JPH0448400Y2 - - Google Patents

Description

[Detailed explanation of the invention] [Industrial application field] This invention relates to the improvement of double-shell cryogenic tanks, and in particular, the outer tank is also constructed of low-temperature material so that low-temperature liquid can be stored even in the event of an emergency. In addition to making it possible to perform water-filled tests on the inner and outer tanks with a double safety structure, the bottom cold insulation material can be sealed and replaced with _N2 gas, making it possible to detect gas leaks.

[Conventional technology]

Liquefied petroleum gas (LPG) and liquefied natural gas (LNG)
To store low-temperature liquids such as liquids, an outer tank is installed to cover the outside of the inner tank in which the low-temperature liquid is stored, and an insulating cold material is filled between the inner and outer tanks to prevent heat from entering from the outside and prevent evaporation. Double-shell cryogenic tanks are often used to reduce gas emissions.

Normally, in a double-shell low-temperature tank, the inner tank, which is in direct contact with the low-temperature liquid, is made of bottom-temperature resistant material, and the outer tank, which is placed on the outside with an insulating cold material in between, is made of room-temperature material.

However, if the inner tank is damaged due to a large earthquake, etc., the leaked low-temperature liquid will come into direct contact with the outer tank, causing brittle failure of the outer tank, and causing damage to the liquid barrier on the outside of the double-shell cryogenic tank. leakage must be stopped.

Therefore, double-shell cryogenic tanks are being constructed that further improve safety by making the outer tank also from low-temperature resistant materials.

In this double-shell cryogenic tank, in the case of an emergency, the outer tank also stores low-temperature liquid, so at the construction stage, like the inner tank,
It is necessary to perform a water filling test on the outer tank.

[Problem that the invention attempts to solve]

By the way, in a normal double shell low temperature tank, the second
As shown in the figure, an outer tank side plate 3 is constructed around an outer tank bottom plate 2 laid on a foundation 1, and an outer tank roof 4 is attached to the upper part, while a bottom cold insulation material 5 is installed on the outer tank bottom plate 2. An inner tank bottom plate 6 is laid through the inner tank bottom plate 6, an inner tank side plate 7 is constructed around this inner tank bottom plate 6, and a suspended deck 8 has a heat insulating cold insulation material attached to the outer tank roof 4 so as to close the upper end of the inner tank. is suspended,
Together with the heat insulating cold insulating material 9 between the inner and outer tanks, it is designed to prevent heat intrusion from the outside.Before filling the insulating and cold insulating material 9 between the inner and outer tanks, water is poured between the inner and outer tanks to perform a water filling test on the outer tank. As a result, water seeps into the bottom cold insulating material 5, resulting in a decrease in performance.

Therefore, in order to prevent water from seeping into the bottom cold insulating material 5, it is necessary to seal the area around the bottom cold insulating material 5 with a steel plate and perform the water filling test. The heat shrinkage of the bottom plate 6 and the inner tank side plates 7 is restricted, which causes stress generation, so that they must be cut and removed after the water test, which is very complicated.

In addition, while operating a double-shell cryogenic tank,
There is also the problem that flammable gases such as LPG and LNG enter between the inner and outer tanks through the gap between the suspended deck 8 and the upper end of the inner tank side plate 7, and mix with the air remaining in the bottom cold insulator 5. be.

This idea was made in view of the problems of the prior art, and it allows for easy water filling tests between the inner and outer tanks, as well as a double-shell low-temperature structure that eliminates the air in the bottom cold insulating material to keep it even safer. It is intended to provide a tank.

[Means for solving problems]

In order to solve the above problems, the double-shell cryogenic tank of this invention has a bottom cold insulating material installed on the bottom plate of the outer tank through the bottom cold insulating material, and a bottom cold insulating material is installed at the annular part between the lower end of the side plate of the inner tank and the bottom plate of the outer tank. A sealing material is provided to seal the interior of the tank as well as to enable a water filling test between the inner and outer tanks.A deformation absorbing portion that can absorb thermal deformation is provided in this sealing material. This is characterized by the provision of purge and gas detection pipes that are piped outside the tank.

[Effect]

A seal plate is installed between the outer tank bottom plate and the lower end of the inner tank side plate of the double-shell low-temperature tank to enable water filling tests between the inner and outer tanks without affecting the bottom cold insulation material in any way. By installing a deformation absorption part such as an expansion or corrugation on the board, it is possible to permanently install it, and by eliminating the air from the bottom cold insulation material part sealed with this sealing board to create a nitrogen atmosphere, it is possible to prevent leakage of stored liquid. I am trying to use it for detection.

〔Example〕

Hereinafter, one embodiment of this invention will be described in detail based on the drawings.

FIG. 1 is a sectional view of an embodiment of the double-shell cryogenic tank of this invention.

The structure of the inner tank 12 and outer tank 11 of this double-shell cryogenic tank 10 is the same as that of the double-shell cryogenic tank explained in FIG. For example, an outer tank bottom plate 2 made of 9% nickel steel is laid, an outer tank side plate 3 made of low temperature resistant material is constructed around this, and the upper part is covered with an outer tank roof 4 to form an airtight structure for the outer tank. On the other hand, an inner tank bottom plate 6 made of a low temperature resistant material such as 9% nickel steel is laid on the outer tank bottom plate 2 through a pearlite concrete ring and a bottom cold insulation material 5 such as foam glass, and the inner tank bottom plate 6 is made of a low temperature resistant material such as 9% nickel steel. A side plate 7 is constructed to form an inner tank 12 with an open upper end, and a suspended deck 8 to which a heat insulating material such as urethane foam is attached is provided from the outer tank roof 4 so as to close the upper end of the inner tank 12. In addition, a heat insulating cold insulation material 9 is added between the inner and outer tanks.
is installed.

A seal plate 13 is arranged between the inner and outer tanks of such a double-shell low temperature tank 10 so as to close the annular portion between the lower end of the inner tank side plate 7 and the outer tank bottom plate 2 corresponding to the lower end of the inner tank side plate 7. The upper edge of the seal plate 13 is welded to the inner tank side plate 7, and the lower edge to the outer tank bottom plate 2.

This sealing plate 13 is made of a thin plate of a low-temperature resistant material such as stainless steel because it will come into contact with low-temperature liquid in the event of an emergency, and a deformation absorbing portion 13a with a semicircular cross section that bulges outward is provided in the middle of the sealing plate 13. are formed integrally or with a welded structure in the form of a helical joint, and can cope with thermal contraction during storage of low-temperature liquids, as well as cope with thermal expansion during discharge of low-temperature liquids.

A pressure-bearing material 14 such as hard urethane foam is interposed between the inner tank side plate 7 and the bottom cold insulating material 5 on the back side of the seal plate 13. The seal plate 13 formed of a thin plate is designed not to be damaged even if liquid head pressure is applied.

In addition, a purge pipe 15 is installed inside the foundation 1 and communicates with the bottom cold insulating material 5 sealed by the seal plate 13.
is buried, and is used to supply nitrogen gas through the on-off valve 16 to replace the air in the bottom cold insulation material 5. During operation, a gas detector is connected through the on-off valve 16, and the gas is stored. Used for gas leak detection.

In the double shell low temperature tank 10 configured as above,
After completing the construction of the inner and outer tanks, first, water is poured into the inner tank 12 to perform a water filling test, and after the test is completed, water is poured between the inner and outer tanks to perform a water filling test of the outer tank 11.
In order to prevent the inner tank 12 from buckling, the inner tank 12 is also filled with water.

When the water filling test of the outer tank 11 is performed in this way, since the bottom between the inner and outer tanks is sealed with the seal plate 13, water does not seep into the bottom cold insulation material 5 and cause a decrease in performance, and furthermore, the back side of the seal plate 5 Since the bearing member 14 is interposed in the seal plate 5, the seal plate 5 will not be damaged.

On the other hand, when the seal plate 13 is left in operation and low-temperature liquid is stored in the inner tank 12, the inner tank 1
2, but since the sealing plate 13 is provided with a deformation absorbing portion 13a, the deformation can be absorbed by this portion, and stress is prevented from being generated in each portion.

Furthermore, when low-temperature liquid is stored, evaporated gas (BOG) will flow between the inner and outer tanks through the gap with the suspended deck 8, but the inner and outer tanks are sealed with a seal plate 13. Moreover, if the air in the bottom cold insulating material 5 is replaced with nitrogen using the purge pipe 15, there will be no mixing of flammable gas such as LPG or LNG with air, further improving safety.

Furthermore, if a gas detector is connected to the purge pipe 15 after replacing the air in the bottom cold insulating material 5 with nitrogen, even if a leak of low-temperature liquid occurs, it will be immediately detected. can be dealt with.

In the above embodiment, the upper end of the inner tank is closed with a suspended deck, but the present invention can also be applied to a double-shell low-temperature tank in which the inner tank is sealed with a roof.

[Effect of idea]

As described above in detail with one embodiment, according to the double-shell cryogenic tank of this invention, a sealing plate having a deformation absorbing portion is provided between the outer tank bottom plate and the lower end of the inner tank side plate. I made sure to close it tightly, so
Water filling tests can be performed on the outer tank by pouring water between the inner and outer tanks without causing any adverse effects such as water seeping into the bottom cold insulation material.

In addition, since the bottom cold insulating material part is also sealed, the air in this part is purged and replaced with nitrogen, preventing flammable gas from mixing with air in the unlikely event of an accident, making it even safer than conventional structures. can be improved, and
This closed space can also be used to detect leaked gas in case of an emergency.

Furthermore, even if the seal plate is permanently installed, the deformation absorbing portion can absorb the thermal contraction and thermal expansion that occur when receiving and discharging low-temperature liquid, so large stresses are not generated on the inner tank side plates or the outer tank bottom plate.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the double-shell cryogenic tank of this invention, and FIG. 2 is a sectional view of a conventional example. 1...Foundation, 2...Outer tank bottom plate, 3...Outer tank side plate, 4...Outer tank roof, 5...Bottom cold insulation material, 6...
Inner tank bottom plate, 7...Inner tank side plate, 8...Suspended deck, 9...Insulating cold insulation material, 10...Double shell low temperature tank, 11...Outer tank, 12...Inner tank, 13...
... Seal plate, 13a ... Deformation absorbing section, 14 ... Pressure bearing material, 15 ... Purge piping, 16 ... Opening/closing valve.

Claims (1)

[Scope of utility model registration request] A sealing material is installed on the bottom plate of the outer tank through the bottom cold insulating material to seal the bottom cold insulating material to the annular part between the lower end of the side plate of the inner tank and the bottom plate of the outer tank, and to enable a water filling test between the inner and outer tanks. A deformation absorbing portion capable of absorbing thermal deformation is provided in this sealing material, and a purge and gas detection pipe is provided that communicates with the space sealed by this sealing material and is piped to the outside of the outer tank. A double-shell cryogenic tank featuring