Liquefied gas storage tank and vessel containing same

Abstract

The present invention relates to a liquefied gas storage tank and a ship including the same. The liquefied gas storage tank of the present invention relates to a liquefied gas storage tank and a ship including the same. The liquefied gas storage tank of the present invention is a liquefied gas storage tank for storing a cryogenic substance, which comprises a primary barrier, a primary insulation wall, a secondary barrier and a secondary insulation wall, and the primary insulation wall includes a connecting insulation wall provided in a space between adjacent fixed insulation walls, in a state in which unit elements formed by stacking the secondary insulation wall, the secondary barrier and a fixed insulation wall which is a part of the primary insulation wall are arranged adjacent to each other, and the connecting insulation wall is inserted between the adjacent fixed insulation walls, and the tank may include a first slit formed between the fixed insulation wall and the connecting insulation wall, a plurality of second slits formed in the longitudinal and width directions of the fixed insulation wall, and a first filling insulation material filling the first slit.

Description

[Technical field]

[0001] The present invention relates to a liquefied gas storage tank and a ship containing same. [Background technology]

[0002] Recently, technological developments have led to the widespread use of liquefied gases such as liquefied natural gas (LNG) and liquefied petroleum gas (LPG) in place of gasoline and diesel.

[0003] In addition, vessels such as LNG carriers, LNG RVs (Regasification Vessels), LNG FPSOs (Floating, Production, Storage and Offloading), and LNG FSRUs (Floating Storage and Regasification Units), which transport or store liquefied gases such as LNG at sea, are equipped with storage tanks (known as "cargo holds") for storing LNG in a cryogenic liquid state.

[0004] In addition, liquefied gas storage tanks can generate boil off gas (BOG) due to heat intrusion from the outside, so the key technology in liquefied gas storage tank design is to lower the boil off rate (BOR), which is the rate at which the evaporative gas vaporizes, through insulation design.In addition, since liquefied gas storage tanks are exposed to various loads such as sloshing, it may be necessary to ensure the mechanical strength of the insulation panels.

[0005] Considering this, the thickness range of the primary insulation wall and the secondary insulation wall may be related to the mechanical strength of the liquefied gas storage tank. For this reason, active research is being conducted to eliminate the low temperature burden on the secondary barrier while maintaining the mechanical strength of the secondary insulation wall. Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been created to solve the problems of the prior art as described above, and an object of the present invention is to provide a liquefied gas storage tank and a ship including the same, which can reduce the low temperature burden and sloshing burden of the secondary barrier while maintaining a constant level of mechanical strength of the secondary barrier by making the thickness of the primary insulation wall the same or similar to that of the secondary insulation wall throughout the entire thickness of the insulation walls.

[0007] Another object of the present invention is to provide a liquefied gas storage tank and a ship including the same, which can reduce the low temperature burden and sloshing burden of the secondary barrier within a range that does not cause brittle fracture of the hull by making the thickness of the primary insulation wall the same or similar to that of the secondary insulation wall throughout the entire thickness of the insulation wall.

[0008] Another object of the present invention is to provide a liquefied gas storage tank and a ship including the same, which can improve the insulation performance by improving the configuration of the secondary barrier.

[0009] Another object of the present invention is to provide a liquefied gas storage tank and a ship including the same, which can improve the configuration of the fixing members that fix the secondary insulation wall to the hull, thereby not only improving the insulation performance but also reducing the amount of labor required.

[0010] Another object of the present invention is to provide a liquefied gas storage tank and a ship including the same, which can improve the stability of the primary insulation wall by optimizing slits provided on the secondary barrier to accommodate contraction and expansion of the primary insulation wall, thereby minimizing the convection phenomenon caused by the slits and heat penetration into the secondary barrier, and reduce the low temperature burden on the secondary barrier. [Means for solving the problem]

[0011] A liquefied gas storage tank according to one aspect of the present invention is a liquefied gas storage tank for storing a cryogenic material, comprising a primary barrier, a primary insulation wall, a secondary barrier and a secondary insulation wall, wherein the primary insulation wall includes a connecting insulation wall provided in a space between adjacent fixed insulation walls in a state in which unit elements formed by stacking the secondary insulation wall, the secondary barrier and a fixed insulation wall which is a part of the primary insulation wall are arranged adjacent to each other, and the connecting insulation wall is inserted between the adjacent fixed insulation walls, and the tank may include a first slit formed between the fixed insulation wall and the connecting insulation wall, a plurality of second slits formed in the longitudinal and width directions of the fixed insulation wall, and a first filling insulation material filling the first slit.

[0012] Specifically, the first filling insulation material may be formed to completely fill the first slit, or may be formed to fill from the entrance of the first slit to a certain depth so as to leave a space at the bottom of the first slit, or may be formed to fill the inside of the first slit in multiple layers so as to leave multiple spaces inside the first slit.

[0013] Specifically, when the first filling insulation material is formed to fill the inside of the first slit in multiple layers so as to create a plurality of spaces inside the first slit, the first filling insulation material includes a first upper filling insulation material formed on the top of the first slit, a first middle filling insulation material formed in the middle of the first slit spaced a certain distance from the first upper filling insulation material, and a first lower filling insulation material formed on the bottom of the first slit spaced a certain distance from the first middle filling insulation material, and each of the first upper filling insulation material, the first middle filling insulation material, and the first lower filling insulation material may be formed of the same insulation material or different insulation materials, and the insulation materials may be glass wool, super lite, a soft foam material, or an aerogel blanket.

[0014] Specifically, the first filling insulation material may be inserted between adjacent fixed insulation walls, and then the first slit may be filled by an insertion method using a jig, or the first slit may be filled by inserting the connecting insulation wall between adjacent fixed insulation walls while the connecting insulation wall is attached to both side surfaces of the connecting insulation wall opposite the side surfaces of the fixed insulation wall using an adhesive member.

[0015] Specifically, when the second slit is formed with a depth similar to the thickness of the fixed insulation wall, a second filling insulation material is filled inside, and the second filling insulation material may be formed to fill from the entrance of the second slit to a certain depth so that a space is formed at the bottom of the second slit, or may be formed to fill the inside of the second slit in multiple layers so that multiple spaces are formed inside the second slit.

[0016] Specifically, when the second filling insulation material is formed to fill the inside of the second slit in multiple layers so as to create a plurality of spaces inside the second slit, the second filling insulation material includes a second upper filling insulation material formed on the top of the second slit, a second middle filling insulation material formed in the middle of the second slit spaced a certain distance from the second upper filling insulation material, and a second lower filling insulation material formed on the bottom of the second slit spaced a certain distance from the second middle filling insulation material, and each of the second upper filling insulation material, the second middle filling insulation material, and the second lower filling insulation material may be formed of the same insulation material or different insulation materials, and the insulation materials may be glass wool, super lite, soft foam material, or aerogel blanket.

[0017] Specifically, at least one third slit is formed in the longitudinal direction of the connecting insulation wall, and when the connecting insulation wall is inserted between the fixed insulation walls, the third slit is located on the same line as the second slit formed in the longitudinal direction, the second slit and the third slit are formed to a depth corresponding to about half the thickness of the fixed insulation wall and the connecting insulation wall, no filling insulation material is filled therein, and the first filling insulation material is formed to be at least longer than the depth of each of the second slit and the third slit, so that the thermal convection path through the first slit, the second slit and the third slit can be discontinuous.

[0018] Specifically, the primary insulation wall and the secondary insulation wall may have the same or similar thickness.

[0019] According to another aspect of the present invention, there is provided a liquefied gas storage tank for storing a cryogenic material, comprising a primary barrier, a primary insulation wall, a secondary barrier and a secondary insulation wall, wherein the primary insulation wall includes a connecting insulation wall provided in a space between adjacent fixed insulation walls in a state in which unit elements formed by stacking the secondary insulation wall, the secondary barrier and a fixed insulation wall which is a part of the primary insulation wall are arranged adjacent to each other, and the tank may include a first step portion formed on front, rear, left and right sides of the connecting insulation wall and a second step portion formed on front, rear, left and right sides of the fixed insulation wall, a first slit formed by the first step portion and the second step portion between the connecting insulation wall and the fixed insulation wall when the connecting insulation wall is inserted between the adjacent fixed insulation walls, and a first filling insulation material filling the first slit.

[0020] Specifically, the first step portion is formed by making the front-rear, left-right width of the upper part of the connecting insulation wall narrower than the front-rear, left-right width of the lower part of the connecting insulation wall, and the second step portion is formed by making the front-rear, left-right width of the upper part of the fixed insulation wall narrower than the front-rear, left-right width of the lower part of the fixed insulation wall, and the first filling insulation material may be filled in the first slit, which is a space provided between the upper part of the connecting insulation wall and the upper part of the fixed insulation wall, by arranging the lower part of the connecting insulation wall and the lower part of the fixed insulation wall adjacent to each other.

[0021] Specifically, the insulating wall includes a plurality of second slits formed in the longitudinal and transverse directions of the fixed insulating wall, and at least one third slit formed in the longitudinal direction of the connecting insulating wall and positioned on the same line as the second slit formed in the longitudinal direction when the connecting insulating wall is inserted between the fixed insulating walls, the second slit and the third slit are formed to a depth corresponding to about half the thickness of the fixed insulating wall and the connecting insulating wall, the first slit, which is not filled with a filling insulating material and is filled with the first filling insulating material, is formed to be at least longer than the depth of each of the second slit and the third slit, and a thermal convection path through the first slit, the second slit and the third slit can be discontinuous.

[0022] Specifically, the primary insulation wall and the secondary insulation wall may have the same or similar thickness. Effect of the Invention

[0023] The liquefied gas storage tank and the ship equipped with the same according to the present invention are configured such that the thickness of the primary insulation wall is the same or similar to that of the secondary insulation wall in the total thickness of the primary insulation wall and the secondary insulation wall including the connecting insulation wall, thereby not only maintaining the mechanical strength of the secondary insulation wall at a constant level, but also reducing the low temperature burden and sloshing burden of the secondary barrier and preventing damage to the secondary barrier.

[0024] In addition, the liquefied gas storage tank and the ship equipped with the same according to the present invention are configured such that the thickness of the primary insulation wall is the same or similar to that of the secondary insulation wall in the total thickness of the primary insulation wall and the secondary insulation wall including the connecting insulation wall, thereby preventing brittle fracture of the hull and reducing the low temperature burden and sloshing burden of the secondary barrier.

[0025] In addition, the liquefied gas storage tank and the ship equipped therewith according to the present invention can further improve the insulation performance at the connecting portion between adjacent secondary insulation walls that form unit elements by providing an auxiliary insulation plate on the underside of the connecting insulation wall installed in the space between adjacent primary insulation walls that form unit elements.

[0026] In addition, the liquefied gas storage tank and the ship equipped with the same according to the present invention can improve the thermal insulation performance by improving the configuration of the secondary barrier.

[0027] In addition, the liquefied gas storage tank and the ship equipped with the same according to the present invention can level the deformed parts of the hull without using conventional mastic and leveling wedges by applying a non-adhesive elastic insulation material between the secondary insulation wall and the hull as a leveling member of the secondary insulation wall, thereby improving the insulation performance of the tank.

[0028] In addition, the liquefied gas storage tank and the ship equipped with the same according to the present invention fix adjacent unit panels of the secondary insulation wall using a cleat structure using a protrusion that protrudes outward from the lower side of the unit panel of the secondary insulation wall and a stud bolt that is fixed to the hull, thereby reducing labor costs compared to a method of drilling holes in the secondary insulation wall and fixing the unit panels with stud bolts.

[0029] In addition, the liquefied gas storage tank and the ship equipped with the same according to the present invention optimize the slits formed on the secondary barrier to accommodate contraction and expansion of the primary insulation barrier, improve the slit structure, and diversify the insulation filling material that fills the slits in order to minimize the convection phenomenon caused by the slits and heat penetration into the secondary barrier. This improves the stability of the primary insulation barrier due to the formation of slits, reduces the low temperature burden on the secondary barrier, and prevents damage to the primary insulation barrier and the secondary barrier. [Brief description of the drawings]

[0030] [Figure 1] 1 is a partial cross-sectional view illustrating a liquefied gas storage tank according to a first embodiment of the present invention. [Diagram 2] FIG. 1 is a partial perspective view illustrating a liquefied gas storage tank according to a first embodiment of the present invention. [Diagram 3] FIG. 2 is a diagram illustrating a primary barrier of the liquefied gas storage tank according to the first embodiment of the present invention. [Figure 4] 13(a) and (b) are diagrams showing the tensile force of the secondary barrier due to changes in thickness of the primary insulation wall and the secondary insulation wall. [Diagram 5] FIG. 2 is a diagram showing the results of a structural analysis in which the thicknesses of the primary insulation wall and the secondary insulation wall of the first case are made different in order to derive the thicknesses of the primary insulation wall and the secondary insulation wall of the liquefied gas storage tank according to the first embodiment of the present invention. [Figure 6] FIG. 2 is a diagram showing the results of a structural analysis in which the thicknesses of the primary insulation wall and the secondary insulation wall of the first case are made different in order to derive the thicknesses of the primary insulation wall and the secondary insulation wall of the liquefied gas storage tank according to the first embodiment of the present invention. [Figure 7] FIG. 2 is a diagram showing the results of a structural analysis in which the thicknesses of the primary insulation wall and the secondary insulation wall of the first case are made different in order to derive the thicknesses of the primary insulation wall and the secondary insulation wall of the liquefied gas storage tank according to the first embodiment of the present invention. [Figure 8]FIG. 2 is a diagram showing the results of a structural analysis in which the thicknesses of the primary insulation wall and the secondary insulation wall of the first case are made different in order to derive the thicknesses of the primary insulation wall and the secondary insulation wall of the liquefied gas storage tank according to the first embodiment of the present invention. [Figure 9] FIG. 11 is a diagram showing the results of a structural analysis performed by varying the thicknesses of the primary insulation wall and the secondary insulation wall of the second case in order to derive the thicknesses of the primary insulation wall and the secondary insulation wall of the liquefied gas storage tank according to the first embodiment of the present invention. [Figure 10] FIG. 11 is a diagram showing the results of a structural analysis performed by varying the thicknesses of the primary insulation wall and the secondary insulation wall of the second case in order to derive the thicknesses of the primary insulation wall and the secondary insulation wall of the liquefied gas storage tank according to the first embodiment of the present invention. [Figure 11] FIG. 11 is a diagram showing the results of a structural analysis performed by varying the thicknesses of the primary insulation wall and the secondary insulation wall of the second case in order to derive the thicknesses of the primary insulation wall and the secondary insulation wall of the liquefied gas storage tank according to the first embodiment of the present invention. [Figure 12] FIG. 11 is a diagram showing the results of a structural analysis performed by varying the thicknesses of the primary insulation wall and the secondary insulation wall of the second case in order to derive the thicknesses of the primary insulation wall and the secondary insulation wall of the liquefied gas storage tank according to the first embodiment of the present invention. [Figure 13] FIG. 11 is a diagram showing the results of a structural analysis performed by varying the thicknesses of the primary insulation wall and the secondary insulation wall of the third case in order to derive the thicknesses of the primary insulation wall and the secondary insulation wall of the liquefied gas storage tank according to the first embodiment of the present invention. [Figure 14] FIG. 11 is a diagram showing the results of a structural analysis performed by varying the thicknesses of the primary insulation wall and the secondary insulation wall of the third case in order to derive the thicknesses of the primary insulation wall and the secondary insulation wall of the liquefied gas storage tank according to the first embodiment of the present invention. [Figure 15] FIG. 11 is a diagram showing the results of a structural analysis performed by varying the thicknesses of the primary insulation wall and the secondary insulation wall of the third case in order to derive the thicknesses of the primary insulation wall and the secondary insulation wall of the liquefied gas storage tank according to the first embodiment of the present invention. [Figure 16]FIG. 11 is a diagram showing the results of a structural analysis performed by varying the thicknesses of the primary insulation wall and the secondary insulation wall of the third case in order to derive the thicknesses of the primary insulation wall and the secondary insulation wall of the liquefied gas storage tank according to the first embodiment of the present invention. [Figure 17] FIG. 11 is a diagram showing the results of a structural analysis performed by varying the thicknesses of the primary insulation wall and the secondary insulation wall of the fourth case in order to derive the thicknesses of the primary insulation wall and the secondary insulation wall of the liquefied gas storage tank according to the first embodiment of the present invention. [Figure 18] FIG. 11 is a diagram showing the results of a structural analysis performed by varying the thicknesses of the primary insulation wall and the secondary insulation wall of the fourth case in order to derive the thicknesses of the primary insulation wall and the secondary insulation wall of the liquefied gas storage tank according to the first embodiment of the present invention. [Figure 19] FIG. 11 is a diagram showing the results of a structural analysis performed by varying the thicknesses of the primary insulation wall and the secondary insulation wall of the fourth case in order to derive the thicknesses of the primary insulation wall and the secondary insulation wall of the liquefied gas storage tank according to the first embodiment of the present invention. [Figure 20] FIG. 11 is a diagram showing the results of a structural analysis performed by varying the thicknesses of the primary insulation wall and the secondary insulation wall of the fourth case in order to derive the thicknesses of the primary insulation wall and the secondary insulation wall of the liquefied gas storage tank according to the first embodiment of the present invention. [Figure 21] 1 is a graph showing the low-temperature stress of the secondary barrier and the probability of brittle fracture of the hull depending on the thickness change of the primary insulation wall and the secondary insulation wall. [Figure 22] 2A to 2C are diagrams illustrating various configurations of the secondary barrier of the liquefied gas storage tank according to the first embodiment of the present invention. [Figure 23] 2A to 2C are diagrams illustrating various configurations of the secondary barrier of the liquefied gas storage tank according to the first embodiment of the present invention. [Figure 24] 2A to 2C are diagrams illustrating various configurations of the secondary barrier of the liquefied gas storage tank according to the first embodiment of the present invention. [Diagram 25] 1 is a partial cross-sectional view illustrating a right-angle corner structure of a liquefied gas storage tank according to a first embodiment of the present invention. FIG. [Figure 26]1 is a partial cross-sectional view illustrating an obtuse-angle corner structure of a liquefied gas storage tank according to a first embodiment of the present invention. FIG. [Figure 27] 1 is a graph showing the thermal conductivity depending on the materials used for the primary insulation and secondary insulation of the liquefied gas storage tank of the present invention. [Figure 28] FIG. 4 is a partial cross-sectional view illustrating a liquefied gas storage tank according to a second embodiment of the present invention. [Figure 29] FIG. 11 is a partial perspective view illustrating a liquefied gas storage tank according to a second embodiment of the present invention. [Diagram 30] FIG. 11 is a partial cross-sectional view illustrating a liquefied gas storage tank according to a third embodiment of the present invention. [Diagram 31] FIG. 11 is an enlarged view of the main parts of a liquefied gas storage tank according to a third embodiment of the present invention. [Diagram 32] FIG. 11 is a partial cross-sectional view illustrating a liquefied gas storage tank according to a fourth embodiment of the present invention. [Diagram 33] This is a diagram to explain the filling insulation material that fills the first slit, which is the gap between the connecting insulation wall and the fixed insulation wall that make up the primary insulation wall, and multiple second slits provided in the fixed insulation wall. [Diagram 34] 1 is a diagram for explaining a filling insulation material according to another embodiment, which fills a first slit, which is a gap between a connecting insulation wall and a fixed insulation wall that constitute a primary insulation wall, and a plurality of second slits provided in the fixed insulation wall. [Diagram 35] 1 is a view for explaining a filling insulation material according to still another embodiment, which fills a first slit, which is a gap between a connecting insulation wall and a fixed insulation wall constituting a primary insulation wall, and a plurality of second slits provided in the fixed insulation wall. [Diagram 36] FIG. 11 is a partial cross-sectional view illustrating a liquefied gas storage tank according to a fifth embodiment of the present invention. [Figure 37] 37 is a cross-sectional view of the interconnected insulating wall taken along line A-A' in FIG. 36. [Figure 38] 37 is a cross-sectional view of a unit element formed by stacking fixed insulating walls constituting a secondary insulating wall, a secondary barrier wall, and a primary insulating wall, taken along line BB' in FIG. 36. [Figure 39] 13 is a diagram for explaining the filling insulation material that fills the first slit, which is the gap between the connecting insulation wall and the fixed insulation wall that make up the primary insulation wall. FIG. [Diagram 40] 13 is a diagram for explaining the filling insulation material that fills the first slit, which is the gap between the connecting insulation wall and the fixed insulation wall that make up the primary insulation wall. FIG. [Diagram 41] 13 is a diagram showing the results of a structural analysis of a liquefied gas storage tank according to a fifth embodiment of the present invention. [Diagram 42] 13 is a diagram showing the results of a structural analysis of a liquefied gas storage tank according to a fifth embodiment of the present invention. [Diagram 43] FIG. 11 is a diagram for comparing and explaining the convection path and the temperature of the secondary barrier that change depending on the structure of the slits in the liquefied gas storage tank according to the fifth embodiment of the present invention and the application of filling insulation material to fill the slits in the liquefied gas storage tank according to the comparative example. [Diagram 44] FIG. 11 is a diagram for comparing and explaining the convection path and the temperature of the secondary barrier that change depending on the structure of the slits in the liquefied gas storage tank according to the fifth embodiment of the present invention and the application of filling insulation material to fill the slits in the liquefied gas storage tank according to the comparative example. [Diagram 45] FIG. 11 is a diagram for comparing and explaining the convection path and the temperature of the secondary barrier that change depending on the structure of the slits in the liquefied gas storage tank according to the fifth embodiment of the present invention and the application of filling insulation material to fill the slits in the liquefied gas storage tank according to the comparative example. [Diagram 46] FIG. 11 is a diagram for comparing and explaining the convection path and the temperature of the secondary barrier that change depending on the structure of the slits in the liquefied gas storage tank according to the fifth embodiment of the present invention and the application of filling insulation material to fill the slits in the liquefied gas storage tank according to the comparative example. [Figure 47] 13 is a graph comparing the temperature of the secondary barrier under the slit depending on whether or not a filling insulation material is filled in the liquefied gas storage tank according to the fifth embodiment of the present invention and a liquefied gas storage tank according to a comparative example. [Figure 48] FIG. 13 is a partial cross-sectional view illustrating a liquefied gas storage tank according to a sixth embodiment of the present invention. [Figure 49] 49 is a cross-sectional view of the interconnected insulating wall taken along line A-A' in FIG. 48. [Figure 50] 49 is a cross-sectional view of a unit element formed by stacking fixed insulating walls constituting a secondary insulating wall, a secondary barrier, and a primary insulating wall, taken along line BB' in FIG. 48. [Figure 51] 2 is an enlarged view showing a state in which a filling insulating material is filled into a first slit, which is a gap between the connecting insulating wall and the fixed insulating wall that make up the primary insulating wall. FIG. [Figure 52] FIG. 13 is a perspective view illustrating a liquefied gas storage tank according to a seventh embodiment of the present invention. [Diagram 53] 53(a) to 53(c) are diagrams showing the plan, side and cross section of a unit element in which fixed insulating walls constituting the secondary insulating wall, secondary barrier and primary insulating wall in FIG. 52 are stacked. [Figure 54] 53(a) to (c) are views showing the plan, side and cross section of a connected insulating wall that constitutes the primary insulating wall in FIG. 52. [Figure 55] 53(a) to 53(c) are views showing the plan, side and cross section of a connected insulating wall according to another embodiment which constitutes the primary insulating wall of FIG. 52. [Figure 56] FIG. 53 is a rear perspective view of a connected insulating wall according to yet another embodiment that constitutes the primary insulating wall of FIG. 52. [Figure 57] FIG. 2 is a diagram showing a cross section of a portion where fixed insulating walls and connecting insulating walls that constitute a primary insulating wall are alternately connected. [Figure 58] FIG. 2 is a diagram showing a cross section of a portion where a plurality of connected insulating walls that make up a primary insulating wall are connected in series. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] The object, particular advantages and novel features of the present invention will become more apparent from the following detailed description and preferred embodiments in conjunction with the accompanying drawings. In addition, in this specification, when referring to the components in each drawing, it should be noted that the same components are referred to by the same numbers as much as possible even if they are displayed on different drawings. In addition, when describing the present invention, if it is determined that a detailed description of related publicly known technology unnecessarily obscures the gist of the present invention, the detailed description will be omitted.

[0032] Furthermore, it should be understood that the attached drawings are intended to facilitate understanding of the embodiments disclosed in this specification, and that the technical ideas disclosed in this specification are not limited by the attached drawings, and include all modifications, equivalents, and alternatives included in the idea and technical scope of the present invention.

[0033] In addition, terms including ordinal numbers such as first, second, etc. are used to describe various components, but the components are not limited by the terms. The terms are used only to distinguish one component from another component.

[0034] In the present specification, liquefied gas may be used to include all gas fuels that are generally stored in a liquid state, such as LNG or LPG, ethylene, ammonia, etc., and gas that is not in a liquid state due to heating or pressurization may be conveniently referred to as liquefied gas. This may also be applied to evaporated gas. In addition, LNG may be used to include not only NG (Natural Gas) in a liquid state, but also LNG in a supercritical state, etc., for convenience, and evaporated gas may be used to include not only evaporated gas in a gaseous state, but also evaporated gas that has been liquefied.

[0035] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0036] Fig. 1 is a partial cross-sectional view for explaining a liquefied gas storage tank according to a first embodiment of the present invention, Fig. 2 is a partial perspective view for explaining a liquefied gas storage tank according to the first embodiment of the present invention, and Fig. 3 is a view for explaining a primary barrier of the liquefied gas storage tank according to the first embodiment of the present invention.

[0037] As shown in Figs. 1 and 2, a liquefied gas storage tank 1 according to a first embodiment of the present invention is installed on a ship and can store liquefied gas such as LNG, which is a cryogenic (approximately -160°C to -170°C) material.

[0038] Although not shown, the ship equipped with the liquefied gas storage tank 1 described below is a concept that includes not only commercial ships that transport cargo from a departure point to a destination, but also marine structures that float at a certain point on the sea and perform specific operations. Also, the liquefied gas storage tank 1 in the present invention includes any type of tank that stores liquefied gas.

[0039] The liquefied gas storage tank 1 may include a primary barrier 2 in contact with the liquefied gas, a primary insulating wall 3 provided outside the primary barrier 2, a secondary insulating wall 4 provided outside the primary insulating wall 3, and a secondary insulating wall 5 disposed outside the secondary barrier 4. The liquefied gas storage tank 1 may be supported on the hull 7 by mastic 6 provided between the secondary insulating wall 5 and the hull 7.

[0040] In order to optimize the insulation performance and storage capacity of the liquefied gas storage tank 1, it may be necessary to optimize the thickness of the primary insulation wall 3 and the secondary insulation wall 5. For example, when polyurethane foam is used as the main material of the primary insulation wall 3 and the secondary insulation wall 5, the total thickness of the primary insulation wall 3 and the secondary insulation wall 5 can be set to be in the range of 250 mm to 500 mm. This will be described with reference to Figs. 4 to 20.

[0041] In the above, the liquefied gas storage tank 1 may include a flat surface and a corner structure. For example, the horizontal walls in the front-rear direction of the liquefied gas storage tank 1, the bottom between the horizontal walls, the vertical walls, and the ceiling may correspond to a flat surface structure. Also, for example, the structure where the horizontal walls, the bottom, the vertical walls, and the ceiling of the liquefied gas storage tank 1 abut against each other may correspond to a corner structure. Here, the corner structure may include an obtuse angle corner structure or a right angle corner structure. When the thickness of the primary insulating wall 3 or the secondary insulating wall 5 changes, the obtuse angle corner structure or the right angle corner structure may change, which will be described with reference to Figs. 25 to 26.

[0042] 1 and 2, the primary barrier 2 forms a storage space for storing liquefied gas, which is a cryogenic material, and may be made of a metal material. For example, the metal material may be, but is not limited to, stainless steel. The primary barrier 2, together with the secondary barrier 4, can prevent the liquefied gas from leaking to the outside.

[0043] The primary barrier 2 is fixedly connected to the top of the primary insulating wall 3 by anchor strips (not shown) and may be provided so as to be in direct contact with the liquefied gas, which is the cryogenic material stored in the liquefied gas storage tank 1 .

[0044] 3, the primary barrier 2 may be divided into a flat portion 21 that contacts the upper surface of the primary insulation wall 3, a curved portion 22 for relieving stress caused by contraction or expansion due to temperature, and a boundary portion 23 between the flat portion 21 and the curved portion 22. For example, the primary barrier may be formed of a corrugation membrane sheet made of a stainless steel material having a thickness of 1.0 to 1.5 mm, preferably a stainless steel material having a thickness of 1.0 to 1.2 mm. That is, the primary barrier may be formed in a wrinkled shape.

[0045] The primary barrier 2 may be formed such that the wrinkles have a first radius of curvature R1 and a second radius of curvature R2. That is, the primary barrier 2 of this embodiment may be formed to have two types of radii of curvature R1 and R2, where the boundary portion 23 between the flat portion 21 and the curved portion 22 has the first radius of curvature R1, and the curved portion 22 has the second radius of curvature R2. For example, the first radius of curvature R1 may be formed smaller than the second radius of curvature R2. The primary barrier 2 having the radii of curvature R1 and R2 has a gentle curve at the top, which makes it easy to perform welding inspection, and also allows for flexible response to sloshing, since the fluid striking from the side flows easily.

[0046] In addition, the primary barrier 2 of this embodiment may be formed with the same size of horizontal and vertical wrinkles in all areas, regardless of whether it is a large corrugation or a small corrugation. That is, since the size of the horizontal and vertical wrinkles is the same in the entire primary barrier 2, it is easy to fabricate the primary barrier.

[0047] Referring to FIG. 1, the primary insulation wall 3 is designed to block heat intrusion from the outside while withstanding external impacts or impacts caused by liquefied gas sloshing inside, and may be provided between the primary barrier 2 and the secondary barrier 4.

[0048] The primary insulation wall 3 may have a structure in which a primary plywood 31 and a primary insulation material 32 are laminated in order on the outside of the primary barrier 2, and may correspond to a thickness that is a combination of the thickness of the primary plywood 31 and the thickness of the primary insulation material 32. The primary insulation wall 3 may be formed to a thickness of 160 mm to 250 mm.

[0049] The primary plywood 31 may be provided between the primary barrier 2 and the primary insulation 32 .

[0050] The primary plywood 31 may be formed to a thickness of 6.5 mm to 15 mm.

[0051] The primary insulation material 32 may be formed from a material having excellent insulation performance and mechanical strength so as to be able to withstand external impacts or impacts caused by liquefied gas sloshing inside while blocking heat intrusion from the outside.

[0052] The primary insulation material 32 may be formed of polyurethane foam between the primary plywood 31 and the secondary barrier 4, and may have a thickness ranging from 150 mm to 240 mm.

[0053] Referring to FIG. 1, a part of the primary insulation wall 3, the secondary barrier 4, and the secondary insulation wall 5 may be stacked to form a unit element. Here, a part of the primary insulation wall 3 forming the unit element may be defined as a fixed insulation wall 3b, and the width of the fixed insulation wall 3b may be smaller than the width of the secondary insulation wall 5 included in the unit element. The fixed insulation wall 3b, the secondary barrier 4, and the secondary insulation wall 5 may be arranged in a fixed state, but are not limited thereto, and each may be separated and arranged in the liquefied gas storage tank 1. As a result, a part of the secondary barrier 4 may be exposed on both sides of the primary insulation wall 3. The unit elements may be arranged adjacent to each other, and in this case, a connecting insulation wall 3a may be provided in a space between adjacent primary insulation walls 3, i.e., a space where the secondary barrier 4 is exposed.

[0054] The secondary barrier 4 may be divided into a main barrier 41 and an auxiliary barrier 42, the main barrier 41 being provided on the upper part of the secondary insulation wall 5 of the unit element, and the auxiliary barrier 42 being provided between the exposed main barrier 41 and the connecting insulation wall 3a. In this case, the auxiliary barrier 42 is provided so as to connect the main barriers 41 provided in the adjacent unit elements to each other. In other words, the unit elements arranged adjacent to each other may be completed by the auxiliary barrier 42 stacked on the main barrier 41 and the connecting insulation wall 3a.

[0055] The laminated structure of the portion where the connecting insulation wall 3a is provided will be described with reference to Fig. 2. The connecting insulation wall 3a may be provided in a form in which connecting plywood 31a and connecting insulation material 32a, which are the same as or similar to those described in the primary insulation wall 3 constituting the unit element, are laminated, and the primary insulation wall 3 in this specification can include the connecting insulation wall 3a and the fixed insulation wall 3b.

[0056] Fig. 2 shows a cross-sectional structure taken along the line A-A' of Fig. 1, and the connected insulating wall 3a may have a structure in which the connected plywood 31a and the connected insulating material 32a are laminated. The thickness of the connected insulating wall 3a may correspond to the total thickness of the connected plywood 31a and the connected insulating material 32a.

[0057] The connecting plywood 31a may be formed to a thickness of 6.5 mm to 15 mm.

[0058] The connecting insulation material 32a may be formed of polyurethane foam between the connecting plywood 31a and the auxiliary barrier 42 of the secondary barrier 4, and may have a thickness in the range of 150 mm to 240 mm.

[0059] As described above, the primary insulation material 32 of the primary insulation wall 3 and the connecting insulation material 32a of the connecting insulation wall 3a may have the same thickness. However, in the case of the connecting insulation material 32a of the connecting insulation wall 3a, since the auxiliary barrier 42 is further laminated in addition to the main barrier 41 of the secondary barrier 4 at the bottom, the connecting insulation material 32a of the connecting insulation wall 3a may have a thickness smaller than the thickness of the primary insulation material 32 of the primary insulation wall 3 by the thickness of the auxiliary barrier 42.

[0060] The above-mentioned connecting insulation wall 3a is provided so as to seal the space formed between adjacent secondary insulation walls 5 together with the auxiliary barrier 42 when unit elements are arranged adjacent to each other, thereby blocking the intrusion of heat from the outside.

[0061] However, since the connecting insulating wall 3a is structured to be inserted between adjacent fixed insulating walls 3b that constitute unit elements, it is vulnerable to protecting the secondary barrier 4 below the connecting insulating wall 3a from extremely low temperatures. This makes it highly likely that problems will occur in the secondary barrier 4 below the connecting insulating wall 3a where the main barrier 41 and auxiliary barrier 42 overlap. Therefore, the following explanation will focus on the connecting insulating wall 3a.

[0062] The secondary barrier 4 may be provided between the primary insulation wall 3 containing the insulation wall 3a and the secondary insulation wall 5, and together with the primary barrier 2, can prevent the liquefied gas from leaking to the outside.

[0063] The secondary barrier 4 at the lower end of the fixed insulation wall 3b is a single barrier and includes a main barrier 41, and the secondary barrier 4 at the lower end of the connecting insulation wall 3a may include a main barrier 41 that connects unit elements to each other and an auxiliary barrier 42 provided on the secondary insulation wall 5 that constitutes the unit element.

[0064] The main barrier 41 is provided on the secondary insulating wall 5 constituting a unit element, and may be formed to a thickness of 0.6 mm to 1.0 mm. Adjacent main barriers 41 may be laminated with auxiliary barriers 42 to make them airtight.

[0065] The auxiliary barrier 42 is configured to connect unit elements to each other, and may be formed to a thickness of 0.6 mm to 1.0 mm and may be laminated on the main barrier 41.

[0066] 1 and 2, the secondary insulation wall 5 can be designed to withstand an external impact or an internal impact due to liquefied gas sloshing while blocking heat intrusion from the outside together with the fixed insulation wall 3b and the connecting insulation wall 3a. The secondary insulation wall 5 can be provided between the secondary barrier 4 and the hull 7, and can include a secondary insulation material 51 and a secondary plywood 52.

[0067] The secondary insulation wall 5 may have a structure in which a secondary insulation material 51 and a secondary plywood 52 are laminated in sequence on the outside of the secondary barrier 4, and the total thickness of the secondary insulation material 51 and the secondary plywood 52 combined can be formed to be 150 mm to 240 mm.

[0068] The secondary insulation material 51 may be formed of a material having excellent insulation performance and mechanical strength so as to be able to withstand external impacts or impacts caused by liquefied gas sloshing inside while blocking heat intrusion from the outside.

[0069] The secondary insulation material 51 may be made of polyurethane foam between the secondary barrier 4 and the secondary plywood 52, and may be formed to a thickness of 140 mm to 230 mm.

[0070] The secondary plywood 52 may be provided between the secondary insulation material 51 and the hull 7. For example, the secondary insulation material 51 may be provided in contact with the secondary plywood 52. The secondary plywood 52 may be formed to a thickness of 6.5 mm to 25 mm.

[0071] As described above, the liquefied gas storage tank 1 according to the present embodiment may be configured such that the primary insulating wall 3 has a thickness of 66% to 166% of the secondary insulating wall 5, and the connecting insulating wall 3a included in the primary insulating wall 3 has a thickness of 67% to 167% of the secondary insulating wall 5, so that the connecting insulating wall 3a has the same or similar thickness as the secondary insulating wall 5. In relation to this configuration, the connecting insulating material 32a of the connecting insulating wall 3a may be configured such that the connecting insulating material 32a of the connecting insulating wall 3a has a thickness of 90% to 110% of the secondary insulating material 51, so that the connecting insulating material 32a of the connecting insulating wall 3a has the same or similar thickness as the secondary insulating material 51. In this embodiment, the fixed insulating wall 3b constituting a unit element when including the connecting insulating wall 3a is not mentioned in detail, but in relation to the secondary insulating wall 5, the fixed insulating wall 3b is also the same or similar to the connecting insulating wall 3a.

[0072] When the connecting insulation wall 3a and the secondary insulation wall 5, or the connecting insulation material 32a of the connecting insulation wall 3a and the secondary insulation material 51 are formed with such a thickness ratio, the upper limit value of the stress of the secondary barrier 4 at low temperatures can be 50 MPa or less at the lower part of the connecting insulation wall 3a. More specifically, the stress value of the secondary barrier 4 at low temperatures can be 40 MPa to 50 MPa at the lower part of the connecting insulation wall 3a. These values ​​were obtained from the results of a structural analysis described later.

[0073] In this embodiment, the thicknesses of the connecting insulation wall 3a and the secondary insulation wall 5, or the thicknesses of the connecting insulation material 32a of the primary insulation wall 3 and the secondary insulation material 51 are configured to be the same or similar, and this will be explained with reference to Figures 4 to 20.

[0074] Figures 4(a) and (b) are diagrams showing the tensile force of the secondary barrier 4 at the bottom of the connecting insulation wall 3a due to the change in thickness of the connecting insulation wall 3a and the secondary insulation wall 5 included in the primary insulation wall 3. In Figures 4(a) and (b), it is assumed that the total thickness of the connecting insulation wall 3a, the secondary barrier 4, the secondary insulation wall 5, etc. is the same.

[0075] Meanwhile, the secondary barrier 4 and the secondary insulation barrier 5 have different amounts of self-shrinkage depending on the temperature to which they are exposed. In the case of the secondary barrier 4 and the secondary insulation barrier 5, the thinner the connecting insulation barrier 3a is, the more the secondary barrier 4 and the secondary insulation barrier 5 are affected by the cold heat of the cryogenic liquefied gas. In this case, the self-temperature decreases, and the amount of shrinkage itself increases, which increases the stress at low temperatures, and the risk of damage to the secondary barrier 4 increases. This problem is particularly likely to occur in the auxiliary barrier 42 that connects the main barriers 41 provided in the adjacent unit elements by bonding or the like at the bottom of the connecting insulation barrier 3a. At the bottom of the connecting insulation barrier 3a, both ends of the auxiliary barrier 42 are connected to the main barriers 41 of each unit element, because the both ends of the auxiliary barrier 42 may be deformed to move away from or closer to each other as the secondary insulation barrier 5 of the unit element shrinks.

[0076] 4(a) shows a case where the connecting insulation wall 3a is formed relatively thinner than the secondary insulation wall 5, and the height of the secondary barrier wall 4 is located above the center of the overall thickness based on the thickness direction. In this case, in order to reduce the mechanical stress applied to the secondary barrier wall 4 when the hull is structurally deformed due to the six-degree-of-freedom motion of the hull 7, the thickness of the secondary insulation wall 5 is ensured to be large, so that the thickness of the secondary insulation wall 5 can be made relatively thicker than the connecting insulation wall 3a.

[0077] Referring to FIG. 4(b), the connecting insulation wall 3a and the secondary insulation wall 5 are formed to have similar thicknesses, and the height of the secondary barrier 4 is located in the center region of the total thickness based on the thickness direction. Here, the center region can be in the range of 40% to 60% of the total thickness. In this case, the amount of shrinkage itself is reduced compared to FIG. 4(a), and stress at low temperatures is reduced. Also, compared to FIG. 4(a), the risk of damage to the secondary barrier is relatively lower.

[0078] The present invention provides a liquefied gas storage tank 1 that can reduce the low temperature burden and sloshing burden of the secondary insulation wall 4 while maintaining the mechanical strength of the secondary insulation wall 5 at a constant level, and this can be understood by referring to the following explanation with reference to Figures 5 to 20.

[0079] 5 to 20 are diagrams showing the results of structural analysis in which the thicknesses of the connecting insulating wall 3a and the secondary insulating wall 5 are made different for each of the first case (FIGS. 5 to 8), the second case (FIGS. 9 to 12), the third case (FIGS. 13 to 16), and the fourth case (FIGS. 17 to 20) in order to derive the thickness of the primary insulating wall 3 and the secondary insulating wall 5 including the connecting insulating wall 3a of the liquefied gas storage tank 1 according to the present embodiment. In this embodiment, the thickness of the connecting insulating wall 3a will be mainly described, but the thickness of the primary insulating wall 3 is the same as or similar to that of the connecting insulating wall 3a.

[0080] The analysis conditions for each case are as follows:

[0081] First, the total thickness of the connecting insulation wall 3a and the secondary insulation wall 5 in the first to fourth cases, which are the analytical models, was set to 400 mm in the same manner.

[0082] Secondly, the thicknesses of the connecting insulating wall 3a and the secondary insulating wall 5 are made different, so that only the position of the secondary barrier 4 is changed.

[0083] Thirdly, taking into consideration the same linear temperature distribution conditions, the temperature at the position of the primary barrier 2 was set to −163° C., which is the temperature of liquefied gas, and the temperature at the position of the hull 7 was set to 20° C., which is room temperature.

[0084] Fourth, the minimum and maximum stress values ​​are fixed and different stresses are displayed using colors; for example, red indicates the highest stress value and blue indicates smaller stress values.

[0085] Fifth, the thickness ratio was set to the ratio of the thickness of the connecting insulating wall 3a to the total thickness (400 mm).

[0086] Structural analysis of the analytical models, Case 1 to Case 4, was carried out under the above analysis conditions.

[0087] Figures 5 to 8 are diagrams showing the results of a structural analysis in which the thicknesses of the connecting insulation wall 3a and the secondary insulation wall 5 of the first case were made different in order to derive the thicknesses of the connecting insulation wall 3a and the secondary insulation wall 5 included in the primary insulation wall 3 of the liquefied gas storage tank according to the first embodiment of the present invention.

[0088] In the first case, as shown in Fig. 5, the thickness of the connecting insulation wall 3a is 100 mm, and the thickness of the secondary insulation wall 5 is 300 mm. That is, in the first case, the thickness of the connecting insulation wall 3a accounts for 0.25 of the total thickness (400 mm) of the connecting insulation wall 3a and the secondary insulation wall 5, and the secondary barrier 4 is located close to the primary barrier 2 side, which is the upper end from the center of the total thickness of the connecting insulation wall 3a and the secondary insulation wall 5 combined.

[0089] In the case of the first case, as shown in Figures 6 to 8, as a result of the structural analysis, with the unit elements arranged adjacent to each other, the portion of the secondary barrier 4 corresponding to the space between adjacent secondary insulation walls 5 was displayed in red, and the stress value was calculated to be 70.12 MPa.

[0090] The reason why stress occurs in the secondary barrier 4 in the first case can be seen from Figure 4. That is, because the thickness of the connecting insulating wall 3a is thin, the secondary barrier 4 is greatly affected by the cold heat of the liquefied gas.

[0091] Figures 9 to 12 are diagrams showing the results of a structural analysis in which the thicknesses of the connecting insulation wall 3a and the secondary insulation wall 5 of the second case were made different in order to derive the thicknesses of the connecting insulation wall 3a and the secondary insulation wall 5 included in the primary insulation wall 3 of the liquefied gas storage tank according to the first embodiment of the present invention.

[0092] In the second case, as shown in Fig. 9, the thickness of the connecting insulation wall 3a is 160 mm, and the thickness of the secondary insulation wall 5 is 240 mm. That is, in the second case, the ratio of the thickness of the connecting insulation wall 3a to the total thickness (400 mm) of the connecting insulation wall 3a and the secondary insulation wall 5 is 0.4, and the secondary insulation wall 4 is positioned slightly offset toward the primary insulation wall 2 from the center of the total thickness, which is the combined thickness of the connecting insulation wall 3a and the secondary insulation wall 5.

[0093] In this second case, as shown in Figures 10 to 12, as a result of the structural analysis, when the unit elements were arranged adjacent to each other, the portion of the secondary barrier 4 corresponding to the space between adjacent secondary insulation walls 5 was displayed in yellow, and the stress value was calculated to be 55.09 MPa.

[0094] Figures 13 to 16 are diagrams showing the results of a structural analysis in which the thicknesses of the connecting insulation wall 3a and the secondary insulation wall 5 of the third case were made different in order to derive the thicknesses of the connecting insulation wall 3a and the secondary insulation wall 5 included in the primary insulation wall 3 of the liquefied gas storage tank according to the first embodiment of the present invention.

[0095] 13, the third case is a case in which the thickness of the connecting insulation wall 3a and the secondary insulation wall 5 are formed to be the same or similar. That is, in the third case, the ratio of the thickness of the connecting insulation wall 3a to the total thickness (400 mm) of the connecting insulation wall 3a and the secondary insulation wall 5 is about 0.5, and the secondary barrier 4 is located adjacent to the center of the total thickness of the connecting insulation wall 3a and the secondary insulation wall 5 combined.

[0096] In this third case, as shown in Figures 14 to 16, as a result of the structural analysis, with the unit elements arranged adjacent to each other, the portion of the secondary barrier 4 corresponding to the space between adjacent secondary insulation walls 5 was displayed in light blue, and the stress value was calculated to be 47.63 MPa.

[0097] Figures 17 to 20 are diagrams showing the results of a structural analysis in which the thicknesses of the connecting insulation wall 3a and the secondary insulation wall 5 in the fourth case were made different in order to derive the thicknesses of the connecting insulation wall 3a and the secondary insulation wall 5 included in the primary insulation wall 3 of the liquefied gas storage tank according to the first embodiment of the present invention.

[0098] 17, the fourth case is a case in which the thickness of the connecting insulation wall 3a is 240 mm, and the thickness of the secondary insulation wall 5 is 160 mm. That is, in the fourth case, the ratio of the thickness of the connecting insulation wall 3a to the total thickness (400 mm) of the connecting insulation wall 3a and the secondary insulation wall 5 is 0.6, and the secondary barrier 4 is located below the center of the total thickness of the connecting insulation wall 3a and the secondary insulation wall 5 combined.

[0099] In this fourth case, as shown in Figures 18 to 20, as a result of the structural analysis, with the unit elements arranged adjacent to each other, the portion of the secondary barrier 4 corresponding to the space between adjacent secondary insulation walls 5 was displayed in light blue, and the stress value was calculated to be 41.21 MPa.

[0100] As described above, the structural analysis of each of the first to fourth cases shows that the secondary barrier 4 at the bottom of the connecting insulation wall 3a shows a tendency for low-temperature stress due to thermal contraction to decrease the farther it is from the primary barrier 2. This will be described with reference to FIG.

[0101] FIG. 21 shows the relationship between the low-temperature stress of the secondary barrier and the probability of brittle fracture of the hull due to changes in the thickness of the primary and secondary insulation walls.

[0102] As shown in the graph of FIG. 21, not only in the first to fourth cases, but also in the secondary barrier 4 at the bottom of the connecting insulating wall 3a, it can be predicted that the stress value due to thermal contraction at low temperatures decreases as the secondary barrier 4 at the bottom of the connecting insulating wall 3a moves away from the primary barrier 2. That is, the temperature of the secondary barrier 4 at the bottom of the connecting insulating wall 3a becomes relatively higher as the secondary barrier 4 moves away from the primary barrier 2 compared to when the temperature is close, so the contraction decreases and the stress decreases. In this embodiment, the secondary barrier 4 at the bottom of the connecting insulating wall 3a will be mainly described, but it is clear that the stress of the secondary barrier 4 at the bottom of the fixed insulating wall 3b, which constitutes the unit element, also decreases as the secondary barrier 4 moves away from the primary barrier 2. The secondary barrier 4 at the bottom of the connecting insulating wall 3a is in a state in which the main barrier 41 and the auxiliary barrier 42 are laminated, and the secondary barrier 4 at the bottom of the primary insulating wall 3 is composed of only the main barrier 41.

[0103] In the liquefied gas storage tank 1 of this embodiment derived in this way, the thickness of the connecting insulation wall 3a is increased in the total thickness including the thickness of the connecting insulation wall 3a and the secondary insulation wall 5, so that the temperature received by the secondary barrier 4 increases (the influence of cold from the cryogenic liquid gas is reduced). As a result, the contraction of the secondary barrier 4 itself due to cold is reduced, and the stress due to cold is reduced, so that damage to the secondary barrier 4 due to cold can be prevented. This principle is also applied to the secondary barrier 4 below the primary insulation wall 3 defined as including the connecting insulation wall 3a.

[0104] In addition, as the thicknesses of the connecting insulation wall 3a and the fixed insulation wall 3b of the secondary barrier 4 increase (the thickness of the secondary insulation wall 5 decreases relatively), the sloshing load and fluid dynamic load transmitted to the secondary barrier 4 are lowered, and the stress due to sloshing is reduced, thereby making it possible to prevent damage due to sloshing. In addition, as the thickness of the secondary insulation wall 5 is reduced (the thickness of the primary insulation wall 3 is relatively thick), it becomes easier to adjust the flatness of the secondary barrier 4.

[0105] In addition, as the thickness of the connecting insulation wall 3a and the fixed insulation wall 3b increases, the thickness of the secondary insulation wall 5 decreases relatively and becomes relatively farther away from the primary insulation wall 2, so that the contraction force of the secondary insulation wall 5 due to cold and heat also decreases. As a result of the reduction in the contraction force of the secondary insulation wall 5, the tensile force of the secondary insulation wall 4 decreases, so that the secondary insulation wall 4 can prevent damage due to the contraction force of the secondary insulation wall 5.

[0106] Considering the low temperature stress of the secondary barrier 4, in the present invention, the connecting insulating wall 3a can be arranged so that it corresponds to 40% or more of the combined thickness of the connecting insulating wall 3a and the secondary insulating wall 5. Preferably, the liquefied gas storage tank 1 of the present invention can be arranged in the range of the second to fourth cases, that is, the connecting insulating wall 3a can be arranged so that it corresponds to 40% to 60% of the combined thickness of the connecting insulating wall 3a and the secondary insulating wall 5. More preferably, the liquefied gas storage tank 1 of the present invention can be arranged in the range of the third case, that is, the connecting insulating wall 3a can be arranged so that it corresponds to 47% to 53% of the combined thickness of the connecting insulating wall 3a and the secondary insulating wall 5.

[0107] However, when the thickness of the connecting insulation wall 3a and the primary insulation wall 3 is increased, the thickness of the secondary insulation wall 5 is relatively reduced, making the secondary insulation wall 5 vulnerable to the mechanical stress applied when the hull 7 is structurally deformed due to the six-degree-of-freedom movement of the hull 7, and as a result, the degree of mechanical stress transmitted to the secondary barrier 4 through the secondary insulation wall 5 increases.

[0108] In addition, when liquefied gas is loaded, an emergency condition may occur in which the primary barrier 2 cracks. In this case, the primary barrier 2 can no longer prevent the leakage of the liquefied gas, and the liquefied gas may come into contact with the secondary barrier 4. In addition, when the secondary barrier 4 comes into contact with extremely low temperature liquefied gas, the temperature of the hull decreases, and the probability of brittle fracture may increase. In addition, the lower the temperature, the higher the material strength of the hull, which causes brittle problems, and the probability of brittle fracture may increase. Here, brittle fracture corresponds to a sudden fracture that occurs with almost no plastic deformation, and can be understood as a brittle crack.

[0109] In this regard, referring to Figure 21, in an emergency, the probability of brittle fracture increases from Case 1 to Case 4 because the secondary barrier 4 that is in contact with the cryogenic liquefied gas is closer to the hull. That is, in Figure 21, the probability of brittle fracture of the hull increases from Case 1 to Case 4, that is, as the thickness of the connecting insulation wall increases compared to the thickness of the secondary insulation wall 5. Also, if the thickness of the connecting insulation wall 3a in Case 4 becomes thicker, the probability of brittle fracture approaches 1, and the hull may crack or split.

[0110] Therefore, the insulation system of the liquefied gas storage tank 1 should be arranged taking into consideration not only the above-mentioned low temperature stress but also the risk of cracking or destruction of the hull. In the present invention, the second to fourth cases in which the secondary barrier 4 is located in the central region of the total thickness of the connecting insulation wall 3a and the secondary insulation wall 5 can be appropriate when all aspects of low temperature stress and hull cracking are considered. Preferably, the third case can be determined to be appropriate in terms of low temperature stress and mechanical aspects of hull cracking.

[0111] Therefore, the present invention reduces low-temperature stress in the secondary barrier 4 by ensuring sufficient thickness of the connecting insulation wall 3a and the primary insulation wall 3, but cases 2 to 4 are suitable embodiments in which the thickness of the secondary insulation wall 4 is appropriately set and a gap is provided between the hull 7 and the secondary barrier 4 to reduce the burden on the secondary barrier 4 against structural stress transmitted from the hull 7. Among these, case 3 is the preferred embodiment in consideration of both low-temperature stress and mechanical strength.

[0112] Meanwhile, the secondary barrier 4 may be made of various materials, which will be described with reference to Figs.

[0113] 22, 23 and 24 are diagrams illustrating various configurations of the secondary barrier of the liquefied gas storage tank according to the first embodiment of the present invention.

[0114] As shown in FIG. 22, the secondary barrier 4 may be formed of a first material having a three-layer structure in which glass cloth (GC) / aluminum foil (AF) / glass-aramid cloth (GAC) are laminated.

[0115] Glass-aramid cloth (GAC) is made by applying aramid material to glass cloth, and can be manufactured by mixing one aramid for every two glass fibers.

[0116] Such a first material may be applied to the auxiliary barrier 42 of the secondary barrier 4, but is not limited thereto, and may also be applied to the main barrier 41 of the secondary barrier 4.

[0117] As shown in FIG. 23, the secondary barrier 4 may be formed of a second material having a five-layer structure in which glass cloth (GC) / aluminum foil (AF) / glass cloth (GC) / aluminum foil (AF) / glass cloth (GC) are laminated.

[0118] Such a second material may be applied to the main barrier 41 of the secondary barrier 4 , but is not limited thereto, and may also be applied to the auxiliary barrier 42 of the secondary barrier 4 .

[0119] As shown in FIG. 24, the secondary barrier 4 is made of inorganic basalt cloth extracted from basalt, and may be formed of a third material having a three-layer structure of laminated basalt cloth (BC) / aluminum foil (AF) / basalt cloth (BC).

[0120] Such a third material may be applied to the main barrier 41 which is the secondary barrier 4, but is not limited thereto, and may also be applied to the auxiliary barrier 42 which is the secondary barrier 4.

[0121] 22 to 24, the secondary barrier 4 of this embodiment may be formed of various materials having a multi-layer structure in which a first member / aluminum foil (AF) / second member are laminated. In this case, at least one of the first member and the second member may be glass cloth (GC), glass-aramid cloth (GAC), basalt cloth (BC), or glass cloth (GC) / aluminum foil (AF) / glass cloth (GC).

[0122] In addition, various materials applied to the secondary barrier 4 may be applied to the main barrier 41 and auxiliary barrier 42 of the secondary barrier 4 in various combinations.

[0123] Figure 25 is a partial cross-sectional view for explaining the right-angle corner structure of a liquefied gas storage tank according to the first embodiment of the present invention, and Figure 26 is a partial cross-sectional view for explaining the obtuse-angle corner structure of a liquefied gas storage tank according to the first embodiment of the present invention.

[0124] 5 to 20, it has been confirmed that a more stable insulation system is obtained when the thickness of the connecting insulation wall 3a or the primary insulation wall 3 and the thickness of the secondary insulation wall 5 are formed within the same or similar range. For example, the same or similar range may be when the secondary barrier 4 is located at 40% to 60% of the total thickness of the connecting insulation wall 3a or the primary insulation wall 3 and the secondary insulation wall 5. This configuration can be similarly applied to the right-angle corner structure of the liquefied gas storage tank 1 shown in FIG. 25 and the obtuse-angle corner structure of the liquefied gas storage tank 1 shown in FIG. 26.

[0125] However, in the right-angle corner structure and obtuse-angle corner structure of the liquefied gas storage tank 1, the secondary barrier 4 is formed in a curved shape, which is more vulnerable to loads from the surrounding environment than a straight section, but this embodiment can alleviate the stress caused by such loads. Also, this embodiment can easily absorb hull deformation.

[0126] Referring to Figure 25, in the right-angle corner structure, the secondary barrier 4 has a radius of curvature that is 25% or more, for example, 25% to 50%, of the thickness of the primary insulation wall 3, because the thickness of the primary insulation wall 3 is thicker than the first and second cases.

[0127] In addition, the secondary barrier 4 in the right-angle corner structure is moved toward the hull 7 compared to the conventional thin primary insulation wall because the thickness of the primary insulation wall 3 is thicker than that of the first and second cases. In this case, the radius of curvature becomes larger, and the larger radius of curvature also increases the length L1 of the part where the secondary barrier 4 is not glued to the secondary insulation wall 5 (secondary barrier scab part not glued). This means that the flexibility of the secondary barrier 4 in the right-angle corner structure increases, and therefore the secondary barrier 4 in the right-angle corner structure can more easily absorb deformation of the surrounding area, for example, hull deformation, and low-temperature stress is also reduced. For example, the length L1 of the part that is not glued may be 100 mm to 200 mm.

[0128] Referring to Figure 26, in the obtuse angle corner structure, the secondary barrier 4 has a radius of curvature that is 15% or more, for example, 15% to 35%, of the thickness of the primary insulation wall 3, because the thickness of the primary insulation wall 3 is thicker than in the first and second cases.

[0129] In addition, the secondary barrier 4 in the obtuse-angle corner structure is moved toward the hull 7 as the thickness of the primary insulation wall 3 is thicker than that of the first and second cases, and the radius of curvature is larger than that of the conventional thin primary insulation wall. In this case, the larger radius of curvature of the secondary barrier 4 increases the length L2 of the part where the secondary barrier 4 is not glued to the secondary insulation wall 5. This means that the flexibility of the secondary barrier 4 in the obtuse-angle corner structure is increased, and therefore the secondary barrier 4 in the obtuse-angle corner structure can more easily absorb deformation of the periphery, for example, hull deformation, and the low-temperature stress is also reduced. For example, the length L2 of the part where the secondary barrier 4 is not glued may be 50 mm to 90 mm.

[0130] As described above, the secondary barrier 4 in the right-angle corner structure and obtuse-angle corner structure of the present invention can reduce stress at low temperatures applied to the conventional secondary barrier compared to the right-angle corner structure and obtuse-angle corner structure of the primary insulation wall, which are formed to be relatively thin. Also, the non-bonded portion is increased, making it easier to absorb hull deformation.

[0131] FIG. 27 is a graph showing the thermal conductivity of the primary and secondary insulation materials used in a liquefied gas storage tank.

[0132] In the above-mentioned embodiment of the liquefied gas storage tank 1 of the present invention, it has been described that the connecting insulation wall 3a, the primary insulation material 32, 32a of the primary insulation wall 3, and the secondary insulation material 51 of the secondary insulation wall 5 are all made of polyurethane foam of the same material, but polyurethane foams of different materials may be selectively used as needed.

[0133] Specifically, reinforced polyurethane foam (RPUF) is made by mixing polyol, isocyanate, and a blowing agent, and HFC-245fa or CO2 may be used as the blowing agent. HFC-245fa can be relatively expensive compared to CO2.

[0134] In this embodiment, the primary insulation materials 32, 32a are formed of reinforced polyurethane foam using CO2 as a foaming agent, and the secondary insulation material 51 is formed of reinforced polyurethane foam using HFC-245fa as a foaming agent.

[0135] Referring to the graph of FIG. 27 showing the thermal conductivity characteristics of the blowing agent HFC-245fa and the blowing agent CO2, the blowing agent HFC-245fa has a lower thermal conductivity value at room temperature compared to the blowing agent CO2, but at extremely low temperatures, they show the same or similar values.

[0136] That is, the thermal conductivity values ​​of the blowing agent HFC-245fa and the blowing agent CO2 are the same or similar at temperatures below -80°C, and at temperatures above that, the blowing agent HFC-245fa exhibits a lower value than the blowing agent CO2.

[0137] Therefore, in this embodiment, the relatively expensive blowing agent HFC-245fa is not used for both the primary insulation 32, 32a and the secondary insulation 51, and in consideration of economic aspects, the primary insulation 32, 32a, which is relatively close to an extremely low temperature, is formed from reinforced polyurethane foam using CO2 as the blowing agent, and the secondary insulation 51 is formed from reinforced polyurethane foam using the blowing agent HFC-245fa.

[0138] FIG. 28 is a partial cross-sectional view for explaining a liquefied gas storage tank according to a second embodiment of the present invention, and FIG. 29 is a partial perspective view for explaining a liquefied gas storage tank according to the second embodiment of the present invention.

[0139] As shown in Figures 28 and 29, the liquefied gas storage tank 1 according to the second embodiment of the present invention may be configured to include a primary barrier 2 that comes into contact with liquefied gas inside, a primary insulation wall 3 and a connecting insulation wall 3a that are provided outside the primary barrier 2, a secondary barrier 4 that is provided outside the primary insulation wall 3 and the connecting insulation wall 3a, and a secondary insulation wall 5 that is disposed outside the secondary barrier 4 and fixed to the hull 7.Compared to the first embodiment described above, the configuration of the connecting insulation wall 3a is different, and the other configurations are the same or similar, so only the different parts will be described below to avoid redundant explanations.

[0140] In this embodiment, the structure of the connecting insulating wall 3a may be different from that of the first embodiment described above.

[0141] Specifically, compared with the first embodiment described above, the connecting insulating wall 3 a may further include an auxiliary insulating plate 33 .

[0142] That is, the connected insulating wall 3a may have a structure in which connected plywood 31a, connected insulating material 32a, and auxiliary insulating board 33 are laminated.

[0143] The auxiliary insulation plate 33 may be 5 mm to 10 mm thick and is made of plywood, high density polyurethane foam (HD PUF), FRP (Fiber Reinforced Plastic), etc., to obtain a load dispersion effect of the secondary barrier 4. Alternatively, the auxiliary insulation plate 33 may be made of VIP (Vacuum Insulation Panel), LD PUF, etc., which have excellent insulation properties, to compensate for insulation weakness in the portion where the connected insulation wall 3a is formed.

[0144] The connecting insulation material 32a of the connecting insulation wall 3a and the primary insulation material 32 of the fixed insulation wall 3b constituting a unit element may be the same thickness. However, in the case of the connecting insulation wall 3a, since an auxiliary barrier 42 is further laminated in addition to the main barrier 41 of the secondary barrier 4 at the bottom and also includes an auxiliary insulation plate 33, the thickness of the connecting insulation material 32a of the connecting insulation wall 3a may be smaller than the primary insulation material 32 of the primary insulation wall 3 by the thickness of the auxiliary barrier 42 and the thickness of the auxiliary insulation plate 33.

[0145] The above-mentioned auxiliary insulation plate 33 may be provided not only under the connecting insulation material 32a of the connecting insulation wall 3a, but also under the primary insulation material 32 of the primary insulation wall 3 constituting a unit element.

[0146] FIG. 30 is a partial cross-sectional view for explaining a liquefied gas storage tank according to a third embodiment of the present invention, and FIG. 31 is an enlarged view of a main part of the liquefied gas storage tank according to the third embodiment of the present invention.

[0147] As shown in Figures 30 to 31, the liquefied gas storage tank 1 according to the third embodiment of the present invention may be configured to include a primary barrier 2 that comes into contact with liquefied gas inside, a primary insulation wall 3 and a connecting insulation wall 3a that are provided outside the primary barrier 2, a secondary barrier 4 that is provided outside the primary insulation wall 3 and the connecting insulation wall 3a, a secondary insulation wall 5 that is disposed outside the secondary barrier 4 and fixed to the hull 7, a leveling member 8 that is provided between the secondary insulation wall 5 and the hull 7, and a fixing member 9 that fixes the secondary insulation wall 5 to the hull 7.Compared to the first embodiment described above, the leveling member 8 and the fixing member 9 are different, and the other configurations are the same or similar.Therefore, in order to avoid redundant explanations, only the leveling member 8 and the fixing member 9, which are components that are different from the first embodiment, and the parts that differ as a result of this will be described below.

[0148] A levelling member 8 may be provided between the secondary insulating wall 5 and the hull 7 .

[0149] The leveling member 8 can level deformed areas of the hull 7, improve the insulating performance of the tank, and support the secondary insulating wall 5, and may be a non-adhesive elastic insulating material such as EPS (Expanded Polystyrene).

[0150] Such leveling members 8 may have a flat upper surface that comes into close contact with the secondary insulation wall 5 due to elastic force, and a curved lower surface that comes into close contact with the hull 7 to accommodate deformation of the hull 7. Deformation of the hull 7 may occur, for example, when the blocks of the hull 7 are welded together.

[0151] That is, the leveling member 8 can level the deformed portion of the hull without using conventional mastic and leveling wedges, although it goes without saying that the leveling wedges can be used selectively.

[0152] In this embodiment, by applying the leveling member 8 as described above, unlike conventional mastics that are applied in various types depending on the size of the gap, it is possible to apply a single size, and since there is no need for the mastic to harden, the work time can be shortened, and by applying an insulating material, the heat retention can be increased.

[0153] The fixing member 9 may be a cleat structure including a protrusion 91 and a stud bolt 92 so that the secondary insulation wall 5 can be fixed to the hull 7 .

[0154] The protrusions 91 may be provided protruding outward from the lower portions of both side surfaces of the unit panel of the secondary insulation wall 5, and may be made of plywood.

[0155] The protrusion 91 may be fixedly installed such that one side extends over the side of the secondary plywood 52 of the secondary insulation wall 5 and over a portion of the side of the secondary insulation material 51 up to a certain height from the secondary plywood 52, and the lower surface has the same level as the lower surface of the secondary plywood 52.

[0156] The width and thickness of the protrusions 91 may be such that, when a plurality of unit panels forming the secondary insulation wall 5 are arranged, a stud bolt 92 can be inserted between the opposing protrusions 91 .

[0157] The stud bolts 92 may be fixed to the hull 7 .

[0158] The stud bolt 92 may be fixedly installed on the hull 7 so as to match the space between adjacent unit panels of the secondary insulation wall 5 when multiple unit panels that form the secondary insulation wall 5 are arranged.

[0159] The stud bolts 92 are provided on each side of the unit panels of adjacent secondary insulation walls 5 and are positioned between two opposing protrusions 91, and the secondary insulation walls 5 can be fixed to the hull 7 by tightening the bolts.

[0160] Figure 32 is a partial cross-sectional view to explain a liquefied gas storage tank according to a fourth embodiment of the present invention, Figure 33 is a diagram to explain filling insulation filling a first slit, which is a gap between the connecting insulation wall and the fixed insulation wall that constitute the primary insulation wall, and a plurality of second slits provided in the fixed insulation wall, Figure 34 is a diagram to explain filling insulation according to another embodiment that fills a first slit, which is a gap between the connecting insulation wall and the fixed insulation wall that constitute the primary insulation wall, and a plurality of second slits provided in the fixed insulation wall, and Figure 35 is a diagram to explain filling insulation according to yet another embodiment that fills a first slit, which is a gap between the connecting insulation wall and the fixed insulation wall that constitute the primary insulation wall, and a plurality of second slits provided in the fixed insulation wall.

[0161] As shown in Figures 32 to 35, the liquefied gas storage tank 1 according to the fourth embodiment of the present invention may be configured to include a primary barrier 2 that comes into contact with liquefied gas inside, a primary insulation wall 3 that is provided outside the primary barrier 2 and consists of a connecting insulation wall 3a and a fixed insulation wall 3b, a secondary barrier 4 that is provided outside the primary insulation wall 3, and a secondary insulation wall 5 that is disposed outside the secondary barrier 4 and fixed to the hull 7.Compared to the first embodiment described above, this embodiment differs in that a first slit SL1, which is the gap between the connecting insulation wall 3a and the fixed insulation wall 3b, is filled and that multiple second slits SL2 are provided in the fixed insulation wall 3b.Since the other configurations are the same or similar, the following description will focus on the different parts to avoid redundant explanations.

[0162] The primary insulating wall 3 and the secondary insulating wall 5 in this embodiment may be of the same or similar thickness as described above.

[0163] The primary insulating wall 3 may be composed of a connecting insulating wall 3a and a fixed insulating wall 3b.

[0164] The connecting insulation wall 3a may be inserted between adjacent fixed insulation walls 3b to seal the space formed between adjacent secondary insulation walls 5 when unit elements including the fixed insulation wall 3b are arranged adjacent to each other, and in this case, a gap may be formed between the connecting insulation wall 3a and the fixed insulation wall 3b.

[0165] The first slit SL1 is a gap formed between the connecting insulating wall 3a and the fixed insulating wall 3b, and may be formed to a depth corresponding to the thickness of the primary insulating wall 3.

[0166] In this embodiment, a plurality of second slits SL2 may be formed at regular intervals in the fixed insulating wall 3b so as to accommodate contraction and expansion of the fixed insulating wall 3b.

[0167] The second slits SL2 may be formed with a depth similar to the thickness of the fixed insulating wall 3b so as to maximally relieve the temperature-induced contraction or expansion stress applied to the fixed insulating wall 3b. For example, when the thickness of the fixed insulating wall 3b is 200 mm, the depth of the second slits SL2 may be, but is not limited to, 185 mm to 195 mm.

[0168] The first slit SL1 and the second slit SL2 can prevent damage to the primary insulation wall 3 by mitigating the stress of contraction or expansion due to temperature, but can increase the low temperature burden on the secondary barrier 4 by acting as a convection path.

[0169] Therefore, in this embodiment, the first slit SL1 is filled completely or partially with a first filling insulation material GW1, and the second slit SL2 is filled partially with a second filling insulation material GW2, thereby preventing damage to the fixed insulation wall 3b due to contraction and expansion and reducing the low temperature burden on the secondary barrier 4, as will be explained in detail below.

[0170] The first filling insulation material GW1 and the second filling insulation material GW2 can be inserted and filled into the first slit SL1 and the second slit SL2 using a jig.

[0171] As shown in Figures 33 to 35, the first filling insulation material GW1 may be formed so as to fill the entire first slit SL1 (see Figure 33), or so as to fill to a certain depth from the entrance of the first slit SL1 so as to create space at the bottom of the first slit SL1 (see Figure 34), or so as to fill in multiple layers inside the first slit SL1 so as to create multiple spaces inside the first slit SL1 (see Figure 35).

[0172] In addition, the second filling insulation material GW2 may be formed so as to fill to a certain depth from the entrance of the second slit SL2 so as to create a space at the bottom of the second slit SL2, as shown in Figures 33 to 35 (see Figures 33 and 34), or it may be formed so as to fill the inside of the second slit SL2 in multiple layers so as to create multiple spaces inside the second slit SL2 (see Figure 35).

[0173] In the above, the first filling insulation material GW1 filled in the first slit SL1 and the second filling insulation material GW2 filled in the second slit SL2 may each be formed to have a (+) tolerance so that the space can be completely sealed when filled in the space between the first slit SL1 and the second slit SL2, thereby absorbing contraction and expansion.

[0174] Referring to FIG. 33, the first filling insulation material GW1 is formed to fill the entire first slit SL1, and the second filling insulation material GW2 may be formed to fill to a certain depth from the entrance of the second slit SL2 so that space is created at the bottom of the second slit SL2.

[0175] The first filling insulation GW1 and the second filling insulation GW2 may be made of glass wool, but are not limited to this.

[0176] In the above, the first filling insulation material GW1 is formed to completely fill the first slit SL1, thereby improving the insulation performance at the connection part between the connecting insulation wall 3a and the fixed insulation wall 3b. The second filling insulation material GW2 is formed to leave a space below the second slit SL2, thereby not only improving the insulation performance of the fixed insulation wall 3b but also allowing the space of the second slit SL2 to absorb the contraction and expansion of the fixed insulation wall 3b.

[0177] Referring to Figure 34, the first filling insulation material GW1 is formed to fill to a certain depth from the entrance of the first slit SL1 so that space is created at the bottom of the first slit SL1, and the second filling insulation material GW2 may be formed to fill to a certain depth from the entrance of the second slit SL2 so that space is created at the bottom of the second slit SL2.

[0178] The first filling insulation GW1 and the second filling insulation GW2 may be made of glass wool, but are not limited to this.

[0179] In the above, the first filling insulation material GW1 is formed to leave a space below the first slit SL1, so that the first filling insulation material GW1 not only improves the insulation performance of the connecting portion between the connecting insulation wall 3a and the fixed insulation wall 3b but also allows the space portion of the first slit SL1 to absorb contraction and expansion of the connecting insulation wall 3a and the fixed insulation wall 3b. The second filling insulation material GW2 is formed to leave a space below the second slit SL2, so that the second filling insulation material GW2 not only improves the insulation performance of the fixed insulation wall 3b but also allows the space portion of the second slit SL2 to absorb contraction and expansion of the fixed insulation wall 3b.

[0180] Referring to Figure 35, the first filling insulation material GW1 may be formed to fill in multiple layers so as to create multiple spaces inside the first slit SL1, and the second filling insulation material GW2 may be formed to fill in multiple layers so as to create multiple spaces inside the second slit SL2.

[0181] The first filling insulation GW1 may consist of a first upper filling insulation GW1-1 formed at the top of the first slit SL1, a first intermediate filling insulation GW1-2 formed in the middle of the first slit SL1 a certain distance away from the first upper filling insulation GW1-1, and a first lower filling insulation GW1-3 formed at the bottom of the first slit SL1 a certain distance away from the first intermediate filling insulation GW1-2.

[0182] The first upper filling insulation GW1-1, the first middle filling insulation GW1-2, and the first lower filling insulation GW1-3 may be made of the same or different insulation materials, such as glass wool, super lite, soft foam material, aerogel blanket, etc.

[0183] The second filling insulation GW2 may comprise a second upper filling insulation GW2-1 formed at the top of the second slit SL2, a second intermediate filling insulation GW2-2 formed in the middle of the second slit SL2 a certain distance away from the second upper filling insulation GW2-1, and a second lower filling insulation GW2-3 formed at the bottom of the second slit SL2 a certain distance away from the second intermediate filling insulation GW2-2.

[0184] The second upper filling insulation GW2-1, the second middle filling insulation GW2-2, and the second lower filling insulation GW2-3 may be made of the same or different insulation materials, such as glass wool, super lite, soft foam material, aerogel blanket, etc.

[0185] In the above, the first filling insulation material GW1 is formed in multiple layers to create multiple spaces inside the first slit SL1, so that the multiple first filling insulation materials GW1-1, GW1-2, GW1-3 not only improve the insulation performance of the connecting portion between the connecting insulation wall 3a and the fixed insulation wall 3b, but also allow the multiple spaces of the first slit SL1 to absorb contraction and expansion of the connecting insulation wall 3a and the fixed insulation wall 3b. The second filling insulation material GW2 is formed in the second slit SL2 to create multiple spaces inside the second slit SL2, so that the multiple second filling insulation materials GW2-1, GW2-2, GW2-3 not only improve the insulation performance of the fixed insulation wall 3b, but also allow the multiple spaces of the second slit SL2 to absorb contraction and expansion of the fixed insulation wall 3b.

[0186] Figure 36 is a partial cross-sectional view for explaining a liquefied gas storage tank according to the fifth embodiment of the present invention, Figure 37 is a cross-sectional view of a connected insulation wall cut along line A-A' in Figure 36, Figure 38 is a cross-sectional view of a unit element formed by stacking fixed insulation walls constituting a secondary insulation wall, a secondary barrier and a primary insulation wall cut along line B-B' in Figure 36, Figures 39 and 40 are views for explaining a filling insulation material filling a first slit, which is a gap between the connected insulation wall and the fixed insulation wall constituting the primary insulation wall, and Figures 41 and 42 are views for explaining a filling insulation material filling a first slit, which is a gap between the connected insulation wall and the fixed insulation wall constituting the primary insulation wall, and Figures 42 are views for explaining a unit element formed by stacking fixed insulation walls constituting a secondary insulation wall, a secondary barrier and a primary insulation wall cut along line B-B' in Figure 36, and Figures 43 and 44 are views for explaining a unit element formed by stacking fixed insulation walls constituting a secondary insulation wall and a primary insulation wall cut along line B-B' in Figure 36, and Figures 44 and 45 are views for explaining a unit element formed by stacking fixed insulation walls constituting a secondary insulation wall and a primary insulation wall cut along line B-B' in Figure 36, and Figures 45 and 46 are views for explaining a unit element formed by stacking fixed insulation walls constituting a secondary insulation wall and a primary insulation wall cut along line B-B' in Figure 36, and Figures 46 and 47 are views for explaining a unit element formed by stacking fixed insulation walls constituting a secondary insulation wall and a primary insulation wall cut along line B-B' in Figure 36, and Figures 47 and 48 are views for explaining a unit element formed by stacking fixed insulation walls constituting a secondary insulation wall and a primary insulation wall cut along line B-B' in Figure 36, and Figures 48 and 49 are views for explaining a 43 to 46 are figures showing the results of a structural analysis of a liquefied gas storage tank according to the fifth embodiment of the present invention and a liquefied gas storage tank according to a comparative example, and are figures for comparatively explaining the convection paths and secondary barrier temperatures that change depending on the structure of the slits and the presence or absence of filled insulation material filling the slits in the liquefied gas storage tank according to the above-mentioned fifth embodiment and a liquefied gas storage tank according to a comparative example. FIG. 47 is a graph comparing the temperature of the secondary barrier at the bottom of the slit depending on the presence or absence of filled insulation material filling the slits in a liquefied gas storage tank according to the fifth embodiment of the present invention and a liquefied gas storage tank according to a comparative example.

[0187] As shown in Figures 36 to 40, the liquefied gas storage tank 1 according to the fifth embodiment of the present invention may be configured to include a primary barrier 2 that comes into contact with liquefied gas inside, a primary insulation wall 3 that is provided outside the primary barrier 2 and consists of a connecting insulation wall 3a and a fixed insulation wall 3b, a secondary barrier 4 that is provided outside the primary insulation wall 3, and a secondary insulation wall 5 that is disposed outside the secondary barrier 4 and fixed to the hull 7.Compared to the above-mentioned fourth embodiment, the first filling insulation material GW1 that fills the first slit SL1, which is the gap between the connecting insulation wall 3a and the fixed insulation wall 3b, and the multiple second slits SL2 provided in the fixed insulation wall 3b are different, and the other configurations are the same or similar, so the following description will focus on the different parts to avoid redundant explanations.

[0188] The primary insulating wall 3 and the secondary insulating wall 5 in this embodiment may be of the same or similar thickness as described above.

[0189] The primary insulation wall 3 may be composed of a connecting insulation wall 3a and a fixed insulation wall 3b, and in this case, the connecting insulation wall 3a may be inserted between adjacent fixed insulation walls 3b to seal a space formed between adjacent secondary insulation walls 5 when unit elements including the fixed insulation walls 3b are arranged adjacent to each other. In this case, a gap may be formed between the connecting insulation wall 3a and the fixed insulation wall 3b.

[0190] The first slit SL1 is a gap formed between the connecting insulating wall 3a and the fixed insulating wall 3b, and may be formed to a depth corresponding to the thickness of the primary insulating wall 3.

[0191] In this embodiment, a plurality of second slits SL2 may be formed at regular intervals in the fixed insulating wall 3b to accommodate contraction and expansion of the fixed insulating wall 3b. The second slits SL2 may be formed not only in the longitudinal direction of the fixed insulating wall 3b but also in at least one width direction as shown in FIG.

[0192] In addition, in this embodiment, at least one third slit SL3 may be formed in the connecting insulating wall 3a to prepare for contraction and expansion of the connecting insulating wall 3a. The third slit SL3 may not be formed in the relatively narrow width direction, but may be formed in at least one longitudinal direction, which is relatively long, as shown in Fig. 37. The third slit SL3 formed in the longitudinal direction may be located on the same line as the second slit SL2 formed in the longitudinal direction when the connecting insulating wall 3a is inserted between the fixed insulating walls 3b.

[0193] In the above, the second slit SL2 may be formed with a depth corresponding to about half the thickness of the fixed insulating wall 3b so as to ensure insulating performance while mitigating the shrinkage or expansion stress due to temperature applied to the fixed insulating wall 3b, and no filling insulating material is filled inside. For example, when the thickness of the fixed insulating wall 3b is 200 mm, the depth of the second slit SL2 may be about 90 mm, but is not limited thereto and may be formed within a range of 100 mm to 50 mm. The third slit SL3 may be formed to be the same as or similar to the second slit SL2.

[0194] If the first slit SL1, the second slit SL2, and the third slit SL3 are not filled with any insulating material at all, the insulating performance of the fixed insulating wall 3b and the connecting insulating wall 3a near the first slit SL1 formed at a deep depth is lower than that of the fixed insulating wall 3b in which the second slit SL2 formed at a shallow depth is formed, as shown in the structural analysis result in Fig. 41. This is because the first slit SL1, which is deep, generates a lot of convection phenomena.

[0195] Therefore, in this embodiment, by partially filling the first slits SL1 with the first filling insulation material GW1, as shown in the structural analysis results in Fig. 42, the first filling insulation material GW1 prevents thermal convection, and the fixed insulation wall 3b and connecting insulation wall 3a near the first slits SL1 formed at a deep depth exhibit insulation performance similar to that of the fixed insulation wall 3b in which the second slits SL2 formed at a shallow depth are formed. In other words, it can be seen that when the first slits SL1 are filled with the first filling insulation material GW1, the depth of low temperature transfer is flattened in all parts.

[0196] In this embodiment, the first filling insulation material GW1 filled in the first slit SL1 must be formed to be at least longer than the depth of the second slit SL2 or the third slit SL3, which are formed to a depth corresponding to approximately half the thickness of the fixed insulation wall 3b or the connecting insulation wall 3a, so as to improve the thermal convection phenomenon caused by the slits.

[0197] Specifically, when the convection path formed in the spatial portion of the first slit SL1, which is partially filled with the first filling insulation material GW1, is connected to the convection path formed in the spatial portion of the second slit SL2 of the fixed insulation wall 3b and the convection path formed in the spatial portion of the third slit SL3 of the connecting insulation wall 3a, the thermal convection phenomenon increases, so in order to prevent the thermal convection phenomenon, the path must be blocked by the first filling insulation material GW1.

[0198] For example, if the depth of the second slit SL2 and the third slit SL3 is 90 mm, and the first filling insulation material GW1 is formed with a length of 80 mm from the entrance of the first slit SL1, a connecting path of 10 mm will be formed, so the first filling insulation material GW1 must be formed with a length of at least 90 mm so as to block the connecting path.

[0199] Furthermore, the first filler insulating material GW1 of this embodiment may be attached by using adhesive members 10 to both side surfaces of the connecting insulating wall 3a that face the side surfaces of the fixed insulating wall 3b, as shown in FIG.

[0200] Conventionally, the connecting insulation wall 3a is provided between the adjacent fixed insulation walls 3b, and then the first filling insulation material GW1 is inserted using a jig, but in this embodiment, the connecting insulation wall 3a with the first filling insulation material GW1 attached to both sides can be directly inserted between the adjacent fixed insulation walls 3b, reducing the installation man-hours. At this time, the first filling insulation material GW1 attached to the fixed insulation wall 3b maintains a compressed state (reduced volume) before the connecting insulation wall 3a is inserted between the adjacent fixed insulation walls 3b, and becomes uncompressed (increased volume) after installation, so that the first slit SL1 can be completely blocked.

[0201] As described above, the first filling insulation material GW1 in this embodiment is partially filled into the first slit SL1, but it goes without saying that it may be formed in a variety of ways, such as being identical to or similar to the first filling insulation material GW1 of the fourth embodiment described with reference to Figures 33 and 35, and then attached to both side surfaces of the connecting insulation wall 3a with adhesive material 10, and the connecting insulation wall 3a may be inserted between adjacent fixed insulation walls 3b.

[0202] Below, with reference to Figures 43 to 47, the convection paths and resulting temperature differences that change depending on the structure of the slits formed in the connecting insulation wall 3a and the fixed insulation wall 3b in the liquefied gas storage tank 1 according to this embodiment and the liquefied gas storage tank 1' according to the comparative example and the application or non-application of filling insulation material to fill the slits will be comparatively explained.

[0203] Figure 43(a) and Figure 45 show the liquefied gas storage tank 1 according to this embodiment, and the connecting insulating wall 3a and the fixed insulating wall 3b are the same as those described above. The right-angle corner structure and the obtuse-angle corner structure shown in Figures 25 and 26 are applied, but are not limited thereto, and other right-angle corner structures and obtuse-angle corner structures may be applied.

[0204] (b) of Figure 43 shows a liquefied gas storage tank 1' according to a comparative example, which differs from the liquefied gas storage tank 1 according to this embodiment in that the first slit SL1' has the same depth but is not filled with the first filling insulation material GW1, and the second slit SL2' is formed to a depth similar to the thickness of the fixed insulation wall 3b, and other configurations can be the same or similar.

[0205] FIG. 44(a) shows the first, second and third convection paths CP1, CP2 and CP3 in the liquefied gas storage tank 1 according to this embodiment.

[0206] The first convection path CP1 is a path corresponding to the first slit SL1, which is a gap formed between the connecting insulation wall 3a and the fixed insulation wall 3b, and it can be seen that a convection blocking path CP1' is formed by the first filling insulation material GW1 above the first slit SL1, so that a path is formed only in the space below the first slit SL1.

[0207] The second convection path CP2 is a path corresponding to the second slit SL2 which is formed at a depth corresponding to approximately half the thickness of the fixed insulation wall 3b, and it can be seen that the path is formed in the space portion of the second slit SL2, but is blocked by the portion of the first filling insulation material GW1 filled in the first slit SL1.

[0208] The third convection path CP3 is a path corresponding to the third slit SL3 which is formed at a depth corresponding to approximately half the thickness of the connecting insulation wall 3a, and it can be seen that the path is formed in the space portion of the third slit SL3, but is blocked by the portion of the first filling insulation material GW1 filled in the first slit SL1.

[0209] FIG. 44(b) shows the fourth, fifth and sixth convection paths CP4, CP5 and CP6 in a liquefied gas storage tank 1' according to a comparative example.

[0210] The fourth convection path CP4 is a path corresponding to the first slit SL1', which is a gap formed between the connecting insulation wall 3a and the fixed insulation wall 3b. Unlike this embodiment, the first slit SL1' is not filled with filling insulation material, so that a path is formed in the entire space of the first slit SL1'.

[0211] The fifth convection path CP5 is a path corresponding to the second slit SL2' formed at a depth similar to the thickness of the fixed insulation wall 3b, and it can be seen that the fifth convection path CP5 formed in the spatial portion of the second slit SL2' is connected to the fourth convection path CP4 formed in the spatial portion of the first slit SL1'.

[0212] The sixth convection path CP6 is a path corresponding to a third slit (not shown) formed with a depth similar to the thickness of the connecting insulation wall 3a, and it can be seen that the sixth convection path CP6 formed in the space portion of the third slit is connected to the fourth convection path CP4 and the fifth convection path CP5.

[0213] As described above, in the liquefied gas storage tank 1 of the present embodiment, the first, second, and third convection paths CP1, CP2, and CP3 are not continuous with each other, and the convection area is reduced. In the liquefied gas storage tank 1' of the comparative example, the fourth, fifth, and sixth convection paths CP4, CP5, and CP6 are continuous, and the convection area is increased.

[0214] Also, as shown in Figure 44 (b), in the liquefied gas storage tank 1' of the comparative example, the fourth, fifth and sixth convection paths CP4, CP5 and CP6 each form a convection space from the primary barrier 2 to the secondary barrier 4, so that the temperature at the primary barrier 2 directly affects the secondary barrier 4, and the temperature drops sharply at the secondary barrier 4. On the other hand, in the liquefied gas storage tank 1 of the present embodiment, the first, second and third convection paths CP1, CP2 and CP3 each can prevent the temperature at the primary barrier 2 from being conducted to the secondary barrier 4 by the first filling insulation material GW1, so that the temperature drop at the secondary barrier 4 of the liquefied gas storage tank 1 of the present embodiment is smaller than that of the liquefied gas storage tank 1' of the comparative example.

[0215] Due to such a difference in the convection path, a temperature difference also occurs in the secondary barrier 4 of the liquefied gas storage tank 1 of this embodiment and the liquefied gas storage tank 1' of the comparative example.

[0216] As shown in FIGS. 45 and 46, when the unit elements are arranged adjacent to each other, a temperature sensor TL is attached in the space between adjacent secondary insulation walls 5 so as to be close to the secondary insulation wall 4 .

[0217] When the temperature of the primary barrier 2 was -196°C and the temperature of the hull 7 was 10°C, the temperature was measured by the temperature sensor TL, and it was -79.3°C in the liquefied gas storage tank 1 of this embodiment and -100.9°C in the liquefied gas storage tank 1' of the comparative example. It can be seen that such a result is due to the fact that the convection path of the liquefied gas storage tank 1 of this embodiment is not continuous compared to the liquefied gas storage tank 1' of the comparative example, as described above, and the convection area is reduced.

[0218] Figure 47 is a graph comparing the temperature of the secondary barrier 4 at the bottom of the first slits SL1, SL1' when the first slit SL1 in the liquefied gas storage tank 1 of this embodiment is filled with first filling insulation material GW1 and when the first slit SL1' in the liquefied gas storage tank 1' of the comparative example is not filled with filling insulation material.

[0219] When the temperature of the primary barrier 2 was -196 degrees, the temperature of the hull 7 was 10 degrees, and the height of the first slits SL1, SL1' was 0.2 mm, the temperature of the secondary barrier 4 at the bottom of the first slit SL1 in this embodiment filled with first filling insulation GW1 was approximately -90 degrees (graph A), and the temperature of the secondary barrier 4 at the bottom of the first slit SL1' in the comparative example not filled with filling insulation was approximately -150 degrees (graph B).

[0220] This shows that the temperature drop in the secondary barrier 4 of the liquefied gas storage tank 1 of this embodiment is smaller (thermal convection prevention) than that of the liquefied gas storage tank 1' of the comparative example.

[0221] Figure 48 is a partial cross-sectional view for explaining a liquefied gas storage tank according to the sixth embodiment of the present invention, Figure 49 is a cross-sectional view of a connected insulation wall cut along line A-A' in Figure 48, Figure 50 is a cross-sectional view of a unit element formed by stacking fixed insulation walls constituting a secondary insulation wall, a secondary barrier and a primary insulation wall cut along line B-B' in Figure 48, and Figure 51 is an enlarged view showing a state in which filling insulation material has been filled into the first slit, which is the gap between the connected insulation wall and the fixed insulation wall constituting the primary insulation wall.

[0222] As shown in Figures 48 to 51, the liquefied gas storage tank 1 according to the sixth embodiment of the present invention may be configured to include a primary barrier 2 that comes into contact with liquefied gas inside, a primary insulation wall 3 that is provided outside the primary barrier 2 and consists of a connecting insulation wall 3a and a fixed insulation wall 3b, a secondary barrier 4 that is provided outside the primary insulation wall 3, and a secondary insulation wall 5 that is disposed outside the secondary barrier 4 and fixed to the hull 7. Compared to the above-mentioned fifth embodiment, the step portions ST1 and ST2 formed on the respective sides of the connecting insulation wall 3a and the fixed insulation wall 3b are different, and the other configurations are the same or similar, so the following will focus on the different parts to avoid redundant explanations.

[0223] The primary insulation wall 3 and the secondary insulation wall 5 in this embodiment may have the same or similar thicknesses as described above.

[0224] The primary insulation wall 3 may be composed of a connecting insulation wall 3a and a fixed insulation wall 3b. In this case, the connecting insulation wall 3a may be inserted between adjacent fixed insulation walls 3b so as to seal the space formed between adjacent secondary insulation walls 5 when unit elements including the fixed insulation walls 3b are arranged adjacent to each other.

[0225] The connecting insulation wall 3a may be divided into an upper part and a lower part as shown in Figures 48 and 49, and the width of the upper part in the front, rear, left and right directions may be narrower than the width of the lower part in the front, rear, left and right directions, so that a positive-shaped first step portion ST1 may be formed on the front, rear, left and right sides of the connecting insulation wall 3a.

[0226] The upper and lower parts of the connecting insulation wall 3a may be divided based on a position about halfway through the thickness of the connecting insulation wall 3a, but are not limited thereto, and may be determined according to the depth of the third slit SL3 formed at a depth similar to the thickness of the connecting insulation wall 3a, which will be understood later. Here, at least one third slit SL3 is formed in the longitudinal direction of the connecting insulation wall 3a, and may be located on the same line as the second slit SL2 formed in the longitudinal direction when the connecting insulation wall 3a is inserted between the fixed insulation walls 3b.

[0227] Furthermore, the connecting heat insulating wall 3a may have a negative chamfer CH formed at the corner of the bottom surface as shown in Figs.

[0228] The chamfer CH serves to facilitate insertion when the connecting insulating wall 3a is installed between the adjacent fixed insulating walls 3b.

[0229] The fixed insulation wall 3b may be divided into an upper part and a lower part as shown in Figures 48 and 50, and the width of the upper part in the front, rear, left and right directions may be narrower than the width of the lower part in the front, rear, left and right directions, so that a positive-shaped second step portion ST2 may be formed on the front, rear, left and right sides of the fixed insulation wall 3b.

[0230] The upper and lower parts of the fixed insulation wall 3b may be divided based on a position that is approximately half the thickness of the fixed insulation wall 3b, but is not limited to this and may be determined according to the depth of the second slit SL2 that is formed at a depth similar to the thickness of the fixed insulation wall 3b, which will be understood later.

[0231] In the above, the first step portion ST1 and the second step portion ST2 may be of the same or similar shape, and when the connecting insulating wall 3a is inserted between adjacent fixed insulating walls 3b, they face each other to define a space, and a first slit SL1 is formed between the connecting insulating wall 3a and the fixed insulating wall 3b, into which the first filling insulating material GW1 is filled.

[0232] That is, the first step portion PS1 is formed by dividing the connecting insulating wall 3a into an upper part and a lower part, and the second step portion PS2 is formed by dividing the fixed insulating wall 3b into an upper part and a lower part, and the front, rear, left and right width of the upper part is narrower than the front, rear, left and right width of the lower part. In this case, the first filling insulating material GW1 can be filled in the first slit SL1, which is a space between the upper part of the connecting insulating wall 3a and the upper part of the fixed insulating wall 3b, by arranging the lower part of the connecting insulating wall 3a and the lower part of the fixed insulating wall 3b so that they are adjacent to each other. The first filling insulating material GW1 filled in the first slit SL1 may be formed to have a (+) tolerance so that the space can be completely sealed when filled in the space of the first slit SL1, and therefore, even if the connecting insulating wall 3a and the fixed insulating wall 3b contract and expand, no thermal convection path is generated in the first slit SL1.

[0233] For example, in order to insert the first filling insulation material GW1 with a thickness of 10 mm into the first slit SL1, the width of the first slit SL1 must be at least about 6 mm in consideration of the compression state of the first filling insulation material GW1, so in this embodiment, the width between the side of the lower part of the connecting insulation wall 3a and the side of the lower part of the fixed insulation wall 3b is set to 2 mm (generally the distance between the connecting insulation wall and the fixed insulation wall), the width of the first step part ST1 provided on the connecting insulation wall 3a is formed to be 2 mm, and the width of the second step part ST2 provided on the fixed insulation wall 3b is formed to be 2 mm. Since the thickness of the first filling insulation material GW1 filling the first slit SL1 can be changed, it goes without saying that the widths of the first step part ST1 and the second step part ST2 in this embodiment can also be changed.

[0234] In this embodiment, the depth of the first step portion ST1 and the second step portion ST2 forming the first slit SL1 is not particularly limited when the second slit SL2 or the third slit SL3, which is formed at a depth corresponding to approximately half the thickness of the fixed insulation wall 3b or the connecting insulation wall 3a, is not formed, but when the second slit SL2 or the third slit SL3 is formed, it needs to be limited in order to prevent thermal convection.

[0235] That is, as explained in the fifth embodiment, considering that in order to prevent thermal convection through the slits, the first filling insulation material GW1 filled in the first slit SL1 must be formed to be at least longer than the depth of the second slit SL2 or the third slit SL3, the depth of the first slit SL1 into which the first filling insulation material GW1 in this embodiment is filled must be formed to be deeper than the depths of the second slit SL2 and the third slit SL3.

[0236] For example, if the depth of the second slit SL2 and the third slit SL3, which are not filled with filling insulation material, is 90 mm, the depth of the first slit SL1, which is filled with the first filling insulation material GW1, must be formed to a depth of at least 90 mm, for example, a depth of 105 mm.

[0237] Figure 52 is an oblique view for explaining a liquefied gas storage tank according to the seventh embodiment of the present invention, Figure 53 (a) to (c) are figures showing the plan, side and cross-section of a unit element in which fixed insulating walls that constitute the secondary insulating wall, secondary barrier and primary insulating wall of Figure 52 are stacked, Figure 54 (a) to (c) are figures showing the plan, side and cross-section of a connected insulating wall that constitutes the primary insulating wall of Figure 52, Figure 55 (a) to (c) are figures showing the plan, side and cross-section of a connected insulating wall according to another embodiment that constitutes the primary insulating wall of Figure 52, Figure 56 is a rear oblique view of a connected insulating wall according to yet another embodiment that constitutes the primary insulating wall of Figure 52, Figure 57 is a figure showing a cross-section of a portion where the fixed insulating walls and connected insulating walls that constitute the primary insulating wall are alternately connected, and Figure 58 is a figure showing a cross-section of a portion where multiple connected insulating walls that constitute the primary insulating wall are continuously connected.

[0238] In the above, Figure 53 (c) is a cross-sectional view of the connected insulated wall cut along line A-A' in Figure 53 (a), Figure 54 (c) is a cross-sectional view of the connected insulated wall cut along line B-B' in Figure 54 (a), and Figure 55 (c) is a cross-sectional view of the connected insulated wall cut along line C-C' in Figure 55 (a).

[0239] As shown in Figures 52 to 58, the liquefied gas storage tank 1 according to the seventh embodiment of the present invention may include a primary barrier that comes into contact with liquefied gas inside, a primary insulation wall 3 that is provided outside the primary barrier and consists of a connecting insulation wall 3a and a fixed insulation wall 3b, a secondary barrier 4 that is provided outside the primary insulation wall 3, and a secondary insulation wall 5 that is disposed outside the secondary barrier 4 and fixed to the hull 7.Compared to the above-mentioned fifth embodiment, it differs in that step portions PS1, PS2, PS3, PS4 are formed on each side of the connecting insulation wall 3a and the fixed insulation wall 3b, and that the step portions PS1, PS2, PS3, PS4 are finished with insulation pads IP1, IP2.Since the other configurations are the same or similar, the following description will focus on the different parts to avoid redundant explanations.

[0240] The primary insulation wall 3 and the secondary insulation wall 5 in this embodiment may have the same or similar thicknesses as described above.

[0241] The primary insulation wall 3 may be composed of a connecting insulation wall 3a and a fixed insulation wall 3b, and in this case, the connecting insulation wall 3a may be inserted between adjacent fixed insulation walls 3b so as to seal a space formed between adjacent secondary insulation walls 5 when unit elements including the fixed insulation walls 3b are arranged adjacent to each other. Hereinafter, the front, rear, left and right sides of the fixed insulation wall 3b are defined as sides connected to the front and rear sides of the connecting insulation wall 3a, and the left and right sides of the connecting insulation wall 3a are defined as sides connected to the left and right sides of another adjacent connecting insulation wall 3a.

[0242] The fixed insulating wall 3b may be divided into an upper part and a lower part as shown in Fig. 52 and Fig. 53(a) to (c). The upper part and the lower part of the fixed insulating wall 3b may be divided based on a position about halfway through the thickness of the fixed insulating wall 3b, but are not limited to this.

[0243] The fixed insulating wall 3b may have a front, rear, left and right width at its upper portion narrower than its lower portion, so that a positive-shaped first step portion PS1 may be formed on the front, rear, left and right sides.

[0244] The first step portion PS1 can overlap with the front and rear side surfaces of the second step portion PS2, the third step portion PS3 or the fourth step portion PS4 formed in the connecting insulating wall 3a (described later) on the front, rear, left and right sides of the fixed insulating wall 3b to form a first slit SL1 as shown in Fig. 57. A first insulating pad IP1 may be bonded onto the first step portion PS1 of the fixed insulating wall 3b, and the first insulating pad IP1 will be described later.

[0245] The connecting insulating wall 3a can be divided into an upper part and a lower part as shown in Fig. 52, Fig. 54(a)-(c), and Fig. 56(a)-(c). The upper part and the lower part of the connecting insulating wall 3a may be divided based on a position about halfway through the thickness of the connecting insulating wall 3a, but are not limited to this.

[0246] The connecting insulation wall 3a is inserted into the linear space formed between two adjacent fixed insulation walls 3b, and as shown in (a) to (c) of Figure 54, the front-to-back width of the upper part is formed wider than the front-to-back width of the lower part, and the left-to-right width of the upper part is formed narrower than the left-to-right width of the lower part, so that second step portions PS2 can be formed on the front-to-back, left-to-right and right-to-left sides.

[0247] The second step portion PS2 may have a positive shape on the left and right side surfaces of the connecting insulation wall 3a as shown in (b) of Figure 54, or may have a negative shape on the front and back side surfaces of the connecting insulation wall 3a as shown in (c) of Figure 54.

[0248] When a plurality of other connecting insulating walls are continuously inserted into the linear space between two adjacent fixed insulating walls 3b, the second step portion PS2 having a positive shape on the left and right side surfaces of the connecting insulating wall 3a overlaps with the step portion having a negative shape on the side surface of the other connecting insulating wall connected adjacently, to form a fourth slit SL4 as shown in FIG. 58. A second insulating pad IP2 may be formed on the second step portion PS2 having a positive shape on the left and right side surfaces of the connecting insulating wall 3a, and the second insulating pad IP2 will be described later. Here, the other connecting insulating wall may be a connecting insulating wall 3a having a negative-shaped third step portion PS3 on one side surface as shown in FIG. 55(b), or a connecting insulating wall 3a having a negative-shaped fourth step portion PS4 on the recessed portions of the front, rear, left, and right sides as shown in FIG. 56.

[0249] When the second step portion PS2, which has a negative shape on the front and rear side surfaces of the connecting insulation wall 3a, is inserted between two adjacent fixed insulation walls 3b, it overlaps with the first step portion PS1, which has a positive shape on the front, rear, left and right side surfaces of the fixed insulation wall 3b, to form a first slit SL1 as shown in Figure 57.

[0250] In addition, the connecting insulation wall 3a is inserted into a linear space formed between two adjacent fixed insulation walls 3b, and as shown in (a) to (c) of Figure 55, the front-to-back width of the upper part is formed wider than the front-to-back width of the lower part, and the left-to-right width of the upper part is formed to be the same as the left-to-right width of the lower part, but is formed to be offset on the left and right sides, so that a third step portion PS3 can be formed on the front-to-back, left and right sides.

[0251] As shown in (b) of Figure 55, the third step portion PS3 has one side that has a negative shape and the other side that has a positive shape of the left and right sides of the connecting insulation wall 3a, and can form a negative shape on the front and rear sides of the connecting insulation wall 3a as shown in (c) of Figure 54.

[0252] When a plurality of other connected insulating walls are continuously inserted into a linear space between two adjacent fixed insulating walls 3b, the negative-shaped third step portion PS3 on the left and right side surfaces of the connected insulating wall 3a can overlap with the positive-shaped step portion on the side surface of the other connected adjacent connected insulating wall to form a fourth slit SL4 as shown in Fig. 58. Here, the other connected insulating wall may be a connected insulating wall 3a having a positive-shaped second step portion PS2 on the left and right side surfaces as shown in Fig. 54(b), or a connected insulating wall 3a having a positive-shaped third step portion PS3 on the other side surface as shown in Fig. 55(b).

[0253] When a plurality of other connecting insulation walls are continuously inserted into the linear space between two adjacent fixed insulation walls 3b, the third step portion PS3 having a positive shape among the left and right side surfaces of the connecting insulation wall 3a overlaps with the step portion having a negative shape formed on the side surface of the other connecting insulation wall connected adjacently, to form a fourth slit SL4 as shown in FIG. 58. A second insulation pad IP2 may be formed on the third step portion PS3 having a positive shape among the left and right side surfaces of the connecting insulation wall 3a, and the second insulation pad IP2 will be described later. Here, the other connecting insulation wall may be a connecting insulation wall 3a having a negative-shaped third step portion PS3 on one side surface as shown in FIG. 55(b), or a connecting insulation wall 3a having a negative-shaped fourth step portion PS4 on the recessed portions of the front, rear, left, and right sides as shown in FIG. 56.

[0254] In addition, the connecting insulation wall 3a is inserted into the intersecting space formed between four adjacent fixed insulation walls 3b, and as shown in Figure 56, the front-to-back, left-to-right width of the upper part is made wider than the front-to-back, left-to-right width of the lower part, so that a fourth step portion PS4 may be formed on the front-to-back, left-to-right side surfaces.

[0255] The fourth step portion PS4 may have a negative shape at the protruding portions of the front, rear, left and right sides of the connecting insulating wall 3a and at the recessed portions of the front, rear, left and right sides of the connecting insulating wall 3a.

[0256] When the negative-shaped fourth step portion PS4 on the protruding portions of the front, rear, left and right side surfaces of the connecting insulating wall 3a is inserted into the intersecting space portion formed between four adjacent fixed insulating walls 3b, it overlaps with the positive-shaped step portion formed on the side surface of another connecting insulating wall provided in the linear space portion formed between two adjacent fixed insulating walls 3b to form a fourth slit SL4 as shown in Fig. 58. Here, the other connecting insulating wall may be a connecting insulating wall 3a having a positive-shaped second step portion PS2 on the left and right side surfaces as shown in Fig. 54(b), or may be a connecting insulating wall 3a having a positive-shaped third step portion PS3 on the other side surface as shown in Fig. 55(b).

[0257] The fourth step portion PS4, which has a negative shape in the recesses on the front, back, left and right sides of the connecting insulation wall 3a, when inserted into the intersection-shaped space formed between four adjacent fixed insulation walls 3b, overlaps with the first step portion PS1, which has a positive shape in the front, back, left and right sides of each of the four adjacent fixed insulation walls 3b, to form a first slit SL1 as shown in Figure 57.

[0258] The first slit SL1 of the present embodiment described above has a curved shape, and is a space formed between the fixed insulating wall 3b and the connecting insulating wall 3a by overlapping the first negative step formed on the side of the connecting insulating wall 3a on the first positive step formed on the side of the fixed insulating wall 3b when the connecting insulating wall 3a is inserted between the adjacent fixed insulating walls 3b, as shown in Fig. 57. Here, the first positive step formed on the side of the fixed insulating wall 3b may be the positive shaped first step PS1 formed on the front, rear, left and right side of the fixed insulating wall 3b, and the first negative step formed on the side of the connecting insulating wall 3a may be the second step PS2 or the third step PS3 formed on the front and rear side of the connecting insulating wall 3a, or the fourth step PS4 formed in the recess of the front, rear, left and right side of the connecting insulating wall 3a.

[0259] Although the bent first slits SL1 reduce the thermal convection phenomenon compared to a straight slit, the thermal convection phenomenon may occur due to the space of the first slits SL1.

[0260] Therefore, in this embodiment, in order to prevent the thermal convection phenomenon, a first insulation pad IP1 is formed and adhered on the first step portion PS1 formed in a positive shape on the front, rear, left and right side surfaces of the fixed insulation wall 3b.

[0261] The first insulation pad IP1 may be adhered to a first positive step portion formed on the side of the fixed insulation wall 3b facing the connecting insulation wall 3a, and when the connecting insulation wall 3a is provided between adjacent fixed insulation walls 3b, the first insulation pad IP1 can be pressed against the first negative step portion formed on the side of the connecting insulation wall 3a facing the fixed insulation wall 3b without being adhered to the connecting insulation wall 3a, thereby blocking the space portion of the first slit SL1.

[0262] The first insulating pad IP1 may be made of an insulating material such as glass wool, but is not limited thereto.

[0263] In addition, as shown in Fig. 58, when a plurality of connecting insulation walls 3a are provided in succession, the fourth slit SL4 of this embodiment is a space formed between adjacent connecting insulation walls 3a by overlapping a second negative step portion formed on a side surface of one of the adjacent connecting insulation walls 3a on a second positive step portion formed on a side surface of the other connecting insulation wall 3a, and has a curved shape. Here, the second positive step portion formed on the side surface of one connecting insulation wall 3a may be the second step portion PS2 or the third step portion PS3 formed on at least one of the left and right sides of the connecting insulation wall 3a, and the second negative step portion formed on the side surface of the other connecting insulation wall 3a may be the third step portion PS3 formed on at least one of the left and right sides of the connecting insulation wall 3a, or the fourth step portion PS4 formed on the protruding portion of the front, rear, left and right sides of the connecting insulation wall 3a.

[0264] Although the bent fourth slits SL4 reduce the thermal convection phenomenon compared to a straight slit, the thermal convection phenomenon may occur due to the space of the fourth slits SL4.

[0265] Therefore, in this embodiment, in order to prevent the thermal convection phenomenon, a second insulation pad IP2 is adhesively formed on the second positive step portion of the second positive step portion or the second negative step portion formed on the left and right side surfaces of adjacent connecting insulation walls 3a.

[0266] The second insulation pad IP2 may be adhered onto a second positive step portion formed on a side of any one of the adjacent connecting insulation walls 3a, and when the adjacent connecting insulation walls 3a are continuously installed between adjacent fixed insulation walls 3b, it can be pressed against the second negative step portion formed on the side of the other of the adjacent connecting insulation walls 3a to block the space portion of the fourth slit SL4.

[0267] The second insulating pad IP2 may be made of an insulating material such as glass wool, but is not limited thereto.

[0268] In the above embodiment, the widths of the first, second, third and fourth step portions PS1, PS2, PS3 and PS4 may be the same or similar, for example, 30 mm, but are not limited thereto.

[0269] Furthermore, the widths of the first and fourth slits SL1, SL4 may be the same or similar, for example, the width between the upper side of the connecting insulation wall 3a and the upper side of the fixed insulation wall 3b may be 2 mm, and the width between the lower side of the connecting insulation wall 3a and the lower side of the fixed insulation wall 3b may be 2 mm, but is not limited to this.

[0270] Furthermore, the thickness and width of each of the first and second insulating pads IP1 and IP2 may be the same or similar, for example, the thickness may be 10 mm and the width may be 30 mm, but is not limited thereto.

[0271] In this manner, in this embodiment, by configuring the thickness of the primary insulation wall 3, 3a to be the same or similar to that of the secondary insulation wall 5 throughout the entire thickness of the primary insulation wall 3 and the secondary insulation wall 5, including the connecting insulation wall 3a, not only can the mechanical strength of the secondary insulation wall 5 be maintained at a constant level, but the low temperature burden and sloshing burden of the secondary insulation wall 4 can be reduced, thereby preventing damage to the secondary insulation wall 4.

[0272] In addition, in this embodiment, by providing an auxiliary insulation plate 33 on the underside of the connecting insulation wall 3a provided in the space between adjacent primary insulation walls 3 that constitute a unit element, the insulation performance in the connecting portion of adjacent secondary insulation walls 5 that constitute a unit element can be further improved.

[0273] In addition, in this embodiment, the structure of the secondary barrier 4 is improved to improve the heat insulating performance.

[0274] In addition, in this embodiment, by applying a non-adhesive elastic insulation material between the secondary insulation wall 5 and the hull 7 as a leveling member 8 for the secondary insulation wall 5, it is possible to level the deformed parts of the hull 7 without using conventional mastic and leveling wedges, thereby improving the insulation performance of the tank.

[0275] In addition, in this embodiment, adjacent unit panels of the secondary insulation wall 5 are fixed using a cleat structure with a protrusion 91 that protrudes outward from the lower side of the unit panel of the secondary insulation wall 5 and a stud bolt 92 that is fixed to the hull 7, thereby reducing labor costs compared to a method of drilling holes in the secondary insulation wall 5 and fixing the unit panels with stud bolts.

[0276] In addition, in this embodiment, the slits formed on the secondary barrier 4 to accommodate contraction and expansion of the primary insulation wall 3 are optimized, and the slit structure is improved to minimize the convection phenomenon caused by the slits and heat penetration into the secondary barrier 4. The insulating filling material filling the slits is diversified, thereby improving the stability of the primary insulation wall 3 due to the formation of the slits and reducing the low temperature burden on the secondary barrier 4, thereby preventing damage to the primary insulation wall 3 and the secondary barrier 4.

[0277] The present invention is not limited to the embodiments described above, and may include combinations of the above embodiments or combinations of at least one of the above embodiments with known techniques as further embodiments. For example, the embodiment of Figs. 28-29 may be combined with the embodiment of Figs. 4-27. Also, the embodiment of Figs. 30-31 may be combined with the insulation system of Figs. 1 and 2 or the insulation system of Figs. 28 and 29. Furthermore, the embodiment of Figs. 32-58 may be combined with the embodiment of Figs. 1-31.

[0278] The present invention has been described in detail above through specific examples. However, these are for the purpose of specifically explaining the present invention, and the present invention is not limited thereto. It is clear that modifications and improvements can be made by those having ordinary knowledge in the art within the technical spirit of the present invention.

[0279] Any simple variations or modifications of the present invention fall within the scope of the present invention, and the specific scope of protection of the present invention will be made clear by the appended claims. [Explanation of symbols]

[0280] 1, 1' Liquefied gas storage tank 2. Primary Barrier 21 Plane part 22 Curved part 23 Boundary 3 Primary insulation wall 3b Fixed insulated wall 31 Primary Plywood 32 Primary insulation material 3a Interlocking insulated walls 31a Interlocking Plywood 32a Interlocking insulation 33 Auxiliary insulation board 4 Secondary Barrier 41 Main Wall 42 Auxiliary Barrier GAC Glass-aramid cloth AF Aluminum foil GC Glass Cloth BC Basalt Cross 5 Secondary insulation wall 51 Secondary insulation 52 Secondary Plywood 6. Mastic 7. Hull 8 Leveling material 9 Fixing member 91 Protrusion 92 Stud bolt 10 Adhesive material SL1, SL1' First slit SL2, SL2' Second slit SL3 3rd slit SL4 4th slit GW1 1st filling insulation material GW1-1 1st upper filling insulation material GW1-2 1st intermediate filling insulation material GW1-3 1st bottom filling insulation material GW2 Secondary filling insulation material GW2-1 2nd upper filling insulation material GW2-2 Second intermediate filling insulation material GW2-3 Second bottom filling insulation material CP1 First convection path CP1' convection blocking pathway CP2 Second convection path CP3 Third convection path CP4 4th convection path CP5 Convection Path No. 5 CP6 Convection Path No. 6 TL Temperature Sensor ST1 First step ST2 Second step CH Chamfer IP1 1st Insulation Pad IP2 2nd Insulation Pad PS1 First step PS2 2nd step PS3 3rd step PS4 4th step

Claims

1. A liquefied gas storage tank for storing a cryogenic material, comprising a primary barrier, a primary insulating wall, a secondary barrier, and a secondary insulating wall, The primary insulation wall is The secondary insulation wall, the secondary barrier, and the fixed insulation wall that is a part of the primary insulation wall are stacked to form unit elements, which are arranged adjacent to each other, and a connecting insulation wall is provided in a space between the adjacent fixed insulation walls, a first slit formed between the fixed insulating wall and the connecting insulating wall when the connecting insulating wall is inserted between adjacent fixed insulating walls; A plurality of second slits are formed in the longitudinal direction and the width direction of the fixed insulating wall; A first filling insulating material that fills the first slit, At least one third slit is formed in the longitudinal direction of the connecting insulation wall, and is positioned on the same line as the second slit formed in the longitudinal direction when the connecting insulation wall is inserted between the fixed insulation walls, The second slit and the third slit are The insulating wall is formed to a depth corresponding to about half the thickness of the fixed insulating wall and the connecting insulating wall, and no insulating material is filled inside. The first filling insulation material is The second slit and the third slit are formed to be at least longer than their respective depths, A liquefied gas storage tank, characterized in that a thermal convection path through the first slit, the second slit and the third slit is discontinuous.

2. The first filling insulation material is The first slit is completely filled, or The first slit is filled to a certain depth from the inlet so that a space is formed under the first slit, 2. The liquefied gas storage tank according to claim 1, wherein the first slit is filled with multiple layers so that a plurality of spaces are formed inside the first slit.

3. The first filling insulation material is When the first slit is filled with multiple layers so that a plurality of spaces are formed inside the first slit, A first upper filling insulation material formed on an upper portion of the first slit; a first intermediate insulating filler formed at a predetermined distance from the first upper insulating filler and at a center of the first slit; a first lower filling insulation material formed below the first slit at a predetermined distance from the first middle filling insulation material, Each of the first upper filling insulation material, the first middle filling insulation material, and the first lower filling insulation material is They may be made of the same or different insulating materials, 3. The liquefied gas storage tank according to claim 2, wherein the insulating material is glass wool, super lite, a soft foam material, or an aerogel blanket.

4. The first filling insulation material is Insert the connecting insulation wall between the adjacent fixed insulation walls, and then fill the first slit by an insertion method using a jig; The liquefied gas storage tank as described in claim 1, characterized in that the first slit is filled by inserting the connecting insulation wall between adjacent fixed insulation walls while the connecting insulation wall is attached to both sides of the connecting insulation wall opposite the sides of the fixed insulation wall using an adhesive material.

5. The second slit is When the insulating wall is formed to a depth similar to the thickness of the fixed insulating wall, a second insulating filler is filled inside the insulating wall, The second filling insulation material is The second slit is filled to a certain depth from the inlet so that a space is formed below the second slit, 2. The liquefied gas storage tank according to claim 1, wherein the second slit is filled with multiple layers so that a plurality of spaces are formed inside the second slit.

6. The second filling insulation material is When the second slit is filled with multiple layers so that a plurality of spaces are formed inside the second slit, A second upper filling insulation material formed on an upper portion of the second slit; a second intermediate insulating filler formed at a predetermined distance from the second upper insulating filler and intermediate the second slit; a second lower filling insulation material formed below the second slit at a predetermined distance from the second middle filling insulation material, Each of the second upper filling insulation material, the second middle filling insulation material, and the second lower filling insulation material is They may be made of the same or different insulating materials, 6. The liquefied gas storage tank according to claim 5, wherein the insulating material is glass wool, super lite, a soft foam material, or an aerogel blanket.

7. The primary insulation wall and the secondary insulation wall are 2. The liquefied gas storage tank of claim 1, having the same or similar thickness.

8. A liquefied gas storage tank for storing a cryogenic material, comprising a primary barrier, a primary insulating wall, a secondary barrier, and a secondary insulating wall, The primary insulation wall is The secondary insulation wall, the secondary barrier, and the fixed insulation wall that is a part of the primary insulation wall are stacked to form unit elements, which are arranged adjacent to each other, and a connecting insulation wall is provided in a space between the adjacent fixed insulation walls, A first step portion formed on the front, rear, left and right side surfaces of the connecting insulation wall; A second step portion formed on the front, rear, left and right side surfaces of the fixed insulating wall; a first slit formed by the first step portion and the second step portion between the connecting insulating wall and the fixed insulating wall when the connecting insulating wall is inserted between the adjacent fixed insulating walls; A first filling insulating material that fills the first slit, A plurality of second slits are formed in the longitudinal direction and the width direction of the fixed insulating wall; At least one third slit is formed in the longitudinal direction of the connecting insulation wall, and is positioned on the same line as the second slit formed in the longitudinal direction when the connecting insulation wall is inserted between the fixed insulation walls. The second slit and the third slit are The insulating wall is formed to a depth corresponding to about half the thickness of the fixed insulating wall and the connecting insulating wall, and no insulating material is filled inside. The first slit into which the first filling insulation material is filled is The second slit and the third slit are formed to be at least longer than their respective depths, A liquefied gas storage tank, characterized in that a thermal convection path through the first slit, the second slit and the third slit is discontinuous.

9. The first step portion is The width of the upper part of the connecting insulation wall is narrower than the width of the lower part of the connecting insulation wall. The second step portion is The fixed insulating wall is formed by forming the width of the upper part of the fixed insulating wall in the front-rear and left-right directions narrower than the width of the lower part of the fixed insulating wall in the front-rear and left-right directions, The first filling insulation material is The liquefied gas storage tank according to claim 8, wherein the lower part of the connecting insulation wall and the lower part of the fixed insulation wall are adjacent to each other, and the first slit, which is a space between the upper part of the connecting insulation wall and the upper part of the fixed insulation wall, is filled with the gas.

10. The primary insulation wall and the secondary insulation wall are 9. A liquefied gas storage tank as claimed in claim 8, characterized in that it has the same or similar thickness.

Images