KR102576201B1 - Insulation Structure of LNG Storage Tank - Google Patents

Abstract

A heat insulation structure of a liquefied natural gas storage tank is disclosed. The present invention includes a secondary insulation wall consisting of a plurality of secondary insulation panels arranged on the inner wall of the hull, a secondary sealing wall installed on the secondary insulation wall, and a plurality of primary insulation panels on the secondary sealing wall. In a liquefied natural gas storage tank in which an arranged primary insulation wall and a primary sealing wall installed on the primary insulation wall are sequentially laminated, a primary sealing wall and a secondary sealing wall are installed at the corners of the storage tank. transverse connectors supporting the wall; And an insulation box installed between the transverse connector and the hull to support the transverse connector, wherein the primary insulation panel and secondary insulation panel include plywood plywood on at least one of the upper and lower surfaces of the polyurethane foam. It is provided in the form of a glued sandwich panel, and the plywood plywood provided in the insulation panel disposed adjacent to the insulation box among the primary and secondary insulation panels has an inclined surface whose thickness increases toward the corner of the storage tank. It provides a heat insulation structure of a liquefied natural gas storage tank, characterized in that it comprises a.

Description

Insulation structure of liquefied natural gas storage tank {Insulation Structure of LNG Storage Tank}

The present invention relates to an insulation structure for a liquefied natural gas storage tank, and more specifically, to an insulation structure for a liquefied natural gas storage tank that prevents buckling of the sealing wall due to height differences occurring at the corners of the storage tank. It's about.

Natural gas is transported in gaseous form through onshore or offshore gas pipelines, or stored in LNG carriers as liquefied natural gas (Liquefied Natural Gas (LNG)) and transported to distant consumers. LNG is obtained by cooling natural gas to extremely low temperatures (approximately -163°C), and its volume is reduced to approximately 1/600 of that of gaseous natural gas, making it very suitable for long-distance transportation by sea.

Structures for transporting or storing LNG, such as LNG carriers that carry LNG on the sea and unload it at land-based destinations, are equipped with storage tanks (commonly referred to as 'cargo holds') that can withstand the extremely low temperatures of LNG.

LNG storage tanks can be classified into independent tank type and membrane type depending on whether the load of the cargo acts directly on the insulation material. Typically, membrane-type storage tanks are divided into GTT's NO 96 type and MARK Ⅲ type, and independent tank-type storage tanks are divided into MOSS type and IHI-SPB type.

The NO 96 type storage tank has primary and secondary sealing walls made of an Invar (36% nickel steel) membrane with a thickness of 0.5 to 0.7 mm, and insulation materials such as perlite powder in a plywood box. It includes primary and secondary insulation walls provided in the form of a filled insulation box.

The NO 96 type storage tank has almost the same level of liquid tightness and strength as the primary sealing wall and the secondary sealing wall, so when the primary sealing wall leaks, the cargo can be safely supported with only the secondary sealing wall for a considerable period of time.

In addition, the NO 96 type storage tank has an insulation wall filled with insulation inside a wooden box, so it can have higher compressive strength and rigidity compared to the MARK Ⅲ type storage tank, and the automation rate is high due to easy welding.

The MARK III type storage tank has a primary sealing wall made of a 1.2mm thick stainless steel (SUS) membrane, a secondary sealing wall made of triplex, and a top or bottom surface of polyurethane foam. It includes primary and secondary insulation walls provided with insulation panels bonded with wood plywood.

The primary sealing wall of the MARK III type storage tank has wave-shaped wrinkles to absorb heat contraction caused by LNG in a cryogenic state, and these wave-shaped wrinkles absorb membrane deformation, so no significant stress is generated within the membrane.

The MARK Ⅲ type storage tank has a disadvantage in terms of installation/manufacturing due to the low welding automation rate of the primary sealing wall with corrugations, but compared to the Invar membrane, the stainless steel membrane and triplex are cheaper and easier to construct, and polyurethane Foam has an excellent insulation effect and is widely used.

The technical problem to be achieved by the present invention is to provide an insulation wall of a liquefied natural gas storage tank composed of an insulation panel made of polyurethane foam, and a secondary sealing wall composed of a flat invar membrane. The goal is to provide an improved panel type insulation system that is capable of doing so.

In addition, another technical problem to be achieved by the present invention is to develop a liquefied natural gas storage tank that can minimize the height difference problem occurring at the corners of a liquefied natural gas storage tank equipped with an improved insulation system as described above. to provide an insulating structure.

In order to achieve the above object, the present invention includes a secondary insulation wall consisting of a plurality of secondary insulation panels arranged on the inner wall of the hull, a secondary sealing wall installed on the secondary insulation wall, and the secondary insulation wall. In a liquefied natural gas storage tank in which a primary insulation wall consisting of a plurality of primary insulation panels arranged on the sealing wall and a primary sealing wall installed on the primary insulation wall are sequentially stacked, the storage tank A transverse connection body installed at a corner portion to support the primary sealing wall and the secondary sealing wall; and an insulation box installed between the transverse connector and the hull to support the transverse connector, wherein at least one of the primary insulation panel and the secondary insulation panel has an upper surface and a lower surface of polyurethane foam. It is provided in the form of a sandwich panel in which plywood plywood is glued to at least one of the above, and among the insulation panels provided in the sandwich panel form, the plywood plywood provided in the insulation panel disposed adjacent to the insulation box is the storage tank. It provides an insulating structure for a liquefied natural gas storage tank, characterized in that it includes an inclined surface whose thickness increases toward the corner of.

The insulation box may be provided as a plywood box filled with insulation material inside.

The secondary sealing wall is made of a flat invar membrane, and the transverse connector is a grid-shaped structure made of an invar material, and is located at both ends of the primary and secondary sealing walls. can support

The primary sealing wall may be made of a stainless steel (SUS) membrane including a plurality of wrinkles formed toward the inside of the storage tank.

Among the primary insulation panel and the secondary insulation panel, the insulation panel disposed adjacent to the transverse connector may be made of polyurethane foam with a higher strength than the remaining insulation panels.

In addition, in order to achieve the above object, the present invention includes a secondary insulation wall installed on the inner wall of the hull, a secondary sealing wall installed on the secondary insulation wall, and 1 installed on the secondary sealing wall. In a liquefied natural gas storage tank in which a secondary insulation wall and a primary sealing wall installed on the primary insulation wall are sequentially laminated, the secondary insulation wall is in the form of plywood plywood glued to polyurethane foam. A plurality of secondary insulation panels are arranged on the inner wall of the hull, and the secondary sealing wall is made of an Invar membrane, and both ends are supported by a transverse connector installed at the corner of the storage tank, The load acting on the secondary sealing wall is transmitted to the hull through the transverse connector, and the transverse connector is provided as a grid-shaped structure, and the interior of the transverse connector and the transverse connector and the hull An insulation box for supporting the transverse connector is installed between them, and among the secondary insulation panels, the insulation panel disposed adjacent to the insulation box is made of plywood plywood for the entire thickness toward the corner of the storage tank. Provides an insulation structure for a liquefied natural gas storage tank, characterized in that the proportion of thickness gradually increases.

The liquefied natural gas storage tank according to the present invention is a storage tank of liquefied natural gas in which the primary and secondary insulation walls are provided as a panel type made of polyurethane foam, and the secondary sealing wall can be composed of a flat invar membrane. In addition to providing an insulating structure, it also provides a solution to the problem of buckling of the sealing wall due to height differences occurring at the corners of the storage tank.

Specifically, the present invention provides the upper plywood and lower plywood of the border panel disposed between the border box and the insulation panel disposed at the corner of the liquefied natural gas storage tank in a form where the thickness increases toward the corner of the storage tank. Accordingly, the height difference that occurs between the border box and the insulation panel during heat shrinkage at extremely low temperatures is made more gentle, thereby preventing buckling in the sealing wall provided with the metal membrane.

Figure 1 is an internal perspective view schematically showing the insulation structure of a liquefied natural gas storage tank according to the present invention.
Figure 2 is a side cross-sectional view showing the insulation structure of a liquefied natural gas storage tank according to an embodiment of the present invention.
Figure 3 is a side cross-sectional view showing the insulation structure of a liquefied natural gas storage tank according to another embodiment of the present invention.

In order to fully understand the present invention, its operational advantages, and the objectives achieved by practicing the present invention, reference should be made to the accompanying drawings illustrating preferred embodiments of the present invention and the contents described in the accompanying drawings.

Hereinafter, the present invention will be described in detail by explaining preferred embodiments of the present invention with reference to the attached drawings. The same reference numerals in each drawing indicate the same member.

In the present invention, the use of the terms 'primary' and 'secondary' refers to the function of primarily sealing or insulating LNG, or the function of secondary sealing or insulating, based on the LNG stored in the storage tank. It is used as a criterion for distinguishing whether or not it is.

Additionally, by convention, the terms 'top' or 'above' applied to elements of a tank refer to a direction towards the inside of the tank, regardless of the direction with respect to gravity, and likewise, the terms 'bottom' or 'below' refer to a direction towards the inside of the tank, regardless of the direction with respect to gravity. Regardless of the direction, it points toward the outside of the tank.

Figure 1 is an internal perspective view schematically showing the insulation structure of a liquefied natural gas storage tank according to the present invention, Figure 2 is a side cross-sectional view showing the insulation structure of a liquefied natural gas storage tank according to an embodiment of the present invention, and Figure 3 is a side cross-sectional view showing the insulation structure of a liquefied natural gas storage tank according to another embodiment of the present invention.

Referring to Figures 1 and 2, the liquefied natural gas storage tank according to the present invention includes a secondary insulation wall 100 made of a plurality of secondary insulation panels 110 arranged on the inner wall of the hull (H), A primary insulation wall (300) consisting of a secondary sealing wall (200) installed on the secondary insulation wall (100) and a plurality of primary insulation panels (310) arranged on the secondary sealing wall (200). , It can be seen that the structure including the primary sealing wall 400 installed on the primary insulating wall 300.

The secondary insulation panel 110 forming the secondary insulation wall 100 is manufactured as a unit panel in the shape of a hexahedron, and a plurality of secondary insulation panels 110 are arranged in the horizontal and longitudinal directions on the inner wall of the hull (H). By doing so, it is possible to form the secondary insulation wall 100 .

The primary insulation panel 310 forming the primary insulation wall 300 is similarly manufactured as a unit panel in the form of a hexahedron, and a plurality of primary insulation panels 310 are installed on the secondary sealing wall 200 in the horizontal and vertical directions. By being arranged in the direction, it is possible to form the primary heat insulation wall (300).

The first and second insulation panels 310 and 110 may be prepared as sandwich panels in which plywood plywood is bonded to the top or bottom of polyurethane foam (PUF), or both.

In addition, the first and second insulation panels 310 and 110 are made of reinforced poly, which has higher rigidity than general polyurethane foam, in order to configure the secondary sealing wall 200 as a flat invar membrane in a flat shape, as will be described later. It is preferably made of urethane foam (Rigid Polyurethane Foam, RPUF).

The secondary insulation wall 100 may be fixed to the inner wall of the hull (H) with an adhesive such as epoxy mastic or studs, and the primary insulation wall 300 may be attached to the secondary insulation wall 100. With the secondary sealing wall 200 interposed between them, the primary insulation panel 310 is coupled to a securing device provided on the upper part of the secondary insulation panel 110, thereby creating a secondary sealing wall ( 200) can be tightly fixed to the upper part.

The secondary sealing wall 200 may be made of a flat Invar membrane. Specifically, a strip-shaped metal plate called an invar strake is continuously welded to a tongue member installed on the upper part of the secondary insulation panel 110, thereby forming the secondary sealing wall 200. It can be installed on the upper part of the secondary insulation wall 100.

A through hole may be formed in the secondary sealing wall 200 to allow a stud bolt included in a fixing device provided on the upper part of the secondary insulation panel 110 to pass through.

The primary sealing wall 400 is in direct contact with and seals the LNG, and may be made of a stainless steel (SUS) membrane with multiple corrugations formed toward the inside of the storage tank to absorb shrinkage caused by cryogenic temperatures.

The primary sealing wall 400 may be made of a plurality of unit membranes having sizes corresponding to the unit panels of the primary insulation panel 310, and a plurality of unit membranes are provided on the upper part of the primary insulation panel 310. By welding to the anchor strip without any gaps, the primary sealing wall 400 can be installed on the upper part of the primary insulation wall 300.

The liquefied natural gas storage tank according to the present invention is provided with a panel type insulation system in which the insulation walls (100, 300) are in the form of insulation panels in which wood plywood is bonded to the upper and/or lower surfaces of polyurethane foam. , The secondary sealing wall 200 is characterized in that it is composed of a flat Invar membrane of a flat shape.

Typically, flat Invar membranes have a low heat contraction coefficient, so they are not suitable for panel-type insulation systems where the insulation panels are made of polyurethane foam. In order to apply a flat Invar membrane, like a conventional NO 96 type storage tank, the insulation wall supporting the membrane must be composed of an insulation box with low heat shrinkage deformation and high rigidity.

However, in the present invention, by providing a structure to reinforce the rigidity of the secondary insulation wall 100, the secondary insulation wall 100 is provided in the form of an insulation panel (made of polyurethane foam) rather than an insulation box, and secondary sealing is achieved. This makes it possible to construct the wall 200 with a flat Invar membrane.

Specifically, the present invention reinforces the rigidity of the secondary insulation wall 100 by installing a transverse connector 500 at the corner of the storage tank to support both ends of the secondary sealing wall 200.

The transverse connector 500 is a grid-shaped structure installed along the edges of the front and rear walls of the storage tank, and one end is welded to an anchoring bar provided on the inner wall of the hull and is fixed to the corner of the storage tank. It is installed, and the other end supports both ends of the primary sealing wall 400 and the secondary sealing wall 200, thereby serving to transmit various loads applied to them to the hull (H).

The transverse connector 500 is preferably made of a highly rigid Invar material, and between the interior of the transverse connector 500 and the transverse connector 500 and the hull (H), a transverse connector ( An insulating box 510 with high rigidity may be interposed to support 500). The insulation box 510 may be provided in a plywood box filled with an insulation material such as perlite powder.

In this way, in the present invention, part of the load applied to the primary and secondary sealing walls (400, 200) is transferred to the hull (H) by the transverse connector (500) installed at the corner of the storage tank, so that it is relieved. , it is possible to construct the secondary insulation wall 100, which supports the secondary sealing wall 200, which is provided with a flat Invar membrane, with an insulation panel that is less rigid than the insulation box.

Therefore, in the present invention, when installing the secondary sealing wall 200 on the upper part of the secondary insulation wall 100, a welding line can be formed as a straight line, and thus automation of welding is possible, thereby improving productivity. There is an effect.

In addition, according to the present invention, as the first and second heat insulating walls 300 and 100 are made of polyurethane foam, heat insulating performance is also excellent. The liquefied natural gas storage tank according to the present invention has a thickness of the primary insulation wall of approximately 40% or more and a thickness of the secondary insulation wall, compared to a conventional NO 96 type storage tank in which the insulation wall is provided in the form of an insulation box. It is possible to achieve the same insulating effect while reducing by about 20% or more.

Meanwhile, in the liquefied natural gas storage tank according to the present invention as described above, the lower part of the sealing wall (200, 400) is generally supported by the insulation panel (110, 310) made of polyurethane foam, while the storage tank's The transverse connector 500 installed at the corner is supported by the insulation box 510.

That is, the liquefied natural gas storage tank according to the present invention is composed of insulation panels (110, 310) in which most of the insulation walls (100, 300) are made of polyurethane foam, but an insulation box (510) is formed at the corners of the storage tank. have a mixed structure.

However, at this time, the rigidity of the insulation box 510 installed at the corner is high, while the rigidity of the insulation panels 110 and 310 is low, so there is a difference in the degree of heat shrinkage between the insulation box 510 and the insulation panels 110 and 310. .

Therefore, during heat contraction by cryogenic LNG, a height difference occurs between the insulation box 510 and the insulation panels 110 and 310, and this height difference causes the sealing walls 200 and 400 made of a metal membrane to buckle. There is a possibility that the following phenomenon may occur.

In order to solve this problem, the present invention uses an insulation panel (hereinafter referred to as a 'border panel') disposed adjacent to the insulation box 510 at the corner of the storage tank among the primary and secondary insulation panels 310 and 110. It is prepared with high-density polyurethane foam that has higher stiffness than the remaining insulation panels (310, 110).

Accordingly, from the insulation box (hereinafter referred to as 'border box') placed on the side of the transverse connector 500, to the border panel (310', 110'), and to the remaining insulation panels (310, 110). It is arranged so that the stiffness gradually decreases.

According to this arrangement, the insulation height according to the difference in the degree of thermal contraction can be gradually achieved as it moves from the border box (510', 510'') to the insulation panels (310, 110), so that the primary and secondary sealing walls Buckling can be prevented from occurring at (400, 200).

In the embodiment shown in FIG. 3, an insulation structure of a liquefied natural gas storage tank according to another embodiment of the present invention is shown to prevent the buckling phenomenon of the sealing walls 200 and 400 as described above.

Referring to Figure 3, in the liquefied natural gas storage tank according to another embodiment of the present invention, the insulation height according to the difference in the degree of heat shrinkage increases as it moves from the border box (510', 510'') to the insulation panel (310, 110). It can be said that the shapes of the border panels 310' and 110' are improved so that they can be made gently.

In this embodiment, the border panels (310', 110') are composed of insulation materials (311', 111') made of polyurethane foam (PUF) or reinforced polyurethane foam (RPUF), and insulation materials (311', 111'). It includes upper plywood (312', 112') and lower plywood (313', 113') that are bonded to the upper and lower surfaces, respectively, to provide mechanical rigidity to the panel.

At this time, as shown in the drawing, the upper plywood (312', 112') and the lower plywood (313', 113') move away from the corner side of the storage tank after the corner side end of the storage tank progresses to a certain thickness. It may be provided in a form where the thickness decreases as the thickness increases.

That is, the upper plywood (312', 112') and the lower plywood (313', 113') of the border panels (310', 110') have an inclined surface (S) whose thickness increases toward the corner of the storage tank. Accordingly, the proportion of the thickness of the plywood plywood (312', 313', 112', 113') to the total thickness of the border panel (310', 110') gradually increases toward the corner of the storage tank. It can increase.

According to this configuration, the height difference that occurs between the border boxes (510', 510'') and the insulation panels (310, 110) during heat shrinkage by cryogenic temperature can be made more gentle.

In this way, if the thickness of the upper plywood (312', 112') and the lower plywood (313', 113') of the border panel (310', 110') is provided in a form with a slope, otherwise (the thickness of the plywood It was verified through actual simulation that the height difference with the insulation box 510 can be reduced by at least 0.3 mm compared to the case where is provided consistently.

In this embodiment, between the border boxes (501', 510''), which are highly rigid in cryogenic conditions, and the relatively flexible insulation panels (310, 110), the upper plywood (312', 112') with an inclined thickness is provided. and lower plywood (313', 113') by arranging the border panels (310', 110') between the border boxes (510', 510'') and the insulation panels (310, 110) during heat shrinkage due to cryogenic temperatures. The height difference can be made more gently, which can have a beneficial effect on the structural behavior of the sealing walls 400 and 200 made of a metal membrane.

In this way, the liquefied natural gas storage tank according to the present invention is provided with a panel-type insulation structure including insulation walls 100 and 300 made of polyurethane foam, and the secondary sealing wall 200 is formed in a flat shape. It is possible to construct it with an Invar membrane, and it can be said to provide a solution to the problem of buckling of the sealing walls 200 and 400 that may occur accordingly.

The present invention is not limited to the described embodiments, and it is obvious to those skilled in the art that various modifications and changes can be made without departing from the spirit and scope of the present invention. Therefore, it should be said that such modifications or variations fall within the scope of the claims of the present invention.

100: secondary insulation wall 110: secondary insulation panel
110': Secondary border panel 111': Secondary insulation material
112': Secondary upper plywood 113': Secondary lower plywood
200: secondary sealing wall
300: Primary insulation wall 310: Primary insulation panel
310': Primary border panel 311': Primary insulation material
312': 1st upper plywood 313': 1st lower plywood
500: Transverse connector 510: Insulation box
510': Primary border box 510'': Secondary border box

Claims (6)

A secondary insulation wall consisting of a plurality of secondary insulation panels arranged on the inner wall of the hull, a secondary sealing wall installed on the secondary insulation wall, and a plurality of primary insulation panels arranged on the secondary sealing wall. In a liquefied natural gas storage tank in which a primary insulation wall consisting of a primary insulation wall and a primary sealing wall installed on the primary insulation wall are sequentially stacked,
a transverse connector installed at a corner of the storage tank to support the primary sealing wall and the secondary sealing wall; and
It includes an insulation box installed between the transverse connector and the hull to support the transverse connector,
At least one of the primary insulation panel and the secondary insulation panel is provided in the form of a sandwich panel in which plywood plywood is bonded to at least one of the upper and lower surfaces of polyurethane foam,
Among the insulation panels provided in the form of sandwich panels, the plywood plywood provided on the insulation panel disposed adjacent to the insulation box is characterized in that it includes an inclined surface whose thickness increases toward the corner of the storage tank. ,
Insulation structure of a liquefied natural gas storage tank. In claim 1,
The insulation box is characterized in that it is a plywood box filled with insulation material inside.
Insulation structure of a liquefied natural gas storage tank. In claim 2,
The secondary sealing wall is made of a flat invar membrane,
The transverse connector is a grid-shaped structure made of Invar material, and supports both ends of the primary and secondary sealing walls.
Insulation structure of a liquefied natural gas storage tank. In claim 3,
The primary sealing wall is characterized in that it is made of a stainless steel (SUS) membrane including a plurality of wrinkles formed toward the inside of the storage tank.
Insulation structure of a liquefied natural gas storage tank. In claim 2,
Among the primary insulation panel and the secondary insulation panel, the insulation panel disposed adjacent to the transverse connector is characterized in that it is made of polyurethane foam with a higher strength than the remaining insulation panels,
Insulation structure of a liquefied natural gas storage tank. A secondary insulation wall installed on the inner wall of the hull, a secondary sealing wall installed on the secondary insulation wall, a primary insulation wall installed on the secondary sealing wall, and installed on the primary insulation wall In a liquefied natural gas storage tank in which the primary sealing walls are sequentially stacked,
The secondary insulation wall is formed by arranging a plurality of secondary insulation panels in the form of plywood plywood glued to polyurethane foam on the inner wall of the hull,
The secondary sealing wall is made of an Invar membrane, and both ends are supported by a transverse connector installed at the corner of the storage tank, so that the load acting on the secondary sealing wall is transmitted to the hull through the transverse connector. is transmitted to,
The transverse connector is provided as a grid-shaped structure, and an insulation box is installed inside the transverse connector and between the transverse connector and the hull to support the transverse connector,
Among the secondary insulation panels, the insulation panel disposed adjacent to the insulation box is characterized in that the proportion of the thickness of the plywood plywood to the total thickness gradually increases toward the corner of the storage tank,
Insulation structure of a liquefied natural gas storage tank.

Images