KR101556259B1 - Membrane of cargo for liquefied gas - Google Patents

Abstract

A membrane of a liquefied gas hold comprising a wrinkle is disclosed. The membranes of the liquefied gas holders according to the embodiments of the present invention may include a plurality of corrugations in different directions and each of the corrugations includes a connection end portion connected to the corrugation portion and a connection valley portion connecting the connection end portion with a curved surface, The first connection portion to which the end portion and the crease portion are connected is provided with a rib or a ridge in the longitudinal direction of the crease portion.

Description

[0001] MEMBRANE OF CARGO FOR LIQUEFIED GAS [0002]

The present invention relates to a membrane of a liquefied gas holding window, and more particularly to a membrane of a liquefied gas holding window including a wrinkle portion.

Liquefied gas refers to a colorless transparent cryogenic liquid that reduces the volume of methane-based natural gas to -162 ° C and reduces its volume by one-sixth.

As such liquefied gas is used as an energy source, an efficient transportation method that can transport a large amount from the production base to the place of purchase of the demand site has been examined in order to utilize this gas as energy. As a part of this effort, A liquefied gas transport vessel capable of being transported by sea was developed.

However, the liquefied gas transportation vessel is required to have a cargo that can store and store the liquefied gas liquefied at an extremely low temperature.

That is, since the liquefied gas has a vapor pressure higher than atmospheric pressure and has a boiling temperature of approximately -162 ° C, in order to safely store and store such a liquefied gas, the cargo window storing the liquefied gas is a material which can withstand extremely low temperatures, It should be made of aluminum steel, stainless steel, 35% nickel steel, etc. It should be designed with a unique insulation panel structure which is resistant to thermal stress and heat shrinkage and prevents heat intrusion. The cargo hold of such a liquefied gas transportation vessel can be classified into a self-supporting type and a membrane type depending on its structure.

If the liquefied gas leaks to the inside of the heat insulating panel, it may cause damage to the cargo window due to rapid volume expansion due to temperature increase. Therefore, it has a two-stage membrane barrier (primary barrier and secondary barrier) to seal the liquefied gas inside the hold.

In the liquefied gas holding window, a plurality of barrier sheets are combined to form a membrane barrier. The barrier walls are thermally shrunk due to cryogenic liquefied gas, and when the thermal shrinkage occurs, the welded portion may be damaged by thermal stress.

Because of this problem, the barriers have a corrugation to have an in-plane stiffness. The wrinkle part deforms a certain amount when heat shrinkage occurs, thereby reducing the thermal stress at the welded part.

However, the conventional membrane has a problem that fatigue failure is reported due to accumulation of fatigue due to thermal stress.

Korean Patent Registration No. 10-0547986 discloses a method for manufacturing a rib type membrane for a liquefied natural gas storage tank.

Korean Patent Registration No. 10-0547986 (Jan. 24, 2006)

Embodiments of the present invention seek to provide a membrane of a liquefied gas hold window that improves fatigue life against thermal stress.

Embodiments of the present invention also provide a membrane of a liquefied gas hold window that facilitates work at a welded site.

According to an aspect of the present invention, there is provided a membrane of a liquefied gas holding window in which a plurality of corrugations in different directions form an intersection, wherein the intersection includes a connection end portion connected to the corrugation portion, A membrane of the liquefied gas hold window may be provided which includes a valley portion, and a first connection portion to which the connection end portion and the wrinkle portion are connected includes a boss or a ridge in a longitudinal direction of the wrinkle portion.

The wrinkle portion may be provided with a membrane of a liquefied gas holding window including a base wrinkle portion having different heights of the floor or different lengths in the width direction and a second connecting portion connecting the base wrinkle portion and the small wrinkle portion .

The longitudinal ribs of the wrinkles may be continuously provided to form ridges or two or more longitudinal ridges of the wrinkles may be continuously provided to form the ribs.

The membrane may be formed by welding a plurality of sheets, and the connected sheet may be provided with a membrane of a liquefied gas holding window in which the base corrugations are welded to each other.

And a membrane of the liquefied gas holding window in which the small boss portion is closer to the intersection than the large wrinkle portion can be provided.

Wherein the rim has a positive radius of curvature, the rim has a negative radius of curvature, and the rim has a negative radius of curvature, The connecting portion may be provided with a membrane of a liquefied gas holding window which is tangential to the ridge portion and the rim portion.

A membrane of a liquefied gas holding window having a curvature radius of the floor portion and a radius of curvature of the edge portion being equal to each other may be provided.

The membrane of the liquefied gas holding window according to the embodiment of the present invention includes the connecting trough portion at the intersecting portion and the corrugation in the width direction of the wrinkle portion near the connecting end portion can improve the fatigue life of the intersection portion which is vulnerable to thermal stress.

Further, it is possible to improve the shape of the welded portion corrugated portion, thereby facilitating the welding work and improving the welding strength.

1 is a perspective view showing a membrane according to a first embodiment of the present invention.
Fig. 2 is a view showing an intersection of Fig. 1. Fig.
FIG. 3 is a cross-sectional view taken along the line AA in FIG.
4 is a perspective view showing a membrane according to a second embodiment of the present invention.
Fig. 5 is a cross-sectional view taken along the line BB in Fig.
6 is an enlarged view showing a connection portion between the main wrinkle portion and the small wrinkle portion.
7 is a cross-sectional view taken along line CC of Fig.
8 is a cross-sectional view showing the configuration of the main wrinkle portion.
9 is a cross-sectional view showing the curvature of the base corrugated portion.
10 is a sectional view showing the configuration of the small pleat portion.

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

The embodiments described below are provided by way of example so that those skilled in the art will be able to fully understand the spirit of the present invention. The present invention is not limited to the embodiments described below, but may be embodied in other forms. In order to clearly explain the present invention, parts not related to the description are omitted from the drawings, and the width, length, thickness, etc. of the components may be exaggerated for convenience. Like reference numerals designate like elements throughout the specification.

The cargo hold of the liquefied gas transportation vessel includes a main wall enclosing a space capable of accommodating the liquefied gas and directly contacting the liquefied gas, an adiabatic panel structure surrounding the main wall and insulating the liquefied gas from the outside, . Further, the heat insulating panel structure is generally composed of a double structure of an upper heat insulating panel structure and a lower heat insulating panel structure, and an auxiliary wall may be provided between the upper heat insulating panel structure and the lower heat insulating panel structure.

The kitchen wall or auxiliary barrier is a stretchable metal material and is commonly referred to as a membrane. The membrane is for airtightly protecting the heat insulating panel structure from the liquefied gas, and a plurality of sheets are joined by welding or the like to block the heat insulating panel structure from the liquefied gas. The membrane can be made of a variety of materials, but generally stainless steel (SUS) materials can be used.

1 is a perspective view showing a membrane according to a first embodiment of the present invention.

A membrane according to an embodiment of the present invention includes a kitchen wall and an auxiliary barrier. Although the wall of the kitchen is in direct contact with the liquefied gas, the risk of fatigue failure due to thermal stress accumulation is greater than that of the auxiliary barrier insulated by the upper insulation panel. However, thermal stress due to thermal deformation This is because there is no fundamental difference.

The membrane may be formed by combining a plurality of sheets, and welding may be used as a joining method in order to maintain airtightness. The membrane has a first direction corrugated portion (1) and a second direction corrugated portion (2) arranged in different directions so as to easily shrink or stretch due to thermal deformation while maintaining airtightness, and an intersection portion (10).

In the reference drawing of the present invention, the two-directional folds 1 and 2 arranged vertically are shown, but they may include three or more folds as required. For example, the three corrugations may be arranged at an angle of 60 degrees with respect to each other.

The membrane undergoes thermal deformation due to the temperature change of the liquefied gas and the wrinkles absorb this thermal deformation and prevent thermal stress from accumulating. The thermal deformation occurring in the first direction can be canceled by the elasticity of the second direction corrugated portion 2, and the thermal deformation occurring in the second direction is caused by the stretchability of the first direction corrugated portion 1 Thermal stress can be relieved. However, since there is no wrinkle portion at the intersection 10, there is little room for thermal deformation. Therefore, fatigue failure due to thermal stress is likely to occur.

Fig. 2 is a view showing the intersection 10 of Fig. The intersection portion 10 includes a connecting end portion 11 connected to the corrugation portion and a connecting valley portion 12 connecting the connecting end portion 11. The intersection 10 and the corrugations 1 and 2 are not divided by physical boundaries. The wrinkled portions 1 and 2 which are linearly arranged in the first direction or the second direction for convenience are defined as the wrinkles 1 and 2 and the portion where the wrinkles of different directions converge at the intersection of the wrinkles 1 and 2 is referred to as the intersection The connecting trough portion 12 connects the connecting end portion 11-1 in the first direction and the connecting end portion 11-2 in the second direction with a curved surface. The first direction corrugated portion 1 has a large thermal deformation occurring in the second direction, but thermal deformation also occurs in the first direction. Similarly, the second direction corrugated portion 2 also undergoes thermal deformation in the second direction. Therefore, thermal deformation occurs in the connecting curved portion 12 of the intersecting portion 10 in different directions, so that the thermal stress is most concentrated.

In addition, stress concentration occurs at a portion where the cross-sectional shape changes abruptly, and is liable to be fatigued. If the first direction corrugated portion 1 and the second direction corrugated portion 2 are directly connected without being connected by the connecting trough portion 12, the connected portion forms a sharp discontinuity surface bent by 90 degrees. Therefore, the connecting trough portion 12 may be curved to gently connect the end portion of the first direction corrugated portion 1 and the end portion of the second direction corrugated portion 2. [

The membrane according to an embodiment of the present invention includes a first connection portion 13 to which the intersection portion 10 and the corrugation portions 1 and 2 are connected and the first connection portion 13 includes a valley 35 . The first connecting portion 13 is not a physical concept but a concept that means the vicinity of the connecting end portion 11 to which the intersecting portion 10 and the corrugation portions 1 and 2 are connected. As has been pointed out before, the crossing portion 10 is likely to have a higher thermal stress than the wrinkles 1 and 2. Therefore, it is necessary to solve this thermal stress and prolong the fatigue life.

3 is a cross-sectional view taken along line A-A of the continuous trough 35. Fig. The thermal deformation acting in the second direction of the intersection 10 is similar to that of the second direction corrugated portion 2 absorbing thermal deformation acting in the first direction of the membrane, Corrugation 35 disposed in the width direction can be absorbed. At this time, the closer the corrugation 35 is to the intersection 10, the more effective it is to relieve the thermal stress of the intersection 10. At this time, since the outer surface is not constant due to the connecting trough portion 12 at the connection point 11-2 toward the center of the intersection 10, it is difficult to form a corrugation. Therefore, it is easy to manufacture the corrugation 35 in the corrugation 2 close to the connection end 11-2.

The corrugation 35 may be formed along the width direction of the corrugated portions 1, 2. Further, a plurality of wrinkles 1, 2 may be provided continuously or intermittently along the longitudinal direction. Further, the corrugation 35 may be continuously formed along the circumferential surface of the corrugated portions 1, 2.

The corrugation may include a valley 35 or a ridge 36. 1 and 3, which are the first embodiment, show a valley 35 as an example of a corrugation, and a ridge 36 is shown as an example of a corrugation in the second embodiment shown in Figs. 4 and 5 have.

A ridge 35-3 may be formed between the valleys 35-1 and 35-2 when the valleys 35 are continuously formed on the corrugated portion 2. [ The rib 35 or the continuous ribs 35-1 and 35-2 formed in the corrugation 2 and the ridge 35-3 between them can be stretchable by thermal deformation, The working thermal stress can be solved.

FIG. 4 is a perspective view showing a membrane according to a second embodiment of the present invention, and FIG. 5 is a B-B cross-sectional view showing a continuous ridge 36. FIG.

When the ridges 36 are continuously formed on the corrugation 2, the corrugations 36-3 can be formed between the ridges 36-1 and 36-2. The ridges 36 or the continuous ridges 36-1 and 36-2 formed in the corrugated portion 2 and the valleys 36-3 between the ridges 36-1 and 36-2 can have elasticity by thermal deformation, The working thermal stress can be solved.

The corrugations 35 and 36 according to the first and second embodiments are different from the height of the corrugation 2 in that the lower valley 35 is formed or the higher ridge 36 is formed Do. However, there is no fundamental difference in that a corrugation capable of thermal deformation in the longitudinal direction of the corrugated portion 2 is formed. It is also noted that, when the troughs 35 or the ridges 36 are continuously formed, the troughs and the ridges appear alternately. However, there may be some differences in stiffness against sloshing impact or ease of fabrication.

6 is an enlarged view showing the second connection portion 40 of the main wrinkle portion 20 and the small wrinkle portion 30, and Fig. 7 is a sectional view taken along the line C-C of Fig. The length direction and the width direction of the wrinkle portion were set with reference to the first direction wrinkle portion 1. The description of the wrinkle portion can be applied commonly to the first direction corrugated portion 1 and the second direction corrugated portion 2. The corrugated portion 1 is formed by the base corrugated portion 20 and the small corrugated portion 30, 2 connecting portion 40. [0034] The major wrinkles 20 and small wrinkles 30 may have different heights a1 and a2 of the floor (the highest portions 21 and 31 of the wrinkles), and the widths b1 and b2 may be different from each other May be different. 6 and 7, the height a1 and the widthwise length b1 of the floor 21 of the base corrugation 20 are set to be greater than the height a2 of the floor 31 of the small- (b2). However, if the floors 21 and 31 have the same height but differ only in the width direction, the floors 21 and 31 may have the same height but different heights.

It is preferable that the curvature of the wrinkle portion is large so that the wrinkle portion effectively responds to thermal deformation. That is, when the wrinkles of the same width are compared, the wrinkles having a larger curvature than the wrinkles having a gentle curvature can actively cope with the thermal deformation, thereby effectively solving the thermal stress.

However, when the curvature of the wrinkle portion is large, there is a disadvantage that welding is difficult at the welding portion connecting the sheet and the sheet. The welding between the sheet and the sheet of the membrane is widely used by laser welding using a robot. At this time, the wrinkles having a large curvature may deteriorate the welding quality and take a long time to weld. Therefore, in order to improve the welding quality and improve the welding convenience, it is advantageous to reduce the curvature and to include as much as possible the straight portion in the cross-sectional shape of the wrinkle portion.

Referring to FIG. 1, the wrinkles 1 and 2 according to the embodiment of the present invention include a small wrinkle portion 30 having a large curvature around an intersection 10 where a relatively large thermal stress is applied, 10, and relatively small thermal stress acts on the portion where the welded portion 4 is located, thereby providing a base wrinkle portion 20 having a small curvature. The connection between the small wrinkle portion 30 and the main wrinkle portion 20 minimizes the discontinuity by the second connection portion 40.

Fig. 8 is a cross-sectional view showing the configuration of the main wrinkle portion 20, and Fig. 9 is a cross-sectional view showing the curvature of the main wrinkle portion 20. Fig.

The base corrugated portion 20 includes the edge portion 24, the floor portion 22, and the third connection portion 23 in the width direction. The edge portion 24 refers to the portion to which the flat surface portion 3 and the corrugation portion 20 are connected and the floor portion 22 refers to the isosceles including the floor 21 and the third connection portion 23 refers to the isosceles Refers to an intermediate surface connecting the rim 24 and the floor 22. Such a division is not made physically, but is divided according to its position and shape.

The edge portion 24 has a negative curvature radius R1. The negative radius of curvature means that the center of curvature radius C1 is located outside the membrane. At this time, as the radius of curvature R1 becomes larger, the curvature of the flat portion 3 and the edge portion 24 becomes smaller, and welding is facilitated.

The floor portion 22 has a positive curvature radius R2. The positive radius of curvature means that the center of curvature radius C2 is located inside the membrane. At this time, as the radius of curvature R2 becomes larger, the curvature of the corrugated portion becomes smaller and welding is easier. 9 shows that the curvature radius R1 of the edge portion 24 is equal to the curvature radius R2 of the floor portion 22. If the two curvature radii R1 and R2 are the same, the convenience of fabrication is increased, but they are not included in the embodiment of the present invention.

The third connecting portion 23 is formed by a virtual circle S1 centered on the curvature center C1 of the edge portion 24 and a virtual circle S2 centered on the curvature center C2 of the floor portion 22. [ As shown in FIG. The reason for forming the common tangent line is to prevent discontinuous points from being concentrated at the discontinuous points, thereby improving the fatigue life. In addition, welding can be easily performed when the welding is performed from the edge portion 24 to the third connecting portion 23 or from the floor portion 22 to the third connecting portion 23 by making the common tangent line, so that the manufacturing time can be shortened.

8 and 9, the configuration of the wrinkle portion has been described with reference to the base wrinkle portion 20. However, such a configuration can also be applied to the small wrinkle portion 30. [ It should be noted that the main corrugated portion 20 has priority to improve the welding convenience and the welding quality and the small corrugated portion 30 has to be shaped in such a manner that it takes priority to solve the thermal stress concentrated on the intersection portion 10 This is different.

10 is a sectional view showing the configuration of the small pleat portion 30. Fig. Hereinafter, the difference between the main wrinkle portion 20 and the small wrinkle portion 30 will be described with reference to FIGS. 8 and 10.

The small bending portion 30 has a relatively small area b2 occupied by the third connecting portion 33 as compared with the base wrinkle portion 20. [ That is, the area b2 occupied by the third connecting portion 33 is not small in comparison with the area a3 occupied by the edge portion 24 and the area a1 occupied by the floor portion 22 in the base corrugated portion 20 . The area b2 occupied by the third connecting portion 33 of the small wrinkle portion 30 is smaller than the area b1 occupied by the floor portion 32, And the area (b3) occupied by the edge portion (34). The effect of this is that the magnitude of the curvature is different. If the area occupied by the third connection portion is large in a state where the curvature is large, the entire width width and height of the wrinkle portion increase.

The curvature of the rim portion 32 and the edge portion 34 of the small wrinkle portion 30 is larger than that of the large wrinkle portion 20. [ Therefore, the small-wrinkled portion 30 forms a corrugation that rises sharply than the large-wrinkled portion 20. As a result, the small wrinkle portion 30 can effectively cope with the thermal deformation acting in the width direction of the wrinkle portion. As described above, since the small wrinkle portion 30 is located adjacent to the intersection 10, it is liable to cause thermal deformation. However, since welding is difficult due to the shape of the small wrinkled portion 30, the provision of the large wrinkled portion 20 in the welded portion 4 is as described above.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, You will understand. Accordingly, the true scope of the invention should be determined only by the appended claims.

1: first direction corrugated portion, 2: second direction corrugated portion,
3: plane portion, 4: welded portion,
10: intersection, 11: connection end,
12: connecting curved portion, 13: first connecting portion,
20: large wrinkled portion, 21: floor,
22: a floor portion, 23: a third connecting portion,
24: edge portion, 30: small wrinkle portion,
31: floor, 32: floor,
33: third connection part, 34: edge part,
35: Goals, 36: Ridge,
40: second connection part,

Claims (7)

A membrane of a liquefied gas holding window, which is provided by connecting a plurality of sheets including a plurality of wrinkled portions arranged in different directions and an intersection portion in which corrugations of different directions cross each other,
Wherein the wrinkle portion includes a small wrinkle portion extending from the intersection portion and a base wrinkle portion continuously connected to the longitudinal direction of the small wrinkle portion and having a height or width in a width direction greater than that of the small wrinkle portion,
Wherein the base corrugation portion extends to an edge of the sheet,
And the adjacent sheets are connected such that the major corrugation portions are connected to each other. The method according to claim 1,
Wherein the crossing portion includes a connection end portion connected to the wrinkle portion extending in a straight line, and a connection bend portion connecting the adjacent connection end portion and connecting the connection end portion with a curved surface,
And a connecting portion to which the connecting end portion and the corrugation portion are connected includes a corrugated or ridge in the longitudinal direction of the corrugated portion. 3. The method of claim 2,
Wherein the ribs of the wrinkle portion are continuously provided in the longitudinal direction of the wrinkle portion to form a ridge,
Wherein at least two ridges of the wrinkles are continuously provided in the longitudinal direction of the wrinkles to form valleys. The method according to claim 1,
Wherein the membrane is formed by welding a plurality of sheets,
And the connected sheet is welded to the base corrugated portion. 5. The method of claim 4,
Wherein the widthwise cross section of the base corrugation section includes edge portions connected to planar portions on both sides of the base corrugation portion and each having a negative curvature radius, a floor portion having a positive curvature radius, and an edge portion connecting the edge portion and the floor portion The membrane of the liquefied gas hold. delete 6. The method of claim 5,
Wherein a radius of curvature of the floor portion and a radius of curvature of the rim portion are equal to each other.

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