EP2419671B3 - Stopper for a secondary diaphragm of an lng vat - Google Patents

Description

Technical field of the invention

The present invention relates to the production of sealed and thermally insulated tanks integrated into a supporting structure.

State of the art

In French patent applications no. FR 2 691 520 and no FR 2,724,623 it has already been proposed a sealed and thermally insulated tank integrated in a supporting structure formed by the double hull of a ship. Each wall of the tank has, successively from inside the tank towards the supporting structure, a primary sealing barrier in contact with the product contained in the tank, a primary heat-insulating barrier, a secondary sealing barrier and a barrier thermally insulating secondary.

The primary thermally insulating barrier, the secondary sealing barrier and the secondary thermal insulating barrier are essentially constituted by a set of prefabricated panels fixed on the supporting structure. Each prefabricated panel is formed, in the first place, of a first rigid plate carrying a layer of thermal insulation and constituting with it a secondary thermally insulating barrier element, secondly, a flexible or rigid sheet adhering substantially to any the surface of the thermal insulating layer of the aforementioned secondary thermal insulating barrier element, said ply forming a secondary sealing barrier element, thirdly, a second thermal insulating layer, which partially overlaps the said web and adhering thereto and, fourthly, a second rigid plate covering the second layer of thermal insulation and constituting with it a primary thermally insulating barrier element.

In an area located at the top of the vertical walls of the tank, the secondary sealing barrier is connected to the supporting structure. This zone called "stop zone of the secondary membrane" is not described in the aforementioned documents.

The figure 1 represents, in section, the stopping zone of the secondary membrane of a tank of the prior art. The supporting structure 1 is constituted by the double hull of a ship. It comprises a vertical pan 2 and a horizontal pan 3. An L-shaped plate 4 is welded to the horizontal pan 3 and extends downwards.

In known manner, prefabricated panels (not shown) are attached to the vertical pan 2 to form the primary heat-insulating barrier, the secondary sealing barrier and the secondary heat-insulating barrier. On the figure 1 . the layer 5 of insulating material and the watertight layer 6 of the prefabricated panel located higher can be seen.

In the stopping zone of the secondary membrane, the ply 6 must be sealingly connected to the supporting structure 1. This is achieved by a flexible ply 7 which is, on the one hand, bonded to the ply 6 of the prefabricated panel and on the other hand, glued to the L-shaped plate 4. The gluing of the sheet 7 to the L-shaped plate 4 is achieved, and two layers of putty 8 are provided, as shown in more detail in FIG. figure 2 . A beam 9 of veneer is bolted to the flat L 4.

This closure system of the secondary membrane has several disadvantages.

On the one hand, the mechanical joining of the ply 7 to the L-shaped plate 4 is complicated to implement since it requires, in addition to the bonding of the ply 7, the application of the two layers of putty 8 and the bolting of the beam 9.

On the other hand, the small surface area bonded between the sheet 7 and the L-shaped plate 4 requires the use of a highly qualified and experienced workforce to carry out this operation and guarantee the gas-tightness of LNG. and liquid.

Summary of the invention

A problem that the present invention proposes to solve is to provide a vessel that does not exhibit at least some of the aforementioned drawbacks of the prior art. In particular, an object of the invention is to provide a tank in which the secondary sealed barrier can be connected more easily to the carrier structure. Another object of the invention is to make it possible to automate and make reliable as much as possible the manufacture of the tank.

The solution proposed by the invention is a tank for liquefied natural gas, comprising a bearing structure and a sealed and thermally insulated tank for containing liquefied natural gas, said tank comprising a plurality of tank walls attached to said supporting structure, each wall of tank having successively, in the direction of the thickness from the inside to the outside of said tank, a primary watertight barrier, a primary heat-insulating barrier, a secondary watertight barrier and a secondary heat-insulating barrier, said tank walls comprising at least one vertical wall, the secondary sealed barrier of said vertical wall comprising a first watertight sheet located at the top of said wall and a connection device sealingly connecting said first watertight sheet to said supporting structure, characterized in that said connecting device comprises a first pl metal plate parallel to said first watertight web, a third watertight web adhered to said first metal plate, and a second watertight web adhered, on the one hand, to said first watertight web and on the other hand to said third watertight web. Alternatively, the second watertight web can be glued directly to the first metal plate.

This tank can be for example a ship or a land tank. Thanks to the above characteristics, the second watertight layer is bonded respectively to two parallel surfaces. This bonding can therefore be achieved easily, automatically and reliably. The bonding of the first waterproof ply can be done before installation in the tank, in the workshop. The first plate being metallic, it can be connected to the supporting structure, directly or indirectly, by continuous welding. This continuous welding can also be done easily, automatically and reliably. Thus, the invention avoids the use of layers of mastic. In addition, the bonding of the second layer does not require a highly qualified and experienced workforce.

Preferably, said second watertight web is flexible and has a non-sized area between the first watertight web and the third watertight web.

The flexibility of the second ply and the non-glued area allow the resumption of displacements imposed by the supporting structure and the thermal insulation secondary to the secondary watertight barrier.

Advantageously, said first metal plate is welded to a metal part connected to the supporting structure.

Preferably, said metal part has a vertical part and a horizontal part, the first metal plate being welded to the vertical part, the horizontal part being connected to the supporting structure.

The length of the horizontal part allows adjustment of the position of the vertical part, during the installation of the metal part. This makes it possible to adjust the position of the vertical part to the position of the first sheet. According to one embodiment, the vertical part, on which is glued the third waterproof ply, is positioned so that the first and the third ply are located in the same plane. This makes it even easier to glue.

Advantageously, said first watertight web is glued on a layer of insulating material or on a plywood plate forming part of the secondary thermally insulating barrier.

According to one embodiment, said support structure comprises vertical concrete wall panels, installed on the ground.

According to another embodiment, said support structure comprises the double shell of a floating structure

Brief description of the figures

• la figure 1 est une vue en coupe d'une cuve de l'art antérieur, au niveau de la zone d'arrêt de la membrane secondaire,
• la figure 2 représente un détail de la figure 1,
• la figure 3 est une vue en coupe d'une cuve selon un mode de réalisation de l'invention, au niveau de la zone d'arrêt de la membrane secondaire,
• les figures 4 et 5 représentent des détails de la figure 3,
• la figure 6 est une vue en perspective de la zone d'arrêt de la membrane secondaire de cuve de la figure 3, au niveau d'un coin,
• les figures 7 et 8 représentent une équerre agencée dans le coin de la figure 6,
• la figure 9 est une vue similaire à la figure 6, où certains éléments ont été retirés,
• la figure 10 est une vue en coupe d'une cuve selon un autre mode de réalisation de l'invention, au niveau de la zone d'arrêt de la membrane secondaire,
• les figures 11 et 12 représentent des détails de la figure 10, et
• la figure 13 est une vue en perspective de la zone d'arrêt de la membrane secondaire de cuve de la figure 10, au niveau d'un coin.

The invention will be better understood, and other objects, details, characteristics and advantages thereof will appear more clearly in the course of the following description of several particular embodiments of the invention, given solely for illustrative and non-limiting purposes. with reference to the accompanying drawings. On these drawings:

• the figure 1 is a sectional view of a vessel of the prior art, at the stop zone of the secondary membrane,
• the figure 2 represents a detail of the figure 1 ,
• the figure 3 is a sectional view of a tank according to one embodiment of the invention, at the stop zone of the secondary membrane,
• the figures 4 and 5 represent details of the figure 3 ,
• the figure 6 is a perspective view of the stopping zone of the secondary cell membrane of the figure 3 , at a corner,
• the Figures 7 and 8 represent a square arranged in the corner of the figure 6 ,
• the figure 9 is a view similar to the figure 6 , where some elements have been removed,
• the figure 10 is a sectional view of a tank according to another embodiment of the invention, at the stop zone of the secondary membrane,
• the figures 11 and 12 represent details of the figure 10 , and
• the figure 13 is a perspective view of the stopping zone of the secondary cell membrane of the figure 10 , at a corner.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The Figures 3 to 9 relate to a tank according to a first embodiment of the invention. The vessel has a plurality of vessel walls and is integrated into a carrier structure 11. The carrier structure 11 may be the double hull of a ship or other type of floating structure.

In known manner, each tank wall has successively, in the direction of the thickness from the inside to the outside of the tank, a primary watertight barrier, a primary heat-insulating barrier, a secondary watertight barrier and a thermally insulating barrier. secondary.

In a manner similar to the prior art mentioned in the introduction, the primary thermally insulating barrier, the secondary sealed barrier and the secondary thermally insulating barrier essentially consist of a set of prefabricated panels fixed on the supporting structure 11.

In particular, the secondary watertight barrier is constituted by an assembly of waterproof plies. Each sheet consists of a composite material whose two outer layers are glass fiber fabrics and whose intermediate layer is a deformable thin aluminum sheet of about 0.1 mm thick. Depending on its manufacturing process, the sheet may be rigid or flexible. Each prefabricated panel therefore comprises, inter alia, a rigid sheet bonded to a layer of thermally insulating material. At the junctions between adjacent panels, strips of flexible ply connect the adjacent rigid plies.

In an area situated at the top of a vertical wall of the tank, the secondary watertight barrier, also called secondary membrane, is connected to the carrying structure 11. The figure 3 represents, in section, this zone called the stopping zone of the secondary membrane. The figures 4 and 5 represent details of the figure 3 .

The carrying structure 11 comprises a vertical pan 12 and a horizontal pan 13. An L-shaped plate 14 is welded to the horizontal pan 13. The plate 14 has a vertical part 27 which extends downwards, parallel to the vertical pan 12, and a horizontal portion 28 located at the lower end of the vertical portion 27 and extending away from the vertical pan 12.

A fixing bracket 20 is fixed below the horizontal portion 28. A U-shaped stirrup 21 is fixed to the plate 14 and to the bracket 20. More precisely, the stirrup 21 has two parallel branches 30 connected by a wall 29 perpendicular to the branches. 30. The branches 30 are fixed respectively to the horizontal portion 28 of the flat 14 and to the square 20.

It may be noted, on the one hand, that the supporting structure 11 and the plate 14 have the same shape as in the prior art of the figure 1 . In other words, the invention does not require modifying the forms of carrier structures usually used. On the other hand, the fixing of the bracket 20 and the stirrup 21 can be easily achieved by continuous welding, in an automated and reliable manner.

We can see on Figures 3 to 5 a layer 15 of thermally insulating material of a prefabricated panel located at the top of the wall. This layer 15 is covered by a rigid ply 16, except at an upper edge. At this upper edge, the layer 15 is thinner and the panel has a recessed face 24 in which is formed a horizontal groove. The face 24 is situated substantially in the same plane as the wall 29 of the stirrup 21, which is possible because the geometry of the stirrup 21 makes it possible, when it is fixed, to adjust the position of the wall 29.

A metal plate 22 is welded to the wall 29 of the stirrup and extends downward, covering the face 24 to the groove 25. At its lower end, the plate 22 has a flange 26 folded in the groove 25. A strip of rigid ply 23 is glued to the plate 22.

As shown in figure 5 , a flexible web strip 17 is bonded, on the one hand, to the web 16 and, on the other hand, to the web 23. An unsized zone is between the webs 16 and 23. It may be noted that this bonding is made respectively on two parallel surfaces, on which there are rigid webs. This bonding can therefore be achieved easily, automatically and reliably. As a variant, there is no strip of web 23 and the strip of web 17 is glued directly on the plate 22.

The foregoing structure makes it possible to seal the ply 16 of the prefabricated panel to the supporting structure 11, via the flexible ply 17, possibly the rigid ply 23, the plate 22, the stirrup 21 and the In addition, the flexibility of the ply 17 allows the resumption of displacements imposed by the supporting structure 11 and the thermal insulation secondary to the secondary sealed barrier, leaving a non-glued area between the ply 23 and the ply 16.

The figure 6 represents, in perspective, a corner of the tank formed by two vertical walls. We can see, for each wall, some of the elements described above.

The figure 7 is similar to the figure 6 and represents a variant in which a bracket 31 is fixed in the angle, to maintain the flexible web 17 in place. Indeed, the flat gluing submits the gluing of the corner areas to a resultant of thermomechanical forces perpendicular to the bonding plane may cause the rupture of the glued joint by peeling. Depending on the size of the tank and the characteristics of the bonding, such a bracket 31 may be necessary or not. The figure 8 shows the bracket 31 and its fixing bolts in more detail.

The figure 9 is similar to the figure 6 but the flexible web 17 has been removed to allow the underlying elements to be seen. It can be seen that the rigid sheet 23 is present along the walls in the form of a flat strip. In known manner, such a flat strip is manufactured from two layers of glass fabric arranged on either side of an aluminum foil, resined together and hot pressed during the polymerization of the resin. In the corner, the rigid ply 23 is in the form of an L-shaped strip. Such a non-planar strip can be made by polymerizing the resin, under heat and under pressure, on a mold with the desired shape. Alternatively, in the corner, is used a flexible web 23 which, by its flexibility, can adapt to a corner area.

The Figures 10 to 13 represent a tank according to a second embodiment of the invention. The vessel has a plurality of vessel walls and is integrated into a carrier structure 111. The carrier structure 111 comprises vertical wall sections of prestressed concrete. In this embodiment, the carrier structure 111 and the tank form a land tank for LNG.

A metal plate 114 is attached to the carrier structure 111. For example, the plate 114 is positioned during casting of the concrete. A metal plate 120 is welded to the plate 114, and extends horizontally.

Similarly to the first embodiment, the primary thermally insulating barrier, the secondary sealed barrier and the secondary thermally insulating barrier of the vessel essentially consist of a set of prefabricated panels fixed on the supporting structure 111. It can be seen in particular on the figure 11 that each upper prefabricated panel comprises a layer 115 of insulating material, covered by a plate 132 of plywood. The plate 132 is covered by a rigid ply 116, except at a lower thicker edge, where the plate 132 has a recessed face 124.

A metal plate 122 is screwed to the panel 132, on the face 124, leaving an uncoated area 133 adjacent the portion of the panel 132 covered by the web 116. The plate 122 is partially covered by a rigid web 123.

As shown in figure 12 , a flexible strip of ply 117 is bonded, on the one hand, to the ply 116 and, on the other hand, to the ply 123. An unsized zone is located between plies 116 and 123. It may be noted that this gluing is made respectively on two parallel surfaces, on which there are rigid webs. This bonding can therefore be achieved easily, automatically and reliably. Preferably, the plies 116 and 123 are located in the same plane, which further facilitates gluing. In a variant, there is no ply 123 and the ply strip 117 is stuck directly on the plate 122.

A metal angle 121 is welded, on the one hand, to the plate 120 and, on the other hand, to the plate 122. Specifically, the angle 121 has a horizontal wall 130 welded to the plate 120 and a vertical wall 129 welded to the plate 122.

Thus, the above structure makes it possible to seal the web 116 of the prefabricated panel to the carrier structure 111, via the flexible ply 117, the rigid ply 123, the plate 122, the angle 121 and plates 120 and 114. The bonding of the web 117 can be performed in an automated and reliable manner. Similarly, the welding of the angle 121 can be performed in an automated and reliable manner. The geometry of the angle 121 allows a position adjustment to coincide with the position of the plate 122.

The figure 13 represents the stopping area of the secondary membrane in perspective. There can be seen a corner area 133 between two adjacent vertical walls. This angle is more open than in the case of the first embodiment so that the risk of peeling off is lower. However, depending on the dimensioning of the tank and the characteristics of the peel, one can optionally fix a clamping bracket, similarly to the bracket 31 of the first embodiment.

Although the invention has been described in connection with several particular embodiments, it is obvious that it is not limited thereto and that it comprises all the technical equivalents of the means described and their combinations if they are within the scope of the invention as defined by the claims.

In the two embodiments described above, the flexible sheet forms, in particular with the plate 22 or 122, a connection device sealingly connecting the napped of a prefabricated panel to the supporting structure. A connecting device has been described in relation to a floating structure and the other with a terrestrial reservoir. The two connecting devices can however be used with a floating structure or a terrestrial reservoir.

Claims (8)

1. Liquefied natural gas container comprising a loadbearing structure (11, 111) and an impermeable and thermally insulated tank designed to contain liquefied natural gas, said tank comprising a plurality of tank walls fixed to said loadbearing structure, each tank wall having in succession, in the direction of the thickness, proceeding from the inside of said tank to the outside, a primary impermeable barrier, a primary thermally insulating barrier, a secondary impermeable barrier and a secondary thermally insulating barrier, said tank walls comprising at least one vertical wall, the secondary impermeable barrier of said vertical wall comprising a first impermeable sheet (16, 116) at the top of said wall and a connecting device which impermeably connects said first impermeable sheet to said loadbearing structure, said container being characterized in that said connecting device comprises a first metal plate (22, 122) parallel to said first impermeable sheet, and a second impermeable sheet (17, 117) which is on the one hand bonded to a first surface of the said first impermeable sheet and on the other hand bonded directly to a second surface of the said first metal plate, the first and the second surface being parallel.
2. Liquefied natural gas container comprising a loadbearing structure (11, 111) and an impermeable and thermally insulated tank designed to contain liquefied natural gas, said tank comprising a plurality of tank walls fixed to said loadbearing structure, each tank wall having in succession, in the direction of the thickness, proceeding from the inside of said tank to the outside, a primary impermeable barrier, a primary thermally insulating barrier, a secondary impermeable barrier and a secondary thermally insulating barrier, said tank walls comprising at least one vertical wall, the secondary impermeable barrier of said vertical wall comprising a first impermeable sheet (16, 116) at the top of said wall and a connecting device which impermeably connects said first impermeable sheet to said loadbearing structure, said container being characterized in that said connecting device comprises a first metal plate (22, 122) parallel to said first impermeable sheet, and a second impermeable sheet (17, 117) which is on the one hand bonded to a first surface of the said first impermeable sheet and on the other hand bonded to a second surface of a third impremebale sheet (23, 123) which is bonded to said first metal plate, the first and the second surface being parallel.
3. Container according to claim 1 or 2, in which said second impermeable sheet is flexible and has an unbonded zone between the first impermeable sheet and the first metal plate.
4. Container according to one of the preceding claims, in which said first metal plate is welded to a metal component (21, 121) connected to the loadbearing structure.
5. Container according to the preceding claim, in which said metal component has a vertical part (29, 129) and a horizontal part (30, 130), the first metal plate being welded to the vertical part and the horizontal part being connected to the loadbearing structure.
6. Container according to one of the preceding claims, in which said first impermeable sheet is bonded to a layer of insulating material (15) or to a plate of plywood (132) forming part of the secondary thermally insulating barrier.
7. Container according to one of the preceding claims, in which said loadbearing structure comprises vertical concrete wall sections installed on land.
8. Container according to one of the preceding claims, in which said loadbearing structure comprises the double hull of a floating vessel.

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