JP7261007B2 - double shell tank - Google Patents

Description

The present invention relates to the structure of a double-hull tank comprising an outer tank and an inner tank.

BACKGROUND OF THE INVENTION Conventionally, double-shell tanks are known as tanks for storing cryogenic liquids. A double-shell tank is generally formed between an inner tank that substantially contains a cryogenic liquid, an outer tank that covers the inner tank from the outside at a predetermined interval, and the inner tank and the outer tank. and a heat insulating layer. The heat insulating layer is formed of, for example, a granular heat insulating material filled between the inner tank and the outer tank, and perlite is used as the granular heat insulating material.

When constructing a double-shell tank, after the inner tank and the outer tank are completed, the granular heat insulating material is filled so as to fill the space between the inner tank and the outer tank while the inner tank is empty. Therefore, when the inner tank is supplied with low-temperature liquid and the inner tank thermally contracts, the gap between the inner tank and the outer tank widens, and the granular heat insulating material filled between the inner tank and the outer tank can settle. have a nature. When the granular heat insulating material settles, a space without the granular heat insulating material is created at the tank top of the double-shell tank, and the thickness of the heat insulating layer at the top of the tank is reduced. If there is an area where the thickness of the heat insulating layer is insufficient in the double-shell tank, the heat insulating properties of that area will be degraded. Due to the deterioration of heat insulation, cold heat from the inner tank may be transferred to the outer tank, causing frost to form on the outer tank and causing corrosion of the outer tank. In addition, if the amount of heat input to the inner tank increases due to the deterioration of the heat insulating properties, the amount of boil-off gas of the low-temperature liquid increases, and the pressure in the inner tank may become excessive.

Therefore, in the double-shell tank of Patent Document 1, an inner heat insulating layer formed of a stretchable material (glass wool) that can be stretched in the radial direction of the inner tank and an outer heat insulating layer formed of a filler (perlite) are used. It has a heat insulating layer consisting of two layers, inner and outer. In this double-shell tank, the gaps formed in the heat-insulating layer due to thermal contraction of the inner tank are filled with the expanded stretchable material, thereby suppressing sedimentation of the filler.

JP 2013-238285 A

In particular, for double-shell tanks installed outdoors, it is essential to reduce the amount of heat input to the top of the tank due to solar radiation. In spite of this, when the insulating layer between the inner tank and the outer tank is formed of the granular heat insulating material, the sedimentation of the granular heat insulating material reduces the heat insulating properties of the top of the tank as described above.

According to the double-shell tank of Patent Document 1, sedimentation of the granular heat insulating material (filler) can be suppressed, but the cost increases because glass wool, which is more expensive than perlite, is frequently used.

The present invention has been made in view of the above circumstances, and its object is to form a heat insulating layer between the inner tank and the outer tank using granular heat insulating material, and to form a heat insulating layer between the inner tank and the outer tank, and To provide a double shell tank capable of maintaining a heat insulating layer having an appropriate thickness on the top of the tank even after a heat insulating material settles.

A double-hulled tank according to one aspect of the present invention comprises:
a spherical shell-shaped inner tank in which a reservoir for storing liquid in a sealed state is formed;
an outer tank covering the inner tank;
a granular heat insulating material that fills a space surrounded by the outer wall of the inner tank and the inner wall of the outer tank to form a heat insulating layer,
The size of the top gap between the inner tank and the outer tank is equal to the size of the bottom gap between the inner tank and the outer tank, and the inner tank is empty and the inner tank contains the liquid. is equal to or greater than the value obtained by adding the level difference between the granular heat insulating material and
The outer tank is composed of a lower hemispherical shell, an upper hemispherical shell, and a cylindrical body connecting the lower hemispherical shell and the upper hemispherical shell, and the center of the inner tank and the lower hemispherical shell. is characterized by matching the center of

According to the double-shell tank, since the size of the gap at the top is larger than the size of the gap at the bottom, when the inner tank is empty, a heat insulating layer thicker than that at the bottom of the tank is formed at the top of the tank. When the low-temperature liquid is supplied to the inner tank and the inner tank shrinks, the gap between the inner tank and the outer tank widens, and the granular heat insulating material filled between the inner tank and the outer tank sinks. A sufficiently thick insulating layer is maintained at the top of the tank even when the granular insulating material has settled. Therefore, according to the above double-shell tank, the insulating layer is formed between the inner tank and the outer tank by the granular heat insulating material, and the tank remains even after the granular heat insulating material settles due to the contraction deformation of the inner tank. It is compatible with keeping an insulating layer of appropriate thickness on the top. Below the equator of the inner tank, a heat insulating layer of constant thickness is formed around it. Above the equator of the inner tank, a heat insulating layer is formed around it which is thicker than the heat insulating layer below the equator of the inner tank. The outer tank has a shape similar to a spherical shell, and can be provided with sufficient strength.

According to the present invention, a heat insulating layer is formed between the inner tank and the outer tank by the granular heat insulating material, and even after the granular heat insulating material settles due to the contraction deformation of the inner tank, the thickness of the heat insulating material is maintained at the top of the tank. It is possible to provide a double-hulled tank compatible with maintaining a thin insulating layer.

FIG. 1 is a cross-sectional view showing the overall configuration of an empty double-shell tank according to Reference Example 1 of the present disclosure . FIG. 2 is a cross-sectional view of the double-shell tank showing a state in which cryogenic liquid is supplied to the inner tank shown in FIG. 1; FIG. 3 is a cross-sectional view showing the overall configuration of an empty double-hulled tank according to the first embodiment of the present disclosure ; FIG. 4 is a cross-sectional view of the double-hull tank showing the cryogenic liquid supplied to the inner tank shown in FIG. FIG. 5 is a cross-sectional view showing the overall configuration of an empty double-shell tank according to Reference Example 2 of the present disclosure . FIG. 6 is a cross-sectional view of the double-shell tank showing a state in which cryogenic liquid is supplied to the inner tank shown in FIG.

[ Reference example 1 ]
Next, reference example 1 of the present disclosure will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing the overall configuration of an empty double-shell tank 1A according to Reference Example 1 of the present disclosure , and FIG. It is sectional drawing of 1 A of double shell tanks which show a state.

A double-shell tank 1A shown in FIGS. 1 and 2 is a tank for storing a cryogenic liquid 7 such as liquid hydrogen, liquid nitrogen, or liquefied natural gas. The double-hull tank 1A is installed on the hull or on the ground while being supported by skirts or struts (not shown).

The double shell tank 1A comprises an inner tank 2, an outer tank 3 covering the inner tank 2, a granular heat insulating material 4 filled between the inner tank 2 and the outer tank 3 to form a heat insulating layer, and the inner tank 2 and a vacuum pump 6 for evacuating the space between the tank and the outer tank 3.

The inner tank 2 has a hollow spherical shell shape, and is formed by welding a number of SUS panels, for example. Inside the inner tank 2, a storage part 21 is formed for storing the low-temperature liquid 7 in a sealed state. The inner tank 2 can allow contraction deformation and deformation recovery due to the temperature difference between the normal temperature when the tank is constructed and the low temperature when the cryogenic liquid 7 is stored.

The outer tank 3 has a hollow spherical shell shape that is one size larger than the inner tank 2, and is formed by, for example, welding a large number of steel plates. The diameter of the outer tub 3 is larger than the diameter of the inner tub 2 . The inner tub 2 is supported by the outer tub 3 by a rod or the like (not shown) connecting the outer wall of the inner tub 2 and the inner wall of the outer tub 3 .

The granular heat insulating material 4 fills the space surrounded by the outer wall of the inner tank 2 and the inside of the outer tank 3 in a compacted state. The granular heat insulating material 4 is, for example, granular perlite. However, as the granular heat insulating material 4, a known granular heat insulating material other than pearlite may be adopted.

A space between the inner tank 2 and the outer tank 3 filled with the granular heat insulating material 4 is forcibly evacuated by a vacuum pump 6 to be in a substantially vacuum state. By making the space filled with the granular heat insulating material 4 substantially vacuum in this way, the heat insulating effect is further enhanced.

A vertical line passing through the center 3c of the outer tank 3 and a vertical line passing through the center 2c of the inner tank 2 coincide with the tank centerline C of the double-shell tank 1A. At the bottom of the tank, the gap between the inner wall of the outer tank 3 and the outer wall of the inner tank 2 on the center line C of the tank is referred to as a "bottom gap G1". At the top of the tank, the gap between the inner wall of the outer tank 3 and the outer wall of the inner tank 2 on the center line C of the tank is called "top gap G2".

In the double-shell tank 1A according to this reference example , the inner tank 2 and the outer tank 3 are arranged such that the top clearance G2 is larger than the bottom clearance G1. In other words, the inner tub 2 and the outer tub 3 are arranged such that the center 3c of the outer tub 3 is located above the center 2c of the inner tub 2. As shown in FIG. The center 3 c of the outer tank 3 is the center of the spherical shell shape of the outer tank 3 , and the center 2 c of the inner tank 2 is the center of the spherical shell shape of the inner tank 2 .

The size L2 of the top gap G2 is the same as the size L1 of the bottom gap G1. It is equal to or greater than the value obtained by adding the level difference ΔL of the heat insulating material 4 . That is, the following formula 1 is established.
L2>L1+ΔL (Formula 1)
The level difference ΔL (that is, the sedimentation amount of the granular heat insulating material 4) can be obtained by calculation or simulation.

As described above, the double-shell tank 1A according to this reference example includes a spherical-shell-shaped inner tank 2 in which a storage part 21 for storing the low-temperature liquid 7 in a sealed state is formed, and the inner tank 2. It comprises an outer tank 3 for covering, and a granular heat insulating material 4 filling a space surrounded by the outer wall of the inner tank 2 and the inner wall of the outer tank 3 to form a heat insulating layer. The size L2 of the top gap G2 between the inner tank 2 and the outer tank 3 is equal to the size L1 of the bottom gap G1 between the inner tank 2 and the outer tank 3. It is equal to or greater than the value obtained by adding the level difference ΔL of the granular heat insulating material 4 to the state in which the low-temperature liquid 7 is accommodated.

In the double-shell tank 1A, since the size L2 of the top gap G2 is larger than the size L1 of the bottom gap G1, when the inner tank 2 is empty, a heat insulating layer thicker than the tank bottom is formed at the top of the tank. (See Figure 1). When the low-temperature liquid 7 is supplied to the inner tank 2 and the inner tank 2 shrinks, the gap between the inner tank 2 and the outer tank 3 widens, and the particles filled between the inner tank 2 and the outer tank 3 are discharged. Although the heat insulating material 4 settles, a heat insulating layer having a sufficient thickness L2' is maintained at the top of the tank even when the granular heat insulating material 4 settles (see FIG. 2).

As described above, according to the double-shell tank 1A according to the present reference example , the heat insulating layer is formed between the inner tank 2 and the outer tank 3 by the granular heat insulating material 4, and the shrinkage deformation of the inner tank 2 results in Thus, it is possible to maintain a heat insulating layer having an appropriate thickness L2' on the top of the tank even after the granular heat insulating material 4 settles.

Further, in the double shell tank 1A according to this reference example , the outer tank 3 has a spherical shell shape, and the center 3c of the outer tank 3 is located above the center 2c of the inner tank 2. As shown in FIG.

In this way, by eccentrically lowering the center 2c of the inner tank 2 with respect to the center 3c of the outer tank 3, both the outer tank 3 and the inner tank 2 have a spherical shell shape excellent in strength, while the inner tank 2 and the inner tank 2 are The size L2 of the top clearance G2 with the outer tub 3 can be made larger than the size L1 of the bottom clearance G1 between the inner tub 2 and the outer tub 3 .

[ First embodiment]
Next, a first embodiment of the present disclosure will be described. FIG. 3 is a cross-sectional view showing the overall configuration of an empty double-hulled tank 1B according to the first embodiment of the present disclosure . FIG. 4 is a sectional view of the double-shell tank 1B showing a state in which the cryogenic liquid 7 is supplied to the inner tank 2 shown in FIG. In the description of the present embodiment, the same or similar members as those of Reference Example 1 described above are denoted by the same reference numerals in the drawings, and the description of Reference Example 1 is cited by reference to avoid overlapping detailed descriptions. omitted.

As shown in FIGS. 3 and 4, the double-shell tank 1B according to the present embodiment includes a spherical-shell-shaped inner tank 2 in which a storage part 21 for storing the low-temperature liquid 7 in a sealed state is formed, An outer tank 3 covering the inner tank 2 and a granular heat insulating material 4 filling a space surrounded by the outer wall of the inner tank 2 and the inner wall of the outer tank 3 to form a heat insulating layer are provided.

The outer tank 3 is composed of a lower hemispherical shell portion 31, an upper hemispherical shell portion 32, and a cylindrical trunk portion 33 connecting the lower hemispherical shell portion 31 and the upper hemispherical shell portion 32 in the vertical direction. The diameters of the lower hemispherical shell portion 31, the upper hemispherical shell portion 32, and the body portion 33 are equal and larger than the diameter of the inner tank 2.

The inner tank 2 and the outer tank 3 are arranged so that the center 2c of the inner tank 2 and the center 31c of the lower hemispherical shell portion 31 are aligned. The inner tub 2 is supported by the outer tub 3 by a rod or the like (not shown) connecting the outer wall of the inner tub 2 and the inner wall of the outer tub 3 .

As described above, in the double shell tank 1B according to the present embodiment, the outer tank 3 connects the lower hemispherical shell portion 31, the upper hemispherical shell portion 32, and the lower hemispherical shell portion 31 and the upper hemispherical shell portion 32. The center 2c of the inner tank 2 and the center 31c of the lower hemispherical shell 31 are aligned.

In the above double shell tank 1B, a heat insulating layer with a constant thickness is formed around the inner tank 2 below the equator, and a heat insulating layer below the inner tank 2 above the equator is formed around the inner tank 2 above the equator. A heat insulating layer thicker than the heat insulating layer is formed. In this manner, the size L2 of the top gap G2 between the inner tank 2 and the outer tank 3 is equal to the size L1 of the bottom gap G1 between the inner tank 2 and the outer tank 3. The double-shell tank 1B having a simple structure is realized with a value equal to or greater than the sum of the level difference ΔL of the granular heat insulating material 4 and the state in which the low-temperature liquid 7 is stored in the tank 2 . Moreover, the inner tank 2 has a spherical shell shape, and the outer tank 3 is also not a spherical shell, but can have a shape similar to a spherical shell, and the outer tank 3 can be provided with sufficient strength.

[ Reference example 2 ]
Next, Reference Example 2 of the present disclosure will be described. FIG. 5 is a cross-sectional view showing the overall configuration of an empty double-shell tank 1C according to Reference Example 2 of the present disclosure . FIG. 6 is a sectional view of the double-shell tank 1C showing a state in which the cryogenic liquid 7 is supplied to the inner tank 2 shown in FIG. In the description of this reference example , the same or similar members as those of the reference example 1 described above are denoted by the same reference numerals in the drawings, and detailed description thereof will be omitted.

As shown in FIGS. 5 and 6, the double-shell tank 1C according to this reference example includes a spherical-shell-shaped inner tank 2 in which a storage part 21 for storing a low-temperature liquid 7 in a sealed state is formed, An outer tank 3 covering the inner tank 2 and a granular heat insulating material 4 filling a space surrounded by the outer wall of the inner tank 2 and the inner wall of the outer tank 3 to form a heat insulating layer are provided.

The outer tub 3 is composed of a main body portion 35 having a spherical shell shape and a dome portion 36 provided on the top of the main body portion 35 . The shape of the dome portion 36 is not particularly limited, but may be, for example, a shape in which a pod is turned upside down. If it is assumed that the dome portion 36 does not exist, ΔV is the volume of the void generated at the top of the main body portion 35 due to the sedimentation of the granular heat insulating material 4 of the main body portion 35 as the inner tank 2 shrinks and deforms. The volume of the dome portion 36 is greater than ΔV. That is, the dome portion 36 is filled with the granular heat insulating material 4 having a volume larger than ΔV.

The inner tub 2 and the outer tub 3 are arranged so that the center 2c of the inner tub 2 and the center 35c of the main body 35 are aligned. The inner tub 2 is supported by the outer tub 3 by a rod or the like (not shown) connecting the outer wall of the inner tub 2 and the inner wall of the outer tub 3 .

As described above, in the double-shell tank 1C according to this reference example , the outer tank 3 is composed of the main body portion 35 having a spherical shell shape and the dome portion 36 provided on the top of the main body portion 35. The center 2c of the tank 2 and the center 35c of the main body 35 are aligned.

In the double shell tank 1</b>C, a dome portion 36 filled with granular heat insulating material 4 is provided on the top of the main outer tank 3 body portion of the outer tank 3 . In this manner, the size L2 of the top gap G2 between the inner tank 2 and the outer tank 3 is equal to the size L1 of the bottom gap G1 between the inner tank 2 and the outer tank 3. The double-shell tank 1B having a simple structure is realized with a value equal to or greater than the sum of the level difference ΔL of the granular heat insulating material 4 and the state in which the low-temperature liquid 7 is stored in the tank 2 .

In the double-shell tank 1C, even if the inner tank 2 shrinks and deforms and the granular heat insulating material 4 filled between the inner tank 2 and the main body part 35 of the outer tank 3 sinks, the settling amount is compensated by the granular heat insulating material 4 filled in the dome portion 36 . Therefore, even when the granular heat insulating material 4 is sedimented, a heat insulating layer having a sufficient thickness L2' is maintained at the top of the tank.

Although the preferred embodiments of the present invention have been described above, the present invention may include modifications of the details of the specific structures and/or functions of the above embodiments without departing from the spirit of the present invention. .

1A, 1B, 1C: Double shell tank 2: Inner tank 2c: Center of inner tank 3: Outer tank 3c: Center of outer tank 4: Granular heat insulating material 6: Vacuum pump 7: Cryogenic liquid 21: Storage part 31: Bottom Hemispherical shell portion 31c: Center of lower hemispherical shell portion 32: Upper hemispherical shell portion 33: Body portion 35: Body portion 35c: Center of body portion 36: Dome portion C: Tank center line G1: Bottom clearance G2: Top clearance ΔL: level difference

Claims (1)

a spherical shell-shaped inner tank in which a reservoir for storing liquid in a sealed state is formed;
an outer tank covering the inner tank;
a granular heat insulating material that fills a space surrounded by the outer wall of the inner tank and the inner wall of the outer tank to form a heat insulating layer,
The size of the top gap between the inner tank and the outer tank is equal to the size of the bottom gap between the inner tank and the outer tank, and the inner tank is empty and the inner tank contains the liquid. is equal to or greater than the value obtained by adding the level difference between the granular heat insulating material and
The outer tank is composed of a lower hemispherical shell, an upper hemispherical shell, and a cylindrical body connecting the lower hemispherical shell and the upper hemispherical shell, and the center of the inner tank and the lower hemispherical shell. coincides with the center of
double shell tank.

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