JPH059598Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention relates to a device for controlling the development of frozen soil that forms in the ground around an underground cryogenic tank buried underground.

[Conventional technology]

For example, in the ground where an underground low-temperature tank for storing low-temperature liquefied gas such as liquefied natural gas (LNG) is buried, the cold energy of the low-temperature liquefied gas stored in the tank , frozen soil forms and develops in the ground around the tank.

Figure 2 is a cross-sectional view showing the frozen ground line (0°C line) of the ground around the tank buried underground.

In Figure 2, 10 is the ground 3 excluding the roof 7.
This is a frozen ground line that is generated in the ground 3 around the tank body 1 buried inside.

If such frozen ground develops too much, the pressure (frozen ground pressure) exerted on the tank body 1 will increase,
In particular, the bottom plate 5 is greatly affected by frozen soil pressure, causing problems in terms of the strength of the tank body 1.

However, a small amount of moderately developed frozen soil has the effect of reducing the amount of vaporized gas (BOG) generated from the liquefied natural gas 9 stored in the tank body 1, and such a small amount of frozen soil , the strength of the tank body 1 is not adversely affected.

Therefore, it is better to develop a certain amount of frozen soil around the tank body, and for this purpose it is necessary to control the development of frozen soil.

For the purpose of controlling the development of frozen soil as described above, conventionally, as shown in the cross-sectional view of the underground cryogenic tank A in Fig. 3, an underground cryogenic tank A is buried in the ground 3 except for the roof 7. A side heater pipe 11 is buried in the ground 3 outside the side wall 4 of the tank body 1, and a bottom heater 12 is buried in the lower surface of the bottom plate 5.

In FIG. 3, 6 is a continuous wall of an underground low-temperature tank A, 8 is a hanging deck, and 9 is a liquefied natural gas.

A plurality of side heater pipes 11 are vertically buried in succession in the ground 3 outside the concrete frame of the side wall 4 at a predetermined interval from the side wall 4 so as to surround the entire side of the tank body 1.

The bottom heater 12 is attached to the entire bottom surface of the bottom plate 5.
It is buried horizontally in close contact with the

As the bottom heater 12, an open type or a closed type is adopted.

Since the bottom heater 12 is embedded in the lower surface of the bottom plate 5 of the tank body 1, if it is damaged for some reason and its heater function is impaired, it is difficult to repair it due to its structure. Therefore, the bottom heater 1
2 has two systems of heater equipment (hot water heater and brine) to prevent all functions of the heater equipment of the bottom heater 12 from stopping due to damage.

[Problem that the invention attempts to solve]

However, conventional underground frozen soil development control devices around cryogenic tanks have the following problems.

Since a total of three systems of heater equipment, one system on the side of the tank body 1 and two systems on the bottom of the tank body 1, are required, the cost is high.

Since the bottom heater 12 is structurally impossible to perform maintenance such as repair, if both heater equipment systems are damaged, the heater function will be impaired. This causes the frozen ground to develop too much, which has a negative impact on the tank.

Therefore, the purpose of this invention is to provide a device for controlling the development of frozen soil around an underground low-temperature tank, which can efficiently control the development of frozen soil, allows maintenance such as repair, and is inexpensive to manufacture. It is in.

[Means for solving problems]

This idea surrounds an underground low-temperature tank with a tank body buried underground, and the development of frozen soil that forms in the ground around the tank body, which is buried underground outside the side walls and bottom plate of the tank body. In a device for controlling frozen soil development around an underground low-temperature tank, the heater pipe surrounds the outside of the side wall of the tank body from the top to the bottom, and
It is characterized in that it is formed in an arc shape that surrounds the outside of the bottom plate in the radial direction and reaches the center of the bottom plate.

Next, this invention will be explained with reference to the drawings. FIG. 1 is a sectional view showing one embodiment of this invention, and FIG. 4 is a plan view showing one embodiment of this invention. Figure 4 shows frozen soil development control device (heater pipe)
This is a diagram showing the tanks being installed radially toward the center of the tank.

As shown in FIGS. 1 and 4, the underground low-temperature tank A has a tank body 1 buried in the ground 3, except for the roof 7.

A heater pipe 2 is buried in the ground 3 outside the side wall 4 and bottom plate 5 of the tank body 1.

The heater tube 2 is formed in an arc shape that surrounds the outside of the side wall 4 from the top to the bottom, surrounds the outside of the bottom plate 5 in the radial direction, and reaches the center of the bottom plate 5, and has an upper end. has reached the ground. By making the shape of the heater tube arcuate, the effect can be expected to be sufficient. The reason is as follows.

Looking at the development of frozen soil in the target underground cryogenic tank, it is expected that the shape of the frozen soil will gradually become hemispherical as it changes over time.

If the frozen soil shape changes after the frozen soil development control device is put into operation, especially if the frozen soil develops too much, the frozen soil pressure on the tank body will increase, causing problems with the strength of the tank body (especially the bottom plate). To maintain the frozen soil shape due to problems.

A plurality of heater pipes 2 are consecutively buried at predetermined intervals so as to surround the entire circumference of the tank body 1 of the underground low temperature tank 1. Although FIG. 4 is a diagram in which 20 heater tubes are arranged, the number is not limited to the above number depending on the installation conditions.

The heater pipe 2 is buried by a circular arc propulsion method (curved propulsion method), which is a pipe propulsion method for laying a pipe curved in the longitudinal direction underground using a trenchless method. The arc propulsion method uses an outer tube that is curved in the longitudinal direction and an inner tube that is equipped with a tip-driven drill at the tip and is also curved in the longitudinal direction. This is a construction method in which the direction correction during cutting is carried out by making the tip of the inner tube eccentric with respect to the outer tube using a guide installed inside the outer tube near the tip. Therefore, by using the arc propulsion method, it is possible to bury and repair the heater pipe.

[Effect]

The device of the present invention controls the development of frozen soil around the tank body 1 using the heater pipe 2. At this time, frozen soil lines (not shown) are generated inside the heater tube 2, and the frozen soil development control efficiency of the present invention is as good as that of conventional devices.

In the present invention, since the heater tube is integrated from the side to the bottom of the tank body 1, the equipment cost of the heater tube 2 is significantly reduced.

Furthermore, the present invention can be easily installed in existing underground cryogenic tanks.

[Effect of idea]

As explained above, this invention has industrially useful effects such as efficient control of frozen soil growth, easy maintenance such as repair of heater pipes, and low cost installation. can get.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of this invention;
Fig. 2 is a sectional view showing the frozen ground line when the frozen ground control and development device is not used, Fig. 3 is a sectional view showing an example of the conventional frozen ground development control device, and Fig. 4 is a plan view showing one embodiment of this invention. It is a diagram. In the drawings, A...underground low temperature tank, 1...tank body,
2... Heater pipe, 3... Ground, 4... Side wall, 5...
... Bottom plate, 6 ... Continuous wall, 7 ... Roof, 8 ... Hanging deck, 9 ... Liquefied natural gas, 10 ... Frozen soil line, 1
1... Side heater pipe, 12... Bottom heater.

Claims (1)

[Scope of Claim for Utility Model Registration] Surrounding an underground low-temperature tank with a tank body buried in the ground, the ground around the tank body is buried in the ground outside the side wall and bottom plate of the tank body. In a device for controlling frozen soil development around an underground low-temperature tank, which includes a heater pipe for controlling the development of generated frozen soil, the heater pipe surrounds the outside of the side wall of the tank body from the top to the bottom, and,
A device for controlling frozen soil development around an underground low-temperature tank, characterized in that it is formed in an arc shape that surrounds the outside of the bottom plate in the radial direction and reaches the center of the bottom plate.