JPS6225597Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a low temperature storage tank having a void space (space) between the side wall of an inner tank and the side wall of an outer tank. The present invention relates to a void space top structure that shields radiant heat from the roof of an outer tank and prevents heat from entering the void space.

A low-temperature storage tank stores a liquefied gas such as LNG, ethylene, or propane at an extremely low temperature (NLG -162°C, ethylene -104°C, propane -45°C). Therefore, this storage tank has a heat-insulating or cold-insulating structure throughout the tank in order to protect the stored liquid from outside air temperature and solar heat.

That is, as for the cold insulation structure, a heat insulating material is attached to the inner peripheral side wall of the outer tank made of steel or concrete to form a cold insulation layer, and this cold insulation layer and the outer peripheral side wall of the inner tank are connected to each other. A void space is provided between the tank side walls to block external heat from the tank side wall, and in the case of the roof, a heat insulating material is pasted on the outer surface of the inner tank roof, and a void space is created between this heat insulating layer and the outer roof. The structure is such that it blocks external heat from the roof.

The conventional upper structure of a void space was the structure shown in FIG. That is, in order to facilitate the breathing of the so-called void space in which the gas expands as the temperature changes, the cold insulation material 5 attached to the inner circumferential side wall of the outer tank 1 and the inner tank 2 are It is formed between the outer peripheral side wall. The upper part of the void space 7 is the roof part 3 of the outer tank and the roof part 4 of the inner tank.
It had a structure in which it communicated with a space 8 between it and a heat insulating layer 6 attached to the outer surface.

As a result, the radiant heat from the roof 3 of the outer tank, which has been heated by solar heat, etc., enters the void space 7 through the communication section, the temperature inside the void space 7 rises, and the stored liquid evaporates due to this heat. This steam cools the roof 4 of the inner tank, which in turn cools the roof 3 of the outer tank, making the roof 3 of the outer tank embrittled and condensing, causing problems such as corrosion. It had the disadvantage of inducing

Further, in the communication section, the volume and pressure of the gas in the void space 7 and the roof space 8 change under the influence of outside temperature and atmospheric pressure, producing a kind of gas flow, and this gas flow causes the void space 7 to change in volume and pressure. Heat is input into the container, or the exposed portion of the outer tank 1 becomes brittle due to cooling, which also causes other problems such as embrittlement, and if the outer tank is made of concrete, it may cause cranking.

The present invention aims to provide a void space superstructure that solves the above-mentioned conventional drawbacks.

In other words, the present invention loads a heat insulating material into the above-mentioned communication section to shield the radiant heat from the outer tank roof and prevent heat from entering the void space, while the gas in the void space is exposed to fluctuations in outside pressure and to the inner tank. Since the outer tank expands and contracts due to minute deformations during operation, the above-mentioned insulating material is made breathable to allow gas to breathe, and at the same time, a cold insulating layer attached to the inner circumferential surface of the outer tank and a cooling layer attached to the inner circumferential surface of the inner tank are used. Load the above insulation material between the cold insulation layer attached to the roof,
It is characterized by preventing heat input into the void space and cooling embrittlement of the exposed surface of the outer tank caused by gas flow in the void space and the roof.

The details will be explained below using examples shown in the drawings.
FIG. 2 shows an embodiment of the present invention. In the figure, a cold insulation layer 5 such as polyurethane foam is attached to the inner peripheral surface of an outer tank 1, and a space is provided between this cold insulation layer 5 and the outer peripheral surface of the inner tank 2 to form a void space 7. It blocks external heat from the side wall. A plurality of brackets 11 are attached to the peripheral wall of the inner tank 2 in the upper part of this void space 7, and a part of the cold insulation layer 5 is removed according to the mounting height of the brackets 11 to form a cold insulation layer 10. A cold insulating layer 6 pasted on the roof 4 covers this bracket 11, and a heat insulating material 9 is loaded between this cold insulating layer 6 and the missing cold insulating layer 10. This insulation material 9
For example, the material is breathable, such as glass wool, or is made of a separate material with structural ventilation holes, and has the property of blocking radiant heat. Note that 12 is a liner that is provided as appropriate depending on the design. In this embodiment configured as described above, radiant heat from the roof portion 3 of the outer tank is shielded by the heat insulating material 9. On the other hand, the gas in the void space 7 and the roof space 8 undergoes volume and pressure fluctuations due to the influence of the temperature and pressure of the outside air, and as a result of these fluctuations, the gas in the void space 7 expands or flows, resulting in what is called breathing. do.

This absorption of breath is carried out by the breathability of the insulation material 9, which balances the pressure between the void space 7 and the roof space 8 and allows the gas inside to circulate. In this way, while the internal gas flows through the heat insulating material 9, the gas temperature in the void space 7 and the gas temperature in the roof space 8 fluctuate smoothly. For example, when gas in the roof space 8 flows into the void space 7 , its temperature is lowered to a temperature almost close to the gas temperature in the void space 7 while passing through the heat insulating material 9 . Furthermore, when this gas passes through, the low-temperature gas does not come into direct contact with the outer tank 1 due to the cold insulation layer 6, so the outer tank is not cooled, and frost formation on the outer surface of the outer tank and embrittlement of the outer tank material are avoided.

As detailed above, according to the present invention, a breathable heat insulating material is loaded in the upper part of the void space and the upper part of the void space is closed, completely shielding the radiant heat from the roof of the outer tank. It facilitates breathing in the void space, and although the gas flowing through this breathing inevitably involves some heat transfer, it minimizes the evaporation of the stored liquid, and at the same time, it also minimizes the evaporation of the storage liquid even when the gas moves up and down. It is possible to obtain a void space superstructure that solves all of the conventional drawbacks, such as eliminating cooling embrittlement and freezing and solving problems such as material deterioration caused by this, and has great practical effects.

[Brief explanation of the drawing]

Both FIG. 1 and FIG. 2 are longitudinal cross-sectional views of a part of a low-temperature storage tank. FIG. 1 shows the upper structure of a conventional void space, and FIG. FIG. 1...outer tank, 2...inner tank, 5...cold layer, 7...
...Void space, 9...Insulation material.

Claims (1)

[Scope of utility model registration request] It is a double-shell low temperature storage tank consisting of an inner tank and an outer tank, and a heat insulating material is attached to the inner peripheral side wall of the outer tank to form a cold insulation layer, and the cold insulation layer and the outer peripheral side wall of the inner tank are connected to each other. In a low-temperature storage tank with a void space formed between the tank, the insulation layer has air permeability between the upper part of the cold insulation layer provided on the inner peripheral surface of the outer tank and the lower edge of the cold insulation layer provided on the roof of the inner tank. A void space top structure of a low temperature storage tank, characterized in that the top of the void space communicating with the roof space is closed by the insulation material.