Insulated tank, ship containing the same, and method for forming a vacuum in an insulated tank

Abstract

The insulated tank according to the present invention includes a first shell for storing liquefied gas and containing liquefied gas inside, a second shell disposed outside the first shell, and an insulated space disposed between the first shell and the second shell, wherein the insulated space is filled with an insulating material and a low vacuum can be formed.

Description

Technical Field

[0001] The present invention relates to a heat-insulating tank, a ship including the same, and a method for forming a vacuum of the heat-insulating tank.

Background Art

[0002] Liquefied hydrogen has a problem that heat intrusion from the outside occurs due to its extremely low temperature, resulting in a large amount of evaporation gas. Therefore, in order to prevent this, an insulating layer must be arranged outside the tank while maintaining a high-vacuum state. Generally, a vacuum insulation structure provided with a multi-layer insulation (MLI) is used. In addition, panels and membranes are also used, and perlite and glass bubbles are used.

[0003] In the case of a small tank, there is no problem in using the above-described heat insulation structure. However, in the case of a large-capacity tank arranged on a ship or an onshore terminal, in order to provide a vacuum insulation structure filled with a heat insulating material while maintaining a vacuum state of several tens of torr or less between the inner container and the outer container, there is a problem that the process of performing the vacuum operation is not easy. That is, in the case of a large tank, since the heat insulation space is quite large, there are technical inconveniences in bringing the heat insulation space to a high-vacuum state. In particular, there is a problem that it takes a long time to provide a high-vacuum heat insulation layer.

[0004] For example, when attaching a multi-layer insulation material, another panel, a spray-type heat insulating material, or a membrane to the inside or outside of the inner container, it is difficult to first perform heat insulating material construction on a large tank. In particular, in the case of a panel, there is a high possibility of heat penetration occurring at the connection part between the panels. <00​​​

[0006] Conventionally used perlite has irregular particle shapes, and glass bubbles, although spherical, have varying particle sizes. Due to their structure, smaller particles fill the spaces between larger particles, resulting in a densely packed vacuum. Therefore, it is practically difficult to create a vacuum in a space filled with perlite or glass bubbles, and even if such a space is vacuumed, it would require a considerably long working period.

[0007] Recently, powdered insulation materials such as perlite and glass bubbles, which are smaller than tens of micrometers in size, have the disadvantage that because they are so small in diameter (tens of micrometers) and fill spaces densely, it is difficult to create a vacuum in a space that is densely filled with powder.

[0008] As described above, in the case of insulated tanks, especially large-capacity insulated tanks, there are disadvantages to vacuum work with vacuum insulation structures. Therefore, there is a need to develop technology that provides insulation performance while also facilitating vacuum work. [Overview of the project] [Problems that the invention aims to solve]

[0009] The present invention was derived to solve the problems of the prior art described above, and aims to provide an insulated tank that reduces the man-hours and time required to create a vacuum in the insulated tank and optimizes the thermal insulation performance of the insulated tank, a ship including the insulated tank, and a method for creating a vacuum in an insulated tank including an insulated space with optimized thermal insulation performance. [Means for solving the problem]

[0010] The insulated tank according to the present invention is an insulated tank for storing liquefied gas, comprising a first shell containing liquefied gas internally, a second shell disposed outside the first shell, and an insulated space disposed between the first shell and the second shell, wherein the insulated space is filled with an insulating material and a low vacuum can be formed.

[0011] Specifically, the gas molecules in the adiabatic space may have at least one of the following flows: viscous flow, fluid flow, and transition flow.

[0012] Specifically, the Knudsen number of gas molecules in the adiabatic space may be 10 or less.

[0013] Specifically, the pressure in the adiabatic space may be between 70 mTorr and 2,400 mTorr.

[0014] Specifically, the pressure in the adiabatic space can be reduced to a predetermined value or less so that the first shell generates an amount of evaporated gas that can be consumed by the customer consuming the evaporated gas.

[0015] Specifically, the system further includes a vacuum pump provided outside the insulated tank for discharging the gas from the insulated space to the outside, the vacuum pump being able to discharge the gas from the insulated space to the outside after the liquefied gas has been loaded into the first shell.

[0016] Specifically, it may further include a vacuum pipe having one end connected to the vacuum pump and the other end extending into the interior of the insulated space.

[0017] Specifically, the vacuum pump may be a low-vacuum pump.

[0018] Specifically, the vacuum piping can be positioned closer to the first shell than to the second shell.

[0019] Specifically, the vessel includes the insulated tank and further includes a customer that consumes the evaporated gas generated in the first shell, wherein the pressure in the insulated space is below a predetermined value such that the amount of evaporated gas generated in the first shell is consuming at the customer, and the evaporated gas generated in the first shell can be consumed as propellant fuel for the vessel.

[0020] The present invention relates to a method for forming a vacuum in an insulated tank, which is a method for forming a vacuum in an insulated space located between a first shell, which is provided inside the insulated tank and contains liquefied gas, and a second shell, which is located outside the first shell, and includes a first vacuum step of reducing the pressure in the insulated space, thereby enabling the formation of a low vacuum in the insulated space.

[0021] Specifically, after loading liquefied gas into the insulated tank, a second vacuum step may be further included in which a vacuum pump provided outside the insulated tank is used to reduce the pressure in the insulated space.

[0022] Specifically, the second vacuum step can be performed after the vessel, which includes the insulated tank, has commenced operations.

[0023] Specifically, the second vacuum step may include a step of measuring the pressure in the insulated tank, and a second vacuum step of repeatedly, if the pressure in the insulated tank is higher than a predetermined pressure, discharging the gas in the insulated space to the outside to lower the pressure in the insulated space to below a predetermined value, and observing the pressure change in the insulated space.

[0024] Specifically, the second vacuum step can discharge the gas in the insulated space to the outside via a vacuum pipe, one end of which is connected to the vacuum pump and the other end of which extends into the interior of the insulated space. [Effects of the Invention]

[0025] The heat-insulating tank according to the present invention, the ship including the same, and the method for forming a vacuum in the heat-insulating tank can ensure the heat-insulating performance in the heat-insulating tank and reduce the time for evacuating the vacuum in the heat-insulating space.

Brief Description of the Drawings

[0026] [Figure 1] It is a figure illustrated to explain the heat-insulating tank according to an embodiment of the present invention and the ship including the same. [Figure 2] It is a figure illustrated to explain the heat-insulating tank according to an embodiment of the present invention. [Figure 3] It is a figure illustrated to explain the heat-insulating tank according to another embodiment of the present invention. [Figure 4] It is a figure illustrated to explain the heat-insulating tank according to another embodiment of the present invention. [Figure 5a] It is a figure illustrated to explain the heat-insulating tank according to another embodiment of the present invention. [Figure 5b] It is a figure illustrated to explain the heat-insulating tank according to another embodiment of the present invention. [Figure 6] It is a figure illustrated to explain the heat-insulating tank according to an embodiment of the present invention. [Figure 7] It is a figure illustrated to explain the heat-insulating tank according to an embodiment of the present invention. [Figure 8] It is a figure illustrated to explain the heat-insulating tank according to an embodiment of the present invention and the storage terminal including the same. [Figure 9] It is a figure illustrated to explain the heat-insulating tank according to an embodiment of the present invention. [Figure 10] It is a figure illustrated to explain the heat-insulating tank according to an embodiment of the present invention. [Figure 11] It is a figure illustrated to explain the heat-insulating tank according to another embodiment of the present invention. [Figure 12] [[ID=HTTP: / / www.doubao.com]] It is a figure illustrated to explain the heat-insulating tank according to another embodiment of the present invention. [Figure 13]This figure illustrates an insulated tank according to another embodiment of the present invention. [Figure 14] This figure illustrates an insulated tank according to another embodiment of the present invention. [Figure 15a] This diagram illustrates an insulated tank and a vessel containing the same according to one embodiment of the present invention. [Figure 15b] This diagram illustrates an insulated tank and a vessel containing the same according to one embodiment of the present invention. [Figure 16] This diagram illustrates an insulated tank and a vessel containing the same according to one embodiment of the present invention. [Figure 17] This diagram illustrates an insulated tank according to one embodiment of the present invention. [Figure 18] This figure illustrates an insulated tank according to another embodiment of the present invention. [Figure 19] This figure illustrates an insulated tank according to another embodiment of the present invention. [Figure 20] This figure illustrates an insulated tank according to another embodiment of the present invention. [Figure 21] This figure illustrates the vacuum piping arranged in an insulated tank according to an embodiment of the present invention. [Figure 22] This figure illustrates the vacuum piping arranged in an insulated tank according to an embodiment of the present invention. [Figure 23] This figure illustrates the vacuum piping arranged in an insulated tank according to an embodiment of the present invention. [Figure 24] This figure illustrates the vacuum piping arranged in an insulated tank according to an embodiment of the present invention. [Figure 25] This figure illustrates an insulated tank according to another embodiment of the present invention. [Figure 26a] This is a diagram illustrating how gas molecules flow in a viscous manner. [Figure 26b] This diagram illustrates how gas molecules flow as molecular currents. [Figure 27] This graph shows the relationship between the Knudsen number and pressure. [Figure 28] This graph shows experimental results regarding the relationship between pressure and vacuum time in an adiabatic space. [Figure 29] This graph shows the relationship between pressure and thermal conductivity in an insulated space. [Figure 30] This is a flowchart of the first vacuum step of a method for creating a vacuum in an insulating space according to one embodiment of the present invention. [Figure 31] This is a flowchart of the second vacuum step of a method for forming a vacuum in an insulating space according to one embodiment of the present invention. [Figure 32] This figure illustrates an insulated tank and a vessel containing the same according to another embodiment of the present invention. [Modes for carrying out the invention]

[0027] The object, particular advantages, and novel features of the present invention will become clearer from the following detailed description relating to the accompanying drawings and from preferred embodiments. It should be noted that, in assigning reference numerals to components in each drawing in this specification, efforts have been made to ensure that the same component has the same number even if it appears in other drawings. Furthermore, in describing the present invention, if it is determined that a specific description of related prior art would obscure the gist of the invention, such detailed description will be omitted.

[0028] Furthermore, in the following, the term "inside-outside direction" is defined by considering the direction toward the center of the storage space as the "inside direction."

[0029] The following describes an insulated tank 600 and a ship 30 including the same according to embodiments of the present invention.

[0030] Figure 1 is a diagram illustrating an insulated tank and a vessel including the same according to one embodiment of the present invention.

[0031] As illustrated in Figure 1, an insulated tank 600 according to one embodiment of the present invention is an independent insulated tank 600 for storing liquefied gas, comprising a first shell 610 containing the liquefied gas, a second shell 620 positioned outside the first shell 610, and an insulated space 630 positioned between the first shell 610 and the second shell 620, wherein the insulated space 630 is a vacuum-sealed space filled with an insulating material 632, and the insulated space 630 can be densely filled with the insulating material 632.

[0032] The thermal insulation material 632 in this invention may include one or more of the following: foamed plastic bead, polyurethane, polystyrene, polyethylene, polyisocyanurate, aerogel blanket, fumed silica, calcium silicate, mineral wool, glass wool, glass microfiber, perlite, and hollow glass microspheres. The hollow glass microspheres may include the 3M Company's trademarked product, Glass Bubbles.

[0033] The insulated space 630, filled with the insulation material 632, may be in a vacuum state.

[0034] In this invention, the thermal insulation performance can be improved by creating a vacuum in the insulated space 630, which has the effect of reducing the generation of evaporated gas from the liquefied gas.

[0035] The vessel 30 according to the present invention includes a first shell 610, a second shell 620, and an insulated space 630 filled with insulating material 632 placed between the first shell 610 and the second shell 620. It may also include a vacuum pump 700 that can adjust the vacuum level of the insulated space 630 of the insulated tank 600, and a compressor 800 used to transfer evaporated gas generated in the insulated tank 600 to the outside of the insulated tank 600.

[0036] Depending on the embodiment, the system may include vacuum piping 710 located within an insulated space 630 between the first shell 610 and the second shell 620.

[0037] Thus, according to one embodiment of the present invention, the insulating space 630 can be filled with insulating material 632 and the insulating space 630 can be vacuumed using only a vacuum pump 700, but according to other embodiments, a vacuum pipe 710 may be further included.

[0038] In another embodiment, the insulated space 630 is filled with polyurethane foam as an insulating material 632, and a vacuum can be created in the insulated space 630 using only a vacuum pump 700. However, in yet another embodiment, a vacuum pipe 710 may also be included.

[0039] When the space between the insulating materials 632 is evacuated while the insulating space 630 is filled with insulating material 632, the exhaust may not be smooth in areas far from the vacuum pump 700 used for vacuuming. As the size of the insulating tank 600 increases, it may become more difficult to evacuate the insulating space 630. Therefore, depending on the embodiment of the present invention, vacuum piping 710 may be further included in the insulating space 630 within the insulating tank 600, and the vacuum piping 710 will be described with reference to Figures 21 to 24 below.

[0040] According to the present invention, the evaporated gas BOG generated in the insulated tank 600 can be transferred to the outside of the insulated tank. A compressor 800 may be included for transferring the evaporated gas BOG generated in the insulated tank 600 to the outside of the insulated tank 600, and by transferring the evaporated gas BOG to the outside via the compressor 800, the internal pressure of the first shell 610 can be reduced to atmospheric pressure or below.

[0041] By keeping the first shell 610 below atmospheric pressure, even if a leak occurs from the first shell 610, the leaked liquefied gas can be safely stored.

[0042] In this invention, the suction pressure of the compressor 800 may be a vacuum, and the suction piping of the compressor 800 may be a double-walled piping. In this case, even if a leak occurs in the piping, there is an advantage that outside air will not flow into the compressor 800.

[0043] Although not shown in the drawings, the vessel 30 according to the present invention may further include a piping system (not shown) that includes a compressor 800 consisting of double piping.

[0044] Furthermore, the vessel 30 of the present invention can use evaporative gas BOG generated in the insulated tank 600 as fuel, and may include engines, fuel cells, and boilers that can be used as fuel.

[0045] Furthermore, the vessel 30 according to the present invention includes a cargo hold 900 filled with an inert gas, and the insulated tank 600 can be placed in the cargo hold 900.

[0046] In this regard, the various components of the insulated tank 600 according to the present invention, as illustrated in Figure 1, will be explained below with reference to Figures 2 to 5.

[0047] The conventionally used perlite has an irregular particle shape, and glass bubbles, while spherical, have varying particle sizes, which caused problems during the process of creating a vacuum after filling the insulation material.

[0048] This is because, in the case of perlite and glass bubbles, the vacuum space is densely filled by a structure in which smaller particles fill the spaces between each particle. Therefore, it is practically difficult to create a vacuum in a space filled with perlite or glass bubbles using a vacuum pump, and even if such a space is created, it would require a considerably long time. Furthermore, in the case of fine particles such as perlite and glass bubbles, which are tens of micrometers or smaller in size, the total surface area increases, and as the area in contact with the flow in the gaps increases, the resistance increases, making it even more difficult to create a vacuum.

[0049] On the other hand, EPS (Expanded Polystyrene) refers to expanded polystyrene, a white foamed plastic material produced from solid polystyrene beads. EPS is a foamed product made by injecting hydrocarbon gas into polystyrene (PS) resin and then expanding it with steam. It has very low thermal conductivity, low hygroscopicity, and excellent cushioning properties. EPS Bead (Expanded polystyrene Bead) refers to expanded polystyrene beads, a material with stable thermal insulation properties manufactured by compressing and molding polystyrene particles (EPS).

[0050] By using semi-noncombustible EPS, fire stability can be ensured. By coating the EPS bead with a noncombustible inorganic material or applying a special treatment, the EPS can retain semi-noncombustible properties on all surfaces even after being cut.

[0051] EPP (Expanded Polypropylene) refers to foamed polypropylene, a product manufactured by foaming polyolefin-based "polypropylene (PP)" material. It has good heat resistance, is resistant to moisture, has strong chemical resistance, and is resistant to external stress. EPP has excellent recovery properties against repeated impacts and deformations, and in the case of foam cast with EPP Bead, it maintains high dimensional stability when exposed to extreme temperatures.

[0052] Figure 2 is a diagram illustrating an insulated tank according to one embodiment of the present invention.

[0053] Figure 3 is a diagram illustrating an insulated tank according to another embodiment of the present invention.

[0054] Figure 4 is a diagram illustrating an insulated tank according to another embodiment of the present invention.

[0055] As shown in Figures 2 to 4, the insulated tank 600 according to the present invention is an independent tank, and may be a MOSS-type (Type-B) spherical tank, and the insulated space 630 located between the first shell 610 and the second shell 620 of the insulated tank 600 may be filled with an insulating material 632.

[0056] The first shell 610 according to one embodiment of the present invention may be an atmospheric pressure tank, and the atmospheric pressure as defined in the first shell 610 of the present invention means a state of 0 to 0.7 barg, taking into account the BOG (boil of gas) generated inside.

[0057] Furthermore, depending on other embodiments, the first shell 610 may be a pressurized tank with a pressure of 0.7 barg or more. 0 barg means 1 atm and corresponds to a pressurization of 1.7 atm.

[0058] According to embodiments of the present invention, a vacuum state is possible in which the vapor pressure inside the first shell 610 is below atmospheric pressure, and the ship 30 can operate even when the vapor pressure of the first shell 610 is below atmospheric pressure (760 torr) in a vacuum state.

[0059] A notification is issued when the vapor pressure inside the first shell 610 is below atmospheric pressure, and since notifications regarding a drop in pressure inside the first shell can occur when the pressure is below atmospheric pressure, the low-pressure alarm value of the first shell 610 may be below atmospheric pressure.

[0060] As explained above, the vessel 30 according to the present invention can be operated even when the internal pressure of the first shell 610 is at a vacuum pressure below atmospheric pressure, and it goes without saying that it can also be operated when the pressure drops below atmospheric pressure during the loading and unloading of the liquefied gas inside the insulated tank 600.

[0061] As illustrated in Figures 3 and 4, the first shell 610 containing the liquefied gas inside the present invention can be made of cryogenic material, and the insulated space 630 between the first shell 610 and the second shell 620, which is filled with an insulating material 632, can be filled with an inert gas.

[0062] Depending on the embodiment, the insulated space 630 may be filled with an inert gas such as nitrogen gas, then the gas may be removed to create a vacuum in the insulated space 630, so that the remaining gas is an inert gas.

[0063] In yet another embodiment, the insulated space 630 may be filled with hydrogen gas, and then evacuated so that the remaining gas is hydrogen gas.

[0064] The second shell 620 can be made of cryogenic material in at least a portion thereof, and Figure 2 illustrates an embodiment in which only a portion of the area, including the lowest end, is made of cryogenic material.

[0065] Figure 4 illustrates an embodiment in which a larger area of ​​the second shell 620 is made of cryogenic material than in Figure 3, and it can be confirmed that the lower hemisphere of the second shell 620 is made of cryogenic material.

[0066] Thus, in the second shell 620, the lower end portion made of cryogenic material can function as a drip tray.

[0067] Furthermore, as illustrated in Figures 3 and 4, a temperature sensor 640 can be placed at the bottom of the second shell 620.

[0068] However, the position of the temperature sensor 640 is not limited to the positions shown in Figures 3 and 4; it can be placed anywhere that allows for measurement of the temperature of the substance accumulating at the lower end.

[0069] Depending on the embodiment of the present invention, a first pressure sensor 650 for measuring the pressure in the insulated space 630 may be included.

[0070] The first pressure sensor 650 can be positioned at any location where the internal pressure of the adiabatic space 630 can be measured, and may further include a gas sensor 660 for sensing the composition of the internal gas in the adiabatic space 630, although this is not shown in Figures 3 and 4.

[0071] The gas sensor 660 can analyze the gas components present in the insulated space 630, and changes in the gas components can be detected, which allows for the determination of whether or not the gas is changing.

[0072] Figures 5a and 5b are diagrams illustrating an insulated tank according to another embodiment of the present invention.

[0073] As another embodiment of the present invention, Figures 5a and 5b illustrate a cargo hold 900 filled with inert gas in which the insulated tank 600 is placed inside a ship 30, showing the insulated tank 600 positioned inside the cargo hold 900 of the ship 30.

[0074] As the inert gas, nitrogen gas can be used, as shown in Figure 5, but it is not limited to this.

[0075] The upper part of the insulated tank 600 may further include a gas sampling configuration, and may further include a gas analysis unit 662 for analyzing the gas components thus collected.

[0076] Depending on the embodiment, as shown in Figure 5, the system may include both a first pressure sensor 650 for measuring the pressure in the insulated space 630 and a second pressure sensor 910 for measuring the pressure in the cargo hold 900, and may further include piping and valves for injecting or discharging nitrogen gas into or out of the cargo hold 900.

[0077] In the insulated tank 600 according to the present invention, if water leakage occurs from the first shell 610, the first pressure sensor 650 senses the change in pressure, and in the case of an LNG tank, the HC of the insulated space 630 is measured, and then the temperature is measured by the drip tray at the lower end of the second shell 620, and water leakage can be detected by whether or not there is a change.

[0078] If a leak occurs in the second shell 620, the leak can be detected by sensing the pressure change in the insulated space 630 and the pressure change in the cargo hold 900, and then by sensing the pressure change in the insulated space 630 with the first pressure sensor 650.

[0079] First, an insulated tank 100 and a storage terminal 10 including the same, according to an embodiment of the present invention, will be described below.

[0080] As illustrated in Figure 6, an insulated tank 100 according to one embodiment of the present invention is an insulated tank 100 for storing liquefied gas, comprising a first shell 120 and a second shell 130, and may include a first insulated space 140 disposed between the first shell 120 and the second shell 130, which is filled with an insulating material 142 and is vacuum-treated, and the first insulated space 140 can be densely filled with the insulating material 142.

[0081] The thermal insulation material 142 in this invention may include one or more of the following: foamed plastic beads, polyurethane, polystyrene, polyethylene, polyisocyanurate, aerogel blanket, fumed silica, calcium silicate, mineral wool, glass wool, glass microfiber, perlite, and hollow glass microspheres.

[0082] For example, the first insulated space 140 between the first shell 120 and the second shell 130 can be filled with an insulating material 142, and the first insulated space 140 filled with the insulating material 142 may be in a vacuum state.

[0083] Depending on the embodiment, the thermal insulation material 142 used in the present invention may be coated, and the coating material may be different from that of the thermal insulation material 142. For example, an EPS bead can be coated with a non-combustible inorganic material, or it may be coated with a flame-retardant material. In addition, it may be coated with a composition of a flame retardant and various other inorganic materials, and the coating material is not limited to those mentioned above.

[0084] In one embodiment of the present invention, the first insulated space 140 may include a getter (not shown).

[0085] The getter is used to maintain a high vacuum within the first adiabatic space 140 for a long period of time. If there are gases generated inside or gases entering from the outside, the getter, which is a gas absorbent, can be included in the first adiabatic space 140 to remove them.

[0086] The getter may be placed at any position within the first insulated space 140, and in one embodiment, it may be attached to one side of the wall formed by the first insulated space 140.

[0087] According to one embodiment of the present invention, a vacuum state is possible in which the vapor pressure inside the first shell 120 is below atmospheric pressure. That is, the first shell 120 can operate even in a vacuum state where the vapor pressure is below atmospheric pressure (760 torr), and a notification may be generated when the vapor pressure inside the first shell 120 is below atmospheric pressure, and the low-pressure alarm value of the first shell 120 may be below atmospheric pressure.

[0088] As described above, the storage terminal 10 according to the present invention can operate at a vacuum pressure where the internal pressure of the first shell 120 is below atmospheric pressure, and it goes without saying that it can also operate when the pressure drops below atmospheric pressure during the process of loading and unloading the liquefied gas inside the insulated tank 100.

[0089] Figure 7 is a diagram illustrating an insulated tank according to one embodiment of the present invention.

[0090] As illustrated in Figure 7, an insulated tank 100 according to one embodiment of the present invention includes a first shell 120 for containing liquefied gas, and a second shell 130 located outside the first shell 120, and may include a first insulated space 140 located between the first shell 120 and the second shell 130.

[0091] Depending on the embodiment, the first insulated space 140 may be in a vacuum state filled with an insulating material 142.

[0092] In other embodiments, the first shell 120 may further include an insulating layer (not shown) where the insulating material can be a membrane, insulating cloth, insulating panel, etc., and can be filled with hydrogen gas.

[0093] The first shell 120 serves to retain the liquefied gas. Depending on the embodiment, it may contain 9% nickel (Ni), and in the case of the second shell 130, it is for maintaining the internal insulation space and serves as a structural element of the insulated tank 100.

[0094] At least one of the first shell 120 and the second shell 130 of the present invention may be made of concrete. That is, at least one of the inside or outside of the first insulated space 140 filled with insulation material will be a structure that is structurally subjected to forces in the form of a concrete structure being placed therein.

[0095] In the present invention, a barrier (not shown) may be placed inside the first shell 120, and the barrier (not shown) may be made of a cryogenic material such as SUS or Invar, but is not limited to this material.

[0096] The first shell 120 can be made of reinforced concrete material, which consists of steel reinforcement and concrete.

[0097] Reinforcing bars are generally made of carbon steel, but in particular, when exposed to seawater in offshore structures, epoxy-coated reinforcing bars, galvanized reinforcing bars, or reinforcing bars made of stainless steel may be used.

[0098] The reinforcing bars used in the first shell 120 of the present invention can be made of cryogenic materials that have excellent resistance in cryogenic environments, and in one embodiment, stainless steel can be used.

[0099] The second shell 130 of the present invention plays a role in maintaining structural strength in the insulated tank 100, and the second shell 130 may be made of a room temperature material, and preferably a concrete material.

[0100] Figure 8 is a diagram illustrating an insulated tank and a storage terminal including the same according to one embodiment of the present invention.

[0101] As illustrated in Figure 8, a storage terminal 10 according to one embodiment of the present invention includes an insulated tank 100 which includes a first shell 120, a second shell 130, and a first insulated space 140 filled with insulating material 142 placed between the first shell 120 and the second shell 130, and may include a vacuum pump 200 and a compressor 300.

[0102] The storage terminal 10 in this invention can be installed on land or at sea.

[0103] The storage terminal 10 may include a vacuum pump 200 that can adjust the vacuum level of the first insulated space 140 of the insulated tank 100.

[0104] The vacuum pump 200 can be operated even after the insulated tank 100 and storage terminal 10 have been fabricated, and the vacuum level of the first insulated space 140 can be adjusted using the vacuum pump 200.

[0105] Depending on the embodiment, a vacuum pipe 210 may be included, which is located within a first insulated space 140 situated between the first shell 120 and the second shell 130.

[0106] According to one embodiment of the present invention, the first insulated space 140 can be filled with an insulating material 142 and the first insulated space 140 can be vacuumed using only a vacuum pump 200, but according to other embodiments, a vacuum piping 210 may be further included.

[0107] When the first insulated space 140 is filled with insulation material 142 and the space between the insulation material 142 is to be evacuated, exhaust may not be performed smoothly in areas far from the vacuum pump 200 used for evacuating. As the size of the insulated tank 100 increases, it may become more difficult to evacuate the first insulated space 140. Therefore, the first insulated space 140 inside the insulated tank 100 may also include vacuum piping 210, which will be explained with reference to Figures 21 to 24 below.

[0108] According to one embodiment of the present invention, the vapor pressure inside the first shell 120 can be reduced to a vacuum state below atmospheric pressure. That is, the inside of the first shell 120 may or may not be a vacuum.

[0109] The first shell 120 can operate in a vacuum state where the vapor pressure is below atmospheric pressure (760 torr), and a notification may be issued when the vapor pressure inside the first shell 120 is below atmospheric pressure, and the low-pressure alarm value of the first shell 120 may also be below atmospheric pressure.

[0110] Furthermore, according to the present invention, the evaporated gas BOG generated in the first shell 120 can be transferred to the outside of the insulated tank 100.

[0111] The present invention may include a compressor 300 used to transfer the evaporated gas BOG generated in the insulated tank 100 to the outside of the insulated tank 100, and by transferring the evaporated gas BOG to the outside via the compressor 300, the internal pressure of the first shell 120 can be reduced to below atmospheric pressure.

[0112] In this invention, the suction pressure of the compressor 300 may be a vacuum.

[0113] The suction piping of the compressor 300 may be a double-walled piping system, which has the advantage that even if a leak occurs in the piping, outside air will not flow into the compressor 300.

[0114] Although not shown in the drawings, the storage terminal 10 according to the present invention may further include a piping system (not shown) including a compressor 300 consisting of double piping, and can use the evaporated gas BOG generated in the insulated tank 100 as fuel, and may include engines, fuel cells, and boilers that can use the gas as fuel.

[0115] If any of the information described in Figures 6 to 8 overlaps with the various embodiments described below, it is included in the corresponding sections of the explanations for Figures 9 to 20.

[0116] The above describes an insulated tank 100 and a storage terminal 10 including the same according to one embodiment of the present invention, and the following describes an insulated tank 400 and a ship 20 including the same according to an embodiment of the present invention.

[0117] Figure 9 is a diagram illustrating an insulated tank according to one embodiment of the present invention.

[0118] As illustrated in Figure 9, an insulated tank 400 according to one embodiment of the present invention is a membrane insulated tank 400 for storing liquefied gas, and includes a first shell 410 containing liquefied gas, a second shell 420 located outside the first shell 410, a first insulated space 430 located between the first shell 410 and the second shell 420, and a second insulated space 440 located between the second shell 420 and the internal wall of the vessel located outside the second shell 420, wherein the first insulated space 430 and the second insulated space 440 may be filled with an insulating material 450 and may be vacuum-sealed insulated spaces, and the first insulated space 430 and the second insulated space 440 can be densely filled with the insulating material 450.

[0119] The thermal insulation material 450 in this invention may include one or more of the following: foamed plastic bead, polyurethane, polystyrene, polyethylene, polyisocyanurate, aerogel blanket, fumed silica, calcium silicate, mineral wool, glass wool, glass microfiber, perlite, and hollow glass microsphere.

[0120] The first insulated space 430 and the second insulated space 440, which are filled with the insulated material 450 according to the present invention, may be in a vacuum state.

[0121] In this invention, by creating a vacuum in the first insulated space 430 and the second insulated space 440, the thermal insulation performance can be enhanced, and the generation of evaporated gas from the liquefied gas can be reduced.

[0122] According to one embodiment of the present invention, a vacuum state is possible in which the vapor pressure inside the first shell 410 is below atmospheric pressure. That is, the first shell 410 can operate even in a vacuum state where the vapor pressure is below atmospheric pressure (760 torr), and a notification may be generated when the vapor pressure inside the first shell 410 is below atmospheric pressure, and the low-pressure alarm value of the first shell 410 may be below atmospheric pressure.

[0123] The various components of the insulated tank according to the present invention, as illustrated in Figure 9, will be explained below with reference to Figures 10 to 15.

[0124] Figure 10 is a diagram illustrating an insulated tank according to one embodiment of the present invention.

[0125] Figure 11 is a diagram illustrating an insulated tank according to another embodiment of the present invention.

[0126] As illustrated in Figures 10 and 11, the insulated tank 400 according to an embodiment of the present invention may include a vacuum pump 470 and a pressure control unit 480.

[0127] As shown in Figure 10, the first insulated space 430 and the second insulated space 440 may be filled with different gases, but as shown in Figure 11, the first insulated space 430 and the second insulated space 440 may be filled with the same gas.

[0128] First, Figure 10 illustrates a scenario where the liquefied gas stored in the insulated tank 400 is liquefied hydrogen, and the second insulated space 440 is filled with nitrogen gas, while the first insulated space 430 is filled with helium gas or hydrogen gas. However, the types of gases used to fill each space are not limited to those listed above.

[0129] When different gases are used, if the liquefied gas contained inside the first shell 410 is liquefied hydrogen, the first insulated space 430 is filled with hydrogen gas or helium gas at a temperature lower than or equal to that of liquefied hydrogen, in order to prevent the formation of ice in the residual gas in the first insulated space 430.

[0130] Furthermore, the second insulated space 440 is filled with nitrogen gas, which is cheaper than hydrogen and helium gas, as it is a gas with a cooling temperature higher than or the same as that of liquefied hydrogen and is not flammable. This has the advantage of reducing costs.

[0131] The insulated tank 400 according to the present invention may include a vacuum pump 470 for creating a vacuum in the first insulated space 430 and the second insulated space 440, which are filled with gas, and a pressure control unit 480 for controlling the pressure in the first insulated space 430 and the second insulated space 440 by supplying the remaining gas in the first insulated space 430 and the second insulated space 440 after the vacuuming operation.

[0132] In other words, as shown in Figure 11, the insulated tank 400 according to the present invention may include a vacuum pump 470 that can adjust the vacuum level of the first insulated space 430 and the second insulated space 440, and the vacuum pump 470 can be operated even after the insulated tank 400 and the ship 20 have dried.

[0133] Unlike Figure 11, Figure 10 shows a case where the first adiabatic space 430 and the second adiabatic space 440 are filled with different gases, and may include a first vacuum pump 472 for creating a vacuum in the first adiabatic space 430 and a second vacuum pump 474 for creating a vacuum in the second adiabatic space 440.

[0134] Furthermore, after the vacuum operation, the system may include a first pressure control unit 482 that supplies the same gas as the remaining gas in the first adiabatic space 430 to control the pressure in the first adiabatic space 430, and a second pressure control unit 484 that supplies the same gas as the remaining gas in the second adiabatic space 440 to control the pressure in the second adiabatic space 440.

[0135] This differs from Figure 11, which includes a single vacuum pump 470 that evacuates the first adiabatic space 430 and the second adiabatic space 440, which are filled with the same gas, and a single pressure control unit 480 that controls the pressure in the first adiabatic space 430 and the second adiabatic space 440 by supplying the same gas as the residual gas in the first adiabatic space 430 and the second adiabatic space 440 after the vacuuming operation. For example, the same residual gas may be nitrogen gas.

[0136] The liquefied gas to be stored in the insulated tank 400 of the present invention may be liquefied hydrogen, as shown in Figure 10, but is not limited to this, and may also include LNG, as shown in Figure 11.

[0137] Figure 12 is a diagram illustrating an insulated tank according to another embodiment of the present invention.

[0138] Figure 13 is a diagram illustrating an insulated tank according to another embodiment of the present invention.

[0139] As illustrated in Figures 12 and 13, an insulated box 460 filled with an insulating material 450 can be placed in the insulated tank 400 according to an embodiment of the present invention.

[0140] In other words, the insulation material 450 is filled inside the insulated box 460, and the insulated box 460 filled with the insulation material 450 can be placed in at least one of the first insulated space 430 and the second insulated space 440.

[0141] Figures 12 and 13 illustrate how insulation boxes 460 are placed in both the first insulation space 430 and the second insulation space 440. In the manufacturing process of the insulation tank 400 shown in Figures 12 and 13, insulation boxes 460 filled with insulation material are placed in the first insulation space 430 and the second insulation space 440, after which the first insulation space 430 and the second insulation space 440 can be evacuated.

[0142] Figure 12 shows an embodiment in which the liquefied gas stored in the insulated tank 400 is liquefied hydrogen, as in Figure 10, and the second insulated space 440 is filled with nitrogen gas, and the first insulated space 430 is filled with helium gas or hydrogen gas.

[0143] In other words, if the first adiabatic space 430 and the second adiabatic space 440 are filled with different gases, the system may include a first vacuum pump 472 for creating a vacuum in the first adiabatic space 430 and a second vacuum pump 474 for creating a vacuum in the second adiabatic space 440. Furthermore, after the vacuuming process, the system may include a first pressure control unit 482 for supplying the same gas as the remaining gas in the first adiabatic space 430 to control the pressure in the first adiabatic space 430, and a second pressure control unit 484 for supplying the same gas as the remaining gas in the second adiabatic space 440 to control the pressure in the second adiabatic space 440.

[0144] Figure 13 shows a case where the first adiabatic space 430 and the second adiabatic space 440 are filled with the same gas, and may include a vacuum pump 470 that creates a vacuum in the first adiabatic space 430 and the second adiabatic space 440 filled with the same gas, and may include a pressure control unit 480 that controls the pressure in the first adiabatic space 430 and the second adiabatic space 440 after the vacuum work by the vacuum pump 470.

[0145] Figure 14 is a diagram illustrating an insulated tank according to another embodiment of the present invention.

[0146] Figure 14 illustrates an insulating box 460 placed inside a first insulating space 430 and a second insulating space 440 according to another embodiment of the present invention, and the insulating box 460 may include channels through which gas moves.

[0147] After placing the insulated box 460, filled with insulation material 450, into the first insulated space 430 and the second insulated space 440, the vacuum operation can be performed by allowing gas to move through the channels of the insulated box 460 during the vacuum creation process.

[0148] Depending on the embodiment, the inside of the insulated box 460 is in a vacuum state filled with insulating material 450, and the insulated box 460 may be a box form consisting of only one space, and multiple single-box-shaped insulated boxes 460 can be arranged to connect to the first insulated space 430 and the second insulated space 440.

[0149] However, the form of the insulated box 460 is not limited to this, and it may also be a structure in which multiple spaces are connected.

[0150] As shown in Figure 14, the insulated box 460 may include one or more reinforcing members that separate one space into two spaces. Therefore, the form of the insulated box 460 is not limited to the forms described above, and any form consisting of a vacuum space filled with insulation material 450 is possible.

[0151] Depending on the embodiment, a load transmission section (not shown) may be further included for transmitting the load of liquefied gas transmitted from inside the insulated tank 400 to the hull wall. The load transmission section (not shown) can take the form of a reinforcing member separating the space in Figure 14 and can include any structure that can transmit the load from the first shell 410 to the hull wall.

[0152] The frame that makes up the structure of the insulated box 460 can be made of plywood or composite material with minimal outgassing.

[0153] Figures 15a and 15b are diagrams illustrating an insulated tank and a vessel including the same according to one embodiment of the present invention.

[0154] As illustrated in Figures 15a and 15b, the vessel 20 according to the present invention includes a first shell 410, a second shell 420, a first insulated space 430 filled with insulating material 450 located between the first shell 410 and the second shell 420, a second insulated space 440 located between the second shell 420 and the internal wall of the vessel located outside the second shell 420, and may include an insulated tank 400 including a vacuum pump 470 for adjusting the vacuum of the first insulated space 430 and the second insulated space 440, and a pressure control unit 480 for adjusting the pressure, and may include a compressor 500.

[0155] As described above, the vessel 20 according to the present invention includes a vacuum pump 470, which makes vacuum operations easier to perform within the vessel 20.

[0156] Depending on the embodiment of the present invention, vacuum piping 476 may be included, which is located within the first insulated space 430 and the second insulated space 440.

[0157] In one embodiment, the first insulated space 430 and the second insulated space 440 are filled with insulating material 450, and the first insulated space 430 and the second insulated space 440 can be vacuumed using only a vacuum pump 470. However, in other embodiments, vacuum piping 476 may be further included.

[0158] When the first insulated space 430 and the second insulated space 440 are filled with insulation material 450, and the space between the insulation material 450 is to be evacuated, exhaust may not be smooth in areas far from the vacuum pump 470. As the size of the insulated tank 400 increases, it becomes more difficult to evacuate the first insulated space 430 and the second insulated space 440. Therefore, vacuum piping 476 can be further included in the first insulated space 430 and the second insulated space 440 within the insulated tank 400, and vacuum piping 476 will be explained with reference to Figures 21 to 24 below.

[0159] Furthermore, as explained above, the vessel 20 according to the present invention can be operated at a vacuum pressure where the internal pressure of the first shell 410 is below atmospheric pressure, and it goes without saying that it can also be operated when the pressure drops below atmospheric pressure during the loading and unloading of the liquefied gas inside the insulated tank 400.

[0160] According to the present invention, the evaporated gas BOG generated in the first shell 410 can be transferred to the outside of the insulated tank 400, and a compressor 500 used for transferring the evaporated gas BOG generated in the insulated tank 400 to the outside of the insulated tank 400 can be included, and by transferring the evaporated gas BOG to the outside via the compressor 500, the internal pressure of the first shell 410 can be reduced to atmospheric pressure or below.

[0161] In this invention, the suction pressure of the compressor 500 may be a vacuum, and depending on the embodiment, the suction piping of the compressor 500 may be a double-walled piping, which has the advantage that even if water leakage occurs in the piping, outside air will not flow into the compressor 500.

[0162] Although not shown in the drawings, the vessel 20 according to the present invention may further include a piping system (not shown) that includes a compressor 500 consisting of double piping.

[0163] Furthermore, the vessel 20 of the present invention can use the evaporated gas BOG generated in the insulated tank 400 as fuel, and may include engines, fuel cells, and boilers that can be used as fuel.

[0164] The following describes an insulated tank 400 and a ship 20 including the same, according to yet another embodiment of the present invention.

[0165] Figure 16 is a diagram illustrating an insulated tank and a vessel containing the same according to one embodiment of the present invention.

[0166] As illustrated in Figure 16, an insulated tank 400 according to one embodiment of the present invention is a membrane insulated tank 400 for storing liquefied gas, comprising a first shell 410 containing liquefied gas, a second shell 420 disposed outside the first shell 410, a first insulated space 430 disposed between the first shell 410 and the second shell 420, and a second insulated space 440 disposed between the second shell 420 and the internal wall of the ship disposed outside the second shell 420, wherein at least one of the first insulated space 430 and the second insulated space 440 is provided with a load transmission member 462 including a transmission section 464, filled with an insulating material 450, and subjected to vacuum treatment.

[0167] The first insulated space 430 and the second insulated space 440 can be densely filled with an insulating material 450, and the insulating material 450 in this invention may include one or more of the following: foamed plastic beads, polyurethane, polystyrene, polyethylene, polyisocyanurate, aerogel blanket, fumed silica, calcium silicate, mineral wool, glass wool, glass microfiber, perlite, and hollow glass microspheres.

[0168] The first insulated space 430 and the second insulated space 440, which are filled with the insulation material 450, may be in a vacuum state.

[0169] In this invention, the thermal insulation performance can be enhanced by creating a vacuum in the first thermal insulation space 430 and the second thermal insulation space 440, which has the effect of reducing the generation of evaporated gas from the liquefied gas.

[0170] The configurations of the insulated tank and the ship containing it according to the present invention, as illustrated in Figure 16, will be described below with reference to Figures 17 to 20.

[0171] According to one embodiment of the present invention, the vapor pressure inside the first shell 410 may be in a vacuum state below atmospheric pressure. That is, it can operate even in a vacuum state where the vapor pressure of the first shell 410 is below atmospheric pressure (760 torr), and a notification can be generated when the vapor pressure inside the first shell 410 is below atmospheric pressure, and the low-pressure alarm value of the first shell 410 may be below atmospheric pressure.

[0172] Figure 17 is a diagram illustrating an insulated tank according to one embodiment of the present invention.

[0173] Figure 18 is a diagram illustrating an insulated tank according to another embodiment of the present invention.

[0174] As illustrated in Figures 17 and 18, the insulated tank 400 according to an embodiment of the present invention may include a load transmission member 462 located in at least one of the first insulated space 430 and the second insulated space 440.

[0175] The thermal insulation material 450 filling the first thermal insulation space 430 and the second thermal insulation space 440 can be filled between the load transmission members 462, and depending on the embodiment, the load transmission members 462 may be made of a non-metallic material with high thermal insulation performance.

[0176] The thermal insulation material 450 that fills the space between the load transmission members 462 can be uniformly distributed within the first thermal insulation space 430 and the second thermal insulation space 440 due to the structure of the load transmission members 462, and at the same time, due to the structure of the load transmission members 462, it has the effect of distributing and transmitting the load transmitted from the thermal insulation tank 400 to the hull.

[0177] In this invention, in order to place the load-transmitting member 462 in the first insulated space 430 and the second insulated space 440, during the manufacturing process of the insulated tank 400, the load-transmitting member 462 is placed in at least one of the first insulated space 430 and the second insulated space 440, then the insulated material 450 is filled, and as the next step, the first insulated space 430 and the second insulated space 440 can be evacuated using a vacuum pump 470.

[0178] The insulated tank 400 according to the present invention may include a vacuum pump 470 and a pressure control unit 480.

[0179] As shown in Figure 17, the first insulated space 430 and the second insulated space 440 can be filled with different gases, but as shown in Figure 18, the first insulated space 430 and the second insulated space 440 may be filled with the same gas.

[0180] Figure 17 illustrates a scenario where the liquefied gas stored in the insulated tank 400 is liquefied hydrogen, and the second insulated space 440 is filled with nitrogen gas, while the first insulated space 430 is filled with helium gas or hydrogen gas. However, the types of gases used to fill each space are not limited to those mentioned above.

[0181] When different gases are used, if the liquefied gas contained inside the first shell 410 is liquefied hydrogen, the first insulated space 430 is filled with hydrogen gas or helium gas at a temperature lower than or equal to that of liquefied hydrogen, in order to prevent the formation of ice in the residual gas in the first insulated space 430.

[0182] Furthermore, the second insulated space 440 is filled with nitrogen gas, which has a cooling temperature higher than or the same as that of liquefied hydrogen, is non-flammable, and is cheaper than hydrogen or helium gas. This has the advantage of reducing costs.

[0183] The insulated tank 400 according to the present invention may include a vacuum pump 470 for creating a vacuum in the first insulated space 430 and the second insulated space 440, which are filled with gas, and a pressure control unit 480 for controlling the pressure in the first insulated space 430 and the second insulated space 440 by supplying the remaining gas in the first insulated space 430 and the second insulated space 440 after the vacuuming operation.

[0184] In other words, as illustrated in Figure 18, the insulated tank 400 according to the present invention includes a vacuum pump 470, which can be operated even after the insulated tank 400 and the ship 20 have dried, and the vacuum level of the first insulated space 430 and the second insulated space 440 can be adjusted using the vacuum pump 470.

[0185] Figure 17 shows a case where the first adiabatic space 430 and the second adiabatic space 440 are filled with different gases, and may include a first vacuum pump 472 for creating a vacuum in the first adiabatic space 430 and a second vacuum pump 474 for creating a vacuum in the second adiabatic space 440.

[0186] Furthermore, after the vacuum operation, the system may include a first pressure control unit 482 that supplies the same gas as the remaining gas in the first adiabatic space 430 to control the pressure in the first adiabatic space 430, and a second pressure control unit 484 that supplies the same gas as the remaining gas in the second adiabatic space 440 to control the pressure in the second adiabatic space 440.

[0187] This differs from Figure 18, which includes a single vacuum pump 470 that evacuates the first adiabatic space 430 and the second adiabatic space 440, which are filled with the same gas, and a single pressure control unit 480 that controls the pressure in the first adiabatic space 430 and the second adiabatic space 440 by supplying the same gas as the residual gas in the first adiabatic space 430 and the second adiabatic space 440 after the vacuuming operation. For example, the same residual gas may be nitrogen gas.

[0188] The liquefied gas to be stored in the insulated tank 400 of the present invention may be liquefied hydrogen, as shown in Figure 17, but is not limited to this, and may also include LNG, as shown in Figure 18.

[0189] Figure 19 is a diagram illustrating an insulated tank according to another embodiment of the present invention.

[0190] Figure 20 is a diagram illustrating an insulated tank according to another embodiment of the present invention.

[0191] Figure 19 illustrates a load transmission member 462 positioned in an insulated tank, which may include an upper plate, a lower plate, and a transmission section 464 that connects the upper plate and lower plate to transmit the load of liquefied gas to the hull wall, positioned parallel to the first shell 410 and the second shell 420.

[0192] Figure 20 shows a cross-section of the load transmission member 462, in which multiple columnar transmission sections 464 can be arranged, and insulating material is uniformly filled between the multiple transmission sections 464.

[0193] As shown in Figures 19 and 20, in the present invention, by using a load transmission member 462 in which an upper plate and a lower plate are connected to a columnar transmission section 464, the load transmitted from inside the insulated tank 400 to the hull is transmitted to the hull via the upper and lower plates and transmission section 464 of the load transmission member 462 that are in contact with the respective shells 410 and 420, and in the process of transmitting the load via the load transmission member 462, the load is uniformly distributed.

[0194] Referring to Figure 16, the vessel 20 according to the present invention includes a first shell 410, a second shell 420, a first insulated space 430 filled with insulating material 450 placed between the first shell 410 and the second shell 420, a second insulated space 440 placed between the second shell 420 and the internal wall of the vessel located outside the second shell 420, an insulated tank 400 including a vacuum pump 470 for adjusting the vacuum of the first insulated space 430 and the second insulated space 440, and a pressure control unit 480 for adjusting the pressure, and may include a compressor 500.

[0195] As described above, the vessel 20 according to the present invention includes a vacuum pump 470, which makes vacuum operations easier to perform within the vessel 20.

[0196] Depending on the embodiment of the present invention, vacuum piping 476 may be included, which is located within the first insulated space 430 and the second insulated space 440.

[0197] Therefore, in one embodiment, the first insulated space 430 and the second insulated space 440 are filled with insulation material 450, and the first insulated space 430 and the second insulated space 440 can be vacuumed using only a vacuum pump 470. However, in other embodiments, vacuum piping 476 may be further included.

[0198] Furthermore, according to another embodiment, the first insulated space 430 and the second insulated space 440 may be filled with polyurethane foam as an insulating material 450, and the first insulated space 430 and the second insulated space 440 may be vacuumed using only a vacuum pump 470, but according to yet another embodiment, a vacuum pipe 476 may be further included.

[0199] When the first insulated space 430 and the second insulated space 440 are filled with insulation material 450, and the space between the insulation material 450 is to be evacuated, the exhaust may not be smooth in areas far from the vacuum pump 470 used for evacuating. As the size of the insulated tank 400 increases, it may become more difficult to evacuate the first insulated space 430 and the second insulated space 440. Therefore, vacuum piping 476 can be further included in the first insulated space 430 and the second insulated space 440 within the insulated tank 400, and vacuum piping 476 will be explained with reference to Figures 21 to 24 below.

[0200] Furthermore, as described above, the vessel 20 according to the present invention can be operated at a vacuum pressure where the internal pressure of the first shell 410 is below atmospheric pressure, and it goes without saying that it can also be operated when the pressure drops below atmospheric pressure during the loading and unloading of the liquefied gas inside the insulated tank 400.

[0201] According to the present invention, the evaporated gas BOG generated in the first shell 410 can be transferred to the outside of the insulated tank 400, and a compressor 500 used to transfer the evaporated gas BOG generated in the insulated tank 400 to the outside of the insulated tank 400 can be included, and by transferring the evaporated gas BOG to the outside via the compressor 500, the internal pressure of the first shell 410 can be reduced to atmospheric pressure or below.

[0202] In this invention, the suction pressure of the compressor 500 may be a vacuum, and depending on the embodiment, the suction piping of the compressor 500 may be a double-walled piping, which has the advantage that even if water leakage occurs in the piping, outside air will not flow into the compressor 500.

[0203] Although not shown in the drawings, the vessel 20 according to the present invention may further include a piping system (not shown) that includes a compressor 500 consisting of double piping.

[0204] Furthermore, the vessel 20 of the present invention can use the evaporated gas BOG generated in the insulated tank 400 as fuel, and may include engines, fuel cells, and boilers that can be used as fuel.

[0205] Figure 21 is a diagram illustrating vacuum piping arranged in an insulated tank according to an embodiment of the present invention.

[0206] Figure 22 is a diagram illustrating vacuum piping arranged in an insulated tank according to an embodiment of the present invention.

[0207] Figure 23 is a diagram illustrating vacuum piping arranged in an insulated tank according to an embodiment of the present invention.

[0208] Figure 24 is a diagram illustrating vacuum piping arranged in an insulated tank according to an embodiment of the present invention.

[0209] In one embodiment of the present invention, the insulated tanks 100, 400, and 600 described in Figures 1 to 20 may further include vacuum piping 210, 476, and 710 connected to vacuum pumps 200, 470 (471, 472), and 700, respectively, which are filled with insulating material 42, 450, and 632 between the first shells 120, 410, and the second shells 130, 420, and 620, and are vacuum-treated insulated spaces 140, 430, 440, and 630.

[0210] Figures 21 to 24 illustrate vacuum piping 710, which is an example applied to an insulated tank 600 consisting of a first shell 610 and a second shell 620. In addition to the insulated tank 600 shown, vacuum piping 210, 476, and 70 can also be applied to the insulated spaces 140, 430, 440, and 630 of insulated tanks 100 and 400, respectively.

[0211] The following describes an embodiment applied to the insulated tank 600.

[0212] As illustrated in Figures 21 to 24, a vacuum-sealed insulated space 630, located between the first shell 610 and the second shell 620, and filled with insulation material 632, may contain vacuum piping 710.

[0213] First, the insulated space 630 of the insulated tank 600 may contain one or more vacuum pipes 710. The vacuum pipes 710 surround the first shell 610 and may be embedded in the insulating material 632 that fills the insulated space 630.

[0214] A suction port 716 and a plug 715 can be formed on the side of the vacuum piping 710. The suction port 716 may be a passage through which gas is drawn between the insulating material 632, and the plug 715 can be connected to the pump piping 711 and the vacuum pump 700. When the vacuum pump 700 is in operation, the gas between the insulating material 632 is drawn into the vacuum piping 710 through the suction port 716 and discharged to the outside, creating a vacuum in the insulating space 630.

[0215] One or more vacuum pipes 710 can be arranged, preferably two or more. The vacuum pipes 710 are arranged in the insulated space 630, and numerous suction ports 716 are formed in the vacuum pipes 710 along the longitudinal direction of the vacuum pipes 710, so that suction can occur at various positions surrounding the vacuum pipes 710.

[0216] A central weld line 714 can be formed by welding the first shell 610 and the second shell 620 together at an intermediate height. If the vacuum piping 710 is fixed to the second shell 620 at the same position as the central weld line 714, the structural stability of the insulated tank 600 and the fixing force of the vacuum piping 710 may be reduced. Therefore, the vacuum piping 710 can be fixed at a distance from each other so as not to overlap with the central weld line 714.

[0217] Depending on the embodiment, the plug 715 can be formed adjacent to the central weld line 714, and the plug 715 can be formed within approximately 10 m vertically from the central weld line 714, preferably within 2 m. Accordingly, the worker can easily connect the pump piping 711 to the plug 715 without using other tools. That is, when the vacuum piping 710 is positioned diagonally or vertically, the worker can connect the pump piping 711 to the vacuum piping 710, thereby increasing the worker's work efficiency.

[0218] Figure 22 shows a cross-section of the insulated tank 600, in which vacuum piping 710 can be arranged in the insulated space 630 between the first shell 610 and the second shell 620, and depending on the embodiment, multiple vacuum piping 710 may be arranged.

[0219] The vacuum piping 710 may be separated from the first shell 610 and the second shell 620 by the same distance from each other within the insulated space 630, and the distances of separation from each may be the same or different.

[0220] If multiple vacuum pipes 710 are arranged in the insulated space 630, each can be positioned close to the second shell 620 or close to the first shell 610 within the insulated space 630.

[0221] The vacuum piping 710 may be equipped with a suction port 716 and can be fixed to the second shell 620 by a connecting portion 712. The vacuum piping 710 may also be equipped with a plug 715, to which the pump piping 711 is connected, allowing gas to be drawn into the insulated space 630 through the suction port 716.

[0222] Figure 23 shows a cross-sectional view of the vacuum piping 710, which may include a suction port 716 formed on its side (width direction) and a filter section 717 covering the suction port 716.

[0223] The vacuum piping 710 is connected to the pump piping 711 via a plug 715, and when the vacuum pump 700 is operating, the internal gas of the insulated space 630 can be drawn into the vacuum piping 710 via the suction port 716 and exhausted to the outside.

[0224] Here, since the insulated space 630 is filled with an insulating material 632 such as powder, when the vacuum pump 700 is operating, the insulating material 632 can be drawn into the suction port 716, and the insulating material 632 can be transmitted to the vacuum pump 700 along the vacuum piping 710. To prevent the insulating material 632 from flowing into the vacuum pump 700 through the suction port 716, the suction port 716 can be covered with a filter section 717.

[0225] The filter section 717 has a porous structure such as a mesh, and depending on the embodiment, it can be arranged in multiple layers to enhance the filtering effect of the thermal insulation material 632. For example, the filter section 717 may be in the form of multiple layers of mesh made of metal or filters made of pulp material.

[0226] The holes formed in the filter section 717 itself, or the holes formed by stacking multiple layers of the filter section 717, may have a diameter smaller than the particle size of the insulating material 632 in order to prevent the insulating material 632 from flowing into the intake port 716. The filter section 717 can be made of various materials other than the aforementioned materials and can be manufactured in various sizes or shapes, but the present invention is not limited thereto.

[0227] The filter section 717 may cover only the area where the suction port 716 is formed, or it may cover the area where the suction port 716 is formed while enclosing the entire vacuum piping 710. However, the present invention is not limited thereto.

[0228] As illustrated in Figure 24, according to one embodiment of the present invention, the vacuum piping 710 can be arranged to be fixed to the second shell 620 by a connecting portion 712.

[0229] Since the connecting portion 712 is provided in the insulated space 630, the connecting portion 712 may receive cold and heat transfer from the first shell 610 and its temperature may decrease. Therefore, the connecting portion 712 can be manufactured from materials that can withstand low temperatures, such as wood, SUS, PTFE (polytetrafluoroethylene), or bakelite.

[0230] However, if the connecting portion 712 is installed on the central weld line 714 of the second shell 620, the structural stability of the insulated tank 600 and the fixing force of the vacuum piping 710 may decrease. Therefore, it is preferable that the vacuum piping 710 be installed spaced apart from each other so as not to overlap with the central weld line 714.

[0231] Figure 25 is a diagram illustrating an insulated tank according to another embodiment of the present invention.

[0232] Referring to Figure 25, an insulated tank 600 according to another embodiment of the present invention is an independent insulated tank for storing liquefied gas, comprising a first shell 1010 containing the liquefied gas, a second shell 1020 located outside the first shell 1010, and an insulated space 1030 located between the first shell 1010 and the second shell 1020, wherein the insulated space 1030 is a space filled with insulating material and under vacuum.

[0233] For example, the thermal insulation material in this invention may be in the form of powder or bead.

[0234] As another example, in the present invention, the thermal insulation material may include, for example, one or more of the following: foamed plastic beads, polyurethane, polystyrene, polyethylene, polyisocyanurate, aerogel blankets, fumed silica, calcium silicate, mineral wool, glass wool, glass microfibers, perlite, and hollow glass microspheres. Hollow glass microspheres may include the 3M branded product Glass Bubbles. In the following description, Glass Bubbles are used as the thermal insulation material, but this is for illustrative purposes only, and the present invention is not limited by the type of thermal insulation material.

[0235] On the other hand, a vacuum pump 1100 can be provided outside the insulated tank 1000 to discharge the gas from the insulated space 1030. Creating a vacuum below means reducing the pressure by discharging the gas using the vacuum pump 1100. The degree of vacuum can indicate the extent to which gas has been discharged from a given space, and increasing the degree of vacuum indicates reducing the pressure by discharging gas from the given space.

[0236] The vacuum pump 1100 may be installed on a ship, and the vacuum pump 1100 can bring the insulated space 1030 to a low vacuum. The vacuum pump 1100 may also be a low vacuum pump. Here, the vacuum pump 1100 is 5m 3 Having a capacity of 10 m³ or more, preferably 10 m³ 3 It can have a capacity of / hr or more. Here, the vacuum pump 1100 can reduce the pressure in the adiabatic space 1030 to 100 mTorr or less, preferably to 10 mTorr or less, and preferably to 1 mTorr or less.

[0237] Here, the insulated tank 1000 can be configured such that the amount of evaporated gas generated within the first shell 1010 is less than the amount of evaporated gas required by the customer (not shown) that uses the evaporated gas. The thermal insulation performance of the insulated tank 1000 can be determined by the vacuum level of the insulated space 1030, and the vacuum level of the insulated space 1030 may be at least low vacuum.

[0238] For example, the pressure in the insulated space 1030 may be 70 mTorr or higher. More preferably, the pressure in the insulated space 1030 may be 100 mTorr, or even 300 mTorr or higher. The higher the pressure in the insulated space 1030 is set, the less labor and time is required to bring the insulated space 1030 into a vacuum state.

[0239] The vacuum piping 1140 can be connected to a vacuum pump 1100 located outside the insulated tank 1000. Specifically, a manifold 1030 can be provided between the vacuum pump 1100 and the insulated tank 1000, and a pump piping 1110 can be provided connecting the vacuum pump 1100 and the manifold 1030, and a manifold piping 1130 can be provided connecting the manifold 1030 and the vacuum piping 1140. A valve (not shown) is formed in at least one of the pump piping 1110 and the manifold piping 1130, and the valve (not shown) can control the flow of gas inside the insulated space 1030.

[0240] The vacuum piping 1140 surrounds the first shell 1010 and may be embedded in the insulating material filling the insulating space 1030.

[0241] The vacuum piping 1140 can be positioned closer to the first shell 1010 than to the second shell 1020. As will be described later, in the adiabatic space 1030, the Knudsen number (Kn) of gas molecules can be smaller as the pressure in the adiabatic space 1030 decreases, and the smaller the Knudsen number (Kn), the easier it is to control the flow of gas molecules in the adiabatic space 1030. This allows the vacuum piping 1140 to be positioned close to the first shell 1010, which has a relatively low temperature, and the gas molecules can be easily discharged to the outside along the vacuum piping 1140 by the vacuum pump 1100, enabling rapid vacuuming of the adiabatic space 1030.

[0242] Multiple vacuum pipes 1140 can be provided, and they can be installed at the top and bottom of the insulated space 1030, and one vacuum pipe 1140 can be formed to surround the first shell 1010.

[0243] The vacuum piping 1140 can be fixed to the first shell 1010 or the second shell 1020 by a support (not shown). The support (not shown) is fixed to the first shell 1010, and the distance between the vacuum piping 1140 and the support (not shown), which is positioned close to the first shell 1010, is reduced, and the length of the support (not shown) can be shortened. The vacuum piping 1140 may include a suction port (not shown) formed on its side (width direction) and a filter section (not shown) that covers the suction port (not shown). The vacuum piping 1140 may be configured such that one end is connected to the manifold piping 1130 and the other end is inserted into the insulated space 1030, where the other end may be provided with a suction port (not shown).

[0244] The vacuum piping 1140 is connected to the pump piping 1110, and when the vacuum pump 1100 is operating, the internal gas of the insulated space 1030 can be drawn into the vacuum piping 1140 through a suction port (not shown) formed in the vacuum piping 1140 and exhausted to the outside.

[0245] Here, since the insulated space 1030 is filled with an insulating material such as powder, when the vacuum pump 1100 is operating, the insulating material can be drawn into the suction port (not shown), and the insulating material can be transmitted to the vacuum pump 1100 along the vacuum piping 1140. To prevent the insulating material from flowing into the vacuum pump 1100 through the suction port (not shown), the suction port (not shown) can be covered with a filter section (not shown).

[0246] The filter section (not shown) has a porous structure such as a mesh, and depending on the embodiment, it can be arranged in multiple layers to enhance the insulating material filtering effect. For example, the filter section (not shown) may be in the form of multiple layers of mesh made of metal or filters made of pulp material stacked on top of each other.

[0247] The holes formed in the filter portion (not shown) itself, or the holes formed by stacking multiple filter portions (not shown), may have a diameter smaller than the particle size of the insulating material in order to prevent the insulating material from flowing into the intake port (not shown). The filter portion (not shown) can be made of various materials other than the material described above and can be manufactured in various sizes or shapes, but the present invention is not limited thereto.

[0248] The filter section (not shown) may cover only the area where the suction port (not shown) is formed, or it may cover the entire vacuum piping 1140 while also covering the area where the suction port (not shown) is formed. However, the present invention is not limited thereto.

[0249] In another embodiment of the present invention, the insulated tank 1000 is configured such that an insulating material is filled into the insulated space 1030, and vacuum piping 1140 is installed within it, thereby enabling the formation of a vacuum even in the insulated space 1030, which is far from the vacuum pump 1100.

[0250] On the other hand, in the case of storage tanks for conventional liquefied hydrogen, if they do not have sufficient insulation performance, a large amount of evaporated gas will be generated, so the insulated space must be made into a high vacuum. However, it takes a lot of time to make the insulated space into a high vacuum.

[0251] Therefore, the present invention can reduce the time and effort required to create a vacuum in the adiabatic space 1030 by creating a low vacuum in the adiabatic space 1030. Specifically, the present invention can determine the pressure range in which a vacuum can be easily created via the Knudsen number (Kn). The Knudsen number will be explained in detail below.

[0252] When creating a low vacuum in an adiabatic space 1030, the Knudsen number can be considered. The Knudsen number is a dimensionless number that describes the characteristics of the flow and can be expressed as the ratio of the mean free path (λ), which is the average distance that fluid molecules travel while continuously colliding, to the characteristic length, which is a representative length that is characteristic of the flow, as shown in the following equation. Here, when fluid molecules pass through an insulating material, the characteristic length is the average pore size (δ) of the insulating material. p ) is also acceptable.

[0253]

number

[0254] JPEG2026519582000003.jpg36152

[0255] Gas molecules contained in the adiabatic space 1030 can move to the vacuum pump 1100 while exchanging kinetic energy with neighboring gas molecules, provided the pressure within the adiabatic space 1030 is not low.

[0256] However, as the Knudsen number increases, this means that the interactions between gas molecules decrease, making it more difficult to control the movement of gas molecules and thus making it difficult to create a vacuum in the adiabatic space 1030 with the vacuum pump 1100.

[0257] Figure 26a is a diagram illustrating the flow of gas molecules in a viscous flow, and Figure 26b is a diagram illustrating the flow of gas molecules in a molecular flow.

[0258] Gas molecules can be classified into viscous flow, fluid flow, transition flow, and molecular flow depending on the Knudsen number. Here, the larger the Knudsen number, the more likely the gas molecule flow is to change from viscous flow to molecular flow.

[0259] In viscous flow, momentum and energy are continuously transferred between molecules, allowing the flow of gas molecules to be controlled by a pump. In contrast, molecular flow occurs when gas molecules are in a rarefied state, and collisions between gas molecules can be ignored, making it difficult to control the flow of gas molecules with a pump.

[0260] Referring to Figure 26a, when gas molecules flow in a viscous flow, the directionality is strong, making it easy to control the gas molecules to pass through the pores of the insulating material using a pump. Referring to Figure 26b, when gas molecules flow in a molecular flow, the directionality is weak, making it difficult to control the gas molecules to pass through the pores of the insulating material using a pump.

[0261] If the Knudsen number is 0.01 or less, gas molecules can flow in a viscous flow; if the Knudsen number is greater than 0.01 and 0.1 or less, gas molecules can flow in a fluid flow; if the Knudsen number is greater than 0.1 and 10 or less, gas molecules can flow in a transition flow; and if the Knudsen number is greater than 10, gas molecules can flow in a molecular flow.

[0262] In the case of molecular flow where the Knudsen number is greater than 10, it is difficult to control the flow of gas molecules. Therefore, in the case of the adiabatic space 1030 of the adiabatic tank 1000 according to one embodiment of the present invention, it is preferable to reduce the pressure to a Knudsen number of 10 or less, that is, it is preferable that the pressure in the adiabatic space 1030 is greater than the pressure at which the Knudsen number becomes 10.

[0263] Furthermore, when a vacuum is created in the adiabatic space 1030, it is preferable that the flow of gas molecules be at least one of viscous flow, fluid flow, and transition flow.

[0264] Figure 27 is a graph showing the relationship between the Knudsen number and pressure. Here, the diameter of the insulating material filling the adiabatic space 1030 is 1,000 μm, the porosity of the insulating material is 0.5, the temperature is 273 K, and the diameter of the gas molecules is 3.63 pm. In this specification, the diameter of the insulating material is the average value of the total diameter of the insulating material filling the adiabatic space 1030.

[0265] Referring to Figure 27, the Knudsen number can increase as the pressure decreases. Therefore, in the process of creating a vacuum in the adiabatic space 1030 according to one embodiment of the present invention, when the pressure in the adiabatic space 1030 falls below a predetermined level, the flow of gas molecules can become a molecular flow. In this case, because it is difficult to control the flow of molecular flow, it may become difficult to create a vacuum in the adiabatic space 1030 using the vacuum pump 1100.

[0266] As shown in Figure 27, for example, if the diameter of the insulating material is 1,000 μm and the pressure in the adiabatic space 1030 is 66 mTorr or less, the Knudsen number can be greater than 10, where the gas molecules within the insulating material can become a molecular flow.

[0267] Thus, the insulated tank 1000 according to one embodiment of the present invention can adjust the Knudsen number according to the diameter of the insulating material filling the insulated space 1030 and the pressure in the insulated space 1030.

[0268] To adjust the Knudsen number, the diameter of the insulation material can be adjusted by filtering the insulation material through a sieve, and the mesh size of the sieve can be determined according to the diameter of the insulation material, and the diameter of the insulation material may be between 10 and 3,000 μm.

[0269] Since it is preferable to reduce the pressure in the adiabatic space 1030 within the range where the flow of gas molecules does not become molecular flow, according to FIG. 27, when the diameter of the heat insulation material is 1,000 μm, it is preferable to form a vacuum until the pressure in the adiabatic space 1030 reaches 66 mTorr.

[0270] On the other hand, glass bubbles (GB) can be supplied as the heat insulation material to the adiabatic space 1030. Table 1 below shows the pressure (KN10) at which the Knudsen number becomes 10 and the pressure (KN100) at which the Knudsen number becomes 100 based on the size of the glass bubbles. When taking a vacuum, the temperature is 30 °C, and the size of the glass bubbles may be 10 to 3,000 μm.

[0271] Since it is preferable to reduce the pressure in the adiabatic space 1030 within the range where the flow of gas molecules does not become molecular flow, it is preferable to reduce the pressure in the adiabatic space 1030 to at least KN10 according to Table 1 below. That is, the pressure in the adiabatic space 1030 is preferably greater than KN10 in Table 1.

[0272]

[0273] As an example, when the diameter of the heat insulation material is 65 μm, it is preferable to form a vacuum until the pressure in the adiabatic space 1030 reaches about 1125.9 mTorr. However, since the Knudsen number can vary depending on the diameter of the heat insulation material, the pressure at which the Knudsen number reaches a predetermined value can vary depending on the diameter of the heat insulation material. As an example, the pressure (KN10) at which the Knudsen number becomes 10 may be 1125.9 mTorr when the diameter of the heat insulation material is 65 μm.

[0274]

Table 1

[0275] ​On the other hand, the vacuum time required to create a vacuum in the adiabatic space 1030 may vary depending on the Knudsen number.

[0276] Figure 28 is a graph showing the experimental results of the relationship between pressure and vacuum time in an adiabatic space.

[0277] Table 2 and Figure 28 below show the results of measuring the pressure and vacuum time in an adiabatic space 1030 on a lab scale. Here, the diameter of the insulating material may be 65 μm.

[0278] Once the pressure in the adiabatic space 1030 reaches a certain pressure, it is difficult for the pressure to drop below that level. For example, referring to Table 2 and Figure 28, the rate at which the pressure in the adiabatic space 1030 decreases slows down from approximately 120 mTorr, and it takes a long time to reduce the pressure in the adiabatic space 1030 below 120 mTorr.

[0279] [Table 2]

[0280] On the other hand, comparing the graph shape of the pressure and elapsed time in the adiabatic space 1030 in Figure 28 with the graph shape of the Knudsen number and the pressure in the adiabatic space 1030 in Figure 27, it can be confirmed that the larger the Knudsen number, the longer the time required to create a vacuum in the adiabatic space 1030 can be.

[0281] Referring to Table 2 above, as an example, the pressure in the insulated space 1030 can be formed within 24 hours, preferably within 12 hours. Here, the pressure in the insulated space 1030 may be 70 mTorr or higher, and more preferably 300 mTorr or higher. The higher the pressure in the insulated space 1030 is set, the less work and time is required to bring the insulated space 1030 into a vacuum state.

[0282] Therefore, the present invention makes it possible to reduce the pressure in the adiabatic space 1030 to a predetermined pressure that can be easily reduced, where the Knudsen number of the gas molecule flow in the adiabatic space 1030 may be 10 or less, and the gas molecule flow in the adiabatic space 1030 may be at least one of viscous flow, fluid flow, and transition flow.

[0283] Figure 29 is a graph showing the relationship between pressure and thermal conductivity in an adiabatic space.

[0284] Figure 29 is a graph showing the thermal conductivity (Absolute k-value) and cold vacuum pressure (CVP) when the insulated space 1030 is filled with insulating materials such as glass bubbles, perlite powder, and aerogel beads and a vacuum is created, and when the insulated space 1030 is not filled with insulating materials and a vacuum is created. The temperature of the insulated space 1030 may be -253°C to 0°C.

[0285] Referring to Figure 29, the lower the pressure in the adiabatic space 1030, the lower the thermal conductivity (k) can be. This means that the lower the pressure in the adiabatic space 1030, the less heat is transferred to the inside of the adiabatic tank 1000.

[0286] On the other hand, liquefied hydrogen can be stored in an insulated tank 1000 according to one embodiment of the present invention. Specifically, liquefied hydrogen can be stored in the first shell 1010 of the insulated tank 1000.

[0287] External heat from the insulated tank 1000 can be transferred to the liquefied hydrogen by passing through the second shell 1020, the insulated space 1030, and the first shell 1030. Here, the liquefied hydrogen may vaporize due to the external heat, generating evaporated gas within the first shell 1010.

[0288] In order to enhance the heat insulation performance of the heat insulation tank 1000, the heat insulation space 1030 can be filled with a heat insulating material and the heat insulation space 1030 can be put into a vacuum state. Here, the vacuum can mean a pressure lower than the external pressure of the heat insulation tank 1000.

[0289] Referring to FIGS. 27 and 28, when the Knudsen number is 10 or less, the pressure in the heat insulation space 1030 can be rapidly decreased. Therefore, it is preferable to decrease the pressure in the heat insulation space 1030 within the range where the Knudsen number is 10 or less.

[0290] Referring also to FIG. 28, the pressure in the heat insulation space 1030 tends not to decrease further after 24 hours have elapsed since the start of evacuating the heat insulation space 1030. Therefore, the pressure in the heat insulation space 1030 may be formed before the evacuation time of the heat insulation space 1030 reaches 24 hours at the longest.

[0291] Conversely, referring to FIG. 29, it is preferable to decrease the pressure in the heat insulation space 1030 to enhance the heat insulation performance of the heat insulation tank 1000.

[0292] That is, referring to FIGS. 27 to 29, it is preferable to decrease the pressure in the heat insulation space 1030 within the range where the Knudsen number is 10 or less in terms of the evacuation time, and it is preferable to decrease the pressure in the heat insulation space 1030 to the maximum extent in terms of the heat insulation performance of the heat insulation tank 1000. However, the pressure in the heat insulation space 1030 can be decreased to a pressure at which the Knudsen number becomes 10 or more, and in the present invention, the pressure in the heat insulation space 1030 is not limited to the range where the Knudsen number becomes 10 or more.

[0293] However, the heat insulation performance of the heat insulation tank 1000 is for reducing the amount of evaporated gas generated in the heat insulation tank 1000 and preventing waste of liquefied hydrogen. If all the evaporated gas generated in the heat insulation tank 1000 can be used as fuel, within the pressure range where usable evaporated gas is generated, the pressure in the heat insulation space 1030 can be increased to rather decrease the heat insulation performance of the heat insulation tank 1000, and the evacuation time of the heat insulation space 1030 can be reduced.

[0294] In other words, the present invention takes into account the thermal insulation performance of the thermal insulation tank 1000 and the time required to create a vacuum in the thermal insulation space 1030, thereby achieving the target thermal insulation performance of the thermal insulation tank 1000 and shortening the time required to create a vacuum in the thermal insulation space 1030.

[0295] An insulated tank 1000 according to one embodiment of the present invention has an insulated space 1030 with a pressure of 300 mTorr or more, and the hydrogen evaporated gas generated in the insulated tank 1000 each day can all be used as propulsion fuel for ships. The use of all the evaporated gas generated in the insulated tank 1000 as propulsion fuel is just one example; the evaporated gas can also be used at other uses such as boilers and power generation equipment. However, the present invention is not limited by the uses of the evaporated gas.

[0296] As an example, referring to Figure 29, if the pressure in the adiabatic space 1030 filled with glass bubbles is 600-700 mTorr, the value of the thermal conductivity (k) may be 6 mW / mK.

[0297] Here, approximately 0.11% of the liquefied hydrogen stored in the insulated tank 1000 evaporates per day, which corresponds to an amount of approximately 300 kg / hr (7.2 tons / day).

[0298] The insulated tank 1000 is installed in a ship that uses liquefied hydrogen as propulsion fuel, and since the ship uses 1.5 tons of hydrogen as fuel per day, all of the hydrogen evaporated gas generated in the insulated tank 1000 each day can be used as propulsion fuel for the ship.

[0299] The insulated tank 1000 of the present invention includes an insulated space 1030 in a low vacuum state having a pressure of 70 mTorr to 2,400 mTorr, preferably an insulated space 1030 having a pressure of 100 mTorr to 1,000 mTorr, and more preferably an insulated space 1030 in a low vacuum state having a pressure of 300 mTorr to 700 mTorr. Here, all of the evaporated gas generated in the insulated tank 1000 can be used as fuel for propulsion.

[0300] Therefore, the pressure in the insulated space 1030 can be determined by considering the total amount of evaporated gas required at various demand points in addition to the propellant fuel. That is, as the amount of evaporated gas required increases, the insulation performance of the insulated tank 1000 may decrease, so the pressure in the insulated space 1030 may increase and the vacuum level may decrease.

[0301] Glass bubbles (GB) can be supplied as insulation material in the insulated space 1030. Table 3 below shows the pressures at which the Knudsen number becomes 10 (KN10) and 100 (KN100), based on the size of the glass bubbles. When a vacuum is created, the temperature is in the low temperature range, and may be approximately -0°C or below. The size of the glass bubbles may be 10 to 3,000 μm.

[0302] Since it is preferable to lower the pressure in the adiabatic space 1030 to a level where the flow of gas molecules does not become a molecular flow, it is preferable to lower the pressure in the adiabatic space 1030 to at least KN10 in the low-temperature region, according to Table 3 below. In other words, it is preferable that the pressure in the adiabatic space 1030 is greater than KN10 in Table 3.

[0303] For example, if the diameter of the insulation material is 65 μm, it is preferable to create a vacuum until the pressure in the insulated space 1030 reaches 580.39 mTorr at -116.5°C, which is the midpoint between the external temperature and the internal temperature of the insulated tank 1000, and it is preferable to create a vacuum until the pressure in the insulated space 1030 reaches approximately 74.32 mTorr at -253°C, which is the temperature at which liquefied hydrogen is stored. However, the Knudsen number may vary depending on the diameter of the insulation material, and the target vacuum value of the insulated space 1030 may vary depending on the diameter of the insulation material.

[0304] Furthermore, the Knudsen number and temperature are proportional; the lower the temperature, the lower the Knudsen number can be. As the temperature of the adiabatic space 1030 decreases, the Knudsen number becomes smaller, allowing the gas molecules in the adiabatic space 1030 to remain as at least one of viscous flow, fluid flow, or transition flow, even at relatively low pressures. This could mean that in the low-temperature range, the adiabatic space 1030 can be reduced to a high vacuum in a short time. That is, at 20°C, it is difficult to reduce the pressure, but at -253°C, the pressure can be reduced rapidly.

[0305] Therefore, at cold vacuum pressure (CVP), the pressure in an adiabatic space 1030 can be reduced to a greater Knudsen number compared to warm vacuum pressure (WVP).

[0306] [Table 3]

[0307] The following describes a method for creating a vacuum in an insulating space according to one embodiment of the present invention.

[0308] Figure 30 is a flowchart of the first vacuum step of a method for creating a vacuum in an insulating space according to one embodiment of the present invention.

[0309] A method for forming a vacuum in an insulating space 1030 according to one embodiment of the present invention includes a first vacuum step (1200) and a second vacuum step (1300).

[0310] A first vacuum step (1200) can be performed before loading liquefied hydrogen into the insulated tank 1000, and a second vacuum step (1300) can be performed after loading liquefied hydrogen into the insulated tank 1000. Referring to Figure 25, here, liquefied hydrogen can be loaded into a first shell 1010 that contains liquefied gas inside the insulated tank 1000. A second shell 1020 is positioned outside the first shell 1010, and an insulated space 1030 can be positioned between the first shell 1010 and the second shell 1020.

[0311] Specifically, the first vacuum step (1200) can be performed by a vacuum pump installed on land, and the second vacuum step (1300) can be performed after the liquefied hydrogen has been loaded into the insulated tank 1000 and the ship carrying the insulated tank 1000 has started operating.

[0312] As a result, the vacuum formation method for the thermal insulation space 1030 according to one embodiment of the present invention allows the vacuum level of the thermal insulation space 1030 to be adjusted while the ship is in operation. Since it is not necessary to significantly lower the vacuum level of the thermal insulation space 1030 in preparation for changes in the vacuum level of the thermal insulation space 1030 while the ship is in operation, the time required to create a vacuum in the thermal insulation space 1030 before the ship is in operation can be greatly reduced.

[0313] In particular, the insulated space 1030 according to one embodiment of the present invention has a relatively high pressure value in a low vacuum state, making it possible to adjust the vacuum level of the insulated space 1030 even while the ship is in operation.

[0314] Furthermore, during the operation of the ship, moisture or gas may be discharged from the insulation material of the insulated space 1030 or from the insulated tank 1000 itself, which may change the vacuum level of the insulated space 1030. In this case, the vacuum pump 1100 inside the ship can discharge moisture, etc., from the insulated space 1030 to the outside, thereby maintaining the vacuum level within the insulated space 1030.

[0315] Referring to Figure 30, the first vacuum step (1200) may include a pre-vacuum step (1210), a first main vacuum step (1220), a vacuum maintenance test step (1230), and a pressure measurement step of the insulated tank (1240).

[0316] The pre-vacuum step (1210) can be performed before the insulating material is filled into the insulated space 1030. In the pre-vacuum step (1210), the vacuum pump 1100 is used to expel the gas from the insulated space 1030 to the outside and reduce the pressure in the insulated space 1030 to below a predetermined value. In the pre-vacuum step (1210), the pressure in the insulated space 1030 can be reduced to 1,000 mTorr or less, preferably 700 mTorr or less, preferably 500 mTorr or less, and preferably 300 mTorr or less.

[0317] Next, the pressure in the insulated space 1030 is measured for a predetermined time, and the pressure change in the insulated space 1030 is observed.

[0318] In this case, if the pressure in the insulated space 1030 increases, moisture, gas, etc., may be discharged from the first shell 1010 or the second shell 1020 of the insulated tank 1000 itself.

[0319] Conversely, if the pressure in the insulated space 1030 decreases, gas leakage may occur from the first shell 1010 or the second shell 1020.

[0320] In the preliminary vacuum step (1210), the pressure in the adiabatic space 1030 is reduced, and the pressure change is observed multiple times. In this way, the pressure in the adiabatic space 1030 is reduced and the pressure change is observed repeatedly, and when the degree of pressure rise in the adiabatic space 1030 falls below a predetermined value, the first main vacuum step (1220) can be performed.

[0321] During the preliminary vacuum step (1210), the pressure in the insulated space 1030 is reduced to below a predetermined value, while moisture and gases contained in the insulated tank 1000 itself can be discharged to the outside.

[0322] The presence or absence of leakage from the insulated tank 1000 can be determined by lowering the pressure in the insulated space 1030 to below a predetermined value. Specifically, the presence or absence of leakage can be determined by whether or not the pressure in the insulated space 1030 reaches 1 mTorr or less. That is, if the pressure in the insulated space 1030 falls below 1 mTorr, it can be determined that no leakage occurs in the insulated tank 1000. The leakage determination step can be performed before lowering the pressure in the insulated space 1030 and observing the pressure change.

[0323] After the pre-vacuum step (1210), the insulated space 1030 can be filled with an insulating material. Here, the insulating material consists of powder or beads, and may preferably be hollow glass microspheres.

[0324] The first vacuum step (1220) can be performed after the insulating space 1030 has been filled with insulating material. After the insulating space 1030 has been filled with insulating material, the vacuum pump 1100 can be used to expel the gas from the insulating space 1030 to the outside, thereby lowering the pressure of the insulating space 1030 to below a predetermined value.

[0325] Here, the pressure in the adiabatic space 1030 is 2,400 mTorr or less, preferably 1,000 mTorr or less, preferably 700 mTorr or less, preferably 500 mTorr or less, and preferably 300 mTorr or less. The temperature in the adiabatic space 1030 is room temperature, and the pressure in the adiabatic space 1030 is room temperature vacuum pressure (WVP).

[0326] The pressure in the insulated space 1030 is preferably as low as possible within the range where the Knudsen number is 10 or less. For example, if the diameter of the insulation material is 65 μm, the pressure in the insulated space 1030 may be 70 mTorr to 2,400 mTorr, preferably 100 mTorr to 1,000 mTorr, and preferably 300 mTorr to 700 mTorr.

[0327] In the vacuum maintenance test step (1230), the vacuum pump 1100 is used to expel the gas from the adiabatic space 1030 to the outside, and the pressure in the adiabatic space 1030 is reduced to below a predetermined value. Then, the pressure in the adiabatic space 1030 is measured for a predetermined time and the change in pressure in the adiabatic space 1030 is observed.

[0328] In this case, if the pressure in the insulated space 1030 increases, moisture, gas, etc., may be discharged from the first shell 1010 or the second shell 1020 of the insulated tank 1000 itself.

[0329] In the vacuum maintenance test step (1230), the pressure in the adiabatic space 1030 is reduced, and the pressure change is observed, and this process can be repeated several times. In this way, by repeatedly reducing the pressure in the adiabatic space 1030 and observing the pressure change, when the degree of pressure rise in the adiabatic space 1030 falls below a predetermined value, liquefied hydrogen can be loaded into the adiabatic tank 1000. The vacuum maintenance test step (1230) can be continued until the pressure in the adiabatic space 1030 falls to approximately 100 mTorr or less, preferably approximately 70 mTorr or less, preferably approximately 50 mTorr or less, preferably approximately 30 mTorr or less, and preferably approximately 10 mTorr or less.

[0330] When liquefied hydrogen is loaded into the insulated tank 1000, the insulated tank pressure measurement step (1240) allows for the measurement of the pressure in the insulated space 1030 (low-temperature vacuum pressure, CVP). The liquefied hydrogen in the insulated tank 1000 can lower the temperature of the insulated space 1030. As the temperature decreases, the pressure in the insulated space 1030 can decrease, and since the Knudsen number also decreases as the temperature decreases, the pressure in the insulated space 1030 can be easily reduced.

[0331] Figure 31 is a flowchart of the second vacuum step of a method for forming a vacuum in an insulating space according to one embodiment of the present invention.

[0332] The second vacuum step (1300) can be performed after loading liquefied hydrogen into the insulated tank 1000. Specifically, the second vacuum step (1300) can be performed after loading liquefied hydrogen into the insulated tank 1000 and after the ship carrying the insulated tank 1000 has started operation.

[0333] The second vacuum step (1300) may include a step of measuring the pressure in the insulated tank (1310), a second main vacuum step (1320), and a vacuum maintenance test step (1330).

[0334] Once the ship begins operation, the pressure (CVP) in the adiabatic space 1030 can be measured periodically. If the pressure in the adiabatic space 1030 is higher than a predetermined pressure, a second vacuum step (1320) can be performed. Here, the pressure in the adiabatic space 1030 may be 70 mTorr to 2,400 mTorr. Preferably, the pressure in the adiabatic space 1030 may be 100 mTorr to 1,000 mTorr, preferably 300 mTorr to 700 mTorr.

[0335] The vacuum pump 1100 used in the second vacuum step (1320) may be installed on a ship and may have specifications that allow it to create a low vacuum in the insulated space 1030.

[0336] In the vacuum maintenance test step (1330), the vacuum pump 1100 is used to expel the gas from the adiabatic space 1030 to the outside, and the pressure in the adiabatic space 1030 is reduced to below a predetermined value. Next, the pressure in the adiabatic space 1030 is measured for a predetermined time, and the change in pressure in the adiabatic space 1030 is observed.

[0337] In this case, if the pressure in the insulated space 1030 increases, moisture, gas, etc., may be discharged from the first shell 1010 or the second shell 1020 of the insulated tank 1000 itself.

[0338] In the vacuum maintenance test step (1330), the pressure in the adiabatic space 1030 is reduced, and the pressure change is observed, and this process can be repeated several times. In this way, the pressure in the adiabatic space 1030 is reduced and the pressure change is observed, and if the pressure rise in the adiabatic space 1030 falls below a predetermined value, the step of periodically measuring the pressure in the adiabatic tank (1310) can be carried out until the ship arrives at its destination.

[0339] The second vacuum step (1300) is performed after loading liquefied hydrogen into the insulated tank 1000. As the temperature of the insulated space 1030 is lowered by the liquefied hydrogen, the Knudsen number also decreases, so that the gas flow in the insulated space 1030 can be maintained as at least one of viscous flow, fluid flow, and transition flow down to a pressure relatively lower than room temperature. In other words, the second vacuum step (1300) maintains a low Knudsen number down to a pressure lower than room temperature, thereby allowing the pressure in the insulated space 1030 to be rapidly reduced to a low pressure.

[0340] Figure 32 is a diagram illustrating an insulated tank and a vessel including the same according to another embodiment of the present invention.

[0341] Referring to Figure 32, another embodiment of the present invention, an insulated tank 1000, is a device for storing liquefied gas, comprising a first shell 1010 containing liquefied gas, a second shell 1020 located outside the first shell 1010, and an insulated space 1030 located between the first shell 1010 and the second shell 1020, wherein the insulated space 1030 is a vacuum-sealed space filled with an insulating material 1040, and the insulated space 1030 can be densely filled with the insulating material 1040.

[0342] As an example, the thermal insulation material 1040 in the present invention may be a thermal insulation material in the form of a powder or a bead.

[0343] As another example, in the present invention, the thermal insulation material 1040 may include one or more of the following: foamed plastic beads, polyurethane, polystyrene, polyethylene, polyisocyanurate, aerogel blanket, fumed silica, calcium silicate, mineral wool, glass wool, glass microfiber, perlite, and hollow glass microspheres.

[0344] The vacuum in the insulated space 1030 filled with the insulation material 1040 may be a low vacuum, and the pressure in the insulated space 1030 may be 70 mTorr to 2,400 mTorr, preferably 100 mTorr to 1,000 mTorr, and preferably 300 mTorr to 700 mTorr.

[0345] In this invention, since it is preferable to reduce the pressure in the insulated space 1030 within the range where the Knudsen number is 10 or less in terms of the time required to take a vacuum, and it is preferable to reduce the pressure in the insulated space 1030 to the maximum extent possible in terms of the thermal insulation performance of the insulated tank 1000, the pressure in the insulated space 1030 is optimized by taking into account the time required to take a vacuum and the thermal insulation performance of the insulated tank 1000.

[0346] In this invention, the thermal insulation performance can be improved by creating a low vacuum in the insulated space 1030, which has the effect of reducing the generation of evaporated gas from the liquefied gas.

[0347] The vessel 30 according to the present invention includes a first shell 1010, a second shell 1020, and an insulated space 1030 filled with insulating material 1040 placed between the first shell 1010 and the second shell 1020. It may also include a vacuum pump 1100 capable of adjusting the vacuum level of the insulated space 1030 of the insulated tank 1000, and a compressor 1400 used to transfer evaporated gas generated in the insulated tank 1000 to the outside of the insulated tank 1000.

[0348] The compressor 1400 can compress the evaporated gas BOG generated in the first shell 1010 and transfer it to the outside of the insulated tank 1000. By transferring the evaporated gas BOG to the outside via the compressor 1400, the internal pressure of the first shell 1010 can be reduced to below atmospheric pressure.

[0349] Furthermore, the vessel 30 may further include a consumer 1500 that can consume the liquefied gas in the first shell 1010. Specifically, the consumer 1500 may be a device that consumes the evaporated gas generated in the first shell 1010. For example, the consumer 1500 may include an engine, a fuel cell, or a boiler. The evaporated gas generated in the first shell 1010 can be supplied by a compressor 1400 to the consumer 1500 that consumes the evaporated gas.

[0350] For example, if the customer 1500 is a propulsion engine, the ship 30 can be propelled using the evaporated gas BOG generated in the insulated tank 1000 as fuel.

[0351] On the other hand, when the insulating space 1030 is filled with insulating material 1040 and the space between the insulating materials 1040 is to be evacuated, the exhaust may not be smooth in areas far from the vacuum pump 1100 used for evacuating, and the larger the size of the insulating tank 1000, the more difficult it becomes to evacuate the insulating space 1030.

[0352] Referring to Figure 25, the vacuum piping 1140 can be placed within the insulated space 1030 located between the first shell 1010 and the second shell 1020. That is, the insulated space 1030 can be filled with insulating material 1040 and the vacuum process can be performed using only the vacuum pump 1100 to create a vacuum in the insulated space 1030. However, the vacuum piping 1140 extends to the back of the insulated space 1030 and is connected to the vacuum pump 1100, allowing it to extract gas from inside the insulated space 1030.

[0353] Thus, the insulated tank 600 according to the present invention solves the problem that exhaust performance deteriorates the further away from the suction port 716 is, by widely distributing the vacuum piping 710 and the suction ports 716 formed in the vacuum piping 710 within the insulated space 630, thereby reducing the distance from the suction ports 716 to each point in the insulated space 630.

[0354] Furthermore, by ensuring that the vacuum piping 710 is fixed to the second shell 620 at a distance from the central weld line 714, it is possible to prevent a decrease in the structural stability and fixing force of the insulated tank 600. In addition, when the vacuum piping 710 is positioned diagonally or vertically, the plug 715 of the vacuum piping 710 is located near the deck, making it easier for workers to connect the pump piping 711 to the plug 715.

[0355] Furthermore, by lowering the pressure in the insulated space 1030 within the insulated tank 1000 to above a predetermined value, the time required to create a vacuum can be reduced. At the same time, by maintaining the pressure in the insulated space 1030 below a predetermined value, it is possible to generate an amount of evaporated gas in the insulated tank 1000 that can be used entirely as fuel.

[0356] Furthermore, by creating a low vacuum in the insulated space 1030, the required specifications for the vacuum pump 1100 are reduced, which lowers the installation and operating costs of the vacuum pump 1100. This also reduces the time required to create a vacuum in the insulated space 1030 while the ship is docked, significantly reducing the preparation time for departure.

[0357] Furthermore, since the pressure in the insulated space 1030 is reduced after loading liquefied hydrogen into the insulated tank 1000, a low Knudsen number is maintained even at pressures lower than room temperature, thereby allowing the pressure in the insulated space 1030 to be rapidly reduced to a low pressure.

[0358] The present invention is not limited to the embodiments described above, and may further include combinations of the embodiments or combinations of at least one of the embodiments with known technologies as other embodiments.

[0359] Although the present invention has been described in detail above with reference to specific embodiments, this is for the purpose of specifically illustrating the present invention, and it goes without saying that the present invention is not limited thereto, and can be modified or improved by those with ordinary skill in the art within the technical concept of the present invention.

[0360] Any simple modification or alteration of the present invention falls within the scope of the present invention, and the specific scope of protection of the present invention is clarified by the appended claims. [Explanation of Symbols]

[0361] 10 Storage Terminals 20, 30 ships 100 Insulated Tanks 120 First Shell 130 Second Shell 140 First Insulated Space 142 Insulation 200 Vacuum pump 210 Vacuum piping 300 Compressor 400 Insulated Tank 410 First Shell 420 Second Shell 430 First Insulated Space 440 Second Insulated Space 450 Insulation 460 Insulated Box 462 Load transmission member 464 Transmission Section 470 Vacuum pump 472 First Vacuum Pump 474. Second Vacuum Pump 476 Vacuum piping 480 Pressure Control Unit 482 First Pressure Control Unit 484 Second Pressure Control Unit 500 Compressor 600 Insulated Tank 610 First Shell 620 Second Shell 630 Insulated Space 632 Insulation 640 Temperature Sensor 650 First pressure sensor 660 Gas Sensor 662 Gas Analysis Department 700 Vacuum Pump 710 Vacuum piping 800 Compressor 900 Cargo hold 910 Second pressure sensor 1000 Insulated Tank 1010 First Shell 1020 Second Shell 1030 Insulated space 1040 Insulation 1100 Vacuum Pump 1110 Pump Piping 1120 Manifold 1130 Manifold Piping 1140 Vacuum piping 1200 First Vacuum Step 1210 Pre-vacuum step 1220 First vacuum step 1230 Vacuum Maintenance Test Step 1240 Pressure measurement step for insulated tanks 1300 Second Vacuum Step 1310 Step of periodically measuring the pressure in an insulated tank. 1320 Second vacuum step 1330 Vacuum Maintenance Test Step 1400 Compressor 1500 Demand destination

Claims

1. An insulated tank for storing liquefied gas, A first shell containing liquefied gas inside, A second shell is positioned outside the first shell, The first shell and the second shell include an insulating space, An insulated tank characterized in that the insulated space is filled with an insulating material, thereby forming a low vacuum.

2. The insulated tank according to claim 1, characterized in that the gas molecules in the insulated space have at least one flow from among viscous flow, fluid flow, and transition flow.

3. The insulated tank according to claim 1, characterized in that the Knudsen number of gas molecules in the insulated space is 10 or less.

4. The pressure in the aforementioned adiabatic space is The insulated tank according to claim 1, characterized in that it is 70 mTorr to 2,400 mTorr.

5. The pressure in the aforementioned adiabatic space is The insulated tank according to claim 1, characterized in that the first shell generates an amount of evaporated gas that can be consumed by a customer that consumes the evaporated gas, such that the amount of evaporated gas generated is below a predetermined value.

6. The system further includes a vacuum pump provided outside the insulated tank for discharging the gas from the insulated space to the outside, The aforementioned vacuum pump is The insulated tank according to claim 1, characterized in that, after liquefied gas is loaded into the first shell, the gas in the insulated space is discharged to the outside.

7. The insulated tank according to claim 6, further comprising a vacuum pipe having one end connected to the vacuum pump and the other end extending into the interior of the insulated space.

8. The aforementioned vacuum pump is The insulated tank according to claim 7, characterized by being a low vacuum pump.

9. The aforementioned vacuum piping is The insulated tank according to claim 8, characterized in that it is positioned closer to the first shell than to the second shell.

10. A vessel comprising the insulated tank described in claim 1, The invention further includes a customer that consumes the evaporated gas generated in the first shell, The pressure in the aforementioned adiabatic space is The amount of evaporated gas generated in the first shell becomes less than or equal to a predetermined value so that it can be consumed by the customer. A ship characterized in that the evaporated gas generated in the first shell is consumed as propellant fuel for the ship.

11. A method for creating a vacuum in an insulating space between a first shell, which is provided inside an insulating tank and contains liquefied gas, and a second shell, which is located outside the first shell, This includes a first vacuum step of reducing the pressure in the adiabatic space, A method for forming a vacuum in an insulated tank, characterized in that a low vacuum is formed in the insulated space.

12. A method for forming a vacuum in an insulated tank according to claim 11, further comprising a second vacuum step of reducing the pressure in the insulated space using a vacuum pump provided outside the insulated tank, after loading liquefied gas into the insulated tank.

13. The second vacuum step is, The method for forming a vacuum in an insulated tank according to claim 12, characterized in that it is performed after the vessel including the insulated tank has commenced operations.

14. The second vacuum step is, The steps include measuring the pressure in the aforementioned insulated tank, A method for forming a vacuum in an insulated tank according to claim 12, characterized in that, if the pressure in the insulated tank is higher than a predetermined pressure, the gas in the insulated space is discharged to the outside to reduce the pressure in the insulated space to below a predetermined value, and the process of observing the pressure change in the insulated space is repeated.

15. The second vacuum step is, A method for forming a vacuum in an insulated tank according to claim 12, characterized in that one end is connected to the vacuum pump and the other end discharges the gas in the insulated space to the outside via a vacuum pipe that extends into the interior of the insulated space.

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