JP2005247353A - Sloshing preventive structure of large tank - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sloshing preventive structure of a large tank capable of suppressing the cost and the construction period by changing big sloshing waves of a long period into small sloshing waves of a short period by necessary and sufficient partitions. <P>SOLUTION: A large partition plate 3 which divides the inside of a tank in plan view and has the depth of ≥ 0.3 time the tank diameter or the tank width from the highest liquid level but does not reach a tank bottom plate 1 is provided inside the large tank to store liquid. A small partition plate 4 which further divides the portions partitioned by the large partition plate 3 in plan view and has the depth of ≥0.3 time the spacing of the portions partitioned by the large partition plate 3 from the highest liquid level but does not reach the tank bottom plate 1 is provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an anti-sloshing structure for preventing a large tank such as an oil tank from being damaged by a long-frequency earthquake motion or the like.

  When a large tank such as an oil tank vibrates due to an earthquake motion containing a lot of long frequency components, a liquid such as a built-in crude oil resonates, and a large long frequency wave is generated. Such a phenomenon is called sloshing. In large tanks, the magnitude of waves due to sloshing may exceed 3 m, and some of the crude oil may cross the tank side wall due to the large long-frequency waves, or the tank side wall may be damaged due to the impact force of the large waves. The crude oil may leak out of the tank. In addition, the floating roof that is installed above the crude oil collides with the side wall of the tank, causing sparks and a major problem for disaster prevention.

Conventionally, large tanks with a diameter exceeding 40 m have been considered as earthquake-resistant structures for the following reasons.
(1) Large tanks with a diameter of more than 40 m have a sloshing cycle exceeding 6 seconds, so it was thought that there was no seismic motion containing many such long frequency components.
(2) The duration of the earthquake motion is about 60 seconds at the longest, and even if a long-frequency component that matches the sloshing period is included in the earthquake motion, the earthquake motion has a long duration so that a large wave is generated by the sloshing Was thought not to occur.

  However, as a result of recent observations and researches, it has been found that, depending on the geological conditions of the site, seismic motion that includes many long-frequency components and has a duration exceeding 240 seconds occurs. The cause of a large tank fire due to a large earthquake is thought to be a long-period seismic motion with a long period.

Therefore, it is necessary to prevent a sloshing phenomenon with a long cycle from occurring in a large tank. It is known that the sloshing period is proportional to the tank diameter (or width) and is generally calculated with high accuracy by 0.1 × √ (D) (D: tank diameter or width). From this, it can be considered that a partition plate is arranged in the tank and a small tank is gathered in order to eliminate a large sloshing wave in a long cycle. And there exists a structure which has arrange | positioned the partition plate to the whole depth of a tank (for example, refer patent document 1).
Japanese Patent Laid-Open No. 10-110773 (paragraph 0024, FIGS. 3 and 4)

  However, for example, in a large tank having a diameter of 40 m or more and a height of 30 m or more, if a partition plate is arranged over the entire depth thereof, the installation amount of the partition plate becomes large, and the cost and construction period are too large to be practical. Moreover, it is necessary to join the partition plate to the tank by welding, and since the welding amount is large, the tank is greatly deformed by welding heat, and there is a problem that it is difficult to repair the tank.

  An object of the present invention is to reduce cost and construction time in a large tank so that a large sloshing wave at a long frequency can be replaced with a small sloshing wave at a short period by a necessary and sufficient partition plate.

In general, when the tank is vibrated, the liquid in the tank is divided into a layer of free water that causes sloshing at the top of the tank and a layer of fixed water that moves in the same manner as the tank body at the bottom of the tank, as shown in FIG. Divided. Here, it is known that the free water layer is 0.3 × D (D: tank diameter or width) from the upper surface of the liquid.
Therefore, if the partition plate has a depth that reaches the fixed water at a depth of 0.3 × D or more from the upper surface of the liquid, the liquid deeper than that is It has been found that it can vibrate integrally and does not affect sloshing, that is, it can exhibit the same effect as the case where a partition plate is arranged over the entire depth of the tank.

  In order to solve the above-described problem, the invention described in claim 1 is, for example, as shown in FIG. 2, the inside of the tank is divided into a large tank for storing the liquid in a plan view, and the tank is separated from the highest liquid level. A partition plate 3 that does not reach the tank bottom plate 1 at a depth of 0.3 times the diameter or the tank width is provided.

According to the first aspect of the present invention, the partition plate is divided into, for example, three parts in plan view, and does not reach the tank bottom plate at a depth of 0.3 times the tank diameter or the tank width from the highest liquid level. When the is placed, the sloshing period is shortened to 1 / √3, the amount of free water is reduced to 1/3, and the impact force of the sloshing wave can be remarkably reduced as compared with the case without the partition plate.
That is, if an appropriate number of partition plates are installed in a large tank, the sloshing cycle can be shortened and the wave motion can be reduced. However, if the partition plate of the present invention is used, the same effect can be realized with a small amount of partition plates. As a result, the cost and construction period for additionally installing the partition plate in the large tank can be greatly reduced, and the practical effect is very large.

  The invention according to claim 2 is the structure for preventing sloshing of the large tank according to claim 1, for example, as shown in FIG. 3, further dividing the portion partitioned by the partition plate 3 in plan view, In addition, a small partition plate 4 that does not reach the tank bottom plate 1 at a depth of 0.3 times or more the interval between the portions partitioned by the partition plate 3 from the highest liquid level is provided.

  According to the second aspect of the present invention, the portion partitioned by the partition plate is further divided into, for example, two parts in plan view, and the depth is 0.3 times or more the interval between the portions partitioned by the partition plate from the highest liquid level. If a small partition plate that does not reach the tank bottom plate is added, the sloshing cycle is shorter to 1 / √ (3 × 2) = 1 / √6 and the amount of free water is 1 / √6 compared to the case without the partition plate. The impact force of the sloshing wave can be further reduced.

According to the present invention, the following effects can be obtained.
(1) The sloshing cycle can be shortened and the sloshing wave can be reduced, as in the case of the partition plate that partitions the entire depth of the tank, and the safety during an earthquake can be greatly improved.
(2) The installation amount of the partition plate can be reduced to half or less of the installation amount of the conventional partition plate, and the installation cost and construction period can be significantly reduced.
(3) Since the partition plate is significantly shorter in depth than the conventional partition plate and is not joined to the tank bottom plate, the welding amount with the tank can be remarkably reduced to about ½ compared to the conventional case. As a result, the flow of welding heat into the tank is reduced, so that deformation due to the welding heat of the tank is greatly reduced, and the repair cost of the existing tank can be greatly reduced.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.
In the present invention, by disposing an appropriate number of partition plates in the large tank at a depth that reaches the fixed water, a large sloshing wave in the long cycle of the large tank is replaced with a small sloshing wave in the short cycle. Intended. To achieve this, the depth of the partition plate reaches fixed water at a depth of 0.3D (D: tank diameter or width) or more from the maximum liquid level of the liquid contained in the tank, and reaches the bottom of the tank. Do not have depth. In practice, it is recommended that the partition plate has a depth of 0.4D or more in view of safety.

FIG. 1 is an explanatory view of free water and fixed water having different properties with respect to the vibration of the liquid in the tank. 1A and 1B, 1 is a tank bottom plate, 2 is a tank outer plate, W1 is fixed water, W2 is free water, and D1 is a tank diameter or width.
As illustrated, the depth of the free water W2 is 0.3D1 from the highest liquid level.

FIG. 2 is an explanatory view of a change in the amount of free water when the partition plate is arranged so that the inside of the tank of FIG. 2 (a) and 2 (b), 3 is a partition plate, W3 is an amount of free water reduction, and D2 is an interval between the partition plates 3.
As shown in the figure, the partition plate 3 is connected to the tank outer plate 2 by dividing the inside of the tank vertically and horizontally in plan view so as not to reach the tank bottom plate 1 at a depth of 0.3D1 or more from the highest liquid level. To install.
As a result of being surrounded by the partition plate 3, the amount of free water W2 is reduced by W3 from FIG. 1 to 1/3 or less (0.3D2) in the case of FIG. 1 without the partition plate, and the sloshing period is 1 / √. 3 Therefore, the impact force of the sloshing wave can be remarkably reduced.

FIG. 3 is an explanatory view of a change in the amount of free water when an additional partition plate is installed so as to further divide the partition plate of FIG. 3 (a) and 3 (b), 3 is a large partition plate, 4 is a small partition plate, W4 is a decrease in free water, and D3 is an interval between the small partition plates 4.
As shown in FIG. 2, in addition to the large partition plate 3 which is divided into three in the vertical and horizontal directions in a plan view so as not to reach the tank bottom plate 1 at a depth of 0.3D1 or more from the highest liquid level, As shown, the portion partitioned by the large partition plate 3 is further divided into two in the vertical and horizontal directions in plan view by a small partition plate 4 having a depth of 0.3D2 or more from the highest liquid level. The small partition plate 4 is installed by connecting to the tank outer plate 2 and the large partition plate 3.
Thus, by being surrounded by the large partition plate 3 and the small partition plate 4, the amount of the free water W2 is reduced by W4 from FIG. 2 to 1/6 or less (0.3D3) in the case of FIG. 1 without the partition plate, The sloshing period is 1 / √6. Therefore, the impact force of the sloshing wave can be further reduced.

[First Embodiment]
FIG. 4 is a longitudinal sectional side view (a) and a transverse plan view (b) showing the configuration of the first embodiment of the tank to which the present invention is applied. FIG. 4B shows a cross section taken along the line AA in FIG. 4A, and FIG. 4A shows a cross section taken along the line BB in FIG. 4B. Yes.
That is, in the first embodiment, in the existing large tank, the inside of the tank is divided into three in the vertical and horizontal directions in plan view by the large partition plate 3 having a depth of 0.5D (D: tank diameter or width) from the highest liquid level. The portion partitioned by the large partition plate 3 is further divided into two in the vertical and horizontal directions in plan view by the small partition plate 4 having a depth of 0.5D from the highest liquid level.
The intersection of the large partition plates 3 is supported by pipe-like columns 5 standing vertically from the tank bottom plate 1, and a float-like floating roof 6 is provided on the liquid surface surrounded by the small partition plates 4. Each is provided.
Here, the reason why the depth from the highest liquid level of the partition plates 3 and 4 is set to 0.5D is because it is considered to cope with the fluctuation of the built-in liquid amount. The support 5 may be H-shaped steel.

[Second Embodiment]
FIG. 5 is a longitudinal side view (a) and a transverse plan view (b) showing the configuration of a second embodiment of the tank to which the present invention is applied. 5A shows a cross section taken along the line AA in FIG. 5A, and FIG. 5A shows a cross section taken along the line BB in FIG. 5B. Yes.
That is, in the second embodiment, in the existing large tank, the inside of the tank is divided into three in the vertical and horizontal directions in plan view by the large partition plate 3 having a depth of 0.5D (D: tank diameter or width) from the highest liquid level. The portion partitioned by the large partition plate 3 is further divided into two in the vertical and horizontal directions in plan view by the small partition plate 4 having a depth of 0.5D2 (D2: interval between the large partition plates 3) from the highest liquid level. It is a thing.
And like 1st Embodiment mentioned above, while supporting the crossing part of the large partition plate 3 with the pipe-shaped support | pillar 5, the float-like floating roof 6 is each on the liquid level enclosed by the small partition plate 4, respectively. Provided.
As described above, the depth of the small partition plate 4 is set to 0.5D2 (D2: the interval between the large partition plates 3), thereby reducing the cost compared to the first embodiment.
Here, the reason why the depth from the highest liquid surface of the small partition plate 4 is set to 0.5D2 is that consideration is given to dealing with fluctuations in the amount of built-in liquid, as in the first embodiment. Further, as in the first embodiment, the support column 5 may be H-shaped steel.

[Third Embodiment]
FIG. 6 is a longitudinal sectional side view (a) and a transverse plan view (b) showing a configuration of a third embodiment of a tank to which the present invention is applied. 6A. FIG. 6B shows a cross section taken along the line AA in FIG. 6A, and FIG. 6A shows a cross section taken along the line BB in FIG. 6B. Yes.
That is, in the third embodiment, an existing large tank is configured to include a large partition plate 3, a small partition plate 4, and a floating roof 6 that are substantially the same as those of the second embodiment described above, and a suspended beam is provided above the partition plate. 7 and a slide guide rail 8 around the periphery.
The suspension beam 7 is arranged in parallel between the large partition plate 3 and the small partition plate 4, and the large partition plate 3 and the small partition plate 4 are suspended from the suspension beam 7 via the junction hinge 71. The suspension beam 7 is supported by a floating roof 6 via a joint hinge 72. In addition, the floating roof 6 is abbreviate | omitted in FIG.6 (b).
The slide guide rail 8 supports the end portions of the large partition plate 3 and the small partition plate 4 so as to be movable up and down, and is provided radially to be fixed to the inner periphery of the tank outer plate 2.
In this manner, the large partition plate 3 and the small partition plate 4 are unitized with the floating roof 6 by the suspension beam 7 and can be moved up and down along the slide guide rail 8 in accordance with the increase or decrease in the amount of built-in liquid. .

[Fourth Embodiment]
FIG. 7 is a longitudinal sectional side view (a) and a transverse plan view (b) showing a configuration of a fourth embodiment of a tank to which the present invention is applied. FIG. 7B shows a cross section taken along the line AA in FIG. 7A, and FIG. 7A shows a cross section taken along the line BB in FIG. 7B. Yes.
That is, in the fourth embodiment, in the existing large tank, the inside of the tank is divided into three in the vertical and horizontal directions in plan view by the large partition plate 3 having a depth of 0.5D (D: tank diameter or width) from the highest liquid level. Above, a necessary part among the parts partitioned by the large partition plate 3 is divided into two by the small partition plate 4 having a depth of 0.5D2 (D2: interval between the large partition plates 3) from the highest liquid level. .
Then, a large floating roof 11 is provided above the large partition plate 3 and the small partition plate 4, a large partition plate 13 having a curved shape is provided around it, and an anchor plate 15 is provided at the lower end thereof.
The floating roof 11 has a large disk float shape with a gap on the inner side of the tank outer plate 2, and has a large number of air vent holes 12 penetrating in the vertical direction in order to cope with fluctuations in the amount of built-in liquid. . The upper ends of the large partition plates 3 and 13 and the small partition plate 4 are joined to the lower surface of the floating roof 11.
The curved large partition plate 13 is joined to the outside of the portion partitioned by the large partition plate 3 and has a cylindrical shape positioned inside the tank outer plate 2 as a whole.
The anchor plate 15 is joined to the lower end of the large partition plate 13 having a cylindrical shape, and has an annular shape as a whole. The anchor plate 15 is for receiving resistance in the liquid and reducing the vertical movement of the floating roof 11.
In this way, the large partition plates 3 and 13 and the small partition plate 4 are integrated as a unit with the floating roof 11 and the anchor plate 15, and can be moved up and down in accordance with the increase or decrease in the amount of built-in liquid.

  The present invention is not limited to the above embodiment, and the tank shape and the specific detailed structure of the partition plate can be changed as appropriate, and can be applied to either a new tank or an existing tank. Of course.

It is explanatory drawing of the free water and fixed water from which the property with respect to the vibration of the liquid in a tank differs, and is the center longitudinal cross-sectional side view (a) and top view (b) of a tank. It is explanatory drawing of the change of the amount of free water at the time of arrange | positioning a partition plate so that the inside of the tank of FIG. 1 may be divided into 3 length and width, and it is the center longitudinal cross-sectional side view (a) and top view (b) of a tank. It is explanatory drawing of the change of the amount of free water at the time of installing an additional partition plate so that between the partition plates of FIG. 2 may be further divided into two in length and width, and is a center vertical side view (a) and a plan view (b) of the tank. It is the vertical side view (a) and transverse plane view (b) which show the structure of 1st Embodiment of the tank to which this invention is applied. It is the vertical side view (a) and transverse plane view (b) which show the structure of 2nd Embodiment of the tank to which this invention is applied. It is the vertical side view (a) and transverse plane view (b) which show the structure of 3rd Embodiment of the tank to which this invention is applied. It is the vertical side view (a) and transverse plane view (b) which show the structure of 4th Embodiment of the tank to which this invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tank bottom plate 2 Tank outer plate 3 Large partition plate 4 Small partition plate 5 Support | pillar 6 Floating roof 7 Hanging beam 71 * 72 Joining hinge 8 Slide guide rail 11 Floating roof 12 Air vent hole 13 Large partition plate 15 Anchor plate

Claims (2)

  Inside the large tank that stores the liquid, the inside of the tank is divided in plan view, and a partition plate that does not reach the tank bottom plate at a depth of 0.3 times or more of the tank diameter or the tank width from the highest liquid level is provided. Sloshing prevention structure for large tanks characterized by   Dividing the portion partitioned by the partition plate further in plan view, and a small partition plate that does not reach the tank bottom plate at a depth of 0.3 times or more the interval of the portion partitioned by the partition plate from the highest liquid level The sloshing prevention structure of the large sized tank of Claim 1 provided.

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