface 4 within such variable range of the liquid levels as may pose sloshing problems. Since the inner body 3 separates the diameter of the liquid surface 4 in the aforesaid tank, the liquid in the interior 6 of the inner body and that in the exterior 7 thereof can have the different natural periods of the sloshing by setting the diameter of the inner body 3 appropriately. This device, upon resonating with a seismic tremor, can make the resonance phenomenon avoidable and prevent the splashing of the liquid surface.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the prevention of sloshing in cylindrical vertical liquid storage tanks.

(Prior Art) As described in Japanese Unexamined Patent Publication No. 63-22385, a conventional device has a hollow truncated conical inner body inside one cylindrical vertical liquid storage tank, and a plurality of hollow truncated conical inner bodies are provided in the lower part of the inner body. It was equipped with a liquid communication port.

(The problem to be solved by the invention) The sloshing phenomenon occurs when the liquid in a liquid storage tank is subjected to an external force due to an earthquake, and the dominant period of the earthquake's displacement wave and the natural period of the liquid's sloshing resonate, causing the liquid level to shake violently. When the liquid storage tank is a cylindrical vertical type, the relationship between the sloshing natural period T, the diameter of the liquid surface, and the sum H of the height to the liquid surface and the wave height is expressed by the following formula. There is a relationship like that.

T18CD/H In the conventional technology described above, the effect on preventing sloshing of the 1-truncated conical inner shell is that when sloshing occurs due to resonance with seismic motion, the liquid inside the 1-truncated conical inner shell increases as the wave height increases. The diameter of T becomes smaller, and therefore the sloshing natural period T becomes smaller according to the above equation, and can deviate from the resonant period.
If the inclination of the generatrix of the truncated conical inner shell is close to vertical, the above effect cannot be expected. - For example, a cylindrical vertical storage tank with a bottom diameter of 40 m and a liquid level of 20 m may reach a liquid level of 25 m due to sloshing. We will discuss the relationship between the change in the natural sloshing period of the liquid inside the truncated conical inner shell and the inclination of the generatrix of the truncated conical inner shell when the wave height increases. When the liquid level changes from 20 m to 25 m, the angles made by the generatrix of the truncated conical inner shell with the horizontal are sequentially 76', 73°, 63°, and 58".
time.

The sloshing natural period is sequentially from 5.8 seconds to 5.5 seconds,
5.2 seconds to 4.8 seconds, 4.7 seconds to 4.1 seconds.

It becomes 3.1 seconds from 4.1 seconds. In this way, even when the liquid level rises several meters due to sloshing.

In order to shift the sloshing natural period by more than 1 second, the slope of the generatrix of the truncated conical inner shell must be made quite gentle.
If there are restrictions on the diameter or height of a cylindrical vertical storage tank, the conventional structure cannot be expected to have much of an effect on preventing sloshing, or if the predominant period of seismic motion is gradual or band-like. If this happens, the liquid level will eventually be allowed to fluctuate.

Also, regarding the communication port provided below the truncated conical inner body, the natural period below the liquid in the storage tank is:

This is because it is longer than the natural period of the liquid level fluctuation near the liquid level.

The liquid inside and outside the truncated conical inner body passes through the communication port more slowly than the fluctuation of the liquid level, and a damping effect corresponding to each phase of the fluctuation of the liquid level cannot be expected.

Further, there is no effect of suppressing liquid level fluctuation when a traveling mode in which liquid moves in the circumferential direction of the cylindrical vertical liquid storage tank occurs.

In addition, as the liquid outside the truncated conical inner body undergoes sloshing and the liquid level rises, the diameter of the liquid surface increases, so there is no significant change in the natural period of sloshing, and fluctuations in the liquid level are suppressed. Hateful.

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid level fluctuation prevention device that suppresses liquid level disturbance due to liquid sloshing and traveling movement, regardless of the liquid level, in a single cylindrical vertical liquid storage tank.

[Means to solve the problem]

In order to achieve the above purpose, a hollow cylindrical liquid storage tank with a hole distribution that always has a plurality of holes located near the liquid level at least in the range of fluctuation of the liquid level where sloshing becomes a problem is installed inside the vertical cylindrical liquid storage tank. The inner shell is concentric with the storage tank side shell, and
By arranging the top of the cylindrical inner shell to be above the liquid level, a flow path for the liquid inside and outside the cylindrical inner shell is ensured no matter the liquid level.

Furthermore, a plurality of support plates are provided inside the cylindrical vertical liquid storage tank in the circumferential direction of the liquid storage tank inner wall, extending vertically inward from the storage tank inner wall and supporting the cylindrical inner body along its generatrix. , which suppresses the movement of the liquid in the storage tank in the travel mode.

[Effect]

If a hollow cylindrical inner shell is installed inside the cylindrical vertical liquid storage tank concentrically with the tank side shell, and with the top of the cylindrical inner shell protruding above the liquid level, the cylindrical inner shell will By appropriately setting the diameter of the cylindrical inner shell to divide the diameter, the liquid inside the cylindrical inner shell and the liquid outside the cylindrical inner shell will have different natural sloshing periods. If the sloshing natural period without the cylindrical inner shell resonates with the predominant period of the earthquake, if a cylindrical inner shell is provided, the liquid inside the cylindrical inner shell and the liquid outside the inner shell will be Since the diameter of the surface becomes smaller, the natural period of sloshing becomes shorter when there is no cylindrical inner shell, and can be shifted from the resonance period, thereby suppressing fluctuation of the liquid level.

The multiple holes provided in the cylindrical inner shell always exist near the liquid level, at least in the range of liquid level fluctuations where sloshing becomes a problem, and the holes prevent the flow of liquid inside and outside the cylindrical inner shell. When the sloshing natural period of the liquid inside the cylindrical inner shell and the liquid outside the cylinder interfere with each other, causing earthquakes and resonance phenomena by disturbing the sloshing natural period. , it is possible to avoid resonance and prevent liquid level fluctuation.

Further, under normal conditions, the hole serves as a flow path, and the liquid levels of the liquid inside and outside the cylindrical inner shell can be kept constant.

Further, vibration of the liquid can be reduced due to fluid friction that occurs when the fluid passes through the hole.

Furthermore, as a method of supporting the cylindrical inner shell, a plurality of support plates are provided in the circumferential direction of the inner wall of the storage tank, extending vertically inward from the inner wall of the storage tank and supporting the cylindrical inner shell along the generatrix. Since the support plates are arranged radially from the vertical center line of the single cylindrical vertical liquid storage tank, it is possible to suppress the traveling mode of the liquid in the circumferential direction and to suppress disturbance of the liquid level.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows a perspective view of a cylindrical vertical liquid storage tank.

FIG. 2 shows a horizontal sectional view of FIG. 1. Inside the cylindrical vertical liquid storage tank consisting of a bottom 1 and a side body 2, there is a hollow cylindrical inner body 3 concentrically with the storage tank side JIM 2, with the top at the liquid level. A plurality of holes 5 are provided in the side surface of the cylindrical inner body 3.The holes 5 are provided so as to protrude above the cylindrical inner body 3. It is provided so as to exist near the liquid level 4. The hole 5 may be of a vertically long slit type as shown in the figure. 0 Since the cylindrical inner shell 3 divides the diameter of the liquid surface 4 of the cylindrical vertical liquid storage tank 1. The liquid inside the cylindrical inner shell 6 and the outside By appropriately setting the diameter of the cylindrical inner shell 3, the liquid No. 7 can have different sloshing natural periods. The liquid on the inside 6 and the liquid on the outside 7 of the inner shell 3 were able to pass through each other, and their sloshing natural periods near the liquid level 4 interfered, disturbing the sloshing natural period and causing resonance with vibrations caused by the earthquake. At times, resonance phenomena can be avoided and liquid level fluctuations can be prevented. Furthermore, a damping effect due to fluid friction when the liquid passes through the hole 5 can be expected.

FIG. 3 shows a perspective view of a cylindrical vertical storage tank according to another embodiment, and FIG. 4 shows a top view of FIG. 3. Inside a cylindrical vertical liquid storage tank consisting of a bottom 1 and a side shell 2, a hollow cylindrical inner shell 3 is provided concentrically with the storage tank side shell 2 so that the top thereof is above the liquid level 4. A plurality of longitudinally penetrating slits 8 are provided on the side surface of the cylindrical inner shell 3.
divides the diameter of the liquid surface 4 of the cylindrical vertical liquid storage tank, so the liquid on the inside 6 and the liquid on the outside 7 of the cylindrical inner shell 3 can be divided into two parts by appropriately setting the diameter of the cylindrical inner shell 3. They will have different sloshing natural periods.

This through-type slit 8 is used as a flow path, and the inner side 6 of the cylindrical inner body
The liquid in the outside 7 can pass through each other, and their sloshing natural periods near the liquid level 4 interfere with each other, disturbing the sloshing natural period, and when resonating with vibrations caused by an earthquake, avoid the resonance period, Fluctuation of the liquid level 4 can be prevented. Furthermore, a damping effect due to fluid friction when the liquid passes through the slit can be expected.

FIG. 5 shows a slope view of another embodiment, and FIG. 6 shows a top view of FIG. A plurality of holes 9 are provided in the side surface of the cylindrical inner body 3, which is arranged concentrically with the storage tank side body 2 and with its top protruding above the liquid level 4. .

The cylindrical inner shell 3 is vertically supported on its generatrix from the inner wall of the side m2 by a support plate 10 extending vertically inward of the storage tank. Since the shell 3 divides the diameter of the liquid surface 4 of the cylindrical vertical liquid storage tank, the liquid in the cylindrical inner IM6 and the liquid on the outer side 7 can have different sloshing by appropriately setting the diameter of the cylindrical inner shell 3. It will have a natural period.

According to this embodiment, a plurality of holes 9 provided on the side surface of the cylindrical inner shell 3 are used as flow paths, and the liquid on the inside 6 and the outer side 7 of the cylindrical inner shell 3 can mutually pass through each other. If the sloshing natural periods of
0 which can avoid the natural period and prevent fluctuation of the liquid level.
The bottom of the cylindrical inner shell 3 is not only welded to the bottom 1 of the liquid storage tank.

Since it is supported by the support plate 10 extending perpendicularly inward from the inner wall of the storage tank side M2, the cylindrical inner shell 3 can be prevented from wobbling in the horizontal direction. In addition, if the bottom of the cylindrical inner shell 3 cannot be welded because the bottom of the storage tank is not flat or there are obstacles, or if the range of fluctuation of the liquid level is limited and only that range is used. The support plate 10 is used when arranging the inner cylinder.
By using this, it is possible to support the cylindrical inner shell 3 in a state where it is floating above the bottom of the storage tank. Since the support plate 10 is arranged radially from the vertical center line of the cylindrical vertical liquid storage tank, it has the effect of suppressing the movement of the liquid and preventing disturbance of the liquid level when the liquid travels in the circumferential direction. There is.

〔Effect of the invention〕

According to the present invention, by providing a cylindrical inner shell having a hole inside a cylindrical vertical liquid storage tank, liquids having different natural sloshing periods on the inside and outside of the cylindrical inner shell are made to interfere with each other, thereby changing the natural sloshing period. This has the effect of suppressing fluctuations in the liquid level.

The shape of the hole may be vertically elongated, or it may be a slit that passes through the inner cylinder.

In addition, a damping effect due to fluid friction occurs when the liquid passes through the holes, and it can be expected to have the effect of preventing fluctuations in the liquid level.

Further, by providing a support plate extending perpendicularly inward from the storage tank inner wall, there is an effect of suppressing the traveling mode of the liquid in the storage tank in the inner circumferential direction and preventing fluctuation of the liquid level.

[Brief explanation of drawings]

FIG. 1 is a perspective view of one embodiment of the present invention, FIG. 2 is a horizontal sectional view of FIG. 1, FIG. 3 is a perspective view of another embodiment, and FIG. 4 is a top view of FIG. FIG. 5 is a diagram showing another embodiment, and FIG. 6 is a top view of FIG. 5. DESCRIPTION OF SYMBOLS 1... Storage tank bottom, 2... Storage tank side shell, 3... Cylindrical inner shell, 4... Liquid level, 5... Hole, 6... Inside of cylindrical inner shell, 7...・Cylindrical inner barrel outer, 8...slit, 9
...hole, 10...inconsistency l Figure 3 Figure ¥, 2 Figure 4 Figure 3 Slit

Claims (1)

[Claims] 1. In a cylindrical vertical liquid storage tank, a hollow cylindrical inner body with a hole distribution such that a plurality of holes are always located near the liquid level at least within a range of fluctuations in liquid level height inside the storage tank. A liquid level fluctuation prevention device for a cylindrical vertical liquid storage tank, characterized in that a cylindrical inner body is provided concentrically with the side body of the storage tank, and the top of the cylindrical inner body protrudes above the liquid level. 2. In claim 1, the method for supporting the cylindrical inner body includes extending vertically inward from the inner wall of the storage tank;
A liquid level fluctuation prevention device for a cylindrical vertical liquid storage tank, characterized in that a plurality of support plates are provided in the circumferential direction to support the cylindrical inner body along the generatrix.