Membrane bonding structure and liquefied gas storage tank comprising the same

Abstract

Disclosed is a membrane bonding structure for bonding a membrane for forming a sealed wall between first and second surfaces of a storage tank for storing liquefied gas. The membrane bonding structure may comprise: a planar portion panel installed on the first and second surfaces so as to thermally insulate the storage tank; a bonding panel installed on the boundary portion between the first and second surfaces together with the planar portion panel; a first membrane attached to the planar portion panel on the first surface and to the bonding panel so as to seal the storage tank; and a second membrane attached to the planar portion panel on the second surface and to the bonding panel so as to seal the storage tank. The first membrane and the second membrane may be attached to the bonding panel so as to make no direct connection.

Claims

1. A membrane bonding structure for bonding membranes for formation of a sealing wall between a first surface and a second surface of a storage tank for storing liquefied gas, the membrane bonding structure comprising: a planar portion panel disposed on each of the first surface and the second surface for thermal insulation of the storage tank; a bonding panel disposed on a boundary between the first surface and the second surface together with the planar portion panel; a first membrane attached to the planar portion panel of the first surface and the bonding panel for sealing of the storage tank; and a second membrane attached to the planar portion panel of the second surface and the bonding panel for sealing of the storage tank, wherein the first membrane and the second membrane are attached to the bonding panel so as not to be directly connected to each other, wherein the bonding panel comprises a pair of plywood sheets, a heat insulator interposed between the pair of plywood sheets, a thermal protector stacked on one of the pair of plywood sheets, and an Invar sheet stacked on the thermal protector, and wherein the pair of plywood sheets is attached to both surfaces of the heat insulator by a bonding agent, respectively, the thermal protector is secured to the one of the pair of plywood sheets by a staple, and the Invar sheet is secured to the thermal protector by a fastening screw coupled to the one of the pair of plywood sheets through the thermal protector.

2. The membrane bonding structure according to claim 1, wherein one surface of the bonding panel is finished with a metallic material to allow the first membrane and the second membrane to be joined thereto by welding.

3. The membrane bonding structure according to claim 1, wherein the bonding panel is disposed on the boundary between the first surface and the second surface instead of the planar portion panel or by partially removing the planar portion panel for thermal insulation of the storage tank.

4. The membrane bonding structure according to claim 1, wherein the first surface is a front surface or a rear surface of the storage tank and the second surface is an inclined surface of the storage tank.

5. The membrane bonding structure according to claim 4, wherein a hypotenuse portion is formed between the front surface and the inclined surface or between the rear surface and the inclined surface, and the bonding panel is linearly arranged in plural on the hypotenuse portion.

6. The membrane bonding structure according to claim 1, wherein the first membrane and the second membrane form a primary sealing layer of the storage tank to directly contact cryogenic liquefied gas, and include a plurality of corrugations to absorb thermal stress resulting from shrinkage and expansion of the cryogenic liquefied gas.

7. The membrane bonding structure according to claim 1, further comprising: a connection membrane having corrugations and disposed at an interface between two bonding panels adjoining each other.

8. The membrane bonding structure according to claim 7, wherein the connection membrane is bonded to the interface between the two bonding panels to connect the first membrane to the second membrane.

9. A storage tank having a polyhedral shape and storing liquefied gas, the storage tank comprising: a heat insulation layer disposed on an inner wall of a hull; a primary sealing layer disposed on the heat insulation layer and directly contacting the liquefied gas; and a membrane bonding structure for bonding membranes for formation of the primary sealing layer between a first surface and a second surface of the storage tank, wherein the membrane bonding structure comprises: a planar portion panel disposed on each of the first surface and the second surface for thermal insulation of the storage tank; a bonding panel disposed on a boundary between the first surface and the second surface together with the planar portion panel; a first membrane attached to the planar portion panel of the first surface and the bonding panel for sealing of the storage tank; a second membrane attached to the planar portion panel of the second surface and the bonding panel for sealing of the storage tank, wherein the first membrane and the second membrane are attached to the bonding panel so as not to be directly connected to each other, wherein the bonding panel comprises a pair of plywood sheets, a heat insulator interposed between the pair of plywood sheets, a thermal protector stacked on one of the pair of plywood sheets, and an Invar sheet stacked on the thermal protector, and wherein the pair of plywood sheets is attached to both surfaces of the heat insulator by a bonding agent, respectively, the thermal protector is secured to the one of the pair of plywood sheets by a staple, and the Invar sheet is secured to the thermal protector by a fastening screw coupled to the one of the pair of plywood sheets through the thermal protector.

Description

DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a perspective view of a typical liquefied gas storage tank having an inclined surface corresponding to sloshing load.

(2) FIG. 2 is a view of a liquefied gas storage tank according to one embodiment of the present invention, illustrating a portion of a corner of a front surface or a rear surface connected to an inclined surface, with primary insulation panels arranged thereon.

(3) FIG. 3 is a view of the liquefied gas storage tank according to the embodiment of the present invention, illustrating a portion of the corner of the front surface or the rear surface connected to the inclined surface, with bonding panels arranged on the primary insulation panels.

(4) FIG. 4 is a view of the liquefied gas storage tank according to the embodiment of the present invention, illustrating a portion of the corner of the front surface or the rear surface connected to the inclined surface, with membranes for formation of a primary sealing wall locally arranged on the primary insulation panels and bonding panels.

(5) FIG. 5A is a perspective view of a bonding panel capable of attaching membranes.

(6) FIG. 5B is a sectional view of the bonding panel capable of attaching membranes.

(7) FIG. 6 is a partially enlarged view illustrating arrangement between the bonding panels and the membranes stacked on the bonding panels.

BEST MODE

(8) Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood that the present invention is not limited to the following embodiments and can also be implemented in different forms.

(9) A liquefied gas storage tank may be used to store, particularly, a hydrocarbon component-containing liquid cargo, such as LNG, LPG, and the like, which can be liquefied at an extremely low temperature. In addition, the liquefied gas storage tank may be a membrane type storage tank that includes sealing and insulation walls in order to store a cryogenic liquid cargo, such as LNG. The sealing and insulation walls are provided to walls of the storage tank in all directions thereof, that is, a front wall, a rear wall, a left-side wall, a right-side wall, an upper wall, and a lower wall, in order to prevent leakage of liquefied gas stored in the storage tank while blocking heat transfer from an external environment.

(10) The sealing and insulation walls of the membrane type LNG storage tank for storing LNG includes a secondary insulation layer disposed on an inner wall of a hull, a secondary sealing layer disposed on the secondary insulation layer, a primary insulation layer disposed on the secondary sealing layer, and a primary sealing layer disposed on the primary insulation layer.

(11) The insulation layers serve to prevent LNG from being heated by external heat by preventing intrusion of the external heat into the cargo tank and the sealing layers serve to prevent leakage of LNG from the storage tank. The cargo tank has a dual sealing structure so as to allow one sealing layer to prevent leakage of LNG even upon damage to the other sealing wall.

(12) For installation of the sealing and insulation walls of the LNG storage tank, plural secondary insulation panels are coupled to each other on the inner wall of the hull to form a secondary insulation layer, a secondary sealing wall is disposed on the secondary insulation layer formed by the secondary insulation panels to form a secondary sealing layer, a primary insulation panel is disposed on the secondary sealing layer formed by the secondary sealing wall to form a primary insulation layer, and a primary sealing wall (for example, a membrane formed of SUS or the like) is finally disposed on the primary insulation layer formed by the primary insulation panel to form a primary sealing layer.

(13) A liquefied gas storage tank including a primary sealing layer formed using membranes according to one embodiment of the present invention may be disposed inside a hull of a marine structure. Herein, the marine structure includes various liquefied gas carriers such as an LNG carrier, vessels such as LNG RVs (LNG Regasification Vessels), and plants, such as LNG FPSO (LNG Floating, Production, Storage and Off-loading), LNG FSRU (LNG Floating Storage and Regasification Unit), LNG FRU (LNG Floating and Regasification Unit), BMPP (Barge Mounted Power Plant), FSPP (Floating and Storage Power Plant), and the like.

(14) FIG. 2 to FIG. 4 are views of a liquefied gas storage tank according to one embodiment of the present invention, illustrating a portion of a corner of a front surface or a rear surface connected to an inclined surface according to installation sequence in manufacture of the storage tank. FIG. 2 shows primary insulation panels arranged thereon, FIG. 3 shows bonding panels arranged on the primary insulation panels, and FIG. 4 shows membranes for formation of a primary sealing wall locally arranged on the primary insulation panels and bonding panels.

(15) Referring to FIG. 2 to FIG. 4, a membrane bonding structure according to one embodiment of the present invention includes a planar portion panel 20 disposed on an inner wall of the storage tank to form the storage tank, a bonding panel 30 disposed on a hypotenuse portion of a front surface and a rear surface of the storage tank together with the planar portion panel 20, and membranes 42, 44 attached to the bonding panel 30.

(16) The planar portion panel 20 is a portion of a primary insulation panel, which will be disposed in flat regions of the front surface and the rear surface of the liquefied gas storage tank, and forms a primary insulation layer. Herein, the planar portion panel 20 is illustrated as the primary insulation panel for formation of the primary insulation layer. Alternatively, the planar portion panel 20 may be a panel module into which a secondary insulation panel, a secondary sealing wall, and the primary insulation panel are integrated.

(17) The planar portion panel 20 may be, for example, a rectangular parallelepiped plate having a constant thickness and a rectangular shape. One side of the planar portion panel 20 disposed on the hypotenuse portion 11a of the front surface and the rear surface of the liquefied gas storage tank may be obliquely cut corresponding to the shape of the hypotenuse portion 11a.

(18) FIG. 2 to FIG. 4 shows only a portion of, for example, the front surface of liquefied gas storage tank, in which only one hypotenuse portion 11a formed between the front surface and an upper right-side inclined surface thereof is shown. However, it should be noted that the front surface (rear surface) of the liquefied gas storage tank is connected to a total of four inclined surfaces (an upper left-side inclined surface, an upper right-side inclined surface, a lower left-side inclined surface and a lower right-side inclined surface) through the hypotenuse portions and the membrane bonding structure according to the present invention may be applied to all of the hypotenuse portions in the same way.

(19) In addition, a metal strip 22 may be mounted on a surface of the planar portion panel 20 in order to allow the primary sealing wall for formation of the primary sealing wall, that is, the membranes 42, 44, to be easily attached to the planar portion panel 20.

(20) The structure, manufacturing method, and installation method of the planar portion panel 20 do not limit the present invention and detailed description thereof will be omitted.

(21) As shown in FIG. 3, the bonding panel 30 may be disposed on the hypotenuse portion of the front surface and the rear surface of the storage tank. The bonding panel 30 may be linearly arranged in plural along the hypotenuse portion.

(22) FIG. 5A and FIG. 5B are a perspective view and a sectional view of the bonding panel 30 to which the membranes 42, 44 are attached, respectively.

(23) As shown in FIG. 3, FIG. 5A and FIG. 5B, the bonding panel 30 may be a portion of the primary insulation panel, which will be disposed in flat regions of the front surface and the rear surface of the liquefied gas storage tank, and may form the primary insulation layer. Herein, the bonding panel 30 is illustrated as being included in the primary insulation panel for formation of the primary insulation layer. Alternatively, the bonding panel 30 may be a panel module into which the secondary insulation panel, the secondary sealing wall, and the primary insulation panel are integrated.

(24) Referring to FIG. 5A, the bonding panel 30 may be, for example, a rectangular parallelepiped plate having a constant thickness and a rectangular shape. Each of the bonding panels 30 disposed at corners of both ends of the hypotenuse portion 11a of the front surface and the rear surface of the storage tank may have a shape corresponding to the shape of the corners excluding a rectangular shape.

(25) Referring to FIG. 5B, each of the bonding panels 30 includes a pair of plywood sheets 31, 33, a heat insulator 32 interposed between the plywood sheets 31, 33, a thermal protector 34 stacked on one plywood sheet 33, and an Invar sheet 35 stacked on the thermal protector 34.

(26) The heat insulator 32 may be formed of, for example, polyurethane foam (PUF), reinforced polyurethane foam (RPUF), and the like. The pair of plywood sheets 31, 33 may be attached to both surfaces of the heat insulator 32 via a bonding agent (for example, pu-glue). The thermal protector 34 may be secured to the plywood sheet 33 by a staple. The Invar sheet 35 may be secured to the thermal protector 34 by a fastening screw coupled to the plywood sheet 33 through the thermal protector 34.

(27) The bonding panel 30 may be provided to the secondary insulation panel (not shown) and the secondary sealing wall (not shown) instead of the planar portion panel or may be provided thereto by partially removing the planar portion panel disposed on the secondary insulation panel (not shown) and the secondary sealing wall (not shown).

(28) As shown in FIG. 4, the membranes 42, 44 may be joined to the primary insulation panel, that is, the planar portion panel 20 and the bonding panel 30, by welding. The membranes 42, 44 form the primary sealing layer and directly contact cryogenic liquefied gas. The membranes 42, 44 include a plurality of corrugations 42a, 44a to absorb thermal stress resulting from shrinkage and expansion of the cryogenic liquefied gas.

(29) FIG. 4 shows the membranes 42, 44 attached to the bonding panel 30, in which the membranes 42, 44 are not stacked in some regions of the planar portion panel 20.

(30) According to the embodiment of the invention, membranes (hereinafter, first membranes 42) to be disposed on the front surface and the rear surface of the storage tank, and membranes (hereinafter, second membranes 44) to be disposed on the inclined surface thereof may be individually bonded to the bonding panel 30 disposed on the hypotenuse portion 11a. Thus, according to the embodiment of the invention, the first membranes 42 are not directly connected to the second membranes 44. Furthermore, intervals between corrugations 42a on the first membrane 42 do not affect intervals between corrugations 44a on the second membrane 44, and the corrugations 42a, 44a on all of the membranes 42, 44 may be arranged at the same intervals.

(31) According to the present invention, the first membranes 42 and the second membranes 44 may have the same shape and may include the corrugations 42a, 44a formed in the same pattern.

(32) Although FIG. 4 shows that the first membranes 42 and the second membranes 44 are arranged on the same plane, it should be understood that this arrangement is provided for illustration and convenience of description.

(33) FIG. 6 is a partially enlarged view illustrating arrangement between the bonding panels 30 and the membranes 42, 44 stacked on the bonding panels 30.

(34) As described above, the first membrane 42 and the second membrane 44 are not directly connected to each other and individually bonded to the bonding panel 30. In addition, the corrugations 42a formed on the first membrane 42 are not directly connected to the corrugations 44a formed on the second membrane 44.

(35) Here, a connection membrane 46 is disposed at an interface between two bonding panels 30 adjoining each other. The connection membrane 46 includes corrugations 46a, which connect the corrugations 42a of the first membrane 42 to the corrugations 44a of the second membrane 44.

(36) The bonding panels 30 are disposed to connect the first membrane 42 to the second membrane 44 at the interface between two bonding panels 30 adjoining each other, whereby the first and second membranes 42, 44 counteract corresponding to thermal deformation of the bonding panels 30, which shrink or expand due to extremely low temperatures of the liquefied gas.

(37) In other words, since the bonding panels 30 shrink towards the center of thermal deformation thereof upon thermal shrinkage, the interface between two bonding panels 30 adjoining each other is subjected to compressive force in opposite directions upon thermal shrinkage. Here, the membranes 42, 44 welded to the bonding panels 30 move corresponding to deformation of the bonding panels 30, thereby causing stress concentration. According to the present invention, stress concentration can be dispersed by the connection membrane 46 including the corrugations 46a.

(38) As shown in FIG. 6, the corrugation 46a formed on one connection membrane 46 may connect one corrugation 42a formed on one first membrane 42, to which the connection membrane 46 is joined, to one corrugation 44a formed on one second membrane 44, to which the connection membrane 46 is joined. In FIG. 6, the first membrane 42 and the second membrane 44 are illustrated in a translucent state to confirm the locations of the bonding panels 30 for convenience of understanding.

(39) According to the present invention, the first membranes 42 and the second membranes 44 may be individually bonded to the bonding panels 30 disposed on the hypotenuse portion of the front and rear surfaces, thereby enabling compensation for errors due to manufacturing tolerance of a hull in installation of the membranes of the liquefied gas storage tank.

(40) Although some embodiments are described above with reference to the accompanying drawings, it will be apparent to those skilled in the art that the present invention is not limited to the above embodiments and that various modifications, changes, alterations, and equivalent embodiments can be made without departing from the spirit and scope of the invention.