KR20230166274A - Membrane sheet having improved shape for welding easiness and liquefied gas insulation system including the same - Google Patents

Abstract

Disclosed is a membrane sheet having wrinkles with an improved shape for welding ease. In a storage tank storing liquefied gas, a large number of the membrane sheets are continuously connected by welding for sealing the liquefied gas. The membrane sheets include a wave-shaped wrinkle formed in a shape of protruding or being indented on a metal sheet for absorbing the thermal contraction by an extremely low temperature of liquefied gas or the deformation by the deformation of a hull. The wave-shaped wrinkle is divided into a welding unit formed on an edge of the metal sheet, and a non-welding unit continuously connected to the welding unit and formed on an inner side of the metal sheet. The cross-sections of the welding unit and the cross-sections of the non-welding unit have different shapes from each other. Therefore, an effective response can be made to the load of the hull and the thermal load, and automatic welding can be effectively conducted.

Description

Membrane sheet having improved shape for welding easiness and liquefied gas insulation system including the same}

The present invention relates to a membrane sheet having an improved form of wrinkles for ease of welding and a liquefied gas insulation system including the same. More specifically, the wrinkles formed to absorb cryogenic heat shrinkage are divided into a welded portion and a non-welded portion. It relates to a membrane sheet that can effectively respond to hull loads and thermal loads by being configured to have different cross-sectional shapes, as well as to effectively perform automatic welding, and a liquefied gas insulation system including the same.

Liquefied Natural Gas (LNG) is obtained by cooling natural gas to a cryogenic temperature of approximately -163°C. Its volume is reduced to approximately 1/600 of that in gaseous form, making it very suitable for long-distance transportation by sea. Suitable.

Structures for transporting or storing LNG, such as LNG carriers (LNGCs) that transport LNG at sea and unload it at land destinations, have specially designed storage tanks (commonly referred to as 'cargo holds') to withstand the extremely low temperatures of LNG. ) is installed.

In general, in order to safely store cryogenic LNG, LNG storage tanks are composed of an insulation system consisting of one or more barriers made of metal membranes and an insulation layer surrounding the barrier. Depending on whether the load of the cargo acts directly on the insulation, the membrane type can be used. It can be divided into (membrane type) and independent type.

A membrane-type storage tank is a tank manufactured as one piece with the hull structure. The insulation system consists of a double seal structure in which a secondary insulation layer, a secondary barrier, a primary insulation layer, and a primary barrier are sequentially stacked on the inner wall of the hull. Representative membrane-type storage tanks include GTT's NO 96 type and MARK Ⅲ type.

The NO 96 type storage tank consists of insulation boxes filled with insulation materials such as perlite powder or glass wool inside a plywood box, and the primary and secondary insulation layers are composed of each It is a structure in which an invar steel (36% nickel steel) membrane with a thickness of 0.5 to 0.7 mm is installed on the top of the insulation layer to form a barrier.

The NO 96 type storage tank has almost the same level of liquid tightness and strength as the primary barrier and the secondary barrier, so when the primary barrier leaks, the secondary barrier alone can safely support the cargo for a considerable period of time. It is composed of an insulated box. The advantage is that the insulation layer can have high compressive strength and rigidity, and the automation rate of welding is high.

The MARK Ⅲ type storage tank consists of primary and secondary insulation layers made of insulation panels made by attaching wood plywood to the upper and lower surfaces of polyurethane foam (PUF), with a thickness of approximately 1.2 mm on top of the primary insulation layer. A thick stainless steel (SUS) membrane is installed to form a primary barrier, and a composite material called triplex is installed on top of the secondary insulation layer to form a secondary barrier.

The MARK Ⅲ type storage tank is advantageous in terms of BOR (Boil-Off Rate) due to the excellent insulation effect of the insulation panel based on polyurethane foam insulation, but is vulnerable to thermal deformation or hull deformation due to the flexible nature of the insulation panel. has Therefore, it is difficult to apply the Invar steel membrane with a low heat contraction coefficient used in the NO 96 type to the MARK Ⅲ type storage tank. Instead, it has a structure that absorbs heat shrinkage deformation by forming a primary barrier with a stainless steel membrane with corrugated corrugations.

In addition, the stainless steel membrane with corrugations has a protruding structure, making it difficult to install between the first and second insulation layers. Therefore, in the current MARK Ⅲ type storage tank, the secondary barrier is called a triplex instead of a metal membrane. It is composed of composite materials. However, the MARK III type storage tank in which the secondary barrier is composed of a triplex composite material has the disadvantage of being vulnerable to watertightness compared to the insulation system in which both the primary and secondary barriers are composed of metal barriers.

In the above, the insulation system in which the insulation layer consists of insulation boxes, such as the NO 96 type storage tank, is called a box type insulation system. In distinction from this, the insulation layer is based on polyurethane foam insulation, such as the MARK Ⅲ type storage tank. An insulation system composed of one insulation panel is also called a panel type insulation system.

Meanwhile, the insulation layer is made up of insulation panels made based on polyurethane foam insulation, which basically takes a panel-type structure, but instead of installing a barrier between the first and second insulation layers, two barriers are built in succession over the entire insulation layer. The KC-1 type storage tank has been developed and is known. The specific structure of the KC-1 type storage tank is clearly shown in Republic of Korea Patent Publication No. 10-0644217 (November 10, 2006).

However, the KC-1 type storage tank has a risk in that the insulation panels that make up the insulation layer are not connected. In a KC-1 type storage tank in which the insulation panels are not connected to each other, the disadvantage of the panel-type insulation system, which is vulnerable to thermal deformation or hull deformation, may be more significant. In addition, the KC-1 type storage tank is structurally very vulnerable to external deformation because the members installed between the first and second barriers are connected to the inner wall of the hull, and heat loss through the connection with the hull also occurs significantly. It has a fatal flaw.

In the MARK III type or KC-1 type storage tank insulation system described above, the membrane constituting the barrier may be wrinkled to absorb heat shrinkage due to cryogenic temperatures. Referring to FIG. 1, a conventional membrane sheet (MS ) is formed so that the wrinkles (C) have a constant cross-section over the entire length from the edge end of the sheet to the opposite end. Sometimes, joggling processing is performed on the wrinkles (C) for overlap welding between neighboring membrane sheets (MS), but this is a form of simply reducing/increasing the magnification of the wrinkles (C), and the cross-sectional shape of the wrinkles is It doesn't change anything.

The present invention seeks to present a new type of liquefied gas insulation system that can take advantage of both the panel-type insulation system, which has excellent insulation performance, and the double metal barrier structure, which is strong against water and is structurally advantageous.

In other words, the present invention enables the application of a double metal barrier structure to a panel-type insulation system that is advantageous in terms of BOR by applying a polyurethane foam-based insulation material, thereby providing superior performance compared to existing products in terms of both insulation performance and structural stability. The purpose is to provide an improved liquefied gas insulation system that can be equipped.

In particular, in implementing a double metal barrier in a panel-type insulation system, the present invention forms multiple wave-shaped wrinkles in the primary and secondary barriers composed of metal membranes to effectively respond to hull load and thermal load, while providing insulation. We would like to propose an improved corrugation form of the membrane sheet that enables effective automatic welding when fixed to the system through welding.

The technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the description below.

According to one aspect of the present invention for achieving the above object, a plurality of membrane sheets are continuously connected by welding to seal the liquefied gas inside a storage tank in which the liquefied gas is stored, wherein the liquefied gas It includes wave-shaped wrinkles formed in a raised or depressed form on the metal sheet to absorb heat shrinkage due to cryogenic temperatures or deformation due to hull deformation, and the wave-shaped wrinkles include a weld formed at an edge of the metal sheet and the welded portion. A membrane having an improved form of wrinkles for ease of welding, characterized in that the cross-sectional shapes of the welded portion and the non-welded portion are formed differently from each other, and is continuously continuous with a non-welded portion formed on the inside of the metal sheet. Sheets may be provided.

The welded portion may be wider and lower in height than the non-welded portion.

The non-welded portion has a cross-sectional shape of a '∩' shape to enable effective response to buckling and thermal load, and the welded portion has a '∧' shaped shape or a gentler curvature than the non-welded portion to enable efficient automatic welding. It may have a '∩' shaped cross-sectional shape.

The welded portion and the non-welded portion may be flexibly connected to each other.

Additionally, the present invention can provide a liquefied gas insulation system including a membrane sheet having the above characteristics.

The liquefied gas insulation system according to the present invention is basically a panel-type insulation system in which the insulation layer is composed of an insulation panel based on polyurethane foam insulation, and can have excellent insulation performance compared to a box-type insulation system.

In addition, the liquefied gas insulation system according to the present invention realizes double airtightness by a double metal barrier continuously installed on the upper part of the insulation layer, so the disadvantage of the conventional MARK III storage tank being vulnerable to watertightness can be complemented, and thus excellent Not only does it have insulation performance, but it also ensures high reliability of the insulation system.

The liquefied gas insulation system according to the present invention is characterized in that the wrinkles formed on the primary barrier protrude toward the inside of the storage tank, and the wrinkles formed on the secondary barrier protrude toward the outside of the storage tank, that is, toward the hull. , According to this structure of the present invention, interference due to wrinkles does not occur between the first and second barriers, so the structure or shape of the inter-barrier structures placed in the corresponding space can be simplified, and the installation structure of the inter-barrier structures can be greatly improved. Simplification can be expected to greatly improve the constructability of the liquefied gas storage tank and shorten the total drying period.

In addition, the present invention divides the wrinkles formed for the purpose of absorbing cryogenic heat shrinkage on the membrane sheet constituting the barrier into a welded area and a non-welded area and configures them to have different cross-sectional shapes, thereby effectively responding to hull load and thermal load. Not only is this possible, but it also has the effect of enabling effective automatic welding when installing barriers.

The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description below.

Figure 1 is a diagram showing a conventional membrane sheet.
Figure 2 is a diagram showing an insulation system in which the wrinkles of the first and second barriers installed adjacently are all directed toward the inside of the storage tank.
Figure 3 is a cross-sectional view of the liquefied gas storage tank insulation system according to the present invention.
Figure 4 is a perspective view showing the layered structure of the liquefied gas storage tank insulation system according to the present invention.
Figure 5 is a diagram showing a membrane sheet according to the present invention.
FIG. 6 is an enlarged view of the portion indicated by A in FIG. 5 and shows two types of wrinkle welds.
Figure 7 is a view showing the cross-sectional shape of the non-welded portion and the welded portion of the wrinkle formed on the membrane sheet according to the present invention.

In order to fully understand the present invention, its operational advantages, and the purposes and effects 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.

Matters expressed in the drawings attached to this specification may be somewhat different from the form actually implemented in schematic drawings to easily explain the embodiments of the present invention, and the sizes of each component shown in the drawings are for explanatory purposes. It can be exaggerated or reduced and does not mean the size that is actually applied.

Additionally, the terms used herein are merely used to describe specific embodiments and are not intended to limit the invention. For example, in this specification, “including” a certain component does not mean excluding other components, but may further include other components, unless specifically stated to the contrary.

In addition, it should be understood that saying that a component is 'connected' to another component includes direct connection as well as indirect connection, and that other components may exist between the two components. Singular expressions may be interpreted to include plural expressions unless the context clearly indicates otherwise.

The liquefied gas storage tank described in this specification includes LNG, a representative liquefied gas, LPG (Liquefied petroleum gas), LEG (Liquefied Ethane Gas), Liquefied Ethylene Gas, Liquefied Propylene Gas, etc. It may include all storage tanks that store various types of liquefied gases that can be liquefied at low temperatures and stored/transported.

In this specification, the terms 'primary' and 'secondary' for liquefied gas storage tanks are used to indicate whether the liquefied gas is primarily sealed or insulated based on the liquefied gas stored inside the storage tank, or secondarily sealed. Or, it was used as a standard for whether or not it was insulated.

In addition, the terms 'upper', 'top' or 'top' conventionally applied to liquefied gas storage tanks refer to the direction toward the inside of the tank regardless of the direction of gravity, and similarly, the terms 'lower' and 'lower' Alternatively, 'down' refers to the direction towards the outside of the tank, regardless of the direction with respect to gravity.

Hereinafter, the present invention will be described in detail by explaining preferred embodiments of the present invention with reference to the accompanying drawings. The embodiments described below are provided so that those skilled in the art can easily understand the technical idea of the present invention, and the present invention is not limited thereto.

Figure 2 is a diagram showing an insulation system in which the wrinkles of the first and second barriers installed adjacently are all directed toward the inside of the storage tank. Figure 3 is a cross-sectional view of the liquefied gas storage tank insulation system according to the present invention, and Figure 4 is a perspective view showing the layered structure of the liquefied gas storage tank insulation system according to the present invention. FIG. 5 is a view showing a membrane sheet according to the present invention, and FIG. 6 is an enlarged view of the portion indicated by A in FIG. 5, showing two types of wrinkle welds. And Figure 7 is a view showing the cross-sectional shape of the non-welded portion and the welded portion of the wrinkle formed on the membrane sheet according to the present invention.

As described above, the present invention seeks to provide a liquefied gas insulation system in which a double metal barrier is installed on the upper part of an insulation layer based on a polyurethane foam-based insulation material. At this time, the double metal barrier is composed of a primary membrane that provides primary airtightness while in direct contact with the liquefied gas, and a secondary membrane that provides secondary airtightness when the primary barrier leaks. You can.

In addition, as the present invention uses an insulation panel with relatively flexible properties, it is intended to apply stainless steel or low-temperature steel with similar properties as the material for both the primary and secondary barriers, and each of the primary and secondary barriers includes We aim to create a structure that can absorb heat shrinkage caused by cryogenic liquefied gas by forming corrugations.

At this time, one can simply consider a method of forming the wrinkles formed on the primary barrier and the secondary barrier in an upward direction, that is, toward the inside of the storage tank, and this structure can be seen in FIG. 2.

Referring to FIG. 2, a secondary barrier 20 and a primary barrier 30 are sequentially placed on the top of the insulation layer 10, and between the secondary barrier 20 and the primary barrier 30, two barriers ( A spacer 40 is installed to support between 20 and 30 and space them apart at regular intervals. The secondary barrier 20 and the primary barrier 30 may be made of a membrane made of stainless steel, and may each include a plurality of wave-shaped wrinkles 21 and 31 formed to absorb heat shrinkage due to cryogenic temperatures. there is.

However, as shown in FIG. 2, both the secondary wrinkles 21 formed on the secondary barrier 20 and the primary wrinkles 31 formed on the primary barrier 30 are directed upward (inside the storage tank). If it is formed to face the direction (direction), interference due to the secondary wrinkles 21 occurs in the space between the secondary barrier 20 and the primary barrier 30, and this interference with the secondary wrinkles 21 In order to avoid this, the spacer 40 must be divided into multiple pieces and placed in the space between the secondary wrinkles 21.

That is, the spacer 40, which is installed as an inter-barrier structure to support and separate the primary barrier 30 and the secondary barrier 20, is adjusted to correspond to the space between the secondary wrinkles 21 formed in large numbers. Since it must be manufactured, it not only creates design constraints, but also increases the amount of materials and installation man-hours, which can reduce constructability.

In addition, the space between adjacent spacers 40 is a space where the secondary wrinkles 21 formed in the secondary barrier 20 should be placed, and can be left empty or left empty after the secondary wrinkles 21 are placed. You can consider inserting an insulating material such as glass wool into the space, but even if additional insulating material is installed, it is difficult to completely prevent heat loss due to convection through the space.

In order to solve the above problems, the present invention has the wrinkles formed on the secondary barrier facing downward (outward direction of the storage tank) and the wrinkles formed on the primary barrier facing upward (inside direction of the storage tank). We would like to propose a liquefied gas insulation system with an improved structure that does not cause wrinkle interference in the space between the first and second barriers. Hereinafter, a preferred embodiment of the liquefied gas insulation system according to the present invention will be described with reference to FIGS. 3 to 7.

Referring to Figures 3 and 4, the liquefied gas insulation system according to the present invention includes an insulation layer 100 installed on the inner wall of the hull (H), a secondary barrier 200 installed continuously on the upper side of the insulation layer 100, and It may be configured to include a primary barrier 300. A supporting plywood 400 may be installed between the secondary barrier 200 and the primary barrier 300 as an inter-barrier structure to separate and support the two barriers 200 and 300.

As will be explained in more detail later, the secondary barrier 200 and the primary barrier 300 may each be composed of a stainless steel membrane, and may include a plurality of corrugated wrinkles 200c, which are formed to absorb heat contraction caused by cryogenic liquefied gas. 300c) may be included. The secondary wrinkles 200c formed on the secondary barrier 200 protrude downward, i.e. toward the outside of the storage tank, and the primary wrinkles 300c formed on the primary barrier 300 protrude upward, i.e. toward the outside of the storage tank. It may protrude in a direction toward the inside.

The insulation layer 100 has the main insulation function in this insulation system, that is, the function of preventing heat intrusion from the outside of the storage tank, and is made of an insulation material such as polyurethane foam or reinforced polyurethane foams (R-PUF). It may be composed of a plurality of insulation panels 110 and bridge panels 120 manufactured based on it.

The insulation panel 110 and bridge panel 120 that make up the insulation layer 100 include polyurethane foam or reinforced polyurethane foam insulation, and are made of plywood or fiber reinforcement to provide mechanical rigidity to the flexible insulation material. Materials such as plastics (Fiber Reinforced Plastics (FRP)) may be provided in a composite form.

More specifically, the insulation layer 100 includes an insulation panel 110 manufactured as a roughly 'convex' shaped module including a lower insulation board 111 and an upper insulation board 112, and adjacent insulation panels ( It may include a bridge panel 120 disposed between 110).

The insulation panel 110 may be provided in a form in which an upper insulation board 112 having a smaller cross-sectional area is stacked on top of a lower insulation board 111 having a rectangular parallelepiped shape. Accordingly, a portion of the edge of the upper surface of the lower insulation board 111 is exposed, and the corresponding area is covered by the bridge panel 120. The upper insulation board 112 and the lower insulation board 111 may be fixed to each other by adhesion.

The lower insulation board 111 may be provided with a lower plate made of plywood or fiber-reinforced plastic attached to the lower surface of the lower insulation material, which is manufactured by processing polyurethane foam or reinforced polyurethane foam insulation into a rectangular parallelepiped shape. The lower plate serves to provide mechanical rigidity to the lower insulation material, which has flexible properties.

The upper insulation board 112 may be provided with a top plate made of plywood or fiber-reinforced plastic attached to the upper surface of the upper insulation material, which is manufactured by processing polyurethane foam or reinforced polyurethane foam insulation into an approximately rectangular parallelepiped shape. Here, the shape of the upper insulation board 112 is expressed as 'approximately' a rectangular parallelepiped, because the receiving groove 112g for receiving the secondary wrinkles 200c is formed on the upper part of the upper insulation board 112. This is because it cannot be seen as .

The receiving groove 112g machined on the upper part of the upper insulation board 112 is formed in the longitudinal and width directions of the upper insulation board 112 in response to the secondary wrinkle 200c structure formed in the secondary barrier 200. A plurality of them may be formed side by side at regular intervals in each direction.

Therefore, a plurality of receiving grooves 112g may be formed in a grid shape on the upper surface of the upper insulation board 112. The drawing shows that the receiving groove (112g) is processed into a 'V' shape, but it would also be possible to process the receiving groove (112g) into a 'U' shape to correspond to the shape of the secondary wrinkle 200c.

Additionally, the receiving groove 112g may include a chamfer shape formed along the upper edge of the upper insulation board 112. The receiving groove 112g formed in a chamfered shape on the upper edge of the upper insulation board 112 is located opposite to the receiving groove formed in a chamfered shape along the upper edge of the bridge panel 120, and is also located in the space between the two. A 'V' or 'U' shaped wrinkle receiving space may be formed.

The upper plate located at the top of the upper insulation board 112 can be divided into a plurality of segments by forming the receiving groove 112g. As will be described later, the flat portion of the secondary barrier 200 is placed on the upper plate, and the secondary wrinkles 200c protruding downward are accommodated in the receiving groove 112g formed between them.

Additionally, a slit (112s) extending vertically downward from the center of the receiving groove (112g) may be formed in the upper insulation board (112). The slits 112s are provided to alleviate the stress concentration phenomenon caused by the load occurring on the insulation layer 100, especially the thermal load, and a plurality of slits 112s are formed along the longitudinal and width directions of the upper insulation board 112. You can. The slit 112s formed along the longitudinal direction and the slit 112s formed along the width direction are orthogonal to each other.

By processing the slit (112s), the upper insulation board (112) can be divided into a number of parts with separate heat contraction behavior, and the heat contraction behavior for each part is achieved separately, thereby structurally liquefying the liquefied gas insulation system. Stability can be improved.

As described above, in the present invention, all components of the insulation panel 110 can be joined by adhesive. The lower insulation material and the lower plate constituting the lower insulation board 111 are coupled to each other by adhesive, the upper insulation material and the upper plate constituting the upper insulation board 112 are coupled to each other by adhesive, and the lower surface of the upper insulation board 112 It is fixed to the upper surface of the lower insulation board 111 by adhesive.

The insulation panel 110 can be modularized and manufactured as an integrated unit including the lower insulation board 111 and the upper insulation board 112, and a plurality of insulation panels 110 manufactured as modules are placed on the inner wall of the hull (H). The insulation layer 100 can be formed by arranging the bridge panels 120 in the space between them in succession.

As such, the present invention is characterized by applying a structure that connects neighboring insulation panels 110 to each other by placing a bridge panel 120 in the empty space between neighboring upper insulation boards 112.

The liquefied gas insulation system according to the present invention is a structure in which both the primary barrier 300 and the secondary barrier 200 are located on the upper side of the insulation layer 100, that is, the insulation layer 100 is located on the barriers 200 and 300. It is a structure that is not separated by In this structure, if the insulation layer 100 is formed as a single layer, structural weakness may occur due to vertical load due to hull deformation.

In addition, when arranging a plurality of insulation panels 110 adjacent to each other, a predetermined gap is generated between neighboring lower insulation boards 111 in consideration of installation tolerance. The gap occurring within the insulation system is a space where convection occurs and where heat loss may occur.

In order to compensate for this weakness, the present invention consists of a double layer insulation panel 110 including a lower insulation board 111 and an upper insulation board 112, and the lower insulation board 111 and the upper insulation layer forming the lower insulation layer. By arranging the vertical edges of the upper insulation board 112 and the bridge panel 120, which make up the insulation layer, to be offset from each other, a structure is created that enables stable behavior of the insulation layer 100 and effectively blocks heat loss through the boundaries between panels. Implement.

The bridge panel 120 is disposed between the upper insulation boards 112 of neighboring insulation panels 110, and therefore may be arranged while covering the boundary portion of the lower insulation boards 111 adjacent to each other.

The bridge panel 120 is smaller than the upper insulation board 112, but may have a similar shape. The bridge panel 120 may be provided in the form of a top plate made of plywood or fiber-reinforced plastic attached to the upper surface of polyurethane foam or reinforced polyurethane foam insulation, and a secondary barrier ( A receiving groove for accommodating the secondary wrinkles 200c formed in 200) and a slit for relieving stress concentration may be formed.

The width of the bridge panel 120 may be the same as the spacing of the slits 112s formed in the upper insulation board 112. In the drawing, in order to distinguish the upper insulation board 112 and the bridge panel 120, the gap formed between the upper insulation board 112 and the bridge panel 120 is the width of the slit 112s formed in the upper insulation board 112. Although shown larger, it is preferable that the gap formed between the upper insulation board 112 and the bridge panel 120 and the width of the slit 112s formed in the upper insulation board 112 are formed at the same level.

An anchor strip may be installed on the upper surface of the bridge panel 120 to secure the secondary barrier 200. The anchor strip is a strip-shaped metal plate with a predetermined width, and can be mechanically fastened to the upper plate of the bridge panel 120 using rivets, screws, staples, etc. Additionally, the anchor strip may be seated and fixed in a groove formed on the upper surface of the upper plate of the bridge panel 120, and the upper surface of the anchor strip may be flush with the upper surface of the upper plate of the bridge panel 120.

Meanwhile, as a receiving groove for receiving the secondary wrinkles 200c is formed on the upper part of the bridge panel 120, the upper plate of the bridge panel 120 is divided into a plurality of segments that are not connected to each other, and thus the upper plate It has a structure in which the anchor strips installed are not connected but are disconnected at regular intervals. Cutting off the anchor strip in this way is an intended structure of the present invention to increase the structural stability of the insulation system by more effectively preventing heat contraction of the secondary barrier 200.

The present invention implements a liquefied gas insulation system with a double metal barrier structure by successively installing the secondary barrier 200 and the primary barrier 300 on the upper side of the insulation layer 100. That is, the present invention eliminates the process of installing a barrier between the upper and lower insulation layers in a conventional insulation system, forms an overall thick insulation layer 100, and then installs a double barrier 200, 300 thereon.

The primary and secondary barriers 300 and 200 serve to seal (liquid-tight/air-tight) the liquefied gas contained within the storage tank. The primary barrier 300 performs a primary sealing function by directly contacting the cryogenic liquefied gas contained within the storage tank, and the secondary barrier 200 performs a secondary sealing function when the primary barrier 300 leaks. It must be designed to enable tightness and support of liquefied gas for a considerable period of time even if leakage of the primary barrier 300 occurs.

The first and second barriers 300 and 200 may be made of a metal material with strong low-temperature brittleness to cope with stress changes caused by the extremely low temperature of the liquefied gas contained inside the storage tank, for example, stainless steel or Invar steel. Alternatively, low-temperature steel such as aluminum alloy may be used.

In the present invention, due to the nature of the structure of the panel-type insulation system in which the insulation layer 100 has flexible properties, it is preferable that the primary and secondary barriers 300 and 200 are made of stainless steel material that is easy to respond to stress changes, The primary and secondary barriers 300 and 200 made of stainless steel membranes may each include a plurality of wavy wrinkles 300c and 200c to cope with heat shrinkage due to cryogenic temperatures.

The secondary barrier 200 may be provided with a plurality of membrane sheets airtightly connected to each other. The unit membrane sheet constituting the secondary barrier 200 is prepared as an approximately rectangular metal sheet with a predetermined length and width, and the edges of adjacent membrane sheets are overlapping and welded to form airtightness at the corresponding level. .

The secondary wrinkles 200c formed on the secondary barrier 200 may be formed to protrude downward, that is, toward the outside of the storage tank. A plurality of secondary wrinkles 200c formed in the secondary barrier 200 may be formed side by side along the length and width directions of the membrane sheet, with longitudinal wrinkles extending in the longitudinal direction and transverse wrinkles extending in the width direction. Wrinkle intersections may be formed in areas where wrinkles intersect. In addition, when welding adjacent membrane sheets, the wrinkles formed on each membrane sheet are connected to each other, so that a plurality of wrinkles extending along the transverse and longitudinal directions can form a grid inside the storage tank.

As described above, the secondary barrier 200 can be fixed to the upper part of the insulation layer 100 by welding with anchor strips installed on the upper surface of the bridge panel 120. More specifically, the edges of the membrane sheets constituting the secondary barrier 200 are fixed on the anchor strip by welding, and at this time, the edges of neighboring membrane sheets may be overlapping and welded to each other.

Meanwhile, the secondary barrier 200 and the primary barrier 300, which are continuously installed on the top of the insulation layer 100, may expand and contract under the influence of the cryogenic temperature of the liquefied gas, so the two barriers 200 and 300 They must be structured so that they do not come into contact with each other, and an insulation system needs to be constructed to prevent them from being influenced by each other as much as possible.

To this end, the present invention separates the first and second barriers (300, 200) at a predetermined interval and uses a supporting fly between the secondary barrier (200) and the primary barrier (300) for the purpose of minimizing mutual influence. Install wood (400).

Supporting plywood 400 is made of plywood in the form of a plate or plate having a predetermined thickness, and the two barriers are separated by separating the primary barrier 300 to the upper side of the secondary barrier 200 by the thickness. (200, 300) plays a role in minimizing the influence of each other and promoting structural stability. However, in the present invention, the material of the supporting plywood 400 is not limited to plywood. Any material that can be used at extremely low temperatures and can function as a load-bearing structural material (for example, a composite material such as fiber-reinforced plastic) can be used as an alternative.

The supporting plywood 400 may be provided as a member in which anchor strips for fixing the primary barrier 300 are installed on a rectangular support plate having a predetermined thickness. The anchor strip may be provided as a strip-shaped metal plate with a predetermined width similar to that installed on the bridge panel 120, and is seated in a groove formed on the upper surface of the supporting plywood 400 to be used for rivets, screws, It can be mechanically fastened and fixed with staples, etc. The upper surface of the anchor strip may be flush with the upper surface of the supporting plywood 400.

The supporting plywood 400 may be fixed by a fixing device (not shown) provided on the top of the insulation layer 100. The fixing device may include a stud that protrudes through the secondary barrier 200, and the area penetrating the secondary barrier 200 must be kept airtight through welding.

Meanwhile, as shown in FIG. 2, both the secondary wrinkles 21 formed on the secondary barrier 20 and the primary wrinkles 31 formed on the primary barrier 30 are directed upward (inside the storage tank). direction), the spacer 40 that separates the two barriers 20 and 30 is divided into multiple pieces to avoid interference with the secondary wrinkle 21, thereby increasing the amount of material and installation man-hours. I mentioned above that there is a problem.

In addition, in the structure shown in Figure 2, in order to prevent overlap between the secondary wrinkles 21 and the primary wrinkles 31, the two barriers 20 and 30 must be spaced apart to the extent that they are not affected by sloshing. The thickness of the spacer 40 increases by the corresponding separation distance, which ultimately leads to an increase in cost. In particular, due to the nature of membrane-type insulation systems applied to cryogenic environments, specific materials that do not become brittle and fractured at cryogenic temperatures must be used rather than general materials, which inevitably leads to greater economic losses.

On the other hand, the liquefied gas insulation system according to the present invention, which forms the secondary wrinkles 200c formed on the secondary barrier 200 downward, has 2 in the space between the secondary barrier 200 and the primary barrier 300. No interference occurs due to the secondary wrinkles 200c. Therefore, the present invention has the great advantage that the unit area of the supporting plywood 400 can be increased without the need to consider the spacing of the secondary wrinkles 200c, and the thickness of the supporting plywood 400 can also be flexibly changed by the designer. It can be expected to have economic effects such as improved productivity and reduced costs due to reduced installation man-hours.

The supporting plywood 400 can be manufactured to be at least larger than the interval between the wrinkles 200c and 300c of the barriers 200 and 300, and more preferably, the same or similar to the lower insulation board 111 of the insulation panel 110. It can be manufactured to a similar size and the installation location can be formed at a position corresponding to the lower insulation board 111.

A separation layer is formed to separate the first and second barriers 300 and 200 from each other by a plurality of supporting plywood 400 arranged in succession. At this time, since no interference due to wrinkles occurs in the space between the first and second barriers (300, 200), it is possible to place the supporting plywood (400) tightly without any gaps, thereby preventing heat loss due to convection. A very effective structure can be implemented.

A primary barrier 300 is installed on the upper part of the separation layer composed of a plurality of supporting plywood 400. The primary barrier 300 may be arranged to be spaced apart from the upper side of the secondary barrier 200 by a height corresponding to the thickness of the supporting plywood 400.

The primary barrier 300 has a similar structure to the secondary barrier 200 described above, except that the direction of the wrinkles protrudes toward the inside of the storage tank and there is no through hole for penetration of the fixing device. .

The primary barrier 300 may be provided with a plurality of membrane sheets airtightly connected to each other. The unit membrane sheet constituting the primary barrier 300 is prepared as an approximately rectangular metal sheet with a predetermined length and width, and the edges of adjacent membrane sheets are overlapping and welded to form airtightness at the corresponding level. .

The primary wrinkles 300c formed on the primary barrier 300 may be formed to protrude upward, that is, toward the inside of the storage tank. A plurality of primary wrinkles 300c formed in the primary barrier 300 may be formed in parallel along the length and width directions of the membrane sheet, with longitudinal wrinkles extending in the longitudinal direction and transverse wrinkles extending in the width direction. Wrinkle intersections may be formed in areas where wrinkles intersect. In addition, when welding adjacent membrane sheets, the wrinkles formed on each membrane sheet are connected to each other, so that a plurality of wrinkles extending along the transverse and longitudinal directions can form a grid inside the storage tank.

As described above, the primary barrier 300 may be welded and fixed to an anchor strip installed on the upper part of the supporting plywood 400. More specifically, the edges of the membrane sheets constituting the primary barrier 300 are fixed on the anchor strip by welding, and at this time, the edges of neighboring membrane sheets may be overlapping and welded to each other.

Referring again to FIG. 3, in the insulation system according to the present invention, the primary wrinkle 300c formed on the primary barrier 300 and the secondary wrinkle 200c formed on the secondary barrier 200 have a pitch. The spacing may be designed differently.

As shown in FIG. 2, when both the wrinkles 31 formed on the primary barrier 30 and the wrinkles 21 formed on the secondary barrier 30 are formed upward, the two wrinkles 21 and 31 can be arranged to overlap each other, but in the case where the secondary wrinkles 200c formed on the secondary barrier 200 are configured downward as presented in a preferred embodiment of the present invention, the heat insulating layer 100 is formed. Processing is required on the panel portion. In this case, processing of approximately 50 mm or more occurs, which means a decrease in insulation performance. In addition, when the secondary wrinkle 200c is configured downward, it must be in a smooth curved shape rather than an elliptical shape for automatic welding, so the range that needs to be processed may be wider. Automatic welding is performed in a direction tangent to the corrugation waveform. When the curve is large, it is difficult for automatic welding to follow the welding line due to the steep slope, resulting in a high defect rate. Therefore, it is advantageous in terms of automatic welding for the wrinkles to have a smooth curved shape.

Accordingly, the present invention is intended to minimize the processing range for accommodating the secondary wrinkles (200c) and satisfy the smooth 'corrugation profile' condition that enables automatic welding. Specifically, by reducing the gap between the secondary wrinkles (200c), the wrinkles are reduced. Configure to reduce profile size. Here, 'profile' refers to the shape and size of the wrinkle waveform. The smaller the height of the wrinkle and the gentler the curve, the more advantageous it is for automatic welding. In other words, as the pitch interval of the wrinkles becomes smaller, the amount of heat shrinkage decreases, and the size of the wrinkle waveform to absorb this can be configured to be small. Therefore, the present invention configures the pitch interval of the secondary wrinkles 200c to be relatively small, thereby reducing the amount of heat shrinkage. By reducing the profile size, a structure advantageous for automatic welding is implemented.

As a result, as shown in FIG. 3, the secondary wrinkles 200c formed on the secondary barrier 200 and the primary wrinkles 300c formed on the primary barrier 300 are arranged to be offset from each other in the vertical direction. At this time, the misalignment between the primary wrinkles 300c and the secondary wrinkles 200c is not formed randomly, and the wrinkle spacing can be determined by considering the number per unit length of the insulation panels 110 constituting the insulation layer 100. there is. Here, 'unit' means based on one insulation panel (110) and does not mean a unit of length. Therefore, the unit length along the width direction of the insulation panel 110 means the width value of one insulation panel 110, and the unit length along the length direction of the insulation panel 110 means the length value of one insulation panel. It must be understood.

First, when explaining based on the width direction of the insulation panel 110, when the unit length (width value) along the width direction of the insulation panel 110 is formed to be 0.8 to 1.3 m, the primary wrinkle 300c is Having three per unit length is optimal in terms of heat shrinkage absorption and automatic welding. Additionally, this takes into account the productive aspect.

On the other hand, in the case of secondary wrinkles (200c), if three or less are provided per unit length, the profile of the wrinkle waveform becomes large, making automatic welding difficult, and the processing range of the panel is widened, which is not good in terms of heat loss. In addition, if more than 6 secondary wrinkles 200c are provided per unit length, the spacing becomes too narrow, resulting in difficulty in manufacturing the membrane sheet. Considering these points, the present invention selected the number of secondary wrinkles 200c per unit length along the width direction of the insulation panel 110 to be 4 to 5, and when considering both minimized panel processing and installation manufacturing aspects, the number of secondary wrinkles 200c per unit length along the width direction of the insulation panel 110 was selected to be 4 to 5. The optimized number is 4.

As a more specific example, as shown in FIG. 3, primary wrinkles 300c may be formed at each point dividing the entire width of the insulation panel 110 into thirds. As a result, the primary wrinkles 300c can be formed at a plurality of locations including the boundaries of the lower insulation boards 111 adjacent to each other.

In the case of the secondary wrinkles 200c, they may be formed at each point dividing the width of the upper insulation board 112 into thirds. As a result, the secondary wrinkles 200c can be formed at a plurality of locations including the boundary between the upper insulation board 112 and the bridge panel 120, and are arranged to be offset from the primary wrinkle 300c in the vertical direction. do.

The above can be equally applied to the longitudinal direction of the insulation panel 110. In the present invention, the insulation panel 110 can be manufactured with a length that is an integer multiple of the width. In this case, the number of wrinkles 200c, 300c per unit length along the longitudinal direction of the insulation panel 110 is the unit length along the width direction. It can be formed as an integer multiple of the number of wrinkles (200c, 300c).

For example, when the insulation panel 110 according to the present invention is provided as a panel of approximately 1 × 3 m, the number of primary wrinkles 300c per unit length along the width direction of the insulation panel 110 is 3, 2 The number of primary wrinkles 200c may be 4 to 5 (most preferably 4), and the number of primary wrinkles 300c per unit length along the longitudinal direction of the insulation panel 110 is 9. , the number of secondary wrinkles 200c may be 12 to 15 (most preferably 12).

According to the structure of the present invention in which the primary wrinkles (300c) and the secondary wrinkles (200c) are arranged misaligned as described above, the 'profile' of the secondary wrinkles (200c) is reduced, thereby reducing the size of the panel constituting the insulation layer (100). This has the effect of minimizing the processing range and facilitating automatic welding of the secondary barrier 200. In addition, it is superior in terms of manufacturing performance compared to the case where the spacing between the primary and secondary wrinkles 300c and 200c is configured to be the same, and there is an advantage that the designer can flexibly change the performance of the secondary barrier 200.

Meanwhile, as described above, in the liquefied gas insulation system according to the present invention, the primary barrier 300 and the secondary barrier 200 are each made up of a plurality of membrane sheets continuously connected by welding, and each barrier ( A plurality of membrane sheets constituting 200 and 300) are overlap-welded on an anchor strip located below them.

At this time, the present invention seeks to improve the shape of the wrinkles formed on the membrane sheet as follows in order to improve the ease of welding performed when installing the barriers 200 and 300.

Specifically, the wrinkles formed on the membrane sheet can be divided into 'welded areas' that are formed at the edges of the sheet and overlap and weld with the wrinkles of other adjacent sheets, and 'non-welded areas' excluding the welded areas, and the present invention provides the wrinkles of the wrinkles. When improving the form, the following matters are taken into consideration.

First, the non-welded part must be able to effectively respond to hull load and thermal load. This also means that the original function of the wrinkles must be maintained to effectively absorb heat shrinkage caused by cryogenic temperatures and deformation caused by the hull.

In the case of the welding part, we want to implement a shape in a way that maximizes the efficiency of automatic welding. In particular, in the present invention, the secondary wrinkles 200c formed on the secondary barrier 200 are installed to face the outside of the storage tank rather than the inside, so for automatic welding of the concave surface of the secondary wrinkles 200c, the wrinkles are required. The cross-sectional shape of is very important.

Refer to FIGS. 5 to 7 for the configuration of the membrane sheet proposed in the present invention and the cross-sectional shape of the wrinkles formed on the membrane sheet. Hereinafter, the features of the present invention will be described as a single membrane sheet 1000 without distinguishing between the primary barrier 300 and the secondary barrier 200. That is, the shape characteristics of the membrane sheet 1000 described below can be applied regardless of whether the primary barrier 300 or the secondary barrier 200 is used. However, as described above, the membrane sheet constituting the primary barrier 300 and the membrane sheet constituting the secondary barrier 200 will be arranged so that the wrinkle directions are opposite to each other, and the pitch intervals of the wrinkles will be set differently. It must be clearly understood.

The membrane sheet 1000 constituting the barriers 200 and 300 in the liquefied gas insulation system according to the present invention has a structure in which a plurality of wrinkles 1100 are formed side by side in the transverse and longitudinal directions on an approximately square metal sheet. .

Here, the wrinkles 1100 can be divided into a welded portion 1101 formed at the edge of the membrane sheet 1000 based on the area indicated by the dotted line, and a non-welded portion 1102 formed on the inside of the sheet excluding the welded portion 1101. there is.

The non-welded portion 1102 is shaped to effectively respond to buckling and thermal load. Specifically, the cross-sectional shape of the non-welded portion 1102 may be approximately in the shape of a '∩'.

On the other hand, in the case of the welding portion 1101, the shape is implemented so that automatic welding can proceed efficiently. In particular, in the case of the secondary barrier 200, the direction of the secondary corrugation 200c is installed toward the outside of the storage tank, so interference with the welding torch may not occur for automatic welding of the concave surface of the secondary corrugation 200c. We want to configure the cross-sectional shape so that Specifically, the cross-sectional shape of the welded portion 1101 is in the shape of a '∧' as shown in (a) of FIG. 6 or a '∩' shape with a gentler curvature than the non-welded portion 1102 as shown in (b) of FIG. 'It can be composed in the form of a letter.

In both forms, the welded portion 1101 is wider than the non-welded portion 1102 and has a lower height. In this way, the welded portion 1101 and the non-welded portion 1102 of the wrinkles 1100 having different cross-sectional shapes are flexibly connected to each other.

In this way, the present invention not only enables effective response to hull load and thermal load by dividing the cross-sectional shape of the wrinkles 1100 formed on the membrane sheet 1000 into a welded portion 1101 and a non-welded portion 1102. However, it has the effect of enabling effective automatic welding. In particular, when the direction of the secondary corrugation 200c, like the secondary barrier 200, is installed to face the outside of the storage tank rather than the inside, the cross-sectional shape can be freely selected for automatic welding of the concave side of the corrugation. effective.

Below, we will look at the construction method of the liquefied gas insulation system according to the present invention in a sequential process.

(1) First, the work of installing the insulation layer 100 on the inner wall of the hull (H) is performed. At this time, the installation of the insulation layer 100 may be carried out in the order of installing the bridge panel 120 in the space between the installation of the insulation panel 110.

(2) Once the installation of the insulation layer 100 is completed, the work of installing the secondary barrier 200 on the top of the insulation layer 100 is performed. Specifically, a plurality of membrane sheets constituting the secondary barrier 200 are overlap welded on the anchor strip installed on the upper surface of the insulation layer 100, and more specifically, on the anchor strip installed on the upper surface of the bridge panel 120. can form a sealed structure. At this time, the wrinkles formed on the membrane sheet constituting the secondary barrier 200 are divided into a welded portion and a non-welded portion, and efficient automatic welding is possible due to the wrinkle cross-sectional shape of the welded portion that is different from the non-welded portion.

(3) After installation of the secondary barrier 200, the work of installing the supporting plywood 400 on the upper part of the secondary barrier 200 is performed. The supporting plywood 400 may be fixed by a fixing device including a stud that penetrates the secondary barrier 200 from the insulation layer 100. Meanwhile, at this time, the liquefied gas insulation system according to the present invention does not generate a wrinkle interference structure between the primary barrier 300 and the secondary barrier 200, so it enlarges the unit area of the supporting plywood 400 and ensures that there are no gaps. can be placed. This is directly related to the effect of being structurally stable and effectively blocking heat loss due to convection. In addition, due to the absence of the wrinkle interference structure, the shape and installation structure of the supporting plywood 400 can be greatly simplified, which will ultimately have the effect of greatly improving the constructability of the liquefied gas storage tank and shortening the total drying period. You can.

(4) Finally, the first barrier 300 installation work is performed. A plurality of membrane sheets constituting the primary barrier 300 are overlapping and welded on the anchor strip installed on the upper surface of the supporting plywood 400 to form a sealing structure, and ultimately, an insulation system with a double metal barrier structure is implemented. You can. At this time, the wrinkles formed on the membrane sheet constituting the primary barrier 300 are divided into a welded portion and a non-welded portion, and efficient automatic welding is possible due to the wrinkle cross-sectional shape of the welded portion that is different from the non-welded portion.

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

100: insulation layer
110: Insulation panel
111: Lower insulation board
112: Upper insulation board
112g: receiving groove
120: Bridge panel
200: Secondary barrier
200c: 2nd wrinkle
300: Primary barrier
300c: 1st wrinkle
400: Supporting plywood
1000: Membrane sheet
1100: wrinkles
1101: Welding part
1102: Non-welded joint

Claims (5)

In order to seal the liquefied gas inside the storage tank where the liquefied gas is stored, a plurality of membrane sheets are continuously connected by welding,
It includes wave-shaped wrinkles formed in a raised or depressed form on the metal sheet to absorb heat shrinkage due to the cryogenic temperature of the liquefied gas or deformation due to hull deformation,
The wave-shaped wrinkles are divided into a welded portion formed at the edge of the metal sheet and a non-welded portion continuously connected to the welded portion and formed on the inside of the metal sheet,
Characterized in that the cross-sectional shapes of the welded portion and the non-welded portion are formed differently from each other,
Membrane sheet with improved corrugation for ease of welding. In claim 1,
The welded portion is characterized in that it is provided in a form that is wider in width and lower in height than the non-welded portion.
Membrane sheet with improved corrugation for ease of welding. In claim 2,
The non-welded portion has a '∩' shaped cross-sectional shape to effectively respond to buckling and thermal load,
The welding part is characterized in that it has a cross-sectional shape of a '∧' shape or a '∩' shape with a gentler curvature than the non-welding part to enable efficient automatic welding.
Membrane sheet with improved corrugation for ease of welding. In claim 3,
Characterized in that the welded portion and the non-welded portion are flexibly connected to each other,
Membrane sheet with improved corrugation for ease of welding. A liquefied gas insulation system comprising the membrane sheet according to any one of claims 1 to 4.

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