Insulation system for liquefied gas storage tank(IMO-B Type), design method, and ship having thereof

Abstract

The present invention is characterized by comprising a liquefied gas selection step for selecting a liquefied gas, a leakage standard setting step for setting a leakage standard for the liquefied gas, a shape adoption step for adopting a shape of a partial secondary barrier, a selection and evaluation step for selecting a target evaporation rate of the liquefied gas and evaluating the leakage amount of the liquefied gas, a step for comparing the target evaporation rate of the liquefied gas with the leakage amount of the liquefied gas, a step for designing the shape of the partial secondary barrier, and a step for installing the partial secondary barrier.

Description

Technology Field

[0001] The present invention relates to an insulation system for a standalone Type B liquefied gas storage tank, a design method, and a ship including the same. By manufacturing a partial secondary barrier according to the type and physical properties of the liquefied gas leaking through the partial secondary barrier, the entire amount of liquefied gas can be vaporized, the barrier can be manufactured in various forms, and changes at each procedural step can be reflected. Background Technology

[0002] Generally, natural gas is transported in a gaseous state through onshore or offshore gas pipelines, or transported to distant consumption sites in the form of liquefied natural gas (LNG) stored on LNG carriers.

[0003] For storage tanks of liquefied gases such as LNG (Liquefied Natural Gas) or LH2 (Liquefied Hydrogen), and for means of transport or structures including such storage tanks, various fittings and equipment are required to store and operate the liquefied gas in these storage tanks. These fittings and equipment must meet all conditions, such as temperature and pressure, required for storing and operating the liquefied gas, and a design that takes these conditions into account is absolutely necessary.

[0004] Representative storage technologies capable of storing liquefied gas include membrane tanks and freestanding tanks, depending on the classification in the IGC code or onshore tank technology. In particular, freestanding tanks can be broadly classified into three types—type A, type B, and type C—depending on the configuration of the secondary barrier. Specifically, freestanding type B requires a partial secondary barrier configuration, and this secondary barrier requires liquid tightness.

[0005] The independent type B tanks applied to ships are designed and manufactured in the form of spherical and prismatic tanks, but the partial secondary barrier is applied by configuring it at the bottom of the tank in the form of a drip tray through a passage through which leaked liquefied gas can be discharged.

[0006] These leak supports are fixed to the bottom surface of the storage tank to contain fluid (LNG) flowing down by gravity. Additionally, the leak supports are constructed as trays with internal spaces and are installed at one or more locations on the bottom surface of the storage tank to collect the flowing cryogenic fluid.

[0007] However, while these leak-proof supports serve to temporarily protect the hull for 15 days, they require a size that is too large to store the cryogenic fluid leaking during that period in liquid form, so there is a need for a realistic alternative that utilizes the fact that gastightness is not required.

[0008] In addition, when the bottom surface of the storage tank is relatively flat, the installation of multiple leak-proof supports is required, which also entails the problem of increased complexity within a confined space. The problem to be solved

[0009] The present invention was created to solve the problems of the prior art as described above, and the purpose of the present invention is to provide an insulation system for a liquefied gas storage tank that satisfies leakage design standards by vaporizing the entire amount within a pipe-type partial secondary barrier instead of the existing drip tray-type partial secondary barrier for collecting liquefied gas leaking from the storage tank.

[0010] In addition, the objective of the present invention is to provide an insulation system for a liquefied gas storage tank that does not unnecessarily occupy space for installing a partial secondary barrier and has no space constraints.

[0011] In addition, the objective of the present invention is to manufacture various types of secondary partial barriers by comparing the target evaporation rate of the liquefied gas with the evaporation rate in the piping of the adopted partial secondary barrier. means of solving the problem

[0012] The present invention comprises a liquefied gas selection step for selecting a liquefied gas, a leakage criterion setting step for setting a leakage criterion for the liquefied gas, and a shape adoption step for adopting a shape of a partial secondary barrier.

[0013] The method is characterized by including a selection and evaluation step of selecting a target evaporation rate of the liquefied gas and evaluating the amount of leakage of the liquefied gas, a step of comparing the target evaporation rate of the liquefied gas with the amount of leakage of the liquefied gas, a step of designing the shape of the partial secondary barrier, and a step of installing the partial secondary barrier.

[0014] The present invention may be characterized in that the leakage criterion of the leakage criterion setting step is composed of the main physical properties and leakage rate of the liquefied gas selected from the selection step.

[0015] The shape adoption step of the present invention may be characterized by setting the material, diameter, thickness, length, and volume of the partial secondary barrier based on the leakage criteria, and adopting a method of extending the length of the partial secondary barrier.

[0016] The above selection and evaluation step of the present invention may be characterized by selecting a target evaporation rate and evaluating the liquefied gas leakage amount by reflecting the pipe shape of the partial secondary barrier adopted from the shape adoption step and the arbitrary length standard volume.

[0017] The comparison step of the present invention may be characterized by comparing the target evaporation rate with the liquefied gas leakage amount, and returning to the procedure of the shape adoption step if the liquefied gas leakage amount is less than the target evaporation rate.

[0018] The present invention may be characterized by resetting the length of the partial secondary barrier to be extended during the shape adoption step.

[0019] The above-described secondary barrier of the present invention may be characterized by being formed as a pipe having an internal space and formed in any one of a straight line, a curve, a zigzag, a spring, or a radial shape to extend its length.

[0020] The present invention relates to a ship comprising a method for designing an insulation system connected to a liquefied gas storage tank. Effects of the invention

[0021] According to the present invention, by completely vaporizing the liquefied gas leaking from the storage tank within a partial secondary barrier in the form of a pipe, the leakage design criteria can be satisfied, and thereby, an insulation system for a liquefied gas storage tank can be provided that does not require the installation of a conventional leakage support.

[0022] In addition, it is possible to provide an insulation system for liquefied gas storage tanks that is free from space constraints and does not unnecessarily occupy space for installing partial secondary barriers in type B independent tanks.

[0023] In addition, by selecting and evaluating the evaporation rate of the liquefied gas, it becomes possible to manufacture partial secondary barriers in various forms by reflecting conditions that change depending on the type of liquefied gas, and it becomes possible to reflect changes at each stage of the procedure. Brief explanation of the drawing

[0024] FIG. 1 is a cross-sectional view of a section where a pipe-type secondary barrier is installed in an insulation system for a liquefied gas storage tank according to one embodiment of the present invention. Figures 2 (a), (b), (c), (d), (e) and (f) are drawings illustrating exemplary shapes of partial secondary barriers in an insulation system for a liquefied gas storage tank according to an embodiment of the present invention. FIG. 3 schematically shows the combined structure of an insulation system for a liquefied gas storage tank according to one embodiment of the present invention. FIG. 4 schematically shows the combined structure of an insulation system for a liquefied gas storage tank according to another embodiment of the present invention. FIG. 5 is a flowchart illustrating the process of designing a partial secondary barrier for a standalone Type B liquefied gas storage tank according to one embodiment of the present invention. FIG. 6 is a flowchart sequentially illustrating a method for designing an independent Type B liquefied gas storage tank insulation system considering the shape of an optimal partial secondary barrier according to one embodiment of the present invention. Specific details for implementing the invention

[0025] The object, specific 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. It should be noted that in assigning reference numerals to the components of each drawing in this specification, identical components are assigned the same number whenever possible, even if they are shown in different drawings. Furthermore, in describing the present invention, detailed descriptions of related prior art are omitted if it is determined that such detailed descriptions would unnecessarily obscure the essence of the invention.

[0026] In addition, the attached drawings are intended only to facilitate understanding of the embodiments disclosed in this specification, and the technical concept disclosed in this specification is not limited by the attached drawings; it should be understood that all modifications, equivalents, and substitutions included within the concept and technical scope of the present invention are included.

[0027] Additionally, terms including ordinal numbers, such as first, second, etc., may be used to describe various components, but said components are not limited by said terms. These terms are used solely for the purpose of distinguishing one component from another.

[0028] In the present specification, the term "liquefied gas" may be used to encompass all gaseous fuels generally stored in a liquid state, such as LNG, liquid hydrogen, liquid nitrogen, LPG, ethylene, ammonia, etc. For convenience, cases where the fuel is not in a liquid state due to heating or pressurization may also be referred to as liquefied gas. This may also apply to boil-off gas. Furthermore, in the present specification, the term "LNG" may be used to encompass not only liquid states but also supercritical states, and the term "boil-off gas" may be used to include not only boil-off gas in a gaseous state but also liquefied boil-off gas.

[0029] In addition, the use of the terms 'primary' and 'secondary' in the present invention is used as a criterion for distinguishing whether the LNG stored in the storage tank performs the function of sealing or insulating the LNG primarily or performing the function of sealing or insulating it secondarily.

[0030] Furthermore, the terms 'upper' or 'top,' conventionally applied to elements of a tank, refer to the direction toward the interior of the tank regardless of the direction of gravity, and likewise, the terms 'lower' or 'bottom' refer to the direction toward the exterior of the tank regardless of the direction of gravity.

[0031] The present invention will be described in detail below by explaining preferred embodiments of the invention with reference to the attached drawings. Identical reference numerals in each drawing indicate identical components.

[0033] It should be noted that the vessel equipped with the liquefied gas storage tank described below is a concept that encompasses not only merchant vessels transporting cargo from a point of origin to a destination, but also offshore structures that float at a certain point on the sea and perform specific operations, although not illustrated. Furthermore, it should be noted that in the present invention, the liquefied gas storage tank includes any type of tank for storing liquefied gas.

[0035] Structure of an insulation system for liquefied gas storage tanks

[0036] The present invention can be applied to a standalone type B in which the secondary barrier is formed as a partial secondary barrier and liquid tightness is required.

[0037] FIG. 1 is a cross-sectional view of a portion where a pipe-type partial secondary barrier is installed in an insulation system for a liquefied gas storage tank according to one embodiment of the present invention, FIG. 2 (a), (b), (c), (d), (e) and (f) are drawings exemplarily illustrating the shapes of the partial secondary barrier according to one embodiment of the present invention in an insulation system for a liquefied gas storage tank, FIG. 3 is a schematic representation of the combined structure of an insulation system for a liquefied gas storage tank according to one embodiment of the present invention, and FIG. 4 is a schematic representation of the combined structure of an insulation system for a liquefied gas storage tank according to another embodiment of the present invention.

[0039] Referring to FIG. 1, an insulation system for a liquefied gas storage tank according to one embodiment of the present invention comprises a primary barrier (100) in contact with liquefied gas, an insulation layer (200) installed on the outer side of the primary barrier (100), a leakage passage (300) located between the primary barrier (100) and the insulation layer (200) through which liquefied gas leaked from the primary barrier (100) moves, a leakage passage (400) inserted into the insulation layer (200) and connected to the leakage passage (300) through which liquefied gas passes, and a partial secondary barrier (500) formed as a pipe and communicating with the leakage passage (400). When leakage occurs from the primary barrier (100), the leaked liquefied gas is entirely vaporized during the process of passing through the partial secondary barrier (500) configured in the form of a pipe.

[0041] Specifically, the primary barrier (100) of the insulation system for a liquefied gas storage tank according to one embodiment of the present invention can be configured to contain the liquefied gas while in direct contact with it, and can be composed of a metal material that can be used depending on the characteristics of the liquefied gas, such as aluminum, nickel alloy steel, high manganese steel, stainless steel, and nickel.

[0043] A leakage passage (300) of an insulation system for a liquefied gas storage tank according to one embodiment of the present invention is formed between a primary barrier (100) and an insulation layer (200) and is a passage through which liquefied gas leaked from the primary barrier (100) moves. Specifically, the leakage passage (300) is a space for allowing liquefied gas, which is in a liquid state contained within the storage tank, to flow out when leakage occurs due to damage to the primary barrier (100).

[0044] Additionally, in the leakage passage (300), an outlet (310) may be formed in the direction of the insulation layer (200) to facilitate the discharge of liquefied gas through the leakage passage (400) to be described later.

[0046] According to one embodiment of the present invention, the leakage passage (400) of the insulation system for a liquefied gas storage tank is positioned by penetrating into the insulation layer (200) and may be configured in the form of a small-diameter pipe through which liquefied gas passes, communicating with the outlet (310) of the leakage passage (300). Specifically, the leakage passage (400) penetrates the insulation layer (200) and is a passage through which leaked liquefied gas moves to the outside of the tank, so it is provided with a material that satisfies the characteristics of the liquefied gas; in the case of LNG, it is preferable to manufacture it with aluminum steel, stainless steel, etc.

[0047] In addition, the leakage passage (400) of the insulation system for a liquefied gas storage tank according to one embodiment of the present invention is positioned by being inserted into the insulation layer (200) at least once, and can be installed at various places in the insulation layer (200) and each inserted at least once in order to discharge all of the liquefied gas leaking from the primary barrier (100) surrounding the storage tank without any residue.

[0049] A partial secondary barrier (500) of an insulation system for a liquefied gas storage tank according to one embodiment of the present invention may be formed as a pipe and may communicate with a leakage passage (400). Specifically, the partial secondary barrier (500) of the present invention may be configured such that one end is connected to the leakage passage (400) and the other end has a gas opening (510) formed therein, so that the leakage liquefied gas flowing into the partial secondary barrier (500) through the leakage passage (400) can be entirely vaporized as it flows toward the gas opening (510). Specifically, the partial secondary barrier (500) is connected to the leakage passage (400) by any one of welding, threading, or bolting so that the leakage liquid does not leak out to the outside, and the leakage passage (400) may be manufactured with a small diameter so that the partial secondary barrier (500) is also manufactured in a small diameter form.

[0050] Additionally, the partial secondary barrier (500) can be manufactured in a long pipe length so that the leaked liquefied gas discharged from the leaked passage (400) can be completely vaporized. That is, the length of the pipe through which the leaked liquefied gas flows can be formed long to increase the surface area for heat release, and to this end, various shapes such as those shown in FIG. 2 can be adopted as the form of the partial secondary barrier (500).

[0051] Meanwhile, the dimensions of the length, diameter, and internal space of the partial secondary barrier (500) of the present invention may be determined by considering the diameter of the leakage passage (400), the size of the storage tank, and the amount of liquefied gas loaded.

[0052] In addition, the partial secondary barrier (500) of the insulation system for a liquefied gas storage tank according to one embodiment of the present invention can be made of a metal barrier material depending on the characteristics of the liquefied gas, and it is preferable that it be made of a material in which heat transfer is easily achieved due to the characteristics of the metal.

[0053] Meanwhile, as illustrated in FIG. 1, a portion of the partial secondary barrier (500) of the insulation system for a liquefied gas storage tank according to one embodiment of the present invention may have a folded section formed, such as an “L” shape. Through such a shape, a shape that stably fixes and supports the leakage passage (400) and the partial secondary barrier (500) can be realized. However, the position and shape of the partial secondary barrier (500) do not need to be fixed and can be appropriately changed and modified to correspond to the structural characteristics of the vessel.

[0054] Meanwhile, the partial secondary barrier (500) of the present invention may be formed in any one of the following shapes: a straight shape (Fig. 2(a)), a circular spiral coil shape (Fig. 2(b)), a fin tube shape (Fig. 2(c)), an angular spiral coil shape (Fig. 2(d)), a zigzag shape (Fig. 2(e)), or a concentric coil shape (Fig. 2(f)), as shown in FIG. 2(a), (b), (c), (d), (d), (e) and (f) of FIG. 2. Any shape that facilitates heat transfer may be adopted. Meanwhile, the circular spiral coil shape, the angular spiral coil shape, or the concentric coil shape may be composed of any one of the series or parallel shapes, and any shape that facilitates rapid heat transfer may be adopted.

[0055] In this way, by configuring the partial secondary barrier (500) of the present invention in the form of a pipe, the configuration of the drip tray that was previously installed to collect leaked liquefied gas can be eliminated, and thus, various problems that occurred due to the installation of the drip tray (e.g., problems such as occupying space inside the ship) can be solved.

[0056] In addition, the partial secondary barrier (500) of the present invention is configured in a pipe form with a much simpler structure compared to a conventional drip tray, so an insulation system without spatial constraints can be realized. Specifically, while the conventional leak support requires installation in a narrow space, such as an insulation means to prevent cooling of the wall surface of the adjacent space in addition to the leak support, the pipe-type partial secondary barrier (500) is implemented in a form that is mounted in space through the connection and support structure between the pipe-type partial secondary barrier (500) and the leak movement passage (400), thereby realizing an insulation system without spatial constraints.

[0058] Meanwhile, the structure is configured such that the liquefied gas flowing into the partial secondary barrier (500) of the insulation system for a liquefied gas storage tank according to one embodiment of the present invention is entirely vaporized and discharged as it flows into the gas opening (510) formed at the other end, and the amount of liquefied gas vaporized can be predicted by calculating the amount of heat intrusion of the liquefied gas flowing into the partial secondary barrier (500) using the following formula.

[0059]

[0060] [Calculation Formula for Liquefied Gas Evaporation Rate]

[0062] In the above formula, Q is the value of heat entering through the partial secondary barrier (500), d is the value of the density of the leaked liquefied gas, V is the value of the volume of the leaked liquefied gas, and L is the value of the latent heat of the leaked liquefied gas. Through the above formula, it is possible to calculate the amount of heat intrusion required to vaporize the entire amount of liquefied gas flowing into the secondary barrier. In addition, once the amount of heat intrusion can be calculated, the amount of liquefied gas required to vaporize the entire amount can be predicted, and the diameter or length of the partial secondary barrier (500) for passing the liquefied gas can also be determined.

[0064] Next, a pressure relief valve is installed at the other end of the partial secondary barrier (500) of the insulation system for a liquefied gas storage tank according to one embodiment of the present invention, and may be configured to block or control liquefied gas through the partial secondary barrier (500). In addition, the degree of opening and closing of the valve can be adjusted through the above formula, and the valve may be configured to be controlled by determining the amount of liquefied gas flowing into the partial secondary barrier (500).

[0066] Meanwhile, the insulation system for a liquefied gas storage tank according to one embodiment of the present invention may further include a connecting pipe to collect all of the liquefied gas leaking from the primary barrier (100).

[0067] Specifically, referring to FIG. 3, the leakage passage (400) and partial secondary barrier (500) of the insulation system for a liquefied gas storage tank according to one embodiment of the present invention are located at the bottom of the storage tank, and the leakage passage (400) can be configured to be located at various points at the bottom of the storage tank to collect all of the liquefied gas leaking from the storage tank. In addition, the leakage passage (400) of the insulation system for a liquefied gas storage tank according to one embodiment of the present invention is installed as at least one, and can be formed in a structure combined with a connecting pipe (610) that connects the leakage passages (400) to each other. The connecting pipe (610) can be structured to connect a plurality of leakage passages (400) in series and to allow the liquefied gas to flow to the partial secondary barrier (500) located at the rear end. Meanwhile, the leaked liquefied gas discharged through the leaked passage (400) may be partially vaporized while passing through the connecting pipe (610) connected to the adjacent leaked passage (400), and may finally be completely vaporized and discharged to the outside while passing through the secondary barrier (500) connected to the rearmost leaked passage (400) among the plurality.

[0069] FIG. 4 schematically illustrates the combined structure of an insulation system for a liquefied gas storage tank according to another embodiment of the present invention. In the embodiments described below, identical or similar reference numerals are assigned to configurations identical or similar to those in the preceding example, and the description thereof is replaced by the first one.

[0070] According to another embodiment of the present invention, the leakage passage (400) of the insulation system for a liquefied gas storage tank may be connected to a connecting pipe (620). Specifically, the leakage passage (400) of the insulation system for a liquefied gas storage tank according to another embodiment of the present invention may be provided with at least one, and may be implemented in a structure in which the leakage passage (400) provided with at least one and the connecting pipe (620) are individually connected. In addition, the connecting pipe (620) connected to each leakage passage (400) may be integrated into a single line and connected to a partial secondary barrier (500), or the leakage liquefied gas discharged from a plurality of leakage passages (400) may be collected in a separate leakage liquid collection device (630) and then transferred to the partial secondary barrier (500).

[0071] Accordingly, in this embodiment, the leaked liquefied gas discharged through the leaked passage (400) may be partially vaporized during the process of being transferred to the partial secondary barrier (500) through the connecting pipe (620), and may be entirely vaporized as heat exchange occurs while passing through the partial secondary barrier (500) and finally discharged to the outside of the hull through the gas opening (510).

[0073] Design method for an insulation system for liquefied gas storage tanks

[0074] FIG. 5 is a flowchart showing the process of designing a partial secondary barrier for a standalone Type B liquefied gas storage tank according to one embodiment of the present invention, and FIG. 6 is a flowchart sequentially showing the method of designing an insulation system for a standalone Type B liquefied gas storage tank considering the shape of the optimal partial secondary barrier according to one embodiment of the present invention.

[0076] The present invention is characterized by comprising a liquefied gas selection step (S100) for selecting a liquefied gas, a leakage standard setting step (S200) for setting a leakage standard for the liquefied gas, a shape adoption step (S300) for adopting a shape of a partial secondary barrier, a selection and evaluation step (S400) for selecting a target evaporation rate of the liquefied gas and evaluating the leakage amount of the liquefied gas, a step (S500) for comparing the target evaporation rate of the liquefied gas with the leakage amount of the liquefied gas, a step (S600) for designing the shape of the partial secondary barrier, and a step (S700) for installing the partial secondary barrier.

[0078] The liquefied gas selection step of the partial secondary barrier design method for an insulation system for a standalone Type B liquefied gas storage tank of the present invention selects the type of natural gas to be transported to a distant consumption site (S100). For example, the liquefied gas selected in the selection step may be LNG at atmospheric pressure.

[0080] In the step of setting leakage criteria for the partial secondary barrier design method of the insulation system for a standalone Type B liquefied gas storage tank of the present invention, leakage criteria for liquefied gas are set by considering the physical properties of the liquefied gas and the leakage rate of the liquefied gas (S200). For example, the leakage criteria for liquefied gas at atmospheric pressure flowing out from the leakage passage is set to 200L per hour.

[0081] Furthermore, in the liquefied gas selection and leakage standard setting stages, not only are the type of liquefied gas and leakage standards set, but all requirements serving as criteria for measuring the liquefied gas evaporation rate can also be established. For example, the external ambient temperature of the storage tank is assumed to be -10°, and the partial secondary barrier is set to not be equipped with separate external insulation. Additionally, to accurately evaluate the liquefied gas evaporation rate, all requirements are configured to be identical, except for differences in the shape of the piping.

[0083] According to one embodiment of the present invention, in the shape adoption step of the partial secondary barrier design method for an insulation system for a standalone Type B liquefied gas storage tank of the present invention, the material, diameter, thickness, length, and volume of the partial secondary barrier are set based on the liquefied gas selected in the liquefied gas selection step and the leakage standard set in the leakage standard setting step, and depending on the implementation, the method of extending the length of the partial secondary barrier may be adopted in any one of the straight line, coil, fin tube, or zigzag shape (S300).

[0085] According to one embodiment of the present invention, the selection and evaluation step of the partial secondary barrier design method for an insulation system for a standalone Type B liquefied gas storage tank of the present invention is characterized by selecting a target evaporation rate and evaluating the liquefied gas leakage amount with the partial secondary barrier adopted from the shape adoption step (S400).

[0086] Specifically, in the selection and evaluation stage of the present invention, the target evaporation rate means that the entire amount of leaking liquefied gas is vaporized. For reference, the target evaporation rate is determined according to design standards provided by classification societies, etc., or evaluated through the analysis of the damage size of the primary barrier of the tank.

[0087] Meanwhile, the selection and evaluation step of the target evaporation rate of the present invention sets the material, diameter, thickness, length, and volume of any partial secondary barrier adopted in the shape adoption step, and calculates the target evaporation rate of the liquefied gas to be evaporated. For example, if the amount of liquefied gas leakage passing through the partial secondary barrier is less than the target evaporation rate, the length of the partial secondary barrier may be manufactured to be extended. Furthermore, although the present invention is limited to controlling the amount of evaporation by extending the length of the partial secondary barrier, it is of course possible to manufacture it by applying a different material to the partial secondary barrier and changing the diameter.

[0088] Meanwhile, the partial secondary barrier can be set to an arbitrary length. For example, a design standard for a pipe-type partial secondary barrier was calculated, in which the partial secondary barrier is manufactured with specifications of 50A #40s and the length of the partial secondary barrier is preferably 105m so that the liquefied gas is completely vaporized through the manufactured partial secondary barrier. This allows for the confirmation of a partial secondary barrier design formed with a number of coilings calculated to be approximately 167 times based on a diameter of 200mm.

[0090] According to one embodiment of the present invention, the comparison step of the partial secondary barrier design method for an insulation system for a standalone Type B liquefied gas storage tank of the present invention is a step of comparing the target evaporation rate of the liquefied gas with the leakage rate of the liquefied gas, and may be characterized by returning to the procedure of the shape adoption step if the leakage rate of the liquefied gas is less than the target evaporation rate (S500).

[0092] According to one embodiment of the present invention, the design step for the shape of the partial secondary barrier of the insulation system for a standalone Type B liquefied gas storage tank of the present invention consists of a step of completing the design by determining the shape of the partial secondary barrier that is close to the target evaporation rate (S600). Specifically, based on the evaporation rate at which the liquefied gas flowing into the internal space of the partial secondary barrier is completely vaporized, the material, diameter, thickness, length, volume, and length extension method of the partial secondary barrier may be specified.

[0094] According to one embodiment of the present invention, the step of installing a partial secondary barrier of the insulation system for a standalone Type B liquefied gas storage tank of the present invention is a step in which the installation of a partial secondary barrier, with a fixed length and shape, etc., is actually carried out. (S700).

[0096] A method for designing a partial secondary barrier of an insulation system for a standalone Type B liquefied gas storage tank according to one embodiment of the present invention is sequentially as follows.

[0097] FIG. 6 is a flowchart sequentially illustrating a method for designing an insulation system for a liquefied gas storage tank considering the shape of an optimal partial secondary barrier according to one embodiment of the present invention, and will be explained with reference to FIG. 6.

[0099] First, the leaking liquefied gas is selected, and leakage criteria are established. Specifically, leakage criteria are established by considering all requirements serving as criteria for calculating the liquefied gas evaporation rate, the physical properties of the selected liquefied gas, and the average evaporation rate of the liquefied gas. Additionally, a target evaporation rate is selected by evaluating the target amount of liquefied gas specified by classification societies or an analysis of the damage magnitude to the tank's primary barrier. For reference, the target evaporation rate can be selected at any stage.

[0100] Subsequently, the material, diameter, thickness, length, and volume of the partial secondary barrier are selected in consideration of the leakage criteria of the present invention. Next, the amount of liquefied gas leakage is compared with the target evaporation rate, and if the amount of liquefied gas leakage is greater than or equal to the target evaporation rate, the shape of the partial secondary barrier is determined, and the partial secondary barrier is designed to be manufactured and installed. However, if the amount of liquefied gas leakage is less than the target evaporation rate, the process returns to the step of selecting the shape of the partial secondary barrier. Then, the liquefied gas evaporation rate is evaluated after changing at least one of the material, diameter, thickness, length, and volume of the partial secondary barrier (e.g., increasing the length). With this design method, it becomes possible to manufacture a partial secondary barrier capable of vaporizing the entire amount of liquefied gas, and various forms of partial secondary barriers can be realized by reflecting the conditions that change according to the design procedure.

[0101] In addition to the embodiments described above, the present invention encompasses all embodiments resulting from a combination of at least two of the above embodiments or a combination of at least one of the above embodiments and known technology.

[0102] Although the present invention has been described in detail through specific embodiments, this is for the purpose of specifically explaining the invention, and the invention is not limited thereto. It will be apparent that modifications or improvements can be made by those skilled in the art within the technical scope of the invention.

[0103] All 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 clarified by the appended claims. Explanation of the symbols

[0104] 100: Primary barrier 200: Insulation layer 300: Leakage passage 310: Outlet 400: Leakage Movement Passage 500: Secondary Barrier 210: Gas vent

Claims

Claim 1 A method for designing an insulation system for an independent Type B liquefied gas storage tank, characterized by comprising: a liquefied gas selection step for selecting a liquefied gas; a leakage standard setting step for setting a leakage standard for the liquefied gas; a shape adoption step for adopting a shape of a partial secondary barrier; a selection and evaluation step for selecting a target evaporation rate of the liquefied gas and evaluating the amount of leakage of the liquefied gas; a step for comparing the target evaporation rate of the liquefied gas with the amount of leakage of the liquefied gas; a step for designing the shape of the partial secondary barrier; and a step for installing the partial secondary barrier. Claim 2 A method for designing an insulation system for an independent Type B liquefied gas storage tank, wherein, in claim 1, the leakage criterion of the leakage criterion setting step is composed of the main physical properties of the liquefied gas and the leakage rate selected from the selection step. Claim 3 A design method for an insulation system for an independent Type B liquefied gas storage tank, characterized in that, in the shape adoption step, the material, diameter, thickness, length, and volume of the partial secondary barrier are set based on the leakage criteria, and a method for extending the length of the partial secondary barrier is adopted. Claim 4 A design method for an insulation system for an independent Type B liquefied gas storage tank, characterized in that, in the selection and evaluation step, a target evaporation rate is selected, and the amount of liquefied gas leakage is evaluated by reflecting the piping shape of the partial secondary barrier and the arbitrary length reference volume adopted from the shape adoption step. Claim 5 A method for designing an insulation system for a standalone Type B liquefied gas storage tank, characterized in that, in the comparison step, the target evaporation rate and the liquefied gas leakage amount are compared, and if the liquefied gas leakage amount is less than the target evaporation rate, the process returns to the shape adoption step. Claim 6 A design method for an insulation system for a standalone Type B liquefied gas storage tank, characterized in that, in the shape adoption step of claim 5, the length of the partial secondary barrier is reconfigured to be extended. Claim 7 A method for designing an insulation system for an independent Type B liquefied gas storage tank, wherein, in paragraph 3, the above-mentioned secondary barrier is formed as a pipe having an internal space and is formed in any one of a straight line, a curve, a zigzag, a spring, or a radial shape to extend its length. Claim 8 A vessel comprising an insulation system and design method for a standalone Type B liquefied gas storage tank according to any one of paragraphs 1 through 7.

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