JPH08285198A - Cryogenic liquid underground storage tank - Google Patents

Abstract

PURPOSE: To inexpensively freeze underground water in the vicinity of a seam between a bottom plate and a side wall by little cold. CONSTITUTION: In a cryogenic liquid storage underground tank where a storage tank 7 is arranged in a space surrounded by a bottom plate 3 arranged underground and a side wall 4 arranged around the bottom plate 3, refrigerating piping 17 to surround the vicinity of a seam 16 between the bottom plate 3 and the side wall 4 is buried inside the side wall 4, and a cooling medium supply pipe 18 and a cooling medium discharge pipe 19 are connected to the refrigerating piping 17 from the ground, and underground water is frozen from a place in close vicinity to the seam 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low temperature liquefied gas underground storage tank for storing LNG and the like.

[0002]

2. Description of the Related Art An example of a low temperature liquefied gas underground storage tank that has been conventionally used will be described with reference to a vertical cross-sectional view of FIG. 4. A gravel layer 2 is formed below the ground surface 1 and a flat surface is formed thereon. A bottom slab 3 having a circular shape is provided, a side wall 4 is provided from the periphery of the bottom slab 3 to slightly above the ground surface 1, and a connecting wall 5 extending around the side wall 4 to a part of underground rock.
A storage tank body 7 made of a membrane whose outer surface is covered with a cold insulator 6 is provided in a space surrounded by the bottom plate 3 and the side wall 4, and the LNG is stored in the storage tank body 7.
The low-temperature liquefied gas underground storage tank is configured to store the low-temperature liquefied gas 8 such as.

Further, in order to pump up groundwater in the gravel layer 2, a pumping pit 9 is provided on the outside of the side wall 4 as shown in the sectional view of FIG. 5, and stainless steel is used at the joint between the bottom slab 3 and the side wall 4. The ring-shaped water stop plate 10 made of a product is provided in a plurality of stages.

Even if the water blocking plate 10 is provided in this way, a minute gap is formed, and ground water permeates from the joint between the bottom slab 3 and the side wall 4, but the low temperature liquefied gas is stored in the storage tank body 7. Under normal conditions of storing 8, the groundwater that has permeated from the joint between the bottom slab 3 and the side wall 4 is frozen by the cryogenic atmosphere of the low temperature liquefied gas 8 and does not permeate to the cold insulator 6. .

However, when the low temperature liquefied gas 8 in the storage tank body 7 is removed and the low temperature liquefied gas underground storage tank is inspected, the low temperature liquefied gas 8 in the storage tank body 7 is checked.
, The groundwater that had been frozen by the cryogenic atmosphere of the low temperature liquefied gas 8 melts at room temperature until it melts, penetrates from the joint between the bottom plate 3 and the side wall 4 to the cold insulator 6, and the cold insulator 6 is used. There was a risk that it would be impossible.

At the time of inspection of such a low temperature liquefied gas underground storage tank, in order to prevent the frozen ground water from being thawed and permeated, at the time of conventional inspection, the inner pipe 11 and the lower end outside thereof are closed. A temporary freezing pipe 13 including an outer pipe 12 is temporarily installed in the ground outside the side wall 4 and in the pumping pit 9, a cooling medium supply pipe 14 is connected to the inner pipe 11, and a cooling medium is connected to the outer pipe 12. A cooling medium such as liquid nitrogen is caused to flow through the temporary freezing pipe 13 by connecting the discharge pipe 15, and a low temperature atmosphere is created from the outside of the side wall 4 by the cold heat to freeze the ground water near the joint between the bottom slab 3 and the side wall 4. Is bottom plate 3 and side wall 4
It was made not to penetrate from the seam to the place of the cold insulator 6.

After the inspection of the low temperature liquefied gas underground storage tank is completed and the low temperature liquefied gas 8 is stored in the storage tank body 7 again, the temporary freezing pipe 13, the cooling medium supply pipe 14 and the cooling medium discharge which have been temporarily installed The pipe 15 was removed.

[0008]

However, in the conventional low temperature liquefied gas underground storage tank as described above, a large number of temporary freezing pipes 13 must be installed at the time of inspection, and ground water is frozen from the outside of the side wall 4. Therefore, a large amount of cryogenic liquid such as liquid nitrogen is required, and the temporary freezing pipe 1
Since 3 is temporarily installed or removed, there are drawbacks that the cost is high and waste is large.

The present invention eliminates such conventional drawbacks,
It is an object of the present invention to provide a low temperature liquefied gas underground storage tank that can efficiently and inexpensively freeze the groundwater near the joint between the bottom plate and the side wall at the time of inspection with a small amount of cold heat.

[0010]

The present invention relates to a low temperature liquefied gas underground storage tank having a storage tank body provided in a space surrounded by a bottom slab provided underground and a side wall provided around the bottom slab, A cryogenic liquefied gas underground storage tank, characterized in that a refrigerating pipe surrounding the vicinity of the joint between the bottom plate and the side wall is buried inside the side wall, and a cooling medium supply pipe and a cooling medium discharge pipe are connected to the refrigerating pipe from the ground. It is related to.

In the low temperature liquefied gas underground storage tank, the cooling medium supply pipe and the cooling medium discharge pipe connected to the refrigeration pipe may be arranged in a pumping pit formed outside the side wall.

[0012]

[Operation] Since the refrigeration pipe surrounding the joint between the bottom slab and the side wall is embedded inside the side wall, the efficiency of cold heat transfer to the joint between the bottom slab and the side wall is improved, and the groundwater that permeates the joint between the bottom slab and the side wall. However, since the cooling medium supply pipe and the cooling medium discharge pipe are permanently installed, it is not necessary to temporarily install the pipe in the ground.

Further, if the cooling medium supply pipe and the cooling medium discharge pipe connected to the refrigeration pipe are arranged in the pumping pit formed outside the side wall, the pipe is buried in the ground. The labor and cost required for it are also greatly reduced.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention, FIG.
2 is a sectional view taken along the line II-II in FIG. 1, and the same portions as those in FIGS. 4 and 5 are denoted by the same reference numerals, and a seam between the bottom plate 3 and the side wall 4 at the time of constructing the low temperature liquefied gas underground storage tank. A refrigerating pipe 17 surrounding the vicinity of 16 is embedded inside the side wall 4.
In the present embodiment, the refrigerating pipe 17 has a ring shape as shown in the perspective view of FIG. 3, and is provided over a plurality of stages (two stages in the example of the figure).

A cooling medium supply pipe 18 and a cooling medium discharge pipe 19 arranged from the ground are connected to each refrigeration pipe 17, and a cooling medium supply pipe connecting portion 20 and a cooling medium discharge pipe connection of the freezing pipe 17 are connected. An orifice 22 for preventing the cooling medium supplied from the cooling medium supply pipe 18 from flowing out to the cooling medium discharge pipe 19 in a form of short-circuiting without going around the freezing pipe 17 is provided between the portion 21 and the portion 21. It is provided.

The cooling medium supply pipe 18 and the cooling medium discharge pipe 19 arranged from the ground may be buried in the ground near the side wall 4, but in this embodiment, as shown in the drawing, in the pumping pit 9. It is located at.

Next, the operation of the above embodiment will be described.

When inspecting the cryogenic liquefied gas underground storage tank, a cooling medium tank, a pump,
A refrigerator is temporarily installed and connected to the cooling medium supply pipe 18 and the cooling medium discharge pipe 19, and the cooled cooling medium is supplied to the cooling medium supply pipe 18
Is supplied to the refrigerating pipe 17 via.

The cooling medium supplied to the freezing pipe 17 radiates cold heat when passing through the freezing pipe 17, and cools and freezes the groundwater near the joint 16 between the bottom plate 3 and the side wall 4. On this occasion,
Most of the cooling medium reaches the cooling medium discharge pipe connecting portion 21 from the cooling medium supply pipe connecting portion 20 almost around the freezing pipe 17 due to the throttling action of the orifice 22. Since it reaches the cooling medium discharge pipe connection portion 21 through it, cold heat is radiated from the entire circumference of the freezing pipe 17 to cool and freeze the groundwater around the entire joint 16 of the bottom plate 3 and the side wall 4.

The cooling medium passing through the freezing pipe 17 is collected on the ground through the cooling medium discharge pipe 19, cooled again by the pump and the refrigerator, and sent to the cooling medium supply pipe 18.

As a result, the low temperature liquefied gas 8 in the storage tank body 7 is used for the inspection of the low temperature liquefied gas underground storage tank.
Even if the groundwater is removed, the groundwater near the joint 16 between the bottom slab 3 and the side wall 4 is kept frozen by the cold heat emitted from the cooling medium passing through the refrigerating pipe 17, and the groundwater is kept cold.
It does not penetrate to.

When the low temperature liquefied gas underground storage tank is inspected and the low temperature liquefied gas 8 is stored in the storage tank body 7 again, the cooling medium tank, pump and refrigerator temporarily installed on the ground are removed.

Thus, when inspecting the low temperature liquefied gas underground storage tank, it becomes possible to freeze the groundwater in the vicinity of the joint 16 between the bottom slab 3 and the side wall 4 efficiently and inexpensively with a small amount of cold heat, and further to the cooling medium supply pipe 18. Cooling medium discharge pipe 1
By arranging 9 in the pumping pit 9, it is possible to further simplify the piping work and to reduce the facility cost.

The present invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

[0026]

According to the low temperature liquefied gas underground storage tank according to claim 1 of the present invention, since the refrigerating pipe surrounding the vicinity of the joint between the bottom slab and the side wall is buried inside the side wall, the ground water is frozen from the outside of the side wall. It is possible to significantly improve the efficiency of cold heat transfer to the seam between the bottom slab and the side wall, compared to the conventional device, and to effectively freeze the groundwater that permeates the seam between the bottom slab and the side wall with less cold heat. Since the cooling medium supply pipe and the cooling medium discharge pipe are permanently installed, there is an effect that the labor and cost of temporarily installing the pipe in the ground can be reduced.

Further, according to the low temperature liquefied gas underground storage tank according to claim 2 of the present invention, the cost for installing the cooling medium supply pipe and the cooling medium discharge pipe is further reduced by utilizing the drainage pit. There is an effect that can be.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a perspective view of an embodiment of a refrigerating pipe used in the present invention.

FIG. 4 is a vertical cross-sectional view showing an example of a conventional low temperature liquefied gas underground storage tank.

FIG. 5 is a sectional view taken along line VV of FIG. 4;

[Explanation of symbols]

 3 Bottom plate 4 Side wall 7 Storage tank body 9 Pumping pit 16 Seam 17 Refrigerating pipe 18 Cooling medium supply pipe 19 Cooling medium discharge pipe

Claims (2)

[Claims] 1. A low temperature liquefied gas underground storage tank having a storage tank body provided in a space surrounded by a bottom slab provided underground and a side wall provided around the bottom slab, wherein a vicinity of a joint between the bottom slab and the side wall. A low-temperature liquefied gas underground storage tank, characterized in that a refrigerating pipe surrounding the is embedded in the side wall, and a cooling medium supply pipe and a cooling medium discharge pipe are connected to the freezing pipe from the ground. 2. The low-temperature liquefied gas underground according to claim 1, wherein the cooling medium supply pipe and the cooling medium discharge pipe connected to the refrigeration pipe are arranged in a pumping pit formed outside the side wall. Storage tank.