JP2022157756A - Multiple shell tank, ship, and gas pressure adjustment method - Google Patents

Abstract

To keep a pressure of a gas layer in an inner tank low, while suppressing condensation of a gas in a space between the inner tank and an outer tank.SOLUTION: A multiple shell tank includes: an inner tank for storing a low temperature liquid inside; an outer tank housing the inner tank; and a housing structure housing the outer tank. A heat insulation space between the inner tank and the outer tank is filled with a gas of the kind same as a gas obtained by vaporization of the low temperature liquid, a pressure of a gas layer inside of the inner tank is higher than a pressure of the heat insulation space, and a pressure of the heat insulation space is lower than a pressure of a holding space between the outer tank and the housing structure.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The present invention relates to a multi-shell tank, a ship and a gas pressure regulation method.

A multi-shell tank is known which has an inner tank in which a cryogenic liquid is stored and an outer tank which houses the inner tank, and in which a heat insulating space between the inner tank and the outer tank is filled with gas. For example, Patent Literature 1 discloses a double-hull tank having an inner tank and an outer tank, which is mounted on a liquefied gas carrier. A heat insulating space between the inner tank and the outer tank is filled with boil-off gas discharged from the inner tank. A holding space is formed around the outer tank by the tank cover and the hull. The holding space is also filled with gas.

International Publication No. 2020/202578

When the gas in the adiabatic space contacts the inner tank and condenses, the condensate falls from the inner tank to the outer tank and then evaporates. If such gas liquefaction and vaporization (absorption and evaporation of latent heat) are repeated, the amount of heat input to the inner tank increases due to the heat pipe effect. Therefore, it is desirable to suppress gas condensation in the space outside the inner tank.

By the way, the higher the pressure of the gas layer in the inner tank of the multi-shell tank, the higher the saturation temperature of the gas filling the gas layer in the inner tank, and the higher the temperature of the liquid layer in the inner tank. If the temperature of the liquid layer in the inner tank is high, for example, when discharging the liquid in the inner tank during unloading, if the liquid temperature is higher than the demand of the receiving terminal on the land side, the inner tank It becomes necessary to lower the liquid temperature inside. In order to lower the temperature of the liquid in the inner tank, the gas in the inner tank is usually exhausted to lower the pressure, which wastes the gas in the inner tank. In addition, since it is necessary to increase the design pressure of the inner tank in order to keep the pressure of the air layer in the inner tank high, an increase in the plate thickness of the multi-shell tank results in an increase in cost.

Therefore, the present invention provides a multi-shell tank, a ship, and a gas tank that can keep the pressure of the air layer in the inner tank low while suppressing the condensation of gas in the space between the inner tank and the outer tank. It is an object of the present invention to provide a pressure regulation method.

In order to solve the above problems, a multi-shell tank according to an aspect of the present invention includes an inner tank in which a cryogenic liquid is stored, an outer tank containing the inner tank, and a container containing the outer tank. and a structure, wherein the heat insulating space between the inner tank and the outer tank is filled with the same kind of gas as the vaporized gas of the low temperature liquid, and the pressure of the gas layer in the inner tank is , the pressure in the insulating space is higher than the pressure in the insulating space, and the pressure in the insulating space is lower than the pressure in the holding space between the outer tank and the housing structure.

According to the above configuration, the adiabatic space between the inner tank and the outer tank is filled with the same kind of gas as the vaporized low-temperature liquid in the inner tank, and the gas layer in the inner tank The pressure is higher than the pressure in the adiabatic space. Therefore, the pressure in the adiabatic space can be made less than the saturated vapor pressure of the gas in the adiabatic space at the temperature of the liquid in the inner tank. Therefore, it is possible to suppress the condensation of the gas in the heat insulating space.

Also, the pressure in the adiabatic space is lower than the pressure in the holding space. Therefore, even if the pressure in the holding space is limited, the pressure in the inner tank can be adjusted to be relatively low regardless of the pressure in the holding space.

Therefore, it is possible to keep the pressure of the air layer in the inner tank low while suppressing condensation of the gas in the heat insulating space outside the inner tank.

A multi-shell tank according to another aspect of the present invention includes an inner tank in which a cryogenic liquid is stored, N outer tanks (N is an integer of 2 or more) containing the inner tank, and the N outer tanks. a housing structure that covers the N-th outermost tank from the inside of the outer tanks and houses the N outer tanks, wherein the outermost tank is disposed between the inner tank and the outermost tank; N heat insulating spaces partitioned by the (N−1) outer tanks excluding are formed, and the first heat insulating space, which is the first heat insulating space from the inside of the N heat insulating spaces, contains the low-temperature liquid The same kind of gas as the vaporized gas is filled, the pressure of the air layer in the inner tank is higher than the pressure of the first heat insulating space, and the pressure of the first heat insulating space is higher than the pressure of the outermost tank and the Lower than the pressure in the holding space between the containment structure.

According to the above configuration, the first heat insulating space that is the first from the inside is filled with the same kind of gas as the vaporized low-temperature liquid in the inner tank, and the pressure of the gas layer in the inner tank is the first. 1 higher than the pressure of the adiabatic space. Therefore, the pressure in the first heat insulating space can be made less than the saturated vapor pressure of the gas in the first heat insulating space at the temperature of the liquid in the inner tank. Therefore, condensation of gas in the first heat insulating space can be suppressed.

Also, the pressure in the first adiabatic space is lower than the pressure in the holding space. Therefore, even if the pressure in the holding space is limited, the pressure in the inner tank can be adjusted to be relatively low regardless of the pressure in the holding space.

Therefore, it is possible to keep the pressure of the air layer in the inner tank low while suppressing condensation of the gas in the first heat insulating space, which is the space outside the inner tank.

A ship according to an aspect of the present invention includes any one of the multi-shell tanks described above.

Further, a gas pressure adjusting method according to an aspect of the present invention includes an inner tank in which a cryogenic liquid is stored, an outer tank that houses the inner tank, and a housing structure that houses the outer tank, In a multi-shell tank in which the insulating space between the inner tank and the outer tank is filled with the same kind of gas as the vaporized gas of the low-temperature liquid, the pressure of the gas layer in the inner tank is and the pressure of the insulating space is lower than the pressure of the holding space between the outer tank and the housing structure, the pressure of the air layer in the inner tank, the pressure of the insulating space and the holding Adjust the pressure in space.

According to the above method, the adiabatic space between the inner tank and the outer tank is filled with the same kind of gas as the vaporized low-temperature liquid in the inner tank, and the gas layer in the inner tank is The pressure of the air layer in the inner tank and the pressure of the heat insulation space are adjusted so that the pressure is higher than the pressure of the heat insulation space. Therefore, the pressure in the adiabatic space can be made less than the saturated vapor pressure of the gas in the adiabatic space at the temperature of the liquid in the inner tank. Therefore, it is possible to suppress the condensation of the gas in the heat insulating space.

Also, the pressure in the heat insulating space and the pressure in the holding space are adjusted so that the pressure in the insulating space is lower than the pressure in the holding space. Therefore, even if the pressure in the holding space is limited, the pressure in the inner tank can be adjusted to be relatively low regardless of the pressure in the holding space.

Therefore, it is possible to keep the pressure of the air layer in the inner tank low while suppressing condensation of the gas in the heat insulating space outside the inner tank.

Further, a gas pressure adjusting method according to another aspect of the present invention includes an inner tank in which a cryogenic liquid is stored, N outer tanks (N is an integer of 2 or more) containing the inner tank, and the a housing structure that covers the N-th outermost tank from the inside of the N outer tanks and houses the N outer tanks, wherein between the inner tank and the outermost tank, the N heat insulating spaces partitioned by (N−1) outer tanks excluding the outermost tank are formed, and the first heat insulating space, which is the first heat insulating space from the inner side of the N heat insulating spaces, includes the In a multi-shell tank filled with the same kind of gas as the vaporized gas of the cryogenic liquid, the pressure of the gas layer in the inner tank is higher than the pressure of the first heat insulating space, and the pressure of the first heat insulating space is The pressure of the air layer in the inner tank, the pressure of the first heat insulating space and the pressure of the holding space are adjusted so as to be lower than the pressure of the holding space between the outermost tank and the housing structure.

According to the above method, the first heat insulating space, which is the first from the inside, is filled with the same kind of gas as the vaporized low-temperature liquid in the inner tank, and the pressure of the gas layer in the inner tank is the first. The pressure of the air layer in the inner tank and the pressure of the first heat insulation space are adjusted so that the pressure becomes higher than the pressure of the first heat insulation space. Therefore, the pressure in the first heat insulating space can be made less than the saturated vapor pressure of the gas in the first heat insulating space at the temperature of the liquid in the inner tank. Therefore, condensation of gas in the first heat insulating space can be suppressed.

Also, the pressure in the first heat insulating space and the pressure in the holding space are adjusted so that the pressure in the first insulating space is lower than the pressure in the holding space. Therefore, even if the pressure in the holding space is limited, the pressure in the inner tank can be adjusted to be relatively low regardless of the pressure in the holding space.

Therefore, it is possible to keep the pressure of the air layer in the inner tank low while suppressing condensation of the gas in the first heat insulating space, which is the space between the inner tank and the outer tank.

ADVANTAGE OF THE INVENTION According to the present invention, a multi-shell tank, a vessel, and a multi-shell tank capable of keeping the pressure of the air layer in the inner tank low while suppressing condensation of gas in the space between the inner tank and the outer tank. A gas pressure adjustment method can be provided.

1 is a schematic side view of a ship including a multi-shell tank according to a first embodiment of the invention; FIG. 2 is a schematic configuration diagram showing the overall configuration of the multi-shell tank shown in FIG. 1. FIG. FIG. 3 is a schematic configuration diagram showing the overall configuration of a multi-shell tank according to a second embodiment of the present invention. FIG. 4 is a schematic configuration diagram showing the overall configuration of a multi-shell tank according to a third embodiment of the present invention. FIG. 5 is a schematic configuration diagram showing the overall configuration of a multi-shell tank according to a fourth embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the specification of the present application, the “inner side” means the side near the center of the space within the inner tank of the multi-shell tank, and the “outer side” means the side far from the center of the space within the inner tank of the multi-shell tank. means side.

<First embodiment>
FIG. 1 is a schematic side view of a ship 1 including a multi-shell tank 10A according to the first embodiment. The vessel 1 is a liquefied gas carrier that carries cryogenic liquids. The ship 1 comprises a multi-hull tank 10A. The multi-shell tank 10A comprises an inner tank 11 and an outer tank 12 containing the inner tank 11 .

In this embodiment, both the inner tub 11 and the outer tub 12 are spherical. The inner tub 11 and the outer tub 12 do not necessarily have to be spherical. For example, the inner tank 11 and the outer tank 12 may have a shape in which a short cylindrical body is sandwiched between the upper hemispheres, may have a horizontal cylindrical shape, or may have a rectangular shape. may be Alternatively, for example, the inner bath 11 and the outer bath 12 may have a shape that bulges in an upward 45-degree angle direction and/or downward 45-degree angle direction from the center of the inner bath 11 . The shape of the inner tank 11 and the shape of the outer tank 12 may be similar or non-similar to each other.

The multi-shell tank 10A does not necessarily have to be mounted on the ship 1 as a cargo tank, and may be mounted as a fuel tank. Moreover, although FIG. 1 shows the ship 1 provided with one multi-shell tank 10A, the ship 1 may be provided with a plurality of multi-shell tanks 10A.

FIG. 2 is a schematic configuration diagram showing the overall configuration of the multi-shell tank 10A shown in FIG. FIG. 2 includes a cross-sectional view of the vessel 1 perpendicular to the longitudinal direction. The upper portion of the outer tub 12 is covered with a tank cover 13 and the remaining portion of the outer tub 12 is covered with a retaining wall 14 . The tank cover 13 and the retaining wall 14 are configured as one housing structure 15 housing the outer tank 12 .

The inner surface of the tank cover 13 faces the outer tank 12, and the outer surface of the tank cover 13 faces the atmosphere. The retaining wall 14 is for example part of the hull 2 . In addition, when the ship 1 is equipped with a plurality of multi-shell tanks 10A arranged in the longitudinal direction, the partition wall provided between two adjacent multi-shell tanks 10A is also included in the storage structure 15 covering the outer tank 12.

A low-temperature liquid is stored in a storage space U inside the inner tank 11 . By covering the inner tank 11 with the outer tank 12 , a sealed heat insulating space V is formed outside the inner tank 11 and inside the outer tank 12 . A heat insulating material is arranged in the heat insulating space V. - 特許庁The heat insulating material may be, for example, a granular material such as perlite, or may be a heat insulating panel attached to the surface of the inner tank 11 or the like. Further, a holding space W is formed inside the housing structure 15 and outside the outer tub 12 by covering the outer tub 12 with the housing structure 15 . That is, the inner tank 11 separates the storage space U and the heat insulating space V, and the outer tank 12 separates the heat insulating space V and the holding space W.

Moreover, at least part of the housing structure 15 (specifically, the tank cover 13) separates the holding space W from the outside air.

The air layer above the storage space U is filled with the boil-off gas that is obtained by vaporizing the low-temperature fluid in the storage space U. A first BOG discharge path 17 is connected to the inner tank 11 . One end of the first BOG discharge passage 17 is arranged in the upper air layer of the storage space U, and the other end of the first BOG discharge passage 17 is connected to gas consumption equipment 18 mounted on the hull 2 . The gas consuming equipment 18 is, for example, a propulsion engine, a power generation engine, a reliquefaction unit, a boiler, a GCU, a fuel cell, or the like. The first BOG discharge passage 17 is provided with a first BOG discharge valve 17a.

In this embodiment, the first BOG discharge valve 17a is a manually operated valve or a remotely operated valve that is operated to open by an operator. By opening the first BOG discharge valve 17 a , the boil-off gas in the inner tank 11 is sent to the gas consumption equipment 18 through the first BOG discharge passage 17 . The first BOG discharge path 17 may be provided with a compressor or an exhaust pump for forcibly sending the boil-off gas from the inner tank 11 to the gas consumption equipment 18 .

A second BOG discharge path 19 is connected to the inner tank 11 . One end of the second BOG discharge passage 19 is arranged in the air layer above the storage space U, and the other end of the second BOG discharge passage 19 is open to the atmosphere. The second BOG discharge passage 19 is provided with a second BOG discharge valve 19a. The second BOG discharge valve 19a is a safety valve that opens when the pressure of the air layer inside the inner tank 11 exceeds the first set upper limit pressure. One end of the second BOG discharge path 19 may not be arranged in the upper air layer of the storage space U. For example, one end of the second BOG discharge path 19 may be connected to the middle of the first BOG discharge path 17 .

In this embodiment, the pressure of the air layer in the inner tank 11 is maintained at a first set lower limit pressure or higher and a first set upper limit pressure or lower. For example, the first set lower limit pressure is the atmospheric pressure. However, the first set lower limit pressure may be lower than the atmospheric pressure.

For example, during the voyage of the ship 1 , heat input causes boil-off gas in the inner tank 11 . The generated boil-off gas is sent to the gas consumption equipment 18 through the first BOG discharge path 17 . When the amount of boil-off gas consumed by the gas consuming equipment 18 is smaller than the amount of boil-off gas generated within the inner tank 11, the pressure of the air layer within the inner tank 11 increases. When the pressure of the air layer in the inner tank 11 exceeds the first set upper limit pressure, the second BOG discharge valve 19a, which is a safety valve, opens to reduce the pressure of the air layer in the inner tank 11 to less than the first set upper limit pressure. . Preferably, the first set upper limit pressure is set, for example, within a range that is equal to or higher than a pressure that is 5 kilopascals higher than the atmospheric pressure and is equal to or lower than a pressure that is 30 kilopascals higher than the atmospheric pressure.

The heat insulating space V is filled with the same kind of gas as the boil-off gas in the inner tank 11 . Further, the holding space W is filled with a different kind of gas from the gas in the heat insulating space V and the boil-off gas in the inner tank 11 . In the present embodiment, for example, the low-temperature liquid in the storage space U is liquefied hydrogen, the gas filled in the heat insulating space V and the boil-off gas in the inner tank 11 are hydrogen gas, and the holding space W is filled. The gas used is nitrogen gas, inert gas, dry air, or the like.

The multi-shell tank 10A has an introduction passage 21 for introducing the boil-off gas of the gas layer in the inner tank 11, that is, the boil-off gas in the storage space U, into the heat insulating space V. As shown in FIG. One end of the introduction path 21 is arranged in the air layer above the storage space U, and the other end of the introduction path 21 is arranged in the heat insulating space V. As shown in FIG. An introduction valve 22 is provided in the introduction path 21 . For example, the introduction valve 22 is a valve that increases the pressure in the heat insulation space V when the pressure in the heat insulation space V drops below the second set lower limit pressure. In this embodiment, the inlet valve 22 is a manually operated valve or a remotely operated valve that is operated to open by an operator.

In addition, the multi-shell tank 10A includes a discharge passage 23 that guides the gas inside the heat insulating space V to the outside of the heat insulating space V. As shown in FIG. One end of the discharge path 23 is arranged inside the heat insulating space V, and the other end of the discharge line 23 is connected to the gas consumption equipment 18 outside the heat insulating space V. As shown in FIG. The gas consumption equipment 18 may be, for example, a gas combustion unit (GCU: Gas Combustion Unit), a propulsion engine, a power generation engine, a gas engine, a reliquefaction device, a boiler, a fuel cell, or the like. The gas consuming equipment 18 connected to the discharge channel 23 may be the same as the gas consuming equipment 18 connected to the first BOG discharge channel 17, or may be different. In addition, in the present embodiment, the other end of the discharge path 23 is maintained at a pressure lower than the pressure of the heat insulation space V. As shown in FIG.

A discharge valve 24 is provided in the discharge path 23 . In this embodiment, the discharge valve 24 is a valve that releases the pressure in the heat insulation space V when the pressure in the heat insulation space V exceeds the second set upper limit pressure. In this embodiment, the discharge valve 24 is a manually operated valve or a remotely operated valve operated by an operator, or a self-powered valve that is automatically opened when the pressure in the heat insulating space V becomes equal to or higher than the second set upper limit pressure. It is an automatic valve (eg safety valve).

The pressure of the gas layer in the inner tank 11 is kept higher than the pressure of the heat insulating space V, and the pressure of the heat insulating space V is kept lower than the pressure of the holding space W. The pressure is kept above atmospheric pressure. That is, in the present embodiment, the pressure of the gas layer in the inner tank 11 and the pressure of the heat insulation space V satisfy the relationship of the following formula (A), and the pressure of the heat insulation space V and the pressure of the holding space W are the following: The relationship of formula (B) is satisfied, and the pressure in the holding space W and the atmospheric pressure satisfy the relationship of formula (C) below.
Pa>Pb (A)
Pc>Pb (B)
Pc≧Po (C)
However, Pa is the pressure of the air layer in the inner tank 11, Pb is the pressure of the heat insulation space V, Pc is the pressure of the holding space W, and Po is the atmospheric pressure.

Various devices are operated, set or controlled so that the above formulas (A), (B) and (C) are satisfied. For example, the discharge valve 24 is opened to reduce the pressure in the heat insulating space V so as to satisfy the above formula (A). For example, the exhaust valve 24 is opened to reduce the pressure in the heat insulating space V so as to satisfy the above formula (B). For example, in order to increase the pressure in the holding space W so as to satisfy the above formula (B) and/or formula (C), a later-described gas supply device 34 for supplying gas to the holding space W or the like is operated.

In the present embodiment, the pressure in the heat insulating space V is maintained at or above the second set lower limit pressure and below the second set upper limit pressure. When the pressure in the adiabatic space V falls below the second set lower limit pressure, the introduction valve 22 is opened to raise the pressure in the adiabatic space V to the second set lower limit pressure or higher. Further, when the pressure in the heat insulating space V exceeds the second set upper limit pressure, the discharge valve 24 is opened to reduce the pressure in the heat insulating space V to less than the second set upper limit pressure.

The second set upper limit pressure is set to be less than the pressure of the gas layer in the storage space U and less than the pressure in the holding space W. Preferably, the second set upper limit pressure is, for example, set to a range that is equal to or higher than the pressure lower than the atmospheric pressure by 30 kilopascals and lower than the atmospheric pressure. More preferably, the second set upper limit pressure is, for example, set to a range equal to or higher than the pressure lower than the atmospheric pressure by 30 kilopascals and lower than the pressure of the gas layer in the storage space U by 5 kilopascals. The second set upper limit pressure may vary according to the pressure of the air layer in the storage space U.

For example, when the first set lower limit pressure is higher than the atmospheric pressure and the second set upper limit pressure is lower than the atmospheric pressure, the relationship of the above formula (A) is satisfied. Further, since the holding space W is filled with gas so that the pressure is equal to or higher than the atmospheric pressure, for example, when the second set upper limit pressure is lower than the atmospheric pressure, the relationship of the above formula (B) is satisfied. It has become.

The pressure of the air layer in the inner tank 11 may be higher or lower than the pressure in the holding space W.

As described above, according to the multi-shell tank 10A according to the present embodiment, in the heat insulating space V between the inner tank 11 and the outer tank 12, the same type of gas as the vaporized low-temperature liquid in the inner tank 11 is provided. and the pressure of the air layer in the inner tank 11 is higher than the pressure of the heat insulating space V. Therefore, the pressure in the heat insulating space V can be made less than the saturated vapor pressure of the gas in the heat insulating space V at the temperature of the liquid in the inner tank 11 . Therefore, condensation of gas in the heat insulating space V can be suppressed.

Further, in the present embodiment, since the pressure in the holding space W is equal to or higher than the atmospheric pressure, it is possible to prevent outside air from entering the holding space W.

Further, in the present embodiment, since the pressure in the heat insulating space V is lower than the pressure in the holding space W, even if the pressure in the holding space W is maintained at or above the atmospheric pressure, the pressure in the holding space W does not affect the inner tank 11 pressure. The pressure of the air layer inside can be adjusted to be relatively low.

Therefore, it is possible to keep the pressure of the air layer in the inner tank 11 low while suppressing condensation of the gas in the heat insulating space V outside the inner tank 11 .

Further, in this embodiment, since the pressure in the heat insulating space V is lower than the pressure in the holding space W, it is possible to prevent the gas in the heat insulating space V from leaking into the holding space W when the outer tank 12 is damaged.

In addition, in the present embodiment, the boil-off gas in the storage space U can be introduced into the heat insulating space V through the introduction path 21, so when the pressure in the heat insulating space V decreases due to temperature changes in the holding space W, , the pressure in the adiabatic space V can be maintained above the second set lower limit pressure.

Further, in the present embodiment, the gas in the heat insulating space V can be guided to the outside of the heat insulating space V through the discharge path 23, so that the heat insulating space V can be decompressed.

<Second embodiment>
FIG. 3 is a schematic configuration diagram showing the overall configuration of a multi-shell tank 10B according to the second embodiment. In addition, in this embodiment, the same code|symbol is attached|subjected to the same or similar member as said 1st Embodiment, and detailed description is abbreviate|omitted.

Also in this embodiment, the pressure of the gas layer in the inner tank 11 is kept higher than the pressure of the heat insulating space V, and the pressure of the heat insulating space V is kept lower than the pressure of the holding space W. , the pressure in the holding space W is kept above the atmospheric pressure.

However, in this embodiment, unlike the first embodiment, the introduction valve 22 and the discharge valve 24 are control valves that are electrically or mechanically controlled. Further, in this embodiment, an exhaust device 25 is provided in addition to the exhaust valve 24 in the exhaust passage 23 . The exhaust device 25 is, for example, a compressor or an exhaust pump such as a vacuum pump. That is, the gas in the heat insulating space V can be forcibly discharged through the discharge path 23 by the exhaust device 25 . For this reason, the other end of the discharge passage 23 opposite to the heat insulation space V does not need to be maintained at a pressure lower than the pressure of the heat insulation space V. As shown in FIG. For example, the other end of the discharge path 23 may be open to the atmosphere.

The multi-shell tank 10B also includes a control device 30, a first pressure gauge 31, a second pressure gauge 32, a third pressure gauge 33 and a gas supply device .

The control device 30 controls the introduction valve 22 , the discharge valve 24 , the exhaust device 25 and the gas supply device 34 . The control device 30 is communicatively connected to the exhaust valve 24, the exhaust device 25 and the gas supply device 34, respectively. In addition, the control device 30 is communicatively connected to the first pressure gauge 31, the second pressure gauge 32 and the third pressure gauge 33, respectively.

The control device 30 is a so-called computer, and has an arithmetic processing section such as a CPU, and a storage section such as a ROM and a RAM (none of which are shown). The storage unit stores programs executed by the arithmetic processing unit, various fixed data, and the like. The arithmetic processing unit transmits and receives data to and from an external device. In the controller 30, the arithmetic processing unit reads out and executes a predetermined gas pressure adjustment program stored in the storage unit, whereby the gas pressure of the air layer in the inner tank 11, the gas pressure of the heat insulating space V, the holding space W A gas pressure adjustment process is performed to adjust at least one of the gas pressures of Note that the control device 30 may be configured by a plurality of computers. In this case, the control device 30 may control the introduction valve 22, the discharge valve 24, and the exhaust device 25 through distributed control by cooperation of a plurality of computers, or the introduction valve 22, the discharge valve 24, and the exhaust device 25 may be controlled individually. can be controlled to

The first pressure gauge 31 measures the pressure of the air layer inside the inner tank 11 . The second pressure gauge 32 measures the pressure in the heat insulating space V. As shown in FIG. A third pressure gauge 33 measures the pressure in the holding space W. As shown in FIG. Information on the pressure measured by each of the first pressure gauge 31 , the second pressure gauge 32 and the third pressure gauge 33 is sent to the control device 30 .

The gas supply device 34 supplies the holding space W with the same kind of gas as the gas filled in the holding space W. As shown in FIG. As the gas is supplied to the holding space W by the gas supply device 34, the gas pressure in the holding space W rises. That is, the gas supply device 34 functions as a booster for boosting the holding space W. As shown in FIG.

The control device 30 controls the discharge valve 24 and the exhaust device 25 so that the pressure measured by the second pressure gauge 32 is kept lower than the pressure measured by the first pressure gauge 31 . That is, when the pressure measured by the second pressure gauge 32 rises too much, the control device 30 opens the discharge valve 24 and operates the exhaust device 25 so as to depressurize the heat insulation space V.

For example, when the second set upper limit pressure is set lower than the first set lower limit pressure, the control device 30 causes the discharge valve 24 to open when the pressure measured by the second pressure gauge 32 exceeds the second set upper limit pressure. The exhaust valve 24 and the exhaust system 25 are controlled so that they are open and the exhaust system 25 is activated. Alternatively, the control device 30 opens the discharge valve 24 when the pressure difference between the pressure measured by the second pressure gauge 32 and the pressure measured by the first pressure gauge 31 becomes equal to or less than a predetermined value. It controls the exhaust valve 24 and the exhaust system 25 so that 25 is activated.

Further, the control device 30 controls the introduction valve 22 so that the pressure measured by the second pressure gauge 32 becomes equal to or higher than the second set lower limit pressure.

Specifically, when the pressure measured by the second pressure gauge 32 is lower than the second set lower limit pressure, the controller 30 determines that the pressure measured by the second pressure gauge 32 is equal to or higher than the second set lower limit pressure. Open the inlet valve 22 until When the pressure measured by the second pressure gauge 32 becomes equal to or higher than the second set lower limit pressure, or becomes equal to or higher than the second set lower limit pressure by a predetermined pressure, the control device 30 closes the introduction valve 22. close up.

The control device 30 controls the gas supply device 34 so that the pressure measured by the third pressure gauge 33 is kept higher than the pressure measured by the second pressure gauge 32 and higher than the atmospheric pressure. That is, the control device 30 operates the gas supply device 34 to increase the pressure in the holding space W so as to satisfy the above formulas (B) and (C). Note that the control device 30 may control the discharge valve 24 and the exhaust device 25 so that the pressure measured by the third pressure gauge 33 is higher than the pressure measured by the second pressure gauge 32 . That is, the control device 30 may open the discharge valve 24 and operate the exhaust device 25 in order to reduce the pressure in the heat insulation space V so as to satisfy the above formula (B).

Also in this embodiment, the same effect as in the first embodiment can be obtained.

In addition, in the present embodiment, since the control device 30 controls the introduction valve 22, when the pressure in the heat insulating space V decreases due to temperature change in the holding space W, the pressure in the heat insulating space V is increased to the second set lower limit pressure or more. can be adjusted in real time so that

In addition, in the present embodiment, since the control device 30 controls the discharge valve 24 and the exhaust device 25, even if the pressure of the heat insulating space V and/or the pressure of the air layer in the inner tank 11 fluctuates, the pressure of the heat insulating space V The pressure can be adjusted in real time to be lower than the pressure of the air layer inside the inner tank 11 .

In addition, in the present embodiment, since the control device 30 controls the gas supply device 34, even if the pressure in the heat insulating space V and/or the pressure in the holding space W fluctuates, the pressure in the holding space W changes to the pressure in the heat insulating space V. It can be adjusted in real time to be higher.

<Third Embodiment>
FIG. 4 is a schematic configuration diagram showing the overall configuration of a multi-shell tank 10C according to the third embodiment. In this embodiment, the same or similar members as those in the first and second embodiments are denoted by the same reference numerals in the drawings, and detailed description thereof will be omitted. Further, the multi-shell tanks 10C and 10D in the present embodiment and a fourth embodiment described later have the first BOG discharge passage 17, the first BOG discharge valve 17a, the second BOG discharge passage 19 and the second BOG discharge as in the first embodiment. Valves 19a are provided, but these are omitted in FIGS. 4 and 5 for clarity of illustration.

As shown in FIG. 4, the multi-shell tank 10C includes a plurality of thermometers 35 and a gas supply device 34. As shown in FIG. In addition, in FIG. 4, only one thermometer 35 out of the plurality of thermometers 35 is shown for simplification of the drawing.

A plurality of thermometers 35 measure the temperature in the heat insulation space V, which is the space inside the holding space W by one. A plurality of thermometers 35 are provided at a plurality of locations in the holding space W, respectively. A plurality of thermometers 35 are communicatively connected to the control device 30 . Information on temperatures measured by the plurality of thermometers 35 is sent to the control device 30 .

The multi-shell tank 10</b>C also includes an escape passage 41 that guides the gas in the holding space W to the outside of the holding space W, and an escape valve 42 provided in the escape passage 41 . One end of the escape path 41 is arranged in the holding space W, and the other end of the escape path 41 is open to the atmosphere. Relief valve 42 is communicatively connected to controller 30 . Relief valve 42 is controlled by controller 30 .

In this embodiment, as in the second embodiment, the pressure of the gas layer in the inner tank 11 and the pressure of the heat insulation space V satisfy the relationship of the above formula (A), and the pressure of the heat insulation space V and the pressure of the holding space W are The pressure satisfies the relationship of formula (B) above, and the pressure in the holding space W and the atmospheric pressure satisfy the relationship of formula (C) above.

Further, in the present embodiment, the control device 30 adjusts the gas pressure in the holding space W so that condensation of gas in the holding space W is suppressed.

Specifically, the control device 30 derives a reference temperature T corresponding to the temperature of the outer bath 12 or the temperature inside the heat insulating space V from the temperatures measured by the plurality of thermometers 35 . In this embodiment, the control device 30 derives the lowest temperature as the reference temperature T among the temperatures measured by the plurality of thermometers 35 .

Then, the control device 30 adjusts the pressure of the gas in the holding space W so that the pressure of the gas in the holding space W at the derived reference temperature T is maintained below the saturated vapor pressure Ps of the gas in the holding space W. That is, the storage unit of the control device 30 stores in advance correspondence information indicating the relationship between the temperature and the saturated vapor pressure of the gas in the holding space W, and the control device 30 stores the holding space at the derived reference temperature T. Derive the saturated vapor pressure Ps of the gas in W. When the pressure measured by the third pressure gauge 33 is equal to or higher than the saturated vapor pressure Ps, the control device 30 controls the relief valve so that the pressure measured by the third pressure gauge 33 is less than the saturated vapor pressure Ps. Open 42.

The control device 30 performs the same control as in the second embodiment except for the control based on the temperature of the thermometer 35 .

This embodiment also provides the same effects as those of the first and second embodiments.

Further, in the present embodiment, the pressure of the gas in the holding space W is adjusted so that the pressure of the gas in the holding space W at the derived reference temperature T is maintained below the saturated vapor pressure Ps of the gas in the holding space W. Therefore, the dew point of the gas in the holding space W can be made lower than the reference temperature T, and as a result, condensation of the gas in the holding space W can be suppressed.

Note that the control device 30 does not need to determine the lowest temperature among the temperatures measured by the plurality of thermometers 35 as the reference temperature T, and determines the average temperature of the temperatures measured by the plurality of thermometers as the reference temperature. Alternatively, a temperature derived using a predetermined calculation formula from temperatures measured by a plurality of thermometers may be determined as the reference temperature T. Alternatively, only one thermometer 35 may be provided in the heat insulating space V, and the temperature thereof may be used as the reference temperature T. Also, one or more thermometers 35 may measure the surface temperature of the outer bath 12 .

Also, the relief valve 42 may be a safety valve that is not controlled by the control device 30 .

<Fourth Embodiment>
FIG. 5 is a schematic configuration diagram showing the overall configuration of a multi-shell tank 10D according to the fourth embodiment. In addition, in this embodiment, the same code|symbol is attached|subjected to the same or similar member as said 1st Embodiment, and detailed description is abbreviate|omitted.

As shown in FIG. 5, the multi-shell tank 10D includes an outer tank 16 (hereinafter referred to as "first outer tank 12") and a housing structure 15, which covers the first outer tank 12. hereinafter referred to as "second outer tank 16"). The upper portion of the second outer tub 16 is covered by the tank cover 13 and the remaining portion of the second outer tub 16 is covered by the retaining wall 14 . That is, the second outer tub 16 covers the housing structure 15 .

A low-temperature liquid is stored in a storage space U inside the inner tank 11 . By covering the inner tank 11 with the first outer tank 12, a sealed first heat insulating space V1 is formed outside the inner tank 11 and inside the outer tank 12. As shown in FIG. A heat insulating material is arranged in the first heat insulating space V1. By covering the first outer tank 12 with the second outer tank 16, a sealed second heat insulating space V2 is formed outside the first outer tank 12 and inside the second outer tank 16. As shown in FIG. A heat insulating material is also arranged in the second heat insulating space V2. A holding space W is formed inside the tank cover 13 and the holding wall 14 and outside the second outer tub 16 by covering the second outer tub 16 with the housing structure 15 .

That is, the inner tank 11 separates a storage space U inside the inner tank 11 containing the low-temperature liquid from a first heat insulating space V1 outside the inner tank 11 and inside the outer tank 12. The outer tank 12 partitions a first heat insulating space V1 and a second heat insulating space V2 outside the first outer tank 12 and inside the second outer tank 16, and the second outer tank 16 serves as the second heat insulating space. The space V2 is partitioned from the holding space W outside the second outer tank 16 and inside the housing structure 15 .

The air layer above the storage space U is filled with the boil-off gas that is obtained by vaporizing the low-temperature fluid in the storage space U. The first heat insulating space V1 and the second heat insulating space V2 are filled with the same kind of gas as the boil-off gas in the inner tank 11 . Further, the holding space W is filled with a different kind of gas from the gas in the first heat insulating space V1 and the second heat insulating space V2 and the boil-off gas in the inner tank 11 . In this embodiment, for example, the low-temperature liquid in the storage space U is liquefied hydrogen, the boil-off gas obtained by vaporizing the low-temperature fluid in the storage space U, and the gas filled in the first heat insulation space V1 and the second heat insulation space V2 are , and hydrogen gas, and the gas filled in the holding space W is nitrogen gas, inert gas, dry air, or the like.

The multi-shell tank 10D includes an introduction passage 21 and an introduction valve 22 provided in the introduction passage 21, as in the first embodiment. In this embodiment, the introduction path 21 and the introduction valve 22 are referred to as the first introduction path 21 and the first introduction valve 22, respectively. The first introduction path 21 introduces the boil-off gas in the storage space U into the first heat insulation space V1 between the inner tank 11 and the first outer tank 12 . One end 21a of the first introduction path 21 is arranged in the upper air layer of the storage space U, and the other end of the first introduction path 21 is arranged in the first heat insulating space V1. For example, the first introduction valve 22 is a valve that increases the pressure in the first heat insulation space V1 when the pressure in the first heat insulation space V1 drops below the second set lower limit pressure. In this embodiment, the first introduction valve 22 may be a manually operated valve or a remotely operated valve that is opened by an operator, or may be an electrically or mechanically controlled control valve.

A second introduction path 51 branches from between the first introduction valve 22 and the end portion 21 a of the air layer above the storage space U in the first introduction path 21 . The second introduction path 51 introduces the boil-off gas guided through the first introduction path 21 into the second heat insulation space V2 between the first outer tank 12 and the second outer tank 16. As shown in FIG. One end of the second introduction path 51 is connected between the end 21a of the gas layer above the storage space U in the first introduction path 21 and the first introduction valve 22, and the other end of the second introduction path 51 The part is arranged in the second heat insulating space V2.

A second introduction valve 52 is provided in the second introduction path 51 . For example, the second introduction valve 52 is a valve that increases the pressure in the second heat insulation space V2 when the pressure in the second heat insulation space V2 drops below the second set lower limit pressure. In this embodiment, the second introduction valve 52 may be a manually operated valve or a remotely operated valve that is opened by an operator, or may be an electrically or mechanically controlled control valve.

Further, the multi-shell tank 10D includes a discharge passage 23 and a discharge valve 24 provided in the discharge passage 23, as in the first embodiment. In this embodiment, the discharge passage 23 and the discharge valve 24 are referred to as the first discharge passage 23 and the first discharge valve 24, respectively. One end of the first discharge passage 23 is arranged inside the first heat insulation space V1, and the other end of the first discharge passage 23 is connected to the gas consumption equipment 18 outside the first heat insulation space V1.

The first discharge valve 24 is a valve that releases the pressure in the first heat insulation space V1 when the pressure in the first heat insulation space V1 exceeds the second set upper limit pressure. In this embodiment, the first discharge valve 24 is a manually operated valve or a remotely operated valve operated by the operator, or is automatically opened when the pressure in the first heat insulating space V1 becomes equal to or higher than the second set upper limit pressure. self-operating automatic valves (eg safety valves).

The multi-shell tank 10D also includes a second discharge passage 53 and a second discharge valve 54 provided in the second discharge passage 53 . The second exhaust path 53 guides the gas inside the second heat insulating space V2 to the outside of the second heat insulating space V2. One end of the second discharge passage 53 is arranged inside the second heat insulation space V2, and the other end of the second discharge passage 53 is connected to the gas consumption equipment 18 outside the second heat insulation space V2. If the gas filled in the second heat insulating space V2 is nitrogen gas or the like, the other end of the second discharge path 53 does not have to be connected to the gas consuming equipment 18 . In this case, the other end of the second discharge path 53 may be open to the atmosphere. Further, in this embodiment, the other end of the second discharge path 53 is maintained at a pressure lower than the pressure of the second heat insulating space V2.

The second discharge valve 54 is a valve that releases the pressure in the second heat insulation space V2 when the pressure in the second heat insulation space V2 exceeds the second set upper limit pressure. The second discharge valve 54 is a manually operated valve or a remotely operated valve operated by the operator, or a self-powered automatic valve that is automatically opened when the pressure in the second heat insulating space V2 exceeds the second set upper limit pressure. A valve (eg a safety valve). The set upper limit pressure at which the second discharge valve 54 opens may be different from the set upper limit pressure at which the first discharge valve 24 opens.

The pressure of the air layer in the inner tank 11 is kept higher than the pressure of the first heat insulating space V1, and the pressure of the first heat insulating space V1 is kept lower than the pressure of the holding space W, The pressure in the holding space W is kept above the atmospheric pressure.

That is, in the present embodiment, the pressure of the gas layer in the inner tank 11 and the pressure of the first heat insulation space V1 satisfy the relationship of the following formula (D), and the pressure of the first heat insulation space V1 and the pressure of the holding space W satisfies the relationship of formula (E) below, and the pressure in the holding space W and the atmospheric pressure satisfy the relationship of formula (F) below.
Pa>Pb1 (D)
Pc>Pb1 (E)
Pc≧Po (F)
However, Pa is the pressure of the air layer in the inner tank 11, Pb1 is the first pressure from the inside of the two heat insulating spaces, Pc is the pressure of the holding space W, and Po is , is atmospheric pressure.

The pressure in the second heat insulating space V2 is preferably lower than the pressure in the holding space W. This is because the gas in the second heat insulating space V2 can be prevented from leaking into the holding space W when the second outer tank 16 is damaged.

Various devices are operated, set or controlled so that the above formulas (D), (E) and (F) are satisfied. For example, the first discharge valve 24 is opened to reduce the pressure in the first heat insulating space V1 so as to satisfy the above formula (D). For example, the first discharge valve 24 is opened to reduce the pressure in the first heat insulating space V1 so as to satisfy the above formula (E). For example, the gas supply device 34 and the like described above are operated to increase the pressure in the holding space W so as to satisfy the above formula (E) and/or formula (F).

As described above, according to the multi-shell tank 10D according to the present embodiment, the first heat insulating space V1 is filled with the same kind of gas as the vaporized low-temperature liquid in the inner tank 11, The pressure of the air layer inside the inner tank 11 is higher than the pressure of the first heat insulating space V1. Therefore, the pressure in the first heat insulating space V1 can be made less than the saturated vapor pressure of the gas in the first heat insulating space V1 at the temperature of the liquid in the inner bath 11 . Therefore, it is possible to suppress condensation of gas in the first heat insulating space V1.

Further, in the present embodiment, since the pressure in the holding space W is equal to or higher than the atmospheric pressure, it is possible to prevent outside air from entering the holding space W.

Also, the pressure in the first heat insulating space V1 is lower than the pressure in the holding space W. Therefore, even when the pressure in the holding space W is maintained at or above the atmospheric pressure, the pressure in the inner tank 11 can be adjusted to be relatively low regardless of the pressure in the holding space W.

Therefore, it is possible to keep the pressure of the air layer in the inner tank 11 low while suppressing condensation of the gas in the first heat insulating space V1 outside the inner tank 11 .

<Other embodiments>
The present invention is not limited to the embodiments described above, and various modifications are possible without departing from the gist of the present invention.

For example, the configurations of the first to fourth embodiments can be combined as appropriate.

Also, the gas supply device 34 described in the second and third embodiments may be provided in the multi-shell tanks 10A and 10D of the first and fourth embodiments. Moreover, the multi-shell tanks 10A, 10B and 10D of the first, second and fourth embodiments may be provided with the relief passage 41 and the relief valve 42 described in the third embodiment.

Also, the multi-shell tank 10D of the first and fourth embodiments may be provided with the controller 30 described in the second and third embodiments. In this case, the controller 30 may control at least one of the inlet valve 22 , the exhaust valve 24 and the gas supply device 34 .

The number of outer tanks provided in the multi-shell tank is not limited to that described in the above embodiment. For example, the number of outer tanks may be three or more.

Moreover, in the above embodiment, the introduction path 21 and the introduction valve 22 may not be provided.

Further, although the low-temperature liquid in the inner tank 11 is liquefied hydrogen in the first to fourth embodiments, the low-temperature liquid in the inner tank 11 is not limited to this. For example, the cryogenic liquid in the storage space U may be liquefied natural gas, and the gas filled in the heat insulating space V (or V1) and the boil-off gas in the inner tank 11 may be natural gas.

In addition, in the first to third embodiments, the holding space W is filled with a different type of gas from the gas in the heat insulating space V and the boil-off gas in the inner tank 11. , the same kind of gas as the gas in the heat insulating space V and the boil-off gas in the inner tank 11 may be filled.

In addition, in the fourth embodiment, the second heat insulation space V2 is filled with the same kind of gas as the boil-off gas in the inner tank 11 and the gas in the second heat insulation space V2. V2 may be filled with a different kind of gas from the boil-off gas in the inner tank 11 and the gas in the second heat insulating space V2. In addition, in the fourth embodiment, the holding space W is filled with a different kind of gas from the gas in the first heat insulating space V1 and the second heat insulating space V2 and the boil-off gas in the inner tank 11. , the holding space W is filled with the same kind of gas as one or both of the gas in the heat insulating space V and the boil-off gas in the inner tank 11 . For example, the gas filled in the first heat insulation space V1 is hydrogen gas, the gas filled in the second heat insulation space V2 is nitrogen gas, and the gas filled in the holding space W is nitrogen gas, inert gas or dry gas. Air or the like may be used.

In the above-described embodiment, the pressure in the holding space W is kept above the atmospheric pressure, but the pressure in the holding space W may be kept below the atmospheric pressure.

The first BOG discharge valve 17a may not be a valve operated to be opened by an operator, but may be controlled by a control device such as that described in the second embodiment.

In the above embodiments, the multi-hull tank was provided on the ship, but the multi-hull tank may be installed on the ground.

The multi-shell tank of the present invention can also be applied to membrane-type tanks. That is, in the membrane-type tank, the primary membrane containing the cryogenic liquid corresponds to the inner tank in the present invention, and the secondary membrane covering the primary membrane corresponds to the outer tank in the present invention. corresponds to the accommodation structure in the present invention. In this case, the insulating space between the primary membrane and the secondary membrane and the retaining space between the secondary membrane and the hull are each provided with thermal insulation and the pressure of the cryogenic liquid in the primary membrane is reduced. The load and weight are supported by the hull via the heat insulating material in the heat insulating space and the heat insulating material in the holding space. the adiabatic space between the primary membrane and the secondary membrane is filled with the same kind of gas as the vaporized gas of the cryogenic liquid, the pressure of the gas layer in the primary membrane is higher than the pressure of the adiabatic space, The pressure in said insulating space is lower than the pressure in the retaining space between the secondary membrane and the hull.

An inner tank in which a cryogenic liquid is stored, an outer tank for containing the inner tank, and a housing structure for containing the outer tank, wherein a heat-insulating space between the inner tank and the outer tank includes , the same kind of gas as the vaporized gas of the low temperature liquid is filled, the pressure of the gas layer in the inner tank is higher than the pressure of the heat insulation space, and the pressure of the heat insulation space is equal to the pressure of the holding space In the lower multi-shell tank of the first embodiment,
At least part of the housing structure may face the atmosphere on the side opposite to the holding space, and pressure in the holding space may be equal to or higher than atmospheric pressure.

According to this configuration, since the pressure in the holding space is equal to or higher than the atmospheric pressure, it is possible to prevent outside air from entering the holding space.

Here, if the pressure in the adiabatic space is higher than the pressure in the holding space, which is equal to or higher than the atmospheric pressure, the pressure Pa of the gas layer in the inner tank, the pressure Pb of the adiabatic space, the pressure Pc of the holding space, and the atmospheric pressure The relationship with Po is expressed by the following formula.
Pa>Pb>Pc≧Po
However, if the pressures Pa, Pb, and Pc are adjusted in this way, it becomes necessary to set the pressure in the inner tank relatively high with respect to the atmospheric pressure. In order to keep the pressure of the air layer in the inner tank high, as described above, gas consumption in the inner tank during unloading and an increase in plate thickness of the multi-shell tank lead to an increase in cost, which is not preferable. On the other hand, according to the multi-shell tank of the first aspect, the pressure in the heat insulating space is lower than the pressure in the holding space, so that the pressure in the inner tank is relatively low (for example, high pressure) regardless of the pressure in the holding space. (to approach atmospheric pressure).

The multi-shell tank of the first aspect may include a discharge passage that guides the gas in the heat insulation space to the outside of the heat insulation space, and a discharge valve and/or an exhaust device provided in the discharge passage. According to this configuration, it is possible to depressurize the heat insulating space.

The multi-shell tank of the first aspect includes a first pressure gauge that measures the pressure of the air layer in the inner tank, a second pressure gauge that measures the pressure of the heat insulating space, and the second pressure gauge. and a control device for controlling the exhaust valve and/or the exhaust device such that the pressure applied is kept lower than the pressure measured by the first pressure gauge. According to this configuration, even if the pressure of the adiabatic space and/or the pressure of the air layer within the inner tank fluctuates, the pressure of the adiabatic space can be adjusted in real time to be lower than the pressure of the air layer within the inner tank.

The multi-shell tank of the first aspect includes an introduction passage for introducing the boil-off gas of the gas layer in the inner tank into the heat insulation space, and an introduction valve provided in the introduction passage, and the control device may control the introduction valve so that the pressure measured by the second pressure gauge is equal to or higher than the set lower limit pressure. According to this configuration, when the pressure in the heat insulating space decreases due to temperature change in the holding space, the pressure in the heat insulating space can be adjusted in real time to be equal to or higher than the second set lower limit pressure.

The multi-shell tank of the first aspect includes a second pressure gauge for measuring the pressure in the heat insulation space, a third pressure gauge for measuring the pressure in the holding space, and the same type of gas as the gas filled in the holding space. gas to the holding space W, and the gas supply device is controlled so that the pressure measured by the third pressure gauge is kept higher than the pressure measured by the second pressure gauge. and a controller for According to this configuration, even if the pressure in the heat insulating space and/or the pressure in the holding space fluctuates, the pressure in the holding space can be adjusted in real time to be higher than the pressure in the heat insulating space.

The multi-shell tank of the first aspect includes one or more thermometers for measuring the temperature of the outer tank or the temperature of the heat insulating space, and the pressure of the gas in the holding space is measured by the one thermometer. It may be maintained below the saturated vapor pressure of the gas in the holding space at a reference temperature, which is a temperature determined based on the measured temperature or the temperatures measured by the plurality of thermometers. According to this configuration, the dew point of the gas in the holding space can be made lower than the reference temperature, and as a result, condensation of the gas in the holding space can be suppressed.

An inner tank in which a cryogenic liquid is stored, N outer tanks (N is an integer equal to or greater than 2) containing the inner tanks, and the N-th outer tank from the inner side of the N outer tanks. and a housing structure for housing the N outer tanks, wherein the (N−1) outer tanks excluding the outermost tank are provided between the inner tank and the outermost tank. N partitioned heat insulating spaces are formed, and the first heat insulating space, which is the first heat insulating space from the inside of the N heat insulating spaces, is filled with the same kind of gas as the vaporized gas of the low temperature liquid. , the pressure of the air layer in the inner tank is higher than the pressure of the first heat insulating space, and the pressure of the first heat insulating space is lower than the pressure of the holding space, in the multi-shell tank of the second aspect,
At least part of the housing structure may face the atmosphere on the side opposite to the holding space, and pressure in the holding space may be equal to or higher than atmospheric pressure.

According to this configuration, since the pressure in the holding space is equal to or higher than the atmospheric pressure, it is possible to prevent outside air from entering the holding space.

Here, if the pressure in the first adiabatic space is higher than the pressure in the holding space, which is equal to or higher than the atmospheric pressure, the pressure Pa in the air layer in the inner tank, the pressure Pb1 in the first adiabatic space, and the pressure Pc in the holding space , and the atmospheric pressure Po is expressed by the following equation.
Pa>Pb1>Pc≧Po
In this case, it is necessary to set the pressure of the inner tank relatively high with respect to the atmospheric pressure. However, according to the multi-shell tank of the second aspect, since the pressure in the first heat insulating space is lower than the pressure in the holding space, the pressure in the inner tank is kept relatively low (for example, high pressure) regardless of the pressure in the holding space. (to approach atmospheric pressure).

Further, the multi-shell tank of the second aspect is provided with one or more thermometers for measuring the temperature of the outermost tank or the temperature of the Nth heat insulating space, and the pressure of the gas in the holding space is It may be maintained below the saturated vapor pressure of the gas in the holding space at a reference temperature, which is the temperature measured by one thermometer or the temperature determined based on the temperatures measured by the plurality of thermometers. . According to this configuration, the dew point of the gas in the holding space can be made lower than the reference temperature, and as a result, condensation of the gas in the holding space can be suppressed.

In the multi-shell tank of the second aspect, the N heat insulating spaces may be filled with the same kind of gas as the vaporized gas of the low-temperature liquid.

Alternatively, in the multi-shell tank of the second aspect, the second to N-th heat insulating spaces from the inner side of the N heat insulating spaces are filled with a gas different from the vaporized gas of the low-temperature liquid. may

1: Vessels 10A, 10B, 10C, 10D: Multi-shell tank 11: Inner tank 12: Outer tank 13: Tank cover 14: Retaining wall 15: Housing structure 16: Outer tank 21: Introduction path 22: Introduction valve 23: Discharge path 24: Exhaust valve 25: Exhaust device 30: Control device 31: First pressure gauge 32: Second pressure gauge 33: Third pressure gauge 34: Gas supply device 35: Thermometer 41: Relief passage 42: Relief valve 51: Third 1 discharge path 52: first discharge valve 53: second discharge path 54: second discharge valve U: storage space V: heat insulation space V1: first heat insulation space V2: second heat insulation space W: retention space

Claims (10)

an inner tank in which a cryogenic liquid is stored;
an outer tank containing the inner tank;
a housing structure that houses the outer tank,
The heat insulating space between the inner tank and the outer tank is filled with the same kind of gas as the vaporized gas of the low temperature liquid,
A multi-shell tank, wherein the pressure of the air layer within the inner tank is higher than the pressure of the insulating space, and the pressure of the insulating space is lower than the pressure of the holding space between the outer tank and the containing structure. at least part of the housing structure faces the atmosphere on the side opposite to the holding space;
A multi-shell tank according to claim 1, wherein the pressure in said holding space is above atmospheric pressure. a discharge path that guides the gas in the heat insulating space to the outside of the heat insulating space;
3. Multi-shell tank according to claim 1 or 2, comprising a discharge valve and/or an exhaust device provided in the discharge passage. a first pressure gauge for measuring the pressure of the air layer in the inner tank;
a second pressure gauge for measuring the pressure in the heat insulating space;
and a control device that controls the exhaust valve and/or the exhaust device so that the pressure measured by the second pressure gauge is kept lower than the pressure measured by the first pressure gauge. A multi-shell tank as described in . an introduction path for introducing the boil-off gas of the air layer in the inner tank into the heat insulation space;
an introduction valve provided in the introduction path,
5. The multi-shell tank according to claim 4, wherein said control device controls said introduction valve so that the pressure measured by said second pressure gauge is equal to or higher than a set lower limit pressure. a second pressure gauge for measuring the pressure in the heat insulating space;
a third pressure gauge that measures the pressure in the holding space;
a gas supply device that supplies the holding space W with the same type of gas as the gas filled in the holding space;
and a control device that controls the gas supply device so that the pressure measured by the third pressure gauge is kept higher than the pressure measured by the second pressure gauge. Multi-shell tank according to paragraph 1. an inner tank in which a cryogenic liquid is stored;
N outer tanks (N is an integer equal to or greater than 2) containing the inner tanks;
a housing structure that covers the Nth outermost tank from the inner side of the N outer tanks and houses the N outer tanks,
Between the inner tank and the outermost tank, N heat insulating spaces partitioned by (N−1) outer tanks excluding the outermost tank are formed, and the N heat insulating spaces The first heat insulating space, which is the first from the inside, is filled with the same kind of gas as the vaporized gas of the low-temperature liquid,
The pressure of the air layer in the inner tank is higher than the pressure of the first heat insulating space, and the pressure of the first heat insulating space is lower than the pressure of the holding space between the outermost tank and the housing structure. shell tank. A ship comprising a multi-hull tank according to any one of claims 1-7. An inner tank in which a low-temperature liquid is stored, an outer tank that houses the inner tank, and a housing structure that houses the outer tank, wherein a heat-insulating space between the inner tank and the outer tank includes: In a multi-shell tank filled with the same kind of gas as the gas from which the cryogenic liquid is vaporized,
In the inner tank, the pressure of the air layer in the inner tank is higher than the pressure in the heat insulating space, and the pressure in the heat insulating space is lower than the pressure in the holding space between the outer tank and the housing structure. A gas pressure adjustment method for adjusting the pressure of the gas layer, the pressure of the adiabatic space and the pressure of the holding space. An inner tank in which a cryogenic liquid is stored, N outer tanks (N is an integer equal to or greater than 2) containing the inner tanks, and the N-th outer tank from the inner side of the N outer tanks. and a housing structure for housing the N outer tanks, wherein the (N−1) outer tanks excluding the outermost tank are provided between the inner tank and the outermost tank. N partitioned heat insulating spaces are formed, and the first heat insulating space, which is the first heat insulating space from the inside, is filled with the same kind of gas as the vaporized gas of the low temperature liquid. in the shell tank,
The pressure of the air layer in the inner tank is higher than the pressure of the first heat insulating space, and the pressure of the first heat insulating space is lower than the pressure of the holding space between the outermost tank and the housing structure. 3. A gas pressure adjusting method for adjusting the pressure of the air layer in the inner tank, the pressure of the first heat insulating space and the pressure of the holding space.

Images