JPH0440077Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field This invention relates to the roof structure of an underground storage tank for storing low-temperature liquids such as LNG.

Prior Art Underground storage tanks for storing low-temperature liquids such as LNG, as shown in Fig. 3, have a liquid-tight and air-tight membrane 2 on the inner surface of a reinforced concrete frame 1 in the shape of an upright cylindrical container, which is generally buried underground. is installed,
A dome-shaped roof 3 is fixed at the top by connecting its periphery to the top of the frame 1. A hanging deck 4 is suspended from the roof 3 above the liquid storage surface, and a heat insulating material 5 is attached to the upper surface of the deck. Also, hanging deck 4
A heat insulating material 6 is also attached between the outer periphery of the membrane 2 and the membrane 2 to close the gap.

FIG. 4 is an enlarged detailed view of the structure of the joint between the body 1 and roof 3 of the storage tank.
A heat insulating material 7 is attached between the membrane 2 and the reinforced concrete structure 1. Since the roof 3 is connected to the reinforced concrete structure 1 near the center of its thickness, the upper part of the membrane 2 is bent outward along the upper end surface of the structure 1, and its outer end is bent upward and airtightly attached by welding or the like to a ring material 8 attached in an annular shape to the inner surface of the roof 3. The suspension deck 4 is in contact with the membrane 2 below the upper end of the reinforced concrete structure 1 via a heat insulating material 6, as shown in Fig. 1.

With the configuration described above, the liquid storage section includes the heat insulating material 5,
6 and 7 block heat input from the outside, the stored liquid is kept at a low temperature, and the membrane etc. keep it liquid-tight.
Airtightness is ensured.

On the other hand, the space between the roof 3 and the upper surface of the insulation material 5 on the hanging deck 4 is maintained at a temperature close to the atmospheric temperature, that is, room temperature, by the insulation materials 5 and 6.
The roof 3 is generally made of room temperature material.
In addition, the membrane 2 in the part above the hanging deck 4,
The ring material 8 is also kept at room temperature and no low temperature shrinkage occurs.
Therefore, the low-temperature shrinkage performance of the membrane 2 does not need to be made very large, even in the unlikely event that it occurs.

By the way, conventionally, the spatial height h between the liquid level in the storage tank and the lower surface of the hanging deck 4 has been set to a height that will not be affected by the sloshing of the stored liquid during an earthquake that is normally expected. For the hanging deck 4 and the cold insulation materials 5 and 6, wave pressure of the stored liquid during an earthquake and immersion by the stored liquid are not taken into consideration.

Therefore, if an unexpectedly large earthquake occurs and there is a large fluctuation in the liquid level, the deck 4 and the cold insulation materials 5 and 6 will be damaged by being subjected to the hydraulic pressure of the fluctuation in the liquid level or being immersed in the stored liquid. There is a danger.

Taking this into consideration, it is possible to secure a larger space height h between the lower surface of the hanging deck 4 and the highest liquid level in the storage tank, but it is possible to simply lower the liquid level and
Alternatively, simply increasing the height of the frame will reduce the storage capacity in proportion to the height of the storage tank, creating a problem that will cause economic disadvantage.

Purpose of the invention The invention solves the problem of conventional underground low-temperature storage tanks with hanging deck structures, which have the risk of damage due to sloshing of stored liquid during large-scale earthquakes. Sufficiently withstands the shaking of stored liquid during large-scale earthquakes, and also provides low-temperature shrinkage at the joint between the reinforced concrete frame and the roof.
The purpose of the present invention is to provide a roof structure for an underground low-temperature storage tank that can ensure safety against thermal stress and is highly economical.

Structure of the invention The roof structure of the underground low-temperature storage tank of the present invention, which achieves the above objectives, consists of a hanging deck installed at a height above the liquid level in the storage tank that will not be affected by sloshing in the event of a large-scale earthquake. , having a shell structure corrugation consisting of a cylindrical part connected to the inner surface of the reinforced concrete frame and a spherical annular part smoothly connecting the cylindrical part and the hanging deck, the cylindrical part of the corrugation is fixed to the frame with bolts so that it can be expanded and contracted by heat in the vertical direction, has a structure that can be expanded and contracted by heat in the circumferential direction, and has an airtight structure between the wave return and the roof, and insulates the space. It is characterized by being filled with material.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

In the underground low-temperature storage tank of this embodiment, as shown in FIG. 1, the maximum liquid level in the storage tank relative to the reinforced concrete frame 1 and roof 3 is not lower than that of the conventional storage tank shown in FIG. 3, and the height of the roof is also reduced. Space height h of hanging deck 4 from the storage liquid surface without raising it
is set to a height that is not affected by the rise in the level of the stored liquid shown by the dashed line during a large-scale earthquake, and a cylindrical shape connected to the inner surface of the structure is installed between the outer periphery of the hanging deck 4 and the upper end of the structure 1. A wave return 9 is airtightly provided, consisting of a spherical annular portion and a spherical annular portion that is smoothly connected to the hanging deck 4. The space between the wave return 9 and the roof 3 is filled with a heat insulating material such as perlite to form a heat insulating layer 12.
is formed. Heat insulating materials 5 and 6 are attached to the upper surface of the hanging deck 4 and its outer periphery to prevent the heat insulating material 12 from scattering.

Figure 2 shows wave return 9 and reinforced concrete frame 1.
It is a figure showing the structure of the upper end joint part in detail.

The lower end of the roof 3 is connected to the vicinity of the center of the thickness of the upper end surface of the frame 1. Further, the lower half of the cylindrical portion 9' at the bottom of the wave return 9 is overlapped with the upper end of the inner surface of the frame 1 via the heat insulating material 7, and is firmly and airtightly attached with bolts 11, 11'. . A heat insulating material 7 is placed between the roof 3 and the wave return 9 in contact with the upper end surface of the frame 1.
The gas seal plate 10 is attached via the
This prevents vaporized gas from entering the heat insulating layer 7. Since the wave return 9 shrinks at a low temperature due to the cooled vaporized gas, the inner and outer peripheral portions of the gas seal plate 10 are bent upward with appropriate curvature, and are attached to the wave return 9 and the roof 3 at their respective tips. Although not shown in the figure, the gas seal plate 10 is provided with radial corrugations so that it can follow the thermal contraction of the corrugations 9.

Bolts 11, 11' to attach the wave return 9 to the frame
A plurality of sets of two bolts arranged in series in the vertical direction are provided at equal intervals in the circumferential direction, and only one bolt 11 or 11' of each set of bolts is connected to the wave return 9 and the frame 1. The other is fixed to only one of the wave return 9 or the frame 1, and is slidable in the vertical direction with respect to the other.

Further, in the cylindrical portion 9' of the wave return 9, a plurality of corrugations 13 extending in the vertical direction are provided at equal intervals in the circumferential direction.

The joint portion between the wave return 9 and the membrane 2 is liquid-tightly and airtightly joined by welding.

In the storage tank of this embodiment, as explained above, the hanging deck 4 is provided at a height that does not touch the rising liquid level of the stored liquid in the event of a large-scale earthquake, and the hanging deck 4 is located at a height that does not touch the rising liquid level of the stored liquid in the event of a large-scale earthquake. Since a wave return 9 is provided to smoothly connect between the two, the liquid level that rose due to the earthquake is returned horizontally by the wave return,
Ceiling 4 is not affected by sloshing. Furthermore, the wave return 9 is composed of a cylindrical part that continues to the membrane 2, and a spherical annular part whose radius decreases as it goes upward, so the radius of the upper end of the wave return is equal to smaller than the radius of
Even if the height of the suspended ceiling 4 is increased, there is no need to raise the height of the roof 3, the amount of stored liquid will not decrease compared to the height of the storage tank, and the economical efficiency will not decrease.

A heat insulating material 6 is provided between the outer circumference of the suspended ceiling 4 and the inner circumference of the wave return 9, and a gas seal plate 10 is airtightly provided between the roof 3 and the vicinity of the lower part of the wave return 9. Therefore, gas does not enter the heat insulating layer 7, and therefore no gas leaks to the outside of the tank.

The wave return 9 is brought into contact with the low-temperature vaporized gas above the liquid level of the liquid storage portion and shrinks at a low temperature.The cylindrical portion 9' of the wave return 9 is provided with a plurality of corrugations 13 extending in the vertical direction. Only one of the bolts in each column for attaching the barb 9 to the frame 1 is fixed to the barb 9 and the frame 1, and the others are fixed only to one of the barb 9 and the frame 1, and can be slid in the vertical direction from the other. Therefore, it is possible to easily follow low-temperature shrinkage, and the stress due to restraint can be reduced.

A heat insulating material 5 is provided on the hanging deck 4, a heat insulating material 6 is provided between the surrounding area and the wave return, and a heat insulating layer 12 is provided between the wave return 9 and the roof 4. , the amount of heat input into the storage tank is reduced.

The wave return 9 is constructed in a shell structure and can be easily thickened and reinforced as necessary.The reaction force of the wave return is easily transmitted to the reinforced concrete frame 1 and to the ground, so that the liquid during sloshing is It can easily withstand rocking pressure.

Effects As described above, according to the present invention, the height of the suspended ceiling can be raised to a position where it will not be affected by sloshing even in the event of a large-scale earthquake, without increasing the size of the storage tank. It does not cause a decrease in economic efficiency such as a decrease in In addition, the liquid agitation pressure during sloshing can be securely transmitted to the concrete frame, making it easy to ensure safety.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing the overall configuration of an underground low temperature storage tank to which the present invention is applied, Figure 2 is a perspective view showing the configuration near the joint between the frame and the ceiling, and Figure 3 is a conventional underground cryogenic storage tank. FIG. 4 is a cross-sectional view of the type low temperature storage tank, and is a perspective view showing the structure near the joint between the frame and the ceiling. 1... Storage tank frame, 2... Membrane, 3... Roof, 4... Hanging deck, 5, 6, 7... Insulation material, 9
... Wave return, 9'... Wave return cylindrical part, 10...
Gas seal plate, 11, 11'... Corrugated fixing bolt, 12... Heat insulation layer, 13... Corrugation.

Claims (1)

[Scope of claim for utility model registration] (1) In the roof structure of an underground storage tank for storing low-temperature liquids such as liquefied natural gas, the height above the liquid level in the storage tank must be at a height that will not be affected by sloshing in the event of a large-scale earthquake. It has a shell structure corrugation consisting of a hanging deck installed in the wall, a cylindrical part connected to the inner surface of the reinforced concrete frame, and a spherical annular part smoothly connecting the cylindrical part and the hanging deck. , The cylindrical part of the above-mentioned wave return is fixed to the frame with bolts so that it can be thermally expanded and contracted in the vertical direction, and has a structure that can be thermally expanded and contracted in the circumferential direction, and the air between the above-mentioned wave return and the roof is The roof structure of an underground low temperature storage tank is characterized by having an airtight structure and being filled with a heat insulating material, and a gas seal plate is provided between the wave return near the frame and the roof. (2) Registration of a utility model characterized in that the structure that enables thermal expansion and contraction in the circumferential direction of the cylindrical part of the wave return is an appropriate number of corrugations extending longitudinally in the cylindrical part. A roof structure according to claim 1. (3) A structure in which the cylindrical part of the wave return is fixed to the building frame with bolts so as to be able to expand and contract in the longitudinal direction is arranged in series in the longitudinal direction, and each vertical row of bolts is provided at equal intervals in the circumferential direction. According to claim 1 of the utility model registration claim, which is characterized in that only one of the bolts is fixed to the frame body and the cylindrical part with the wave return, and the others are fixed only to either the frame body or the wave return. Roof structure as described.