Method for manufacturing non-adhesive insulation system for liquefied gas storage tank, non-adhesive insulation system for liquefied gas storage tank manufactured thereby, and ship including same

Abstract

The present invention relates to a method for manufacturing a non-adhesive insulation system for a liquefied gas storage tank, the method comprising the steps of: installing first separation members to fit same onto studs disposed on an outer wall of a liquefied gas storage tank; installing second separation members in spaces between the studs; installing a sheet layer on the first separation members and the second separation members such that the sheet layer surrounds the outer wall to form a leakage path in the gap between the outer wall and the sheet layer; forming an insulation unit on the sheet layer; injecting gas into the leakage path; and checking, to detect a defect, whether the pressure in the leakage path is maintained at a reference pressure or higher. The step of forming an insulation unit includes the steps of: forming some insulation layers among a plurality of insulation layers; fastening fixing units to the studs; and forming the remaining insulation layers on the some insulation layers.

Description

Method for manufacturing a non-adhesive insulation system for a liquefied gas storage tank, a non-adhesive insulation system for a liquefied gas storage tank manufactured thereby, and a ship including the same

[0001] The present invention relates to a method for manufacturing a non-adhesive insulation system for a liquefied gas storage tank, an insulation system manufactured thereby, and a ship including the same. More specifically, by separating the behavior of the outer wall of the storage tank and the behavior of the insulation part under cryogenic environments, the invention effectively suppresses the possibility of damage to the insulation part even with large deformation of the outer wall of the tank due to the enlargement of the storage tank, thereby enabling the storage and insulation of various cryogenic cargoes. Furthermore, by identifying and repairing defect points in the insulation structure in advance prior to hull installation and sea trials, the invention enables efficient performance of drying operations and inert gas replacement operations after the installation of the storage tank.

[0002] Due to the recent tightening of environmental pollution regulations for ships, interest in eco-friendly, high-efficiency liquefied gas fuels, such as Liquefied Natural Gas (LNG) or Liquefied Petroleum Gas (LPG), is increasing.

[0003] Liquefied natural gas is obtained by cooling and liquefying methane produced by refining natural gas extracted from gas fields, while liquefied petroleum gas is a fuel made by compressing gases composed mainly of propane and butane, which are found along with petroleum in oil fields, into a liquid at room temperature.

[0004] In particular, liquefied natural gas (hereinafter referred to as 'LNG') is obtained by cooling natural gas to a cryogenic temperature (about -163°C), and since its volume is reduced to approximately 1 / 600 of that of natural gas in a gaseous state, it is very suitable for long-distance transportation by sea.

[0005] Liquefied gas is transported in a gaseous state through onshore or offshore gas pipelines, or transported to distant consumption sites while stored in a liquid state on transport vessels.

[0006] Liquefied gas carriers that transport liquefied gas, such as LNG, to sail the seas and unload the liquefied gas at onshore destinations, or LNG RVs (Regasification Vessels) that transport LNG to sail the seas, arrive at onshore destinations, and then regasify the stored LNG to unload it in the form of natural gas, are equipped with liquefied gas storage tanks (commonly referred to as 'cargo tanks') capable of withstanding the cryogenic temperatures of LNG.

[0007] In addition, liquefied gas storage tanks installed on LNG carriers or LNG RVs are also included in offshore structures such as LNG FPSO (Floating, Production, Storage and Offloading), which is used to liquefy and store produced natural gas directly at sea and transfer the stored LNG to an LNG carrier when necessary, and LNG FSRU (Floating Storage and Regasification Unit), which stores LNG unloaded from an LNG carrier at sea and then vaporizes the LNG as needed to supply it to onshore demand centers.

[0008] These liquefied gas storage tanks can be classified into membrane type and independent type depending on whether the load of the cargo acts directly on the insulation material.

[0009] Membrane-type storage tanks are divided into No. 96 and Mark III types, and independent storage tanks are divided into Type A, Type B, and Type C according to the regulations of the International Maritime Organization (IMO). Among these, Type B independent storage tanks include spherical MOSS tanks and prismatic SPB tanks.

[0010] The membrane-type storage tank is directly connected to the structure of the hull and is not separated from the hull, and has a structure in which a primary barrier and a secondary barrier are laminated on the inner wall of the hull. As the membrane-type tank is directly connected to the hull, the load of the liquefied gas stored inside is not supported by the storage tank but is transferred to the hull.

[0011] In contrast, standalone storage tanks are manufactured to be mounted on the hull separately from the hull structure and feature a structure in which insulation surrounds the outer walls. Since standalone storage tanks are separated from the hull and supported by support structures installed inside the hull, the load of the liquefied gas stored inside acts directly on the tank.

[0012] Unlike membrane storage tanks, independent storage tanks do not have a complex barrier structure and are relatively advantageous in terms of structural stability against sloshing compared to membrane storage tanks. In addition, since insulation is provided on the outer wall of the storage tank, maintenance by workers becomes easier.

[0013] Meanwhile, since a leak of liquefied gas from the outer wall of such an independent storage tank can cause fatal damage to the hull, which is vulnerable to cryogenic temperatures, a leak path must be provided between the outer wall of the tank and the insulation so that the leaked liquefied gas can flow to a drip tray by gravity, and a partial secondary barrier structure is required to prevent the leaked liquefied gas from coming into contact with the hull and to safely collect or recover the leaked liquefied gas.

[0014] In conventional technology, an adhesive insulation method was applied to the insulation of storage tanks by directly spraying foam insulation onto the outer wall of the tank; however, since the outer wall and the insulation were completely bonded, it was difficult to form a leakage path in the event of a liquefied gas leak. Furthermore, due to the difference in the coefficient of thermal expansion between the material of the outer wall and the insulation, there is a very high possibility of shear cracks occurring at the interface between the tank and the insulation.

[0015] In order to overcome the disadvantages of such adhesive insulation methods, a non-adhesive insulation method is being attempted in which a sheet layer is installed that surrounds the outer wall of a tank body at a certain distance and a spacing member that supports it, and an insulation section is formed on the sheet layer.

[0016] The aforementioned technical configuration is provided as background technology to aid in understanding the present invention and does not constitute prior art widely known in the technical field to which the present invention belongs.

[0017] The above-described non-adhesive insulation method maintains the height of the gap space at a certain level by utilizing a spacing member and a sheet layer. However, as the spacing between studs provided on the outer wall of the storage tank has widened due to the recent increase in the size of liquefied gas storage tanks, the spacing between the spacing members installed on the studs has also widened. Consequently, wrinkles may occur in the sheet layer on the gap space that is not supported by the spacing member, which may lead to a problem where the insulation formed on the sheet layer is not sufficiently separated from the outer wall of the storage tank.

[0018] In addition, the outer wall of a tank storing cryogenic liquefied gas at high pressure can be deformed due to thermal shrinkage or internal pressure. Furthermore, as the storage tank becomes larger, the large movement of the outer wall can cause the gap between the outer wall and the insulation to fail to maintain a certain height, resulting in insufficient leakage paths or the movement of the outer wall being directly transmitted to the insulation, potentially causing damage to the insulation.

[0019] Meanwhile, generally, a standalone storage tank that has been manufactured is temporarily kept outdoors until it is loaded onto a hull after the insulation structure formation process is completed. In the insulation structure formation process, if the insulation structure is formed on the entire outer surface of the standalone storage tank, interference may occur at connection points, etc., when the standalone storage tank is loaded onto the hull. Therefore, considering this, a pending area is created where the formation of the insulation structure is partially withheld. During this temporary waiting period, rainwater flows in through the pending area and continuously accumulates in the upper and lower parallel sections and corners of the tank via leakage paths. Consequently, there is a problem in that a significant amount of time is required for drying and inert gas replacement work to prevent condensation before injecting cryogenic liquefied gas after loading onto the hull.

[0020] Furthermore, when forming a multi-layered insulation structure for standalone storage tanks using spray foam, inspecting the foam for defects on each layer individually would result in an excessively long timeframe for the formation process. Consequently, inspections are currently conducted only on the final surface after the entire insulation structure is completed. In this process, it is difficult to identify and address micro-defects or potential defects that may arise during the curing of the spray foam in advance. As a result, there is a problem where rainwater may infiltrate through micro-defects and potential defects in the insulation structure.

[0021] The present invention aims to provide a method for manufacturing a non-adhesive insulation system for a liquefied gas storage tank, an insulation system manufactured thereby, and a vessel including the same, which enables the storage and insulation of various cryogenic cargoes by separating the behavior of the outer wall of the storage tank and the behavior of the insulation section under cryogenic environments, thereby effectively suppressing the possibility of damage to the insulation section even with large deformation of the outer wall of the tank due to the enlargement of the storage tank, and by identifying and repairing defect points in the work hold area and / or insulation structure in advance after the completion of the insulation structure formation process and before installation on the hull, thereby allowing the drying and inert gas replacement operations to be performed quickly and effectively after installation on the hull.

[0022] To solve the above-mentioned problem, the present invention comprises the steps of: installing a first spacing member so as to be fitted into a stud provided on the outer wall of a liquefied gas storage tank; installing a second spacing member in the space between the studs provided on the outer wall of the liquefied gas storage tank; installing a sheet layer on the first spacing member and the second spacing member to surround the outer wall of the liquefied gas storage tank, thereby forming a leakage path in the space between the outer wall of the liquefied gas storage tank and the sheet layer; applying a spray foam insulation material on the sheet layer to form an insulation section including a plurality of insulation layers; injecting gas into the leakage path; and a defect verification step to check whether the pressure within the leakage path is maintained above a reference pressure; wherein the step of forming the insulation section comprises the step of forming some of the insulation layers among the plurality of insulation layers; and the step of fastening a fixing member to a stud provided on the outer wall of the liquefied gas storage tank. A method for manufacturing a non-adhesive insulation system for a liquefied gas storage tank is provided, comprising the step of forming a remaining insulation layer on a portion of the insulation layer.

[0023] In the above manufacturing method, the liquefied gas storage tank may be an independent storage tank.

[0024] In the above manufacturing method, the defect verification step may further include: a step of verifying a defect point of the insulation formed on the sheet layer when the pressure within the leakage path is not maintained above a reference pressure; and a step of repairing the verified defect point of the insulation.

[0025] In the above manufacturing method, the defect point of the insulation part may be identified by visual inspection or soapy water inspection.

[0026] In the above manufacturing method, the reference pressure of the defect verification step may be atmospheric pressure.

[0027] In the above manufacturing method, the gas injected into the leakage path may be a dry gas.

[0028] In the above manufacturing method, the first spacing member may be in the form of a strip that is integrally fitted onto two or more studs.

[0029] In the above manufacturing method, the first spacing member may be in the form of an annular strip surrounding the outer wall of the liquefied gas storage tank.

[0030] In the above manufacturing method, the second spacing member may be made of a porous elastic material.

[0031] In the above manufacturing method, the second spacing member may be in the form of a patch, a strip, or a combination thereof.

[0032] In the above manufacturing method, the fixing part may include a cushioning member surrounding the outer surface of the fixing part.

[0033] In the above manufacturing method, the buffer member may be made of a porous insulating material.

[0034] In addition, the present invention provides a non-adhesive insulation system for a liquefied gas storage tank manufactured by the above manufacturing method.

[0035] In addition, the present invention provides a vessel comprising a non-adhesive insulation system for the liquefied gas storage tank.

[0036] The present invention prevents wrinkles from forming in the sheet layer installed spaced apart from the storage tank by installing an additional spacing member in the space between the studs provided on the outer wall of the storage tank, and ensures that the insulation member always forms a space of at least a certain height from the outer wall of the storage tank even with large deformation of the outer wall of the storage tank, thereby sufficiently securing a leakage path for liquefied gas.

[0037] In addition, the present invention includes a cushioning member on the outer surface of a fixing member that fixes the insulation member to the outer wall of a storage tank, so that the movement of the fixing member due to deformation of the outer wall of the storage tank is absorbed through the cushioning member, thereby effectively suppressing the possibility of damage to the insulation member.

[0038] In addition, the present invention can secure excellent thermal insulation performance and structural stability of the insulation by injecting gas into a leakage path formed in the gap between the outer wall of the storage tank and the sheet layer surrounding the outer wall of the storage tank to pressurize it, and by checking whether the pressure within the leakage path is maintained above a reference pressure, thereby detecting in advance micro-defects that are difficult to identify by simple visual inspection and potential defects existing within the insulation part.

[0039] In addition, the present invention can prevent rainwater from entering and accumulating through defective areas on the insulation or work hold areas during the waiting period before the independent storage tank with an insulation structure is installed on the hull by checking for defects in the insulation structure and repairing them in advance, thereby saving time required for drying and inert gas replacement work after the storage tank is installed on the hull.

[0040] FIG. 1 is a schematic diagram illustrating a portion of the cross-section of a non-adhesive insulation system for a liquefied gas storage tank according to one embodiment of the present invention.

[0041] FIG. 2 is a cross-sectional view centered on the second spacing member of a non-adhesive insulation system for a liquefied gas storage tank according to one embodiment of the present invention, schematically illustrating (a) a case where no deformation occurs in the outer wall of the storage tank and (b) a case where deformation occurs.

[0042] FIG. 3 is a schematic plan view illustrating that a second spacing member in the form of a patch is installed on the outer wall of a liquefied gas storage tank in a non-adhesive insulation system for a liquefied gas storage tank according to one embodiment of the present invention.

[0043] FIG. 4 is a schematic plan view illustrating a strip-shaped second spacing member installed on the outer wall of a liquefied gas storage tank in a non-adhesive insulation system for a liquefied gas storage tank according to another embodiment of the present invention.

[0044] FIG. 5 is a cross-sectional view focusing on the fixed part and the buffer member of a non-adhesive insulation system of a liquefied gas storage tank according to one embodiment of the present invention, schematically illustrating the behavior of the fixed part when deformation occurs on the outer wall of the storage tank.

[0045] FIG. 6 is a cross-sectional view schematically illustrating the state in which a defect verification system is installed to check whether a defect exists in the insulation part of the present invention.

[0046] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0047] First, it should be noted that when adding reference numerals to the components of each drawing, the same components are to have the same numeral whenever possible, even if they are shown on different drawings.

[0048] In addition, in describing the present invention, if it is determined that a detailed description of related known components or functions may obscure the essence of the invention, such detailed description is omitted.

[0049] Preferred embodiments of the present invention will be described below, but the technical concept of the present invention is not limited thereto and can be modified and implemented in various ways by those skilled in the art.

[0050] In describing the present invention, liquefied gas may include all gaseous fuels generally stored in a liquefied state, such as LNG (Liquefied Natural Gas) at cryogenic temperatures (approximately -163°C), LPG (Liquefied Petroleum Gas), or liquefied ethylene gas, and the term liquefied gas may include not only liquefied gas in a liquid state but also vaporized liquefied gas.

[0051] FIG. 1 is a schematic diagram illustrating a portion of the cross-section of a non-adhesive insulation system for a liquefied gas storage tank according to one embodiment of the present invention; FIG. 2 is a cross-sectional view centered on a second spacing member of a non-adhesive insulation system for a liquefied gas storage tank according to one embodiment of the present invention, schematically illustrating (a) a case where no deformation occurs in the outer wall of the storage tank and (b) a case where deformation occurs; FIG. 3 is a plan view schematically illustrating a second spacing member in the form of a patch installed on the outer wall of a liquefied gas storage tank in a non-adhesive insulation system for a liquefied gas storage tank according to one embodiment of the present invention; FIG. 4 is a plan view schematically illustrating a second spacing member in the form of a strip installed on the outer wall of a liquefied gas storage tank in a non-adhesive insulation system for a liquefied gas storage tank according to another embodiment of the present invention; and FIG. 5 is a diagram centered on a fixing part and a buffer member of a non-adhesive insulation system for a liquefied gas storage tank according to one embodiment of the present invention This is a cross-sectional view schematically illustrating the behavior of the fixed part when deformation occurs in the outer wall of the storage tank.

[0052] Hereinafter, based on FIGS. 1 to 5, a method for manufacturing a non-adhesive insulation system for a liquefied gas storage tank according to the present invention will be described in detail.

[0053] The manufacturing method of the present invention includes the step of installing a first spacing member so as to be fitted into a stud provided on the outer wall of the liquefied gas storage tank.

[0054] A liquefied gas storage tank (T) has a space formed inside to accommodate liquefied gas. The outer wall (10) of the storage tank can be made of an alloy that is resistant to low temperatures, such as aluminum alloy, stainless steel (SUS), or 9% nickel alloy (9% Nickel steel), and preferably, it can be made of high-manganese steel, which is inexpensive and has excellent brittleness resistance at low temperatures, so it can withstand ultra-low temperatures.

[0055] The above liquefied gas storage tank may be an independent liquefied gas storage tank provided separately from the structure of the hull and mounted on the hull, and preferably may be an independent liquefied gas storage tank of IMO Type B.

[0056] A plurality of studs (11) are provided on the outer wall (10) of the storage tank. The studs (11) can be installed vertically on the outer surface of the outer wall (10) of the storage tank through welding or the like, and can be made of the same material as the outer wall (10) of the storage tank.

[0057] The first separation member (20) is provided between the outer wall (10) of the liquefied gas storage tank and the sheet layer (40) described later, and is installed to be fitted into the stud (11). The first separation member (20) serves to separate the outer wall (10) of the storage tank and the sheet layer (40) at a certain distance, and the separation space (S) formed accordingly can be utilized as a leakage path through which liquefied gas leaked from the liquefied gas storage tank can move to a drip tray (not shown) provided at the bottom of the outer wall (10) of the storage tank.

[0058] In one embodiment of the present invention, the first spacing member may be a plastic mesh material having excellent low-temperature toughness. Additionally, the first spacing member may be in the form of a strip that is integrally fitted onto two or more studs for ease of installation and formation of a spacing space (S), or in the form of an annular strip that surrounds the outer wall of the liquefied gas storage tank. When the first spacing member (20) is in the form of a strip or an annular strip, it is preferable because it can be integrally fitted onto two or more studs, making installation easy, and it is easy to form a spacing space (S) between each first spacing member (20).

[0059] In addition, the manufacturing method of the present invention includes the step of installing a second spacing member in the space between studs provided on the outer wall of the liquefied gas storage tank.

[0060] The second spacing member (30) is provided between the outer wall (10) of the liquefied gas storage tank and the sheet layer (40) described later, but unlike the first spacing member (20) which is installed to be fitted into the studs (11), it is installed in the space between the studs (11) provided on the outer wall (10) of the storage tank.

[0061] To address the problems of conventional adhesive insulation methods, which involve forming an insulating layer by directly spraying it onto the outer surface of a storage tank, a non-adhesive insulation method is being attempted in which a spacing member is installed at each stud and a sheet layer is installed thereon. However, due to the recent surge in demand for liquefied gas, storage tanks are becoming larger. Consequently, the spacing between the studs on the outer wall of the tank has widened, resulting in the sheet layer installed in the empty space not being sufficiently supported, causing wrinkles. Consequently, there is a problem in that the insulating layer formed on the sheet layer is not sufficiently separated from the outer wall of the storage tank.

[0062] The present invention is characterized by providing a second spacing member (30) in the space between the studs (11) provided on the outer wall (10) of the storage tank to solve the above problem.

[0063] In this regard, FIG. 2 is a cross-sectional view centered on the second spacing member of a non-adhesive insulation system of a liquefied gas storage tank according to one embodiment of the present invention, schematically illustrating (a) a case where no deformation occurs in the outer wall of the storage tank and (b) a case where deformation occurs.

[0064] Referring to FIG. 2(a), the second spacing member (30) provided in the space between the studs (11) additionally supports the sheet layer (40) installed in the space between the studs. Accordingly, wrinkles can be prevented from forming on the sheet layer (40), and the insulation portion (50) formed on the sheet layer (40) can be sufficiently spaced from the outer wall (10) of the storage tank, thereby ensuring the structural integrity of the non-adhesive insulation system of the liquefied gas storage tank.

[0065] Additionally, referring to Fig. 2(b), even when the outer wall (10) of the storage tank is deformed in the direction of the insulation part (50) due to thermal shrinkage or internal pressure, the second spacing member (30) is compressed and deformed in the spacing space (S) so that the outer wall (10) of the storage tank and the sheet layer (40) do not come into direct contact, thereby safely protecting the insulation part (50) from deformation of the outer wall (10) of the storage tank and preventing damage thereto.

[0066] In one embodiment of the present invention, the second separation member (30) is provided in direct contact with the outer wall (10) of the storage tank, so it may be made of a material capable of maintaining excellent strength even in a cryogenic temperature range. Additionally, the second separation member (30) is provided in the separation space (S) between the outer wall (10) of the storage tank and the sheet layer (40), and since the separation space (S) is utilized as a leakage path for leaked liquefied gas, it may be made of a porous material with excellent water resistance / corrosion resistance. Furthermore, the second separation member (30) may be made of a porous elastic material to absorb deformation of the outer wall of the storage tank and safely protect the insulation part (50). That is, it is preferable that the second separation member (30) be made of a porous elastic material that maintains excellent strength even in a cryogenic temperature range and has excellent water resistance / corrosion resistance, and may be made of, for example, a resilient blanket material.

[0067] In one embodiment of the present invention, the second spacing member may be in the form of a patch, a strip, or a combination thereof, and may be installed alternately so as not to overlap with the first spacing member (20) installed on the outer surface (10) of the storage tank.

[0068] FIGS. 3 and 4 are schematic plan views illustrating a second spacing member in the form of a patch or strip installed on the outer wall of a liquefied gas storage tank in a non-adhesive insulation system for a liquefied gas storage tank according to one embodiment of the present invention.

[0069] Referring to FIG. 3, a second spacing member (30-1) in the form of a patch according to one embodiment of the present invention may be installed in multiple numbers at regular intervals in the space between the stud (11) and the first spacing member (20). In FIG. 3, the second spacing member (30-1) is shown as having a patch shape with a square shape, but the shape of the second spacing member (30-1) is not limited thereto and may have other polygonal shapes such as a pentagon, a circle, or an ellipse.

[0070] Referring to FIG. 4, a strip-shaped second spacing member (30-2) according to one embodiment of the present invention may be installed in the space between the stud (11) and the first spacing member (20). The strip-shaped second spacing member (30-2) may have various cross-sectional shapes and is preferably installed to enable smooth movement of leaked liquefied gas across the entire outer wall (10) of the storage tank. FIG. 4 illustrates that one second spacing member (30-2) is installed in the space between the stud (11) and the first spacing member (20); however, it is obvious to a person skilled in the art that if necessary, such as due to the enlargement of the storage tank, a plurality of second spacing members (30-2) may be installed spaced apart from each other in the space between the stud (11) and the first spacing member (20).

[0071] In addition, the manufacturing method of the present invention includes the step of installing a sheet layer on the first and second spacing members to surround the outer wall of the liquefied gas storage tank, thereby forming a leakage path in the space between the outer wall of the liquefied gas storage tank and the sheet layer.

[0072] The sheet layer (40) surrounds the outer wall (10) of the storage tank and is installed at a certain distance from the outer wall of the liquefied gas storage tank, and can be fixed to the outer surface of the outer wall (10) of the storage tank through a fixing part (60) described later by inserting a stud (11) formed on the outer surface of the outer wall (10) of the storage tank through it.

[0073] In one embodiment of the present invention, a through hole (not shown) having a size equal to or similar to the diameter of a stud (11) may be pre-formed on the sheet layer (40), and the sheet layer (40) may be installed so that the stud protrudes through the stud (11).

[0074] Additionally, although not shown in detail in the drawing, the sheet layer (40) may be formed by laminating a metal film capable of liquid tight or air tight, such as an aluminum film, and a reinforcing sheet of the glass fiber type.

[0075] In one embodiment of the present invention, the metal film may be made of a metal material that is resistant to low-temperature brittleness, such as aluminum, and may have watertight or airtight properties in the area excluding the part where the stud (11) is inserted through, thereby minimizing the penetration of liquefied gas leaked from the liquefied gas storage tank into the insulation part (50).

[0076] In one embodiment of the present invention, the sheet layer (40) can improve adhesion with the spray foam insulation material forming the insulation part (50) and reduce the possibility of cracks occurring in the insulation part (50) in a cryogenic environment by placing (or laminating) a glass fiber-based reinforcing sheet on the upper surface of the metal film, more specifically on the surface in contact with the insulation part (50).

[0077] The above sheet layer (40) may be provided in the form of a single large sheet to cover the entire outer surface of the storage tank outer wall (10), but to improve ease of installation, it may be divided into multiple unit sheets and installed so as to be in close contact with each other on the outer surface of the storage tank outer wall (10).

[0078] A non-adhesive insulation system for a liquefied gas storage tank according to one embodiment of the present invention can minimize the penetration of liquefied gas leaking from the outer wall (10) of the storage tank into the insulation section (50) by installing a sheet layer (40) capable of liquid-tight or water-tight between the outer wall (10) of the storage tank and the insulation section (50).

[0079] In one embodiment of the present invention, it is obvious to a person skilled in the art that the sheet layer (40) may be configured by stacking a metal film and a reinforcing sheet in three or four layers or more as needed.

[0080] In addition, the manufacturing method of the present invention includes the step of applying a spray foam insulation material onto the sheet layer to form an insulation portion comprising a plurality of insulation layers.

[0081] The insulation section (50) can be formed by applying spray foam insulation material onto the sheet layer (40), and can have a thickness that ensures sufficient insulation performance by considering the size of the outer wall (10) of the storage tank or the type or density of the insulation material applied onto the sheet layer (40).

[0082] In one embodiment of the present invention, the insulation section (50) may be formed in multiple layers to maintain the liquefied gas stored inside the tank body in a cryogenic state. Hereinafter, for convenience of explanation, the insulation section (50) of this embodiment is described as an example in which spray foam is sprayed and laminated multiple times on a sheet layer (40) to form three layers, and is divided into a first insulation layer (51), a second insulation layer (52), and a third insulation layer (53), respectively, in a direction away from the outer surface of the outer wall (10) of the storage tank. In other words, the insulation section (50) according to one embodiment of the present invention may be composed of three layers in which the first insulation layer (51), the second insulation layer (52), and the third insulation layer (53) are sequentially installed on the sheet layer (40).

[0083] In one embodiment of the present invention, the first to third insulation layers (51, 52, 53) may be formed by spraying and laminating multiple insulation materials having the same material and density, or at least one of the first to third insulation layers (51, 52, 53) may be formed with the same material but with a density different from the others.

[0084] In addition, when the first to third insulation layers (51, 52, 53) are applied with different densities, it may be desirable to form a higher density as it is relatively closer to the outer wall (10) of the storage tank, and it may be desirable to form a thinner thickness as the density increases.

[0085] Meanwhile, a sheet layer (40) and a gap (S) are installed between the outer wall (10) of the storage tank and the insulation part (50) to relieve stress caused by the difference in thermal expansion coefficients between the outer wall (10) of the storage tank and the insulation part (50), but since the insulation part (50) may be separated from the sheet layer (40) in a cryogenic environment, it is necessary to fix the insulation part (50) to the outer wall (10) of the storage tank.

[0086] In addition, in the manufacturing method of the present invention, the step of forming the insulation portion (50) comprises: forming some of the insulation layers among a plurality of insulation layers; fastening a fixing portion (60) to a stud (11) provided on the outer wall (10) of the liquefied gas storage tank; and forming the remaining insulation layer on the portion of the insulation layer.

[0087] The fixing part (60) may include an extension member (61) in which one end is connected to a stud (11) and the other end extends outwardly toward the outer wall (10) of the storage tank, a washer member (62), and a fixing nut (63) that is connected to the other end of the extension member (61).

[0088] The extension member (61) may have a diameter larger than that of the stud (11) to accommodate the end of the stud (11) protruding on the sheet layer (40), and may have a screw groove (not shown) formed on the inner surface of one end corresponding to the screw thread (not shown) formed on the outer surface of the stud (11).

[0089] The washer member (62) is fitted onto the other end of the extension member (61) so as to be positioned on some of the insulation layers forming the insulation portion (50) before the fixing nut (63) is fastened to the other end of the extension member (61). An insertion hole corresponding to the end diameter of the other end of the extension member (61) may be formed in the central part of the washer member (62).

[0090] The washer member (62) is formed to have an inner diameter larger than the outer diameter of the stud (11), but it may be preferable for the inner diameter to be smaller than the diameter of one end of the extension member (61). That is, the fixing part (60) according to the present invention is structured such that a fixing nut (63) fastened to the other end of the extension member (61) presses the washer member (62), which is located on some of the insulation layers among the plurality of insulation layers forming the insulation part (50), and the sheet layer (40) and the insulation part (50) can be fixed through a simple screw connection method.

[0091] Referring again to FIG. 1, the washer member (62) is shown to be positioned on the first insulation layer (51) to fix the sheet layer (40) and the insulation part (50) to the stud (11), but it is obvious to a person skilled in the art that the washer member (62) may be positioned on the second insulation layer (52) or the third insulation layer (53) as needed.

[0092] In one embodiment of the present invention, the insulation member (50) may be manufactured by a process of forming a first insulation layer (51) on the sheet layer (40) by spraying after attaching one end of an extension member (61) to a stud (11) protruding through the sheet layer (40), attaching a first reinforcing member (81) on the first insulation layer (51), seating a washer member (62) so as to be fitted to the other end of the extension member (61), and then attaching a fixing nut (63) to a thread formed on the other end of the extension member (61), forming a second insulation layer (52), attaching a second reinforcing member (82) on the second insulation layer (52), forming a third insulation layer (53) on the second reinforcing member (82), and forming a coating layer (90) on the upper part of the third insulation layer (53).

[0093] In one embodiment of the present invention, the fixing part (60) may include a cushioning member (70) surrounding the outer surface of the fixing part (60).

[0094] The outer walls of tanks storing cryogenic liquefied gases at high pressures can deform due to thermal shrinkage or internal pressure. This deformation of the outer walls is transmitted to the insulation through fasteners attached to the walls, posing a problem that may result in damage to the insulation. Furthermore, with the recent trend toward larger liquefied gas storage tanks, there is an increasing demand for new insulation structures capable of preventing such damage.

[0095] Accordingly, the present invention further includes a cushioning member (70) that surrounds the outer surface of a fixing part (60), which is essential for fixing the sheet layer (40) and the insulation part (50) to the outer wall (10) of the storage tank. Accordingly, the behavior of the outer wall (10) of the storage tank and the behavior of the insulation part (50) are separated under cryogenic environments, so that the possibility of damage to the insulation part (50) can be effectively suppressed even with large deformation of the outer wall (10) due to the enlargement of the storage tank.

[0096] FIG. 5 is a cross-sectional view focusing on the fixed part and the buffer member of a non-adhesive insulation system of a liquefied gas storage tank according to one embodiment of the present invention, schematically illustrating the behavior of the fixed part when deformation occurs on the outer wall of the storage tank.

[0097] Referring to FIG. 5, even when the fixing part (60) fixed to the outer wall (10) of the storage tank is deformed significantly and moves out of its original position, the fixing part (60') after deformation is still located within the range of the cushioning member (70). In this way, by blocking the transmission of the deformation of the outer wall (10) of the storage tank to the insulation part (50), damage to the insulation part (50) around the fixing part (60) can be effectively suppressed.

[0098] In one embodiment of the present invention, the cushioning member (70) may be made of a porous material with excellent deformation absorption capacity, as it is necessary to prevent deformation of the outer wall (10) of the storage tank transmitted through the fixing part (60) from being transmitted to the insulation part (50). Additionally, the cushioning member (70) may be made of a porous insulation material, as it is provided to surround the fixing part (60) which is installed in a manner that penetrates part or all of the insulation part (50). That is, it is preferable that the cushioning member (70) be made of a porous insulation material with excellent deformation absorption capacity, and may be made of, for example, a resilient blanket or glass wool material.

[0099] In one embodiment of the present invention, the insulation member (50) may further include a reinforcing member (80) installed within the insulation member (50). The reinforcing member (80) may be provided in the form of a mesh made of glass fiber or SUS material and may serve as a reinforcing material that prevents the progression of cracks in the thickness direction of the insulation member (50). Additionally, the reinforcing member (80) may serve to prevent the insulation member (50) from detaching due to pressure rise caused by leakage of liquefied gas in a cryogenic environment or external impact.

[0100] In one embodiment of the present invention, the reinforcing member (80) may essentially be placed on the upper surface of the first insulation layer (51) where the fixing member (60) is installed, and it may be preferable for a plurality of reinforcing members (81, 82, etc.) to be spaced apart from each other within the insulation member (50) depending on the thickness of the insulation member (50). Accordingly, direct contact between the insulation member (50) and the fixing member (60) is blocked, thereby avoiding the risk of damage to the spray foam insulation material caused by the fixing member (60).

[0101] Referring again to FIG. 1, the reinforcing member (80) is shown as having a first reinforcing member (81) installed between the first insulation layer (51) and the second insulation layer (52), and a second reinforcing member (82) installed between the second insulation layer (52) and the third insulation layer (53), but as described above, the number of reinforcing members (80) can be appropriately adjusted according to the thickness and stacking structure of the insulation member (50).

[0102] In one embodiment of the present invention, the insulation member (50) may further include a coating layer (90) formed on the insulation member (50) to prevent damage to the insulation member (50) caused by moisture, contamination, and impact from the outside.

[0103] The coating layer (90) can be formed on the outer surface of the insulation part (50) through any one of the following methods: polyurea coating, metal cladding, or fiber reinforced plastic coating. In addition, various other methods can be applied as long as they are configured to block moisture entering from the outside and prevent damage caused by external forces.

[0104] In addition, the manufacturing method of the present invention includes the step of injecting gas into the leakage path; and the defect verification step of checking whether the pressure within the leakage path is maintained above a reference pressure.

[0105] The steps of injecting the gas and checking for defects may utilize a defect checking system. In this regard, FIG. 6 is a cross-sectional view schematically illustrating a state in which a defect checking system is installed to check whether a defect exists in the insulation part of the present invention. Referring to FIG. 6, the defect checking system includes an injection unit (100), a gas storage unit (200), an outlet unit (300), and a pressure gauge (500), and may further include a flow meter (400) as needed.

[0106] The injection section (100) is connected to the gas storage section (200) described later and provides a path for injecting gas into a leakage path formed in the gap (S) between the outer wall (10) of the liquefied gas storage tank (T) and the sheet layer (40) surrounding the outer wall (10) of the liquefied gas storage tank. An injection section control valve (not shown) capable of controlling the supply amount of the injected gas may be provided on the injection section (100).

[0107] In one embodiment of the present invention, the defect verification system of the present invention may further include a flow meter (400) for verifying the flow rate of gas injected into the leakage path, and the flow meter (400) may be provided on the injection part (100).

[0108] The flow rate of the gas injected into the above leakage path is not particularly limited, but may be 3 to 15 L / min, and preferably 5 to 10 L / min, in order to shorten the time to check for defects without damaging the insulation part.

[0109] The gas storage unit (200) is connected to the injection unit (100) and stores gas to be injected into a leakage path formed between the outer wall (10) of the storage tank and the sheet layer (40). At this time, the gas injected into the leakage path through the injection unit may be dry gas.

[0110] The above dry gas refers to a gas that does not contain water vapor. The above dry gas may be dry air or an inert gas, and the inert gas may be pure nitrogen, helium, argon, carbon dioxide, or a mixture thereof, but is not limited thereto, and preferably nitrogen may be used.

[0111] The outlet section (300) provides a path for discharging gas injected into the leakage path to the outside. In order to increase the efficiency of checking for defects on the insulation section (50), it is preferable that the outlet section (300) be installed far apart from the injection section (100). An outlet section control valve (310) capable of controlling the discharge amount of the discharged gas may be provided on the outlet section (300).

[0112] The pressure gauge (500) measures the pressure in the leakage path pressurized by the gas injected through the injection part (100). The pressure gauge (500) may be provided on the injection part (100), the outlet part (300), or the leakage path, and it is preferable that the pressure gauge (500) be provided on the outlet part (300) in order to ensure accuracy in measuring the pressure in the leakage path and to minimize damage to the insulation part (50).

[0113] The injection section (100) and the outlet section (300) may be temporarily fixed by penetrating the sheet layer (40) and the insulation section (50) installed on the liquefied gas storage tank (T). Even if the injection section (100) and the outlet section (300) are not fixed to the liquefied gas storage tank (T), the injection section (100) and the outlet section (300) can be temporarily fixed through the insulation section (50) because they penetrate the insulation section (50).

[0114] Additionally, the injection section (100) and the outlet section (300) may be connected to separate pipes provided in a purging system for discharging liquefied gas leaked from a liquefied gas storage tank (T) in a leak path. When a purging system is provided in the liquefied gas storage tank (T), the injection section (100) may be connected to a purging gas injection pipe, and the outlet section (300) may be connected to a purging gas outlet pipe.

[0115] Meanwhile, although FIG. 6 illustrates an example in which one injection part (100) and one outlet part (300) are provided, it is obvious to a person skilled in the art that multiple injection parts (100) and outlet parts (300) may be provided, taking into account the size of the liquefied gas storage tank (T), the structure of the insulation part (50), etc.

[0116] After injecting gas into the leakage path through the injection section (100), the pressure within the leakage path is checked to see if it is maintained above a reference pressure, thereby checking for defects in the insulation section (50) formed on the sheet layer (40). If the pressure gauge (500) is provided on the outlet section (300), the pressure within the leakage path can be checked by measuring the pressure at the outlet section where the injected gas is discharged. The reference pressure is not particularly limited, but since a pressure within the leakage path that is too high can cause damage to the insulation section (50), it may be desirable to use atmospheric pressure as the reference pressure.

[0117] After injecting gas into the leakage path through the injection part (100), if the pressure within the leakage path is maintained above the reference pressure, it can be determined that there is no defect in the insulation part (50). Additionally, if the liquefied gas storage tank (T) has a pending area in which the formation of a partial insulation structure is withheld, it can be determined that the airtightness and watertightness of the pending area are maintained.

[0118] Meanwhile, if only micro-defects exist on the insulation section (50), the pressure within the leakage path may be maintained above the reference pressure, making it difficult to confirm the existence of micro-defects. Accordingly, a gas other than oxygen is injected into the leakage path, and the amount of oxygen within the leakage path is checked through the oxygen detector to determine whether micro-defects exist in the insulation section (50).

[0119] At this time, it is preferable that the diameter of the outlet section (300) be the minimum diameter into which an oxygen detector can be inserted. Since the outlet section (300) can be installed to be temporarily fixed by penetrating the insulation section (50), it is preferable that the smaller the diameter, the more the damage to the insulation section (50) can be minimized during temporary fixation.

[0120] After injecting gas into the leakage path through the injection part (100), if the pressure within the leakage path is not maintained above a reference pressure, it can be determined that there is a defect in the insulation part (50). Additionally, if the liquefied gas storage tank (T) has a pending area in which the formation of a partial insulation structure is withheld, it can be determined that the airtightness and watertightness of the pending area are not maintained.

[0121] If there is a defect in the insulation section (50) or the work hold area, the defect point can be identified using a visual inspection or a soap water inspection, and the identified defect point can be repaired in advance. In this way, by identifying and repairing defect points in the work hold area and / or insulation structure in advance before mounting the storage tank with the insulation structure onto the hull, the drying work and inert gas replacement work can be performed quickly and effectively after mounting onto the hull.

[0122] In the case of conventional technology, rainwater enters the leakage path through a defect point on the insulation section (50) or the work hold area, and thus a significant amount of time is required for drying and inert gas replacement work to prevent condensation in the leakage path before injecting cryogenic liquefied gas after hull installation. In contrast, if the defect point is repaired in advance by applying the manufacturing method of the non-adhesive insulation system of the liquefied gas storage tank of the present invention, the entry of rainwater into the leakage path can be blocked, and accordingly, the time required for drying and inert gas replacement work can be minimized.

[0123] In addition, the present invention provides a non-adhesive insulation system for a liquefied gas storage tank manufactured by the method for manufacturing a non-adhesive insulation system for a liquefied gas storage tank according to the present invention.

[0124] In addition, the present invention provides a vessel comprising a non-adhesive insulation system for the liquefied gas storage tank.

[0125] The above-mentioned vessel includes all types of vessels equipped with a propulsion engine capable of transporting liquefied gas or using liquefied gas as fuel, and preferably may be a liquefied gas carrier. Representative examples of the above-mentioned liquefied gas carrier include vessels with self-propulsion capabilities such as LNG carriers, LPG carriers, liquid hydrogen carriers, or ammonia carriers.

[0126] In addition, the vessel may be an offshore structure such as an FPSO (Floating, Production, Storage and Offloading) or FSRU (Floating Storage and Regasification Unit) that is floating on the sea for the storage and / or supply of liquefied gas, even though it does not have propulsion capabilities.

[0127] The above description is merely an illustrative explanation of the technical concept of the present invention, and those skilled in the art to which the present invention pertains will be able to make various modifications, changes, and substitutions within the scope of the essential characteristics of the present invention without departing from its nature.

[0128] The embodiments disclosed in this invention and the accompanying drawings are intended to explain, not limit, the technical concept of the invention, and the scope of the technical concept of the invention is not limited by these embodiments and accompanying drawings.

[0129] Furthermore, the scope of protection of the present invention shall be interpreted by the claims below, and all technical ideas within an equivalent scope shall be interpreted as being included within the scope of rights of the present invention.

[0130] [Explanation of the symbol]

[0131] T: Liquefied gas storage tank

[0132] S: Separation space (leakage path)

[0133] 10: Storage tank outer wall

[0134] 11: Stud

[0135] 20: First separation member

[0136] 30: Second separation member

[0137] 30-1: Patch-shaped second spacing member

[0138] 30-2: Strip-shaped second spacing member

[0139] 40: Sheet layer

[0140] 50: Insulation section

[0141] 51~53: 1st insulation layer ~ 3rd insulation layer

[0142] 60: Fixed part

[0143] 60': Fixed part after deformation

[0144] 61: Extension member

[0145] 62: Washer member

[0146] 63: Fixing nut

[0147] 70: Buffer member

[0148] 80: Reinforcement part

[0149] 81~82: 1st reinforcement section~2nd reinforcement section

[0150] 90: Coating layer

[0151] 100: Injection part

[0152] 200: Gas storage unit

[0153] 300: Exit section

[0154] 310: Outlet control valve

[0155] 400: Flow meter

[0156] 500: Pressure gauge

Claims

1. A method for manufacturing a non-adhesive insulation system for a liquefied gas storage tank, A step of installing a first spacing member so as to be fitted into a stud provided on the outer wall of the above-mentioned liquefied gas storage tank; A step of installing a second spacing member in the space between studs provided on the outer wall of the above-mentioned liquefied gas storage tank; A step of installing a sheet layer on the first and second spacing members to surround the outer wall of the liquefied gas storage tank, thereby forming a leakage path in the space between the outer wall of the liquefied gas storage tank and the sheet layer; A step of forming an insulation section comprising a plurality of insulation layers by applying spray foam insulation material onto the above sheet layer; Step of injecting gas into the above leakage path; and A defect verification step for checking whether the pressure within the above leakage path is maintained above a reference pressure; is included, The step of forming the above-mentioned insulation part is, A step of forming some of the insulation layers among a plurality of insulation layers; A step of fastening a fixing part to a stud provided on the outer wall of the above-mentioned liquefied gas storage tank; and A manufacturing method comprising the step of forming the remaining insulation layer on the above-mentioned partial insulation layer.

2. In Claim 1, The above liquefied gas storage tank is a standalone storage tank, and the manufacturing method.

3. In Claim 1, In the above defect verification step, if the pressure within the leakage path is not maintained above the reference pressure, A step of identifying a defect point of the insulation portion formed on the above sheet layer; and A manufacturing method further comprising the step of repairing the defect point of the insulation identified above.

4. In Claim 3, A manufacturing method in which the defect point of the above-mentioned insulation part is identified by visual inspection or soapy water inspection.

5. In Claim 1, A manufacturing method in which the reference pressure of the defect verification step is atmospheric pressure.

6. In Claim 1, A manufacturing method in which the gas injected into the above leakage path is a dry gas.

7. In Claim 1, A manufacturing method in which the first spacing member is in the form of a strip that is integrally fitted onto two or more studs.

8. In Claim 7, A manufacturing method in which the first spacing member is in the form of an annular strip surrounding the outer wall of the liquefied gas storage tank.

9. In Claim 1, The above second spacing member is made of a porous elastic material, a manufacturing method.

10. In Claim 1, A manufacturing method in which the second spacing member is in the form of a patch, a strip, or a combination thereof.

11. In Claim 1, A manufacturing method in which the above-mentioned fixed part includes a cushioning member surrounding the outer surface of the fixed part.

12. In Claim 11, The above-mentioned buffer member is made of a porous insulating material, and the manufacturing method.

13. A non-adhesive insulation system for a liquefied gas storage tank manufactured by the method of any one of claims 1 to 12.

14. A vessel comprising the non-adhesive insulation system of the liquefied gas storage tank of Claim 13.

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