JPS5844920B2 - Cryogenic tank structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cryogenic tank structure, and in particular to a barrier (membrane panel) as an inner wall structure that substantially accommodates a cryogenic storage liquid in an underground or semi-underground cryogenic tank.
Even if the stored liquid leaks due to rupture, it can be retained within the inner wall structure to prevent it from leaking to the outside and be purged, and this leakage can be detected accurately. The present invention relates to a low-temperature tank structure that can support even if a bottom plate and a bottom plate are relatively displaced without directly transmitting the amount of displacement to an inner wall structure including a cold insulating material layer formed on an inner wall of an outer shell tank.

As a low-temperature tank for storing low-temperature liquefied gas such as LPG>LNG, underground or semi-underground low-temperature tanks are generally known.

These tanks include a bottomed cylindrical concrete outer shell buried underground, and an inner wall structure formed on the wall of the outer shell, which includes a heat insulating and cold insulating material layer, and which essentially stores the low-temperature liquid. It mainly consists of a barrier.

By the way, conventional underground tanks are designed and manufactured under the condition that periodic inspections and the like are not carried out like above-ground tanks.

However, if the barrier (membrane panel), which serves as an inner wall structure that essentially contains the low-temperature liquid, is torn for some reason, the liquid will leak or leak into the heat-insulating and cold-insulating material layer. Become.

Particularly if the gas stored in the tank is flammable gas, it is necessary to remove the leaked gas when repairing the inner wall structure.
Ji1. At the same time, it is necessary to detect whether or not there is a leak.

Furthermore, in conventional tanks, the surrounding side walls and the bottom plate, which constitute the concrete tank body, are separated from each other in order to relieve thermal stress between the two.

However, since the cryogenic tank is buried underground, if the ground partially sinks or freezes and rises, a relative displacement will occur between the surrounding side wall and the bottom plate.

In this way, when the relative displacement between the surrounding side wall and the bottom plate becomes large, the inner wall structure formed on the wall of the outer shell tank body will be directly affected.

Therefore, the present invention has been devised in view of the problems that conventional outer shells of this type of low-temperature tank have, and to effectively solve these problems.

The purpose of the present invention is to detect and discharge or purge leakage from an inner wall structure that substantially accommodates liquid storage, and to improve the safety of tank repair work as much as possible. We provide the structure of a low-temperature tank that can be used.

Furthermore, it is an object of the present invention to maintain the inner wall structure of an underground or semi-underground cryogenic tank at a constant level even when the outer tank body buried in the ground is affected by changes such as subsidence or uplift of the ground that is the foundation of the tank. The purpose of the present invention is to provide a cryogenic tank structure that can maintain the temperature of the cryogenic tank, thereby improving the safety of this type of cryogenic tank as much as possible.

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

As shown in Figures 1 and 3, the outer tank body 1 buried underground is mainly composed of a concrete surrounding 1N+1 wall 2 and a bottom plate 3, and is a substantially bottomed cylinder with an opening above ground. It is formed into a body shape.

The surrounding side wall 2 and the bottom plate 3 are formed separately from each other.

The surrounding side wall 2 is formed in a cylindrical shape, and the bottom plate 3 is provided on the inner peripheral side of the bottom of the surrounding side wall 2 and is formed in a disc shape.

The joint or cut 5 in the joint 4 between the surrounding side wall 2 and the bottom plate 3 is configured such that the surrounding side wall 2 and the bottom plate 3 are allowed to move vertically relative to each other, as shown in FIG.

In particular, annular stepped portions 6°6 that are open to the inside of the tank body 1 and face each other are formed at the joint 4 between the surrounding side wall 2 and the bottom plate 3,
A support plate 7 is interposed within these stepped portions 6 to connect the surrounding side wall 2 and the bottom plate 3.

As shown in the figure, the joint portion 4 is formed in an annular shape at a part of the bottom corner, and the step portion 6 is formed in an annular shape along this.

The step portion 6 formed on the side wall 2 is constituted by a support piece 6a having an oval-shaped side cross section.

In addition, one or both of the stepped portions 6 have their bottom walls 8.
It may be formed so that it has an inclined taper so that it descends to the outside.

A support plate 7 that spans and spans the surrounding side wall 2 and the bottom plate 3 is fitted into the annular step portions 6, 6 formed in this way.

This support plate γ is made of reinforced concrete and has an appropriate thickness.
In addition, it is formed by blocks divided into an arbitrary number along the annular step portion 6.

Further, as shown in FIG. 3, the support plate 7 is formed to have a substantially rectangular cross section, and has horizontal or flat front and back surfaces.

Therefore, the flat surface portion 10 supports the bottom corner portion of the inner wall structure 11, which will be described later.

Inside the outer shell tank body 1 formed in this way, there is an inner wall structure 1.
1 will be formed.

As shown in FIGS. 1 to 3, this inner wall structure 11 mainly includes an auxiliary barrier 12, a heat-insulating cold-insulating material layer 13 formed on this auxiliary barrier 12, and a coating formed on this heat-insulating cold-insulating material layer 13. and a main barrier 14 which substantially contains a reservoir of liquid.

As shown in FIGS. 1 and 2, a segment 15 is stretched on the inner wall of the surrounding side wall 2 made of concrete, and an auxiliary barrier 12 is covered on the segment 15 in a sealed manner.

This auxiliary barrier 12 is formed by skin play 1-.

The segments 15 are formed of appropriately divided blocks, which are connected by connecting fittings 16 as shown in FIG.

The auxiliary barrier 15 is partially cut off at this connection, but the seal plate 15 is attached to cover this cut.
7 is provided.

Further, an auxiliary barrier 12 extending along the side wall 2 is formed at the joint portion of the bottom plate 3 .

As shown in FIG. 3, the auxiliary barrier 12 covers the support plate 7 and has its end fixed on the bottom plate 3.

Further, a telescopic joint 18 is interposed between the auxiliary barrier 12 covering the side wall 2 and the auxiliary barrier 12 covering the bottom plate 3.

A heat insulating and cold insulating material layer 13 having a predetermined thickness is formed on the auxiliary barrier 12 that covers the concrete tank inner wall in this manner.

A main barrier 14 is formed on the cold insulating material layer 13 to substantially accommodate the stored liquid.

The main barrier 14 is formed of a membrane panel formed from a 9% Ni steel plate or an alloy steel plate that has sufficient low temperature toughness to withstand low temperature liquid storage.

As shown in FIG. 2, the main barrier 14 is provided with an expandable joint 19, such as a corrugation, to allow for thermal contraction.

In particular, the main barrier 14 covering the joint 11 between the side wall 2 and the bottom plate 3 is provided with a telescopic joint 19 .

The main barrier 14 is also supported from the auxiliary barrier 12 by a fixed piece 20 made of a heat insulating material such as wood.

As shown in the figure, a leakage discharge inspection pipe 21 is provided between the auxiliary barrier 12 and the main barrier 14 to discharge and detect leakage such as leak gas leaked from the main barrier 14. .

As shown in FIG. 1, the base end 22 of this tube 21 passes through the tank body plate 26 and extends to the outside.

Further, holes 23 for nozzles are formed in this tube 21 at appropriate intervals.

The operation of the present invention having the above configuration will be described.

Since the inner wall structure of the concrete tank body 1 has a double structure of the main barrier 14 and the auxiliary barrier 12, even if the stored liquid leaks from the main barrier 14, the auxiliary barrier 12 acts as a secondary barrier. This will improve airtightness.

In the actual example shown in FIG. 3, the auxiliary barrier 12 is not formed in the center of the bottom plate 3, but this is because the concrete layer is thicker than the side wall 2.
This is because it is difficult for liquid etc. leaked from 4 to pass through.

Therefore, if the bottom plate 3 is thin due to soil conditions, etc., it goes without saying that an auxiliary barrier 12 may be provided to cover the entire bottom plate 3.

Since a leakage discharge inspection tube 21 is provided between the main barrier 14 and the auxiliary barrier 12, by extracting the atmosphere in this gap using the inspection tube 21, stored liquid etc. can be prevented from leaking from the main barrier 14. It is possible to check whether the

Further, since the liquid leaked between the main barrier 14 and the auxiliary barrier 12 remains without flowing out to the outside, it can be easily discharged and purged to the outside through the pipe 21.

Particularly in the conventional structure, gas purge during this period was extremely difficult because there is a possibility that leaked gas or the like would permeate into the ground.

For this reason, in the past, the space between the main barrier and the concrete tank wall and inside the tank could only be purged with nitrogen (N2) gas, so oxygen supply equipment must be worn during inspection and repair work. The workability was extremely poor.

However, in the present invention, the leaked gas or liquid between the main barrier 14 and the auxiliary barrier 12 can be completely purged, so the atmosphere inside the tank can be replaced with air, which improves work efficiency. 61 to improve over time.

Furthermore, if a plurality of gas concentration detection sensors are provided at arbitrary locations on the pipe 21, the efficiency of the purging operation can be further improved.

Next, at the beginning of construction of the tank, the step 6 formed at the joint 4 between the surrounding side wall 2 and the bottom plate 3 forming the outer tank body 1
Inside, the support plate 7 is placed at a predetermined level or horizontally and supports the bottom periphery of the inner wall structure 11.

By the way, as shown in Figure 4, when the bottom plate 3 sinks all around or partially as shown by the imaginary line due to ground movement, etc., the support plate 7 is located at the step 6 and extends from the enclosure side wall 2 side. Rotate to the bottom plate 3 side.

By rotating the support plate 7 in this manner, the bottom of the inner wall structure 11 is supported by the support plate 7, and the amount of displacement δ of the bottom plate 3 following the subsidence is not directly transmitted to the inner wall structure 11.

That is, even if a relative displacement occurs between the bottom plate 3 and the surrounding side wall 2 as the bottom plate 3 sinks, the support plate 7 rotates from the surrounding side wall 2 on the orientation side toward the bottom plate 3 and supports the inner wall structure 11. Therefore, the inner wall structure 11 will not be destroyed due to sufficient buffering.

In particular, no forced displacement is applied to the main barrier 14, cold insulating material layer 13, pipe 21, auxiliary barrier 12, etc.

Note that the support plate 7 may be pivoted at one end by a pin structure to allow rotation.

In addition, in the illustrated example, the leakage discharge inspection pipe 21 is provided in close contact with the auxiliary barrier 12, but where should it be located so as to be provided near the attachment part of the expandable joint 19? You can.

In the figure, 24 is sand, and 25 is a liquid-proof plate.

In summary, the present invention exhibits the following effects.

(1) It is possible to prevent the liquid stored in the tank from flowing out from the inner wall structure through the concrete tank body or from these gaps, improving the sealing performance of the tank as much as possible. can be done.

(2) Gas leaking into the inner wall structure can be completely purged, and tank repair and inspection can be carried out safely.

(3) Relative displacement between the side wall and the bottom plate due to fluctuations in liquid level or abnormal subsidence of the bottom plate can be absorbed, and the safety of the tank can be improved.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view showing a preferred embodiment of the present invention, and FIG.
The figure is a side sectional view showing the surrounding side wall portion of the tank body according to the present invention,
FIG. 3 is a cross-sectional view showing the joint between the side wall and the bottom plate of the tank body according to the present invention, and FIG. 4 is a cross-sectional view showing the working state of the joint shown in FIG. 3. In the figure, 1 is a concrete tank body, 2 is a surrounding side wall, 3 is a bottom plate, 4 is a joint, 6 is a step, 7 is a support plate, 11 is an inner wall structure, 12 is an auxiliary barrier, and 13 is a heat insulating cold insulation material. layer, 14
is the main barrier. 21 is the leakage discharge inspection pipe.

Claims (1)

[Claims] 1. Separate the surrounding side wall and bottom plate that form a bottomed cylindrical concrete tank body, and form annular step portions facing each other and open to the inside of the tank body at the joint between the surrounding side wall and the bottom plate. , a support plate is provided in the stepped portion to span the surrounding side wall and the bottom plate; an auxiliary barrier is coated on the inner walls of the surrounding side wall, the bottom plate, and the support plate to seal and cover the same; A heat insulating cold insulating material layer is formed on the heat insulating cold insulating material layer, a main barrier that substantially accommodates the liquid storage is formed on the heat insulating cold insulating material layer, and leakage from the main barrier is discharged between the supranuclear barrier and the auxiliary barrier. A low-temperature tank structure characterized by having a leakage discharge inspection tube for detecting leakage.