JPH0425700A - Liquefied gas storage underground tank - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an underground tank for storing liquefied gas.

(Prior Art) As a means for storing liquefied gas, underground tanks, which are wholly or partially buried underground, are known.

In this type of underground tank, if liquefied gas leaks outside from attached piping, the surrounding ground may freeze over time, and the expansion pressure may cause the retaining walls to collapse and the ground to deform.

FIG. 4 shows an example of a conventional underground tank.

The underground tank shown in the figure consists of an annular side wall 1 and this side wall 1.
It has a disk-shaped bottom plate 2 provided at the lower end of the side wall 1, and inside the side wall 1, an inner tank 3. Cold insulation material 4. Outer tank 5 that holds the cold insulation material 4. A slab 6 supporting the inner and outer tanks 2 and 5 and a column 7 supporting the slab 6 are provided. .

Further, rainwater is collected in a rainwater drainage pit 8 and discharged to the outside by a drainage pump 9.

However, underground tanks with such a structure have the following technical problems.

(Problem to be Solved by the Invention) That is, in the underground tank having the structure shown in FIG. 4, when liquefied gas leaks from the attached piping, etc., the side wall 1. It takes several tens of millimeters for the liquefied gas to stagnate in the area surrounded by the bottom plate 2 and disappear through natural evaporation.

Therefore, during this time, the ground around the outer periphery of the side wall 1 and the ground under the bottom slab 2 freeze, and there is a risk of deformation such as freezing and expansion, and it is impossible to recover the liquefied gas using the normal drainage pump 9.

This invention was made in view of such conventional problems, and its purpose is to provide a collection pit for leaked liquefied gas separately from the rainwater drainage pit, without adversely affecting the ground. An object of the present invention is to provide an underground tank for storing liquefied gas that can efficiently and quickly recover leaked liquefied gas.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an underground tank having a tank body for storing liquefied gas and an earth retaining wall constructed at intervals around the outer circumference of the tank body. In this method, an annular liquid collection groove is formed between the tank body and the earth retaining wall to collect the liquefied gas leaked from the tank body or attached piping, etc., and liquid collection pits are provided at appropriate locations in this liquid collection groove. The present invention is characterized in that a discharge device is provided to discharge leaked liquefied gas collected in the liquid collection pit.

(Operations and Effects of the Invention) According to the underground tank for storing liquefied gas having the above configuration, since the liquid collection groove, the liquid collection pit, and the discharge device are provided between the tank body and the earth retaining wall, leaked liquefied gas If the amount of leaked liquid is small, the leaked liquid will be collected in the liquid collection pit, minimizing the impact on the side walls and bottom plate of the tank body, and the liquid in the liquid collection pit can be easily recovered with a discharge device.

Furthermore, even if a large amount of leaked liquefied gas occurs, it can be recovered in a short time by driving the discharge device installed in the liquid collection pit, and freezing of the surrounding ground can be avoided.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 to 3 show an embodiment of an underground tank for storing liquefied gas according to the present invention.

The underground tank shown in the figure includes a tank main body 10 that stores liquefied gas G such as LNG or LPG, and an annular earth retaining wall built around the tank main body 10 at intervals. 12.

The tank body 10 includes an inner tank 10a, an outer tank 10b, a cold insulating material 10c provided between the inner tank 10a and the outer tank 10b, and a bottom plate part 10d that closes the lower ends of the inner and outer tanks 10a and 10b.
It is composed of. .

In this embodiment, the earth retaining wall 12 includes a continuous underground wall section 12a constructed from above ground, and an inner wall section formed integrally on the inner surface of the continuous underground wall section 12a by cutting the inside after constructing the underground wall section 12a. It is composed of a winding wall portion 12b.

A foundation slab 14 is integrally formed at the lower end of the inner wall portion 12b with a gravel layer 13 provided below. It is installed on a slab 17 that is supported by pillars 16 at a predetermined distance from the foundation slab 14.

In this embodiment, the lower end portion of the inner wall 12b is bent inward in an abbreviated shape, as shown in detail in FIG. A concave liquid collection groove 18 is formed.

The liquid collection groove 18 is formed in an annular shape along the inner side of the lower end of the inner wall 12b when viewed from the top side.

The liquid collecting groove 18 is for collecting the liquefied gas G leaking from the inside of the tank body 10 or the attached piping 19, etc., and is used to efficiently collect the liquid leaked onto the foundation slab 14 in the liquid collecting groove 18. For example, a slope may be provided on the upper surface of the foundation slab 14 that slopes toward the liquid collecting groove 18 side.

On the other hand, deep concave two-stage pits 20 are provided at appropriate locations in the liquid collection groove 18, as shown in detail in FIG. At least the liquid collecting groove 1
One or more locations are provided for every 8.

This pit 20 is filled with liquefied gas G that is collected in the liquid collection a18.
It further collects liquid, and inside it, for example,
A drain pump 22a that is automatically driven when rainwater reaches a predetermined level, and a drain pump 22b that is automatically driven when the collected liquefied gas G reaches a predetermined level are installed. The water pumped up by the pumps 22a and 22b.

The liquid is sent to the ground via the vibrators 24a and 24b and is processed by a processing device (not shown).

Now, in the underground tank configured as described above, a liquid collection groove 18 and a pit 20 are provided between the tank body 10 and the earth retaining wall 12.
b and a drain pump 22b are provided, so if the leaked liquefied gas G is a small amount, the leaked liquid is collected in the liquid collection pit 20 and is collected on the side wall 10a of the tank body 10 or outside. ! Minimizing the impact on 10b, pit 2Ob
The liquid inside can be easily collected with the pump 22b.

In addition, even if a large amount of liquefied gas G leaks, the pit 2
Since a plurality or a large number of the pumps 0b and the pumps 22b can be provided, by driving the pumps 22b at the same time, the surrounding ground can be recovered before it freezes.

[Brief explanation of the drawing]

FIG. 1 is an overall sectional view showing an embodiment of an underground tank for storing liquefied gas according to the present invention, FIG. 2 is an enlarged view of section A in FIG. 1, and FIG. 3 is an enlarged view of section B in FIG. FIG. 4 is an overall sectional view showing a conventional underground tank. 10...Tank body 12a...Continuous underground wall part 14...Foundation slab 20b...Pit 12...Earth retaining wall 12b...Inner wall part 18 ...Liquid collection groove 22b...Pump (discharge device)

Claims (1)

[Claims] In an underground tank that has a tank body that stores liquefied gas and an earth retaining wall constructed at intervals around the outer periphery of the tank body, leakage from the tank body or attached piping between the tank body and the earth retaining wall is detected. An annular liquid collection groove is formed to collect the liquefied gas, and liquid collection pits are provided at appropriate locations in this liquid collection groove, and a discharge device is provided to discharge the leaked liquefied gas collected in the liquid collection pit. An underground tank for storing liquefied gas characterized by: