JP6920098B2 - Cold liquid storage tank - Google Patents

Description

The present invention relates to a cold liquid storage tank for storing a low temperature liquid such as liquefied natural gas.

Conventionally, a cold liquid storage tank for storing a low temperature liquid such as liquefied natural gas has been known. For example, in Patent Document 1, a cylindrical prestressed concrete (hereinafter, “PC”) liquid barrier, an outer tank provided inside the PC liquid barrier, and an inner tank of the outer tank. A cold liquid storage tank provided with an inner tank for storing the low temperature liquid is disclosed.

The PC liquid barrier is designed to accommodate the entire amount of the stored liquid in the inner tank in case the low temperature liquid stored in the inner tank leaks out. The outer tank has a cylindrical outer tank side plate attached to the inner peripheral surface of the PC liquid barrier and a spherical outer tank roof plate having a peripheral edge supported at the upper end of the PC liquid barrier. .. The inner tank consists of a cylindrical inner tank side plate erected inside the outer tank side plate, a spherical inner tank roof plate provided below the outer tank roof plate, and the upper end and inner tank of the inner tank side plate. It has a knuckle plate that connects to the peripheral edge of the roof plate. Since the knuckle plate exerts a compressive force in the circumferential direction due to the action of the internal pressure of the inner tank, the plate thickness is made larger than that of the inner tank side plate and the inner tank roof plate connected to the knuckle plate to ensure the strength.

Japanese Unexamined Patent Publication No. 2015-96758

By the way, it is desired that such a low temperature liquid storage tank be designed so that the maximum liquid storage amount is increased as much as possible, but the height and diameter of the low temperature liquid storage tank cannot be easily increased. is the current situation. For example, if the height of the tank exceeds a predetermined height (for example, 60 m), it is necessary to install an aviation obstruction light with an explosion-proof structure in the tank to indicate the existence of the tank to the aircraft in flight, which is not realistic. No. Therefore, there is a demand that the height of the tank should be suppressed to a height that does not require the installation of obstruction lights. Further, when the diameter of the tank, that is, the diameter of the cylindrical portion of the inner tank is increased, the thickness of the knuckle plate is also increased. However, for a knuckle plate using a low-temperature steel material such as 9% Ni steel, if the thickness exceeds a predetermined thickness, the on-site weld must be heat-treated, and the inner tank is such that the knuckle plate is within the predetermined thickness. The diameter of the cylindrical part is also limited. As described above, there are various restrictions on the tank height and the diameter of the inner tank cylinder, and it is difficult to design and manufacture a tank having a larger maximum liquid storage capacity than the conventional tank.

Therefore, an object of the present invention is to provide a low temperature liquid storage tank designed to increase the maximum liquid storage amount while suppressing the tank diameter and the tank height.

In order to solve the above problems, the low temperature liquid storage tank according to one aspect of the present invention includes an outer tank having a tubular outer tank side plate and an outer tank roof plate, and a PC liquid barrier surrounding the outer tank side plate. And the tubular inner tank side plate erected inside the outer tank side plate, the inner tank roof plate provided below the outer tank roof plate, and the upper end of the inner tank side plate and the inner tank roof. An inner tank having a knuckle plate connecting the peripheral edge of the plate is provided, and a design liquid level of a low temperature liquid stored in the internal space of the inner tank is set between the lower end and the upper end of the knuckle plate. The upper end of the PC liquid barrier is above the upper end of the knuckle plate.

According to the above configuration, since the design liquid level is above the lower end of the knuckle plate, it is the maximum compared to the conventional tank designed so that the design liquid level is below the lower end of the knuckle plate. The amount of liquid stored can be increased. Further, since the upper end of the PC liquid barrier is located above the upper end of the knuckle plate, even if the knuckle plate is damaged, the low temperature liquid does not leak to the outside of the PC liquid barrier.

Further, in the above-mentioned cold liquid storage tank, the outer tank roof plate and the inner tank roof plate are substantially spherical, and the center of curvature of the outer tank roof plate is from the center of curvature of the inner tank roof plate. It may be located below. According to this configuration, the center of curvature of the outer tank roof plate is located below the center of curvature of the inner tank roof plate, so that even if the upper end of the PC liquid barrier is above the upper end of the knuckle plate, the outer tank The top of the roof plate can be kept low and the tank height can be suppressed.

Further, the low temperature liquid storage tank may further include a receiving pipe having a discharge port above the upper end portion of the knuckle plate. According to this configuration, the discharge port of the receiving pipe is above the upper end of the knuckle plate, so that the low temperature liquid can be reliably discharged even if the liquid level is present at the height between the upper end and the lower end of the knuckle plate. It can be released into the gas phase.

Further, in the low temperature liquid storage tank, the receiving pipe is the first receiving pipe penetrating the inner tank roof plate, and the low temperature liquid storage tank penetrates the inner tank roof plate and is inside the inner tank. A second receiving pipe having a discharge port at the lower part of the tank is further provided, and the first receiving pipe is located on the center side of the inner tank roof plate with respect to the position where the second receiving pipe penetrates the inner tank roof plate. It may penetrate the inner tank roof plate. According to this configuration, the second receiving pipe can be easily supported on the side surface of the inner tank, and the distance from the position where the first receiving pipe penetrates the inner tank roof plate to the design liquid level is widened to increase the distance between the first receiving pipe and the design liquid level. The discharge port can be reliably positioned above the liquid level of the low temperature liquid in the inner tank.

Further, the low-temperature liquid storage tank sucks boil-off gas (hereinafter, “BOG”) in which the low-temperature liquid has evaporated in the inner tank from a suction port arranged in the center of the inner tank roof plate, and the inner tank. A BOG pipe that discharges to the outside of the knuckle plate, extending from the suction port in the radial direction outward along the roof plate of the inner tub, and above the upper end of the knuckle plate. A BOG pipe penetrating the roof plate and the outer tank roof plate may be further provided. According to this configuration, the BOG piping extends radially outward from the suction port along the inner tank roof plate, and the inner tank roof plate and the outer tank roof plate are located above the upper end of the knuckle plate. The BOG pipe can be arranged below the top of the outer tank roof plate. As a result, the BOG in the inner tank having a higher temperature can be discharged from the low temperature liquid storage tank through the BOG pipe while suppressing the tank height.

Further, in the low temperature liquid storage tank, the BOG pipe extends radially outward from the suction port along the inner tank roof plate, and once extends downward from the end of the stretched portion and is folded back. A hole for discharging the liquid reliquefied by the BOG in the BOG pipe to the outside may be formed in the lower portion of the U-shaped curved portion including the U-shaped curved portion extending upward. According to this configuration, the liquid reliquefied by the BOG in the BOG pipe can be reliably discharged from the BOG pipe.

Further, in the above-mentioned cold liquid storage tank, the lowermost portion of the U-shaped curved portion may be above the upper end portion of the knuckle plate. According to this configuration, it is possible to prevent the low temperature liquid stored in the inner tank from entering the U-shaped curved portion through the hole.

According to the present invention, it is possible to provide a low temperature liquid storage tank designed to increase the maximum liquid storage amount while suppressing the tank diameter and the tank height.

It is the schematic sectional drawing of the cold liquid storage tank which concerns on one Embodiment.

(Knowledge that became the basis of the present invention)
The inventors of the present invention examined the design of a low-temperature liquid storage tank in which the amount of liquid stored was increased as compared with the conventional tank. By increasing the tank diameter and tank height, the amount of liquid stored in the tank can be increased. However, as described above, there are various restrictions on the tank diameter and tank height, so the tank diameter and tank height should be increased. It was desired to increase the maximum liquid storage amount while suppressing it.

Therefore, the inventors of the present invention paid attention to the design liquid level of the conventional tank. In the conventional tank, the design liquid level is set below the knuckle plate of the inner tank. However, if the design liquid level can be set within the height range of the knuckle plate, it is possible to increase the maximum liquid storage amount while suppressing the tank diameter and the tank height.

When the liquid is stored up to the knuckle plate, the liquid pressure is applied to the outside instead of the gas pressure. Therefore, the inventors of the present invention move to the inner tank by the internal pressure when the liquid is stored up to the knuckle plate. We examined the influence of. When the liquid level is below the knuckle plate as in a conventional tank, the inner tank roof plate and inner tank side plate bulge outward due to internal pressure, thereby the knuckle plate between the inner tank roof plate and the inner tank side plate. Deforms to dent inward of the inner tank. On the other hand, it was found that when the liquid is stored up to the knuckle plate, the knuckle plate is deformed so as to bulge outward in the same manner as the inner tank roof plate and the inner tank side plate connected to the knuckle plate. It was found that the deformation of the inner tank when the liquid is stored within the height range of the knuckle plate tends to relieve the stress generated in the inner tank due to the internal pressure as compared with the case where the liquid level is below the knuckle plate. rice field. The present invention has been made based on such findings.

(Embodiment)
Hereinafter, the low temperature liquid storage tank according to the embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic cross-sectional view of the low temperature liquid storage tank 1 according to the embodiment. The low temperature liquid storage tank 1 is a tank in which low temperature liquid such as liquefied natural gas is stored. The low-temperature liquid storage tank 1 includes a cylindrical PC liquid barrier 2, an outer tank 3 provided inside the PC liquid barrier 2, and a low-temperature liquid provided inside the outer tank 3. It is provided with an inner tank 4 in which the water is stored. The PC liquid barrier 2, the outer tank 3, and the inner tank 4 are installed on a reinforced concrete foundation plate 5.

The outer tank 3 has an outer tank bottom plate 31, an outer tank side plate 32, and an outer tank roof plate 33. The outer tank 3 has an airtight structure with an outer tank bottom plate 31, an outer tank side plate 32, and an outer tank roof plate 33. The outer tank bottom plate 31 is laid on the foundation plate 5. The outer tank side plate 32 has a cylindrical shape and is provided so as to rise from the peripheral edge of the outer tank bottom plate 31. The outer tank side plate 32 is attached to the inner peripheral surface of the cylindrical PC liquid barrier 2 provided so as to surround the outer tank side plate 32. The outer tank roof plate 33 has a substantially spherical shape that opens downward, and the peripheral edge portion of the outer tank roof plate 33 is fixed to the upper end portion 21 of the PC liquid barrier 2.

The inner tank 4 has an inner tank bottom plate 41, an inner tank side plate 42, an inner tank roof plate 43, and a knuckle plate 44. The inner tank 4 has a liquid-tight and airtight structure by the inner tank bottom plate 41, the inner tank side plate 42, the inner tank roof plate 43, and the knuckle plate 44, and the low temperature liquid is stored inside the inner tank 4. The inner tank bottom plate 41 is provided on the outer tank bottom plate 31 via a cold insulating material 61. The inner tank side plate 42 has a cylindrical shape, and is erected inside the outer tank side plate 32 with a predetermined gap. A cold insulating material 62 is filled between the inner tank side plate 42 and the outer tank side plate 32. The inner tank roof plate 43 has a substantially spherical shape that opens downward, and is provided below the outer tank roof plate 33 with a predetermined gap. A cold insulating material 63 is filled between the inner tank roof plate 43 and the outer tank roof plate 33.

The knuckle plate 44 connects the upper end portion of the inner tank side plate 42 and the peripheral edge portion of the inner tank roof plate 43. More specifically, the upper end of the inner tank side plate 42 is connected to the lower end of the knuckle plate 44, and the upper end of the knuckle plate 44 is connected to the peripheral edge of the inner tank roof plate 43. The knuckle plate 44 is formed to be thicker than the upper end portion of the inner tank side plate 42 and the peripheral edge portion of the inner tank roof plate 43. The knuckle plate 44 is configured to withstand internal pressure due to its own thickness.

In the present embodiment, the design liquid level L of the low temperature liquid stored in the inner tank 4 is set between the lower end portion 44b and the upper end portion 44a of the knuckle plate 44. Here, the design liquid level L is the highest liquid level at which the low temperature liquid is allowed to be stored in the inner tank 4. Further, the upper end portion 21 of the PC liquid barrier 2 is above the upper end portion 44a of the knuckle plate 44. That is, as shown on the left side of FIG. 1, the position HPC of the upper end portion 21 of the _PC liquid barrier 2 is above the design liquid level L.

Further, in the present embodiment, in order to lower the top 33a of the outer tank roof plate 33 to suppress the tank height, the curvature center C1 of the outer tank roof plate 33 is lower than the curvature center C2 of the inner tank roof plate 43 (vertical). It is located below). The relative positions of the center of curvature C1 and the center of curvature C2 are set so that sufficient cold insulation performance can be obtained even in the portion where the distance between the outer tank roof plate 33 and the inner tank roof plate 43 is minimized, that is, in the vicinity of the tops 33a and 34a. NS.

Further, the low temperature liquid storage tank 1 includes a first receiving pipe 7 and a second receiving pipe 8 for guiding the low temperature liquid from the outside to the inner tank 4. The first receiving pipe 7 discharges the low temperature liquid guided from the outside to the gas phase of the internal space of the inner tank 4, and the second receiving pipe 8 releases the low temperature liquid guided from the outside into the internal space of the inner tank 4. It is released to the bottom of the liquid phase. For example, the low-temperature liquid having a high heavy content is discharged to the gas phase of the internal space of the inner tank 24 via the first receiving pipe 7, and the low-temperature liquid having a low heavy content is inside through the second receiving pipe 8. By discharging it to the bottom of the liquid phase in the internal space of the tank 4, homogenization of the components in the liquid phase is achieved. In the present embodiment, one first receiving pipe 7 and / or one second receiving pipe 8 is provided in each of the low temperature liquid storage tank 1, but a plurality of first receiving pipes 7 or a plurality of second receiving pipes 7 or a plurality of second receiving pipes 7 are provided. The pipe 8 may be provided in the low temperature liquid storage tank 1.

The outer tank roof plate 33 is provided with a first outer through hole 33b through which the first receiving pipe 7 penetrates and a second outer through hole 33c through which the second receiving pipe 8 penetrates. Further, the inner tank roof plate 43 is provided with a first inner through hole 43b through which the first receiving pipe 7 penetrates and a second inner through hole 43c through which the second receiving pipe 8 penetrates. The first outer through hole 33b and the first inner through hole 43b are arranged so as to be arranged in the vertical direction, and the second outer through hole 33c and the second inner through hole 43c are arranged so as to be arranged in the vertical direction. Has been done. The first outer through hole 33b and the first inner through hole 43b are arranged so as to be at equal distances from the center of the low temperature liquid storage tank 1 when the low temperature liquid storage tank 1 is viewed in a plan view. Further, the second outer through hole 33c and the second inner through hole 43c are arranged so as to be at equal distances from the center of the low temperature liquid storage tank 1 when the low temperature liquid storage tank 1 is viewed in a plan view. .. When the low temperature liquid storage tank 1 is viewed in a plan view, the first inner through hole 43b (or the first outer through hole 33b), the second inner through hole 43c (or the second outer through hole 33c), and the inner The top 43a of the tank roof plate 43 (or the top 33a of the outer tank roof plate 33) may or may not be aligned in a straight line.

The first receiving pipe 7 extends downward from above the outer tank roof plate 33 through the first outer through hole 33b and the first inner through hole 43b, and a discharge port 71 is provided at the end thereof. .. The first receiving pipe 7 is supported by the outer tank roof plate 33 via the expansion pipe in the first outer through hole 33b. Further, the first receiving pipe 7 is welded to the inner tank roof plate 43 at the first inner through hole 43b. The discharge port 71 is located above the upper end portion 44a of the knuckle plate 44. Therefore, even when the liquid level exists at the height between the lower end portion 44b and the upper end portion 44a of the knuckle plate 44, the low temperature liquid can be reliably discharged to the gas phase from the first receiving pipe 7. The first receiving pipe 7 may be developed in a ring shape in a substantially horizontal direction at the lowermost portion, and in this case, a plurality of discharge ports 71 may be formed in the ring-shaped portion.

The second receiving pipe 8 extends downward from above the outer tank roof plate 33 through the second outer through hole 33c and the second inner through hole 43c, and a discharge port 81 is provided at the end thereof. .. The second receiving pipe 8 is supported by the outer tank roof plate 33 via a telescopic pipe at the second outer through hole 33c. The second receiving pipe 8 is welded to the inner tank roof plate 43 through the second inner through hole 43c, and is supported by a support member 82 fixed to the inner peripheral surface of the inner tank side plate 42.

In the present embodiment, the first inner through hole 43b is arranged on the central side of the inner tank roof plate 43 with respect to the second inner through hole 43c. In other words, the first receiving pipe 7 penetrates the inner tank roof plate 43 on the center side of the inner tank roof plate 43 rather than the position where the second receiving pipe 8 penetrates the inner tank roof plate 43. Here, the "center of the inner tank roof plate" means the inside of the inner tank 4 (inner tank side plate 42) more than half of the radius when the inner tank 4 is viewed in a plan view.

Further, the low temperature liquid storage tank 1 includes a BOG pipe 9 for discharging the boil-off gas generated in the inner tank 4 to the outside. The BOG pipe 9 has a suction port 91 arranged in the center of the inner tank roof plate 43, and the BOG in the inner tank 4 is sucked from the suction port 91.

The outer tank roof plate 33 and the inner tank roof plate 43 are provided with a third outer through hole 33d and a third inner through hole 43d through which the BOG pipe 9 penetrates, respectively, so as to line up in the vertical direction. The third outer through hole 33d and the third inner through hole 43d are located above the upper end portion 44a of the knuckle plate 44. The BOG pipe 9 extends in the inner tank 4 from the suction port 91 along the inner tank roof plate 43 in the radial direction outward of the inner tank 4, and penetrates the inner tank roof plate 43 and the outer tank roof plate 33. The BOG pipe 9 is supported by the outer tank roof plate 33 via a telescopic pipe at the third outer through hole 33d. Further, the BOG pipe 9 is welded to the inner tank roof plate 43 through the third inner through hole 43d, and is supported by a plurality of support members 92 fixed to the lower surface of the inner tank roof plate 43.

The BOG pipe 9 once extends downward from the extension portion 93 extending outward in the radial direction of the inner tank 4 from the suction port 91 and the end portion of the extension portion 93 opposite to the suction port 91 in the inner tank 4. It has a U-shaped curved portion 94 that is folded back and extends upward toward the third inner through hole 43d. The stretched portion 93 does not necessarily have to be parallel to the radial direction of the inner tank 4, and may be in any form as long as it extends outward in the radial direction as a whole. For example, the stretched portion 93 may be linear in a plan view or may include a curved portion.

A hole 95 is formed in the lower portion of the U-shaped curved portion 94 for discharging the liquid in which the boil-off gas is reliquefied in the BOG pipe 9 to the outside. The liquid in which the BOG is reliquefied in the stretched portion 93 and the U-shaped curved portion 94 flows to the lower part of the U-shaped curved portion 94, is discharged from the hole 95, and is returned to the low temperature liquid stored in the inner tank 4.

Further, the lowermost portion of the U-shaped curved portion 94 is above the upper end portion 44a of the knuckle plate 44. Therefore, the hole 95 formed in the U-shaped curved portion 94 can be reliably positioned above the liquid level of the low-temperature liquid in the inner tank 4, so that the low-temperature liquid stored in the inner tank 4 becomes the hole 95. It can be prevented from entering the U-shaped curved portion 94 through the U-shaped curved portion 94.

As described above, in the low temperature liquid storage tank 1 of the present embodiment, since the design liquid level L is above the lower end portion 44b of the knuckle plate 44, the design liquid level L is higher than the lower end portion 44b of the knuckle plate 44. The maximum liquid storage capacity can be increased compared to the conventional tank designed to be on the lower side. Further, since the upper end 21 of the PC liquid barrier 2 is located above the upper end 44a of the knuckle plate 44, even if the knuckle plate 44 is damaged, the low temperature liquid does not leak to the outside of the PC liquid barrier 2. ..

Further, in the present embodiment, the center of curvature C1 of the outer tank roof plate 33 is located below the center of curvature C2 of the inner tank roof plate 43. Therefore, even when the upper end 21 of the PC liquid barrier 2 is above the upper end 44a of the knuckle plate 44, the top 33a of the outer tank roof plate 33 can be kept low and the tank height can be suppressed.

Further, in the present embodiment, the first inner through hole 43b is closer to the center side of the inner tank roof plate 43 than the second inner through hole 43c. That is, the first receiving pipe 7 penetrates the inner tank roof plate 43 on the center side of the inner tank roof plate 43 rather than the position where the second receiving pipe 8 penetrates the inner tank roof plate 43. Therefore, the second receiving pipe 8 can be easily supported on the inner tank side plate 42 via the support member 82, and the distance from the first inner through hole 43b to the design liquid level is widened to increase the distance between the first receiving pipe 7 and the design liquid level. The discharge port 71 can be reliably positioned above the liquid level of the low-temperature liquid in the inner tank 4.

Further, in the present embodiment, the BOG pipe 9 extends radially outward from the suction port 91 along the inner tank roof plate 43 in the inner tank 4, and is located above the upper end portion 44a of the knuckle plate 44. Since the roof plate 43 and the outer tank roof plate 33 are penetrated, the BOG pipe 9 can be arranged below the top 33a of the outer tank roof plate 33. As a result, the BOG in the inner tank 4 having a higher temperature can be discharged from the low temperature liquid storage tank 1 through the BOG pipe 9 while suppressing the tank height.

(Other embodiments)
The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.

For example, in the above embodiment, the center of curvature C1 of the outer tank roof plate 33 is located below the center of curvature C2 of the inner tank roof plate 43, but the present invention is not limited to this, and the center of curvature C1 of the outer tank roof plate 33 is not limited to this. The center of curvature C2 of the inner tank roof plate 43 may coincide with the center of curvature C2.

Further, in the above embodiment, the discharge port 71 of the first receiving pipe 7 is arranged above the upper end portion 44a of the knuckle plate 44, but the present invention is not limited to this, and for example, the discharge port 71 of the first receiving pipe 7 is arranged. It may be located between the lower end 44b and the upper end 44a of the knuckle plate 44. However, when the discharge port 71 of the first receiving pipe 7 is arranged above the upper end portion 44a of the knuckle plate 44, there is no possibility that the low temperature liquid will flow back from the discharge port 71, which is particularly preferable.

Further, the arrangement and configuration of the first receiving pipe 7 and the second receiving pipe 8 are not limited to the above-described embodiment. For example, in the above embodiment, the first inner through hole 43b is arranged closer to the center of the inner tank roof plate 43 than the second inner through hole 43c, but the second inner through hole 43c and the first inner through hole 43b However, when the low temperature liquid storage tank 1 is viewed in a plan view, they may be arranged so as to be at equal distances from the center of the low temperature liquid storage tank 1.

Further, the BOG pipe 9 is not limited to the above configuration, and for example, the BOG pipe 9 may have a configuration that penetrates the top 43a of the inner tank roof plate 43 and the top 33a of the outer tank roof plate 33. However, as in the above embodiment, the BOG pipe 9 extends in the inner tank 4 from the suction port 91 in the radial direction of the inner tank 4 along the inner tank roof plate 43, and the inner tank roof plate 43 and the outer tank When penetrating the roof plate 33, the BOG pipe 9 can be arranged below the top 33a of the outer tank roof plate 33. Therefore, the height of the inner tank 4 is increased while maintaining the height of the entire tank including the BOG pipe 9 as compared with the conventional tank provided with the BOG pipe penetrating the top of the outer tank roof plate. , The maximum liquid storage amount can be further increased.

1 Low temperature liquid storage tank 2 PC liquid barrier 3 Outer tank 32 Outer tank side plate 33 Outer tank roof plate 4 Inner tank 42 Inner tank side plate 43 Inner tank roof plate 44 Knuckle plate 7 1st receiving pipe 71 Discharge port 8 2nd receiving Piping 81 Discharge port 9 BOG piping 91 Suction port L Design liquid level C1, C2 Center of curvature

Claims (6)

An outer tank having a tubular outer tank side plate and an outer tank roof plate,
A prestressed concrete (hereinafter, "PC") liquid barrier that surrounds the outer tank side plate,
A tubular inner tank side plate erected inside the outer tank side plate, an inner tank roof plate provided below the outer tank roof plate, and an upper end portion of the inner tank side plate and the inner tank roof plate. and the inner tub having a knuckle plate to connect a peripheral portion, a low-temperature liquid storage tank to Ru with a lower end and an upper end of the designed liquid surface of the cold liquid reserved in the inner space of the inner tub is the knuckle plate parts is set between the upper end of the PC dikes is Ri upper near than the upper end of the knuckle plate,
The low temperature liquid storage tank penetrates the inner tank, has a discharge port above the upper end portion of the knuckle plate, and discharges the low temperature liquid guided from the outside to the gas phase of the internal space of the inner tank. further Ru comprising a receiving pipe, a low temperature liquid storage tank. The outer tank roof plate and the inner tank roof plate are spherical and have a spherical shape.
The low temperature liquid storage tank according to claim 1, wherein the center of curvature of the outer tank roof plate is located below the center of curvature of the inner tank roof plate. The receiving pipe is a first receiving pipe that penetrates the inner tank roof plate.
The low temperature liquid storage tank further includes a second receiving pipe that penetrates the inner tank roof plate and has a discharge port at the lower part of the inner tank.
The low-temperature liquid according to claim 1 , wherein the first receiving pipe penetrates the inner tank roof plate on the central side of the inner tank roof plate rather than a position where the second receiving pipe penetrates the inner tank roof plate. Storage tank. A BOG pipe that sucks in boil-off gas (hereinafter, "BOG") in which the low-temperature liquid has evaporated in the inner tank from a suction port arranged in the center of the roof plate of the inner tank and discharges it to the outside of the inner tank. The inside of the inner tank extends radially outward from the suction port along the inner tank roof plate, and penetrates the inner tank roof plate and the outer tank roof plate at a position above the upper end portion of the knuckle plate. The low temperature liquid storage tank according to any one of claims 1 to 3 , further comprising a BOG pipe. The BOG pipe has an extending portion extending radially outward from the suction port along the inner tank roof plate, and a U-shaped curved portion extending downward from the end of the extending portion and then folded back and extending upward. The low-temperature liquid storage tank according to claim 4 , wherein a hole is formed in the lower portion of the U-shaped curved portion for discharging the liquid reliquefied in the BOG pipe to the outside. The low temperature liquid storage tank according to claim 5 , wherein the lowermost portion of the U-shaped curved portion is above the upper end portion of the knuckle plate.

Images