RU2763100C1 - Sealed and heat-insulating tank - Google Patents

Abstract

FIELD: storage.

SUBSTANCE: group of inventions relates to sealed and heat-insulating tanks for storing liquefied gas. The tank comprises a wall with a heat-insulating barrier and a sealing membrane supported by said heat-insulating barrier. The heat-insulating barrier comprises two insulation panels, wherein each has an upper sheet forming a support surface whereon the sealing membrane rests. The upper sheet of one of the two insulation panels comprises a recess along the transverse edge of said insulation panel facing the other insulation panel. The recess therein extends perpendicularly to the longitudinal direction from one end of said insulation panel to the other so that the bars are not supported by the support surface of said insulation panel along said transverse edge of the insulation panel. Also described is a vessel for transporting a fluid medium, containing a double hull and said tank located in the double hull. Also described is a system for transferring a fluid medium, containing said vessel. Additionally described is a method for loading or unloading said vessel.

EFFECT: group of inventions is aimed at reducing the width of the gaps between the insulation panels without a significant deterioration in the fatigue characteristics of the membrane.

12 cl, 13 dwg

Description

TECHNICAL FIELD OF THE INVENTION

The present invention relates to the field of sealed and heat-insulating membranes for storage and / or transportation of a fluid, such as liquefied gas.

Sealed and insulated membrane tanks are particularly used for storing liquefied natural gas (LNG), which is stored at atmospheric pressure and temperatures around -163 ° C. Such tanks can be installed on land or on a floating structure. In the case of a floating structure, the tank may be designed to transport liquefied natural gas or to receive liquefied natural gas used as fuel to propel the floating structure.

LEVEL OF TECHNOLOGY

Document WO 2014096600 discloses a sealed and heat-insulating tank for storing liquefied natural gas, where the tank is located in a supporting structure, and its walls have a multilayer structure, namely in the direction from the outside to the inside of the tank, an auxiliary thermal insulation barrier attached to the supporting structure, an auxiliary a sealing membrane that is supported by a secondary insulation barrier, a primary insulation barrier that is supported by a secondary sealing membrane, and a primary sealing membrane that is supported by a primary insulation barrier that is designed to contact the LNG stored in the tank.

Each primary and secondary thermal barrier comprises a set of respective primary and secondary insulation panels, having a general parallelepiped shape, which are adjacent to each other and thus form a support surface for the respective sealing membrane. Each of the primary and secondary sealing diaphragms contains a continuous layer of folded metal strips that are welded to parallel welding posts. The L-shaped supports for welding attachment are fixed in grooves formed in the insulation panels of the primary or secondary insulation barrier. The primary and secondary insulation panels can deform, which can lead to a level difference between adjacent insulation panels in the direction of the tank wall thickness. Such deformations, in particular, can occur due to the phenomenon of fluid movement within the tank (a phenomenon known as the "splash effect"), as well as due to the phenomenon of thermal gradients that can cause compression of the insulation panels.

The applicant has found that in a tank of the above type, it is necessary to maintain a minimum gap between adjacent insulating panels and, in particular, between the transverse edges of the panels, which are orthogonal to the direction of the supports to be joined by welding. This is because a decrease in the distance between the transverse edges of two adjacent insulating panels leads to the fact that due to the level difference that can occur between adjacent insulating panels, the angular deformation of the support for joining by welding and the membrane attached to the said insulating panels increases, which leads to an increase in the fatigue stress of the membrane. Therefore, if the minimum clearance is not maintained, the diaphragm may be damaged.

In particular, fatigue tests of the above-mentioned type of tank seal membranes were carried out when the size of the gap formed between the adjacent transverse edges of the two insulation panels was less than a minimum value.

Each fatigue test contains about 2000 cycles. In each of the cycles, a level difference is created in the direction of the tank wall thickness between the adjacent transverse edges of the two insulation panels of the order of several millimeters. This test is an indicator of the life of the vessel.

During the tests it was found, in particular, that in the area of the gap between the adjacent transverse edges of the insulating panels:

- the flat middle sections of the sealing membrane strips are susceptible to bending and possibly cracking, resulting in a lack of sealing,

- The folded edges of the planks and the areas where the folded edges are connected to the flat middle section of the planks are subject to deformation, which leads to unevenness and possibly cracking, which in turn leads to a lack of compaction.

However, maintaining the minimum clearance between the transverse edges of the insulation panels degrades the thermal performance of the thermal insulation barrier.

SUMMARY OF THE INVENTION

One idea underlying the invention is to make it possible to reduce the width of the gaps between primary and / or secondary insulating panels that are longitudinally adjacent to one another for welded attachment without significantly impairing the fatigue characteristics of the membrane.

One idea underlying the invention is to provide a sealed and heat-insulating tank for storing liquefied gas, comprising a wall having in series in the direction of the wall thickness from the outside to the inside of the tank, a heat-insulating barrier and a sealing membrane resting on said heat-insulating barrier ;

the thermal insulation barrier comprises at least two insulation panels, each of which has a top sheet defining a support surface on which the sealing membrane rests, said insulation panels being longitudinally aligned and each having two transverse edges that are perpendicular to the longitudinal direction;

the sealing membrane comprises at least two metal strips that extend parallel to the longitudinal direction on both sides of the support for connection by welding, extending, and said support for welded connection extends parallel to the longitudinal direction and is held on the top sheet of the insulating panels, wherein the strips have a middle section, resting on the support surfaces, and two folded edges that extend parallel to the longitudinal direction, with one of the folded edges of each of the two strips being welded to the welding support;

at least the top sheet of one of the two insulation panels comprises, along a transverse edge of said insulation panel, which faces the other insulation panel, a recess, the recess extending perpendicular to the longitudinal direction from one end of the top sheet of said insulation panel to the other, so that the strips are not supported by the support the surface of said insulation panel along said transverse edge of the insulation panel.

Thus, the recess makes it possible to limit the angular deformation p of the sealing membrane at the level of the gap between the transverse edges of the insulation panels in the event of a level difference between adjacent insulation panels. Thus, the deformations of the sealing membrane remain in the area of elastic deformations and do not lead to irreversible deformations in the case of pressures usually characteristic of reservoirs. This prevents or limits shear deformations of the sealing membrane.

According to one embodiment, the top sheet of each of the two insulation panels comprises, along a transverse edge of said insulation panel that faces the other insulation panel, a recess, the recess extending perpendicular to the longitudinal direction from one end of said insulation panel to the other, so that the strips are not supported a supporting surface of said insulating panel along said transverse edge.

According to one embodiment, the recess is formed such that the topsheet is recessed at least in a certain region above a plane that is inclined at an angle of 55 ° with respect to the abutment surface and which intersects the transverse edge of the insulation panel at a distance of 6 mm from the abutment surface in the direction wall thickness.

In accordance with one embodiment, one or each recess is formed by a cut, beveled cut or fillet formed in the topsheet along the transverse edge of the insulation panel.

In accordance with one embodiment, the support for attachment by welding extends in the longitudinal direction and includes a weld flange and a mounting flange that is angled relative to the weld flange; wherein each of the top sheets of the two insulating panels has a groove in which a support for welding connection is installed, each groove protruding on the support surface and has a branch in which a fastening flange of the support for welding connection is located, the branch forming in the corresponding insulation panel between the branch and by the supporting surface, a holding portion, by which the fastening flange is held, for holding the welding support on said insulating panel.

In accordance with one embodiment, each groove extends into one of the recesses so that the support for welding is not held against the thermal barrier in the region of said recess.

In accordance with one embodiment, the groove of each of the insulation panels has one end facing the other insulation panel, which continues with a recess protruding on the abutment surface, each of which is formed at least in the longitudinal extension of said groove and the holding portion, so that the support for attachment by welding is not held on said insulating panel in the region of said recess.

Thus, the welded connection support is not retained on the thermal barrier in the region of the recess, and the welded connection support and sealing membrane have greater flexibility at the level of the gap formed between the insulating panels, thus limiting the stresses acting on the welded connection supports and the sealing membrane. when there is a difference in level between adjacent main insulation panels, and at the same time allows you to reduce the gap value to optimize the thermal performance of the insulation.

According to one embodiment, the adjacent transverse edges of the insulation panels are spaced apart from each other with a gap that has a longitudinal width of less than 5 mm, for example of the order of 1 mm.

According to one embodiment, the sum of the longitudinal dimension of the recess of each of the two insulation panels and the width of the gap formed between the insulation panels is between 7 mm and 70 mm.

According to one embodiment, the sum of the longitudinal dimension of the recess of each of the two insulation panels and the width of the gap formed between the insulation panels is between 7 and 25 mm when each groove extends into one of the recesses through the recess. In such a case, the dimension in the longitudinal direction of the recess is, for example, 3 to 12 mm.

According to another embodiment, the sum of the longitudinal dimension of the recess of each of the two insulation panels and the width of the gap formed between the insulation panels is 20 to 70 mm, preferably 25 to 45 mm and in particular 30 to 40 mm, when each the groove goes directly into one of the recesses. In such a case, the dimension in the longitudinal direction of the recess is, for example, 14.5 to 29.5 mm.

According to one embodiment, the grooves of the insulating panels are spaced apart from each other with a gap i, the size of which in the longitudinal direction is from 20 to 70 mm, preferably from 25 to 45 mm and in particular from 30 to 40 mm. In other words, the size of the support for welding attachment that is not supported on the insulating panels in the region of the gap between the transverse edges of the insulating panels is 20 to 70 mm, preferably 25 to 45 mm and in particular 30 to 40 mm. This makes it possible, on the one hand, to limit the stresses that can act on the welded support and the sealing membrane within the permissible range, and on the other hand, to properly hold the sealing membrane on the insulating panels so that it does not come off.

According to one embodiment, one or each of the recesses has a dimension n in the longitudinal direction ranging from 5 mm to 30 mm.

According to one embodiment, one or each of the recesses has a depth p that is equal to and preferably greater than the depth of the grooves. This makes it possible to limit the stresses on the weld attachment support and the sealing membrane when the transverse edge of the insulating panel having said recess is raised relative to the adjacent transverse edge of the other insulating panel.

In accordance with one embodiment, the recess has a bottom and side walls connecting the bottom to the abutment surface.

According to one embodiment, the bottom of the recess is inclined so that the depth p of the recess decreases in the direction of the groove.

In accordance with one embodiment, the side walls of the recess are connected to the groove by means of chamfers or fillets. Such chamfers or fillets allow the support for the welded connection to be guided into the groove and thus facilitate the installation of the support for the connection by welding in the groove.

According to one embodiment, the side walls of the recess consist of a flat portion and are connected to the groove by means of a cylindrical portion.

According to one embodiment, the recess has a general triangle or trapezoidal shape that tapers towards the groove.

In accordance with one embodiment, the groove has an inverted T-section.

According to one embodiment, the weld attachment support has an L-shaped cross-section.

In accordance with one embodiment, the topsheet is made of plywood.

In accordance with one embodiment, the topsheet has a thickness of 9 to 15 mm.

In accordance with one embodiment, the thermal insulation barrier is the main thermal insulation barrier, and the sealing membrane is the main sealing membrane, and the ( tank ) wall comprises, in series, from the outside to the inside of the tank, an auxiliary thermal barrier attached to the supporting structure, an auxiliary sealing membrane supported by the secondary thermal barrier, the primary thermal barrier, and the primary sealing membrane.

In accordance with one embodiment, the sealing membrane is made of a material selected from stainless steel, iron and nickel alloys having an expansion coefficient of 1.2 x 10 ^-6 to 2 x 10 ^-6 K ^-1 , and iron and manganese alloys, the expansion coefficient of which is less than 15 × 10 ^-6 K ^-1 .

In accordance with one embodiment, the support for attachment by welding is made of a material selected from stainless steel, iron and nickel alloys, the expansion coefficient of which is from 1.2 × 10 ^-6 to 2 × 10 ^-6 K ^-1 , and iron alloys and manganese, the expansion coefficient of which is less than 15 × 10 ^-6 K ^-1 .

In accordance with one embodiment, at least one of the insulation panels comprises a backsheet, an intermediate sheet located between the backsheet and the topsheet, a first layer of insulation foam located between the backsheet and the intermediate sheet, and a second layer of insulation foam located between the intermediate sheet and the top sheet. This design is advantageous in that it allows bending loads resulting from different compression of the materials of the insulating panel to be limited.

According to another embodiment, at least one of the insulating panels further comprises a bottom sheet and load-bearing partitions extending in the direction of the tank wall thickness between the bottom sheet and the top sheet and defining a plurality of compartments filled with an insulating filler such as perlite.

In accordance with one embodiment, the thermal barrier comprises a plurality of insulating panels, each of which has a top sheet defining a support surface against which the sealing membrane rests, each of the top sheets having one or more grooves in which the support for welded attachment is mounted, when each of the ends of each groove has a recess protruding from the support surface and formed at least in the longitudinal extension of the groove and the retaining portion, so that the support for welding is not held on said panel in the region of said recess.

In accordance with one embodiment, the thermal barrier comprises a plurality of insulating panels, each of which has a topsheet defining a support surface against which the sealing membrane rests, the topsheet of each of the insulating panels comprises a recess along each of its transverse edges, the recess extending perpendicular to the longitudinal direction from one end of said insulation panel to the other, so that the strips are not supported by a support surface along the transverse edges of each insulation panel.

Such a tank may be part of an onshore storage facility, for example, for storing LNG, or it may be installed on a floating, offshore or offshore structure such as a methane tanker, a floating regasification and storage unit (FSRU), a floating production unit, storage and shipment of oil (FPSO), etc.

In accordance with one embodiment, the cryogenic fluid transport vessel comprises a double hull and the aforementioned reservoir disposed in the double hull.

In accordance with one embodiment, the double body comprises an inner body that forms the supporting structure of the tank.

In accordance with one embodiment, the invention also provides a method for loading or unloading a ship in which fluid is supplied through insulated pipelines from an offshore or onshore storage facility to a vessel's tank, or vice versa.

In accordance with one embodiment, the invention also provides a fluid transfer system, the system comprising the above vessel, insulated pipelines adapted to connect a vessel installed in the ship's hull to an offshore or onshore storage facility, and a pump for supplying fluid through insulated pipelines from offshore or onshore storage to a ship's tank or from a ship's tank to a floating or onshore storage.

BRIEF DESCRIPTION OF DRAWINGS

The present invention will become clearer and other objects, details, features and advantages will become more apparent from the following description of several specific embodiments of the invention, which are provided purely by way of non-limiting illustration with reference to the accompanying drawings.

FIG. 1 is a perspective cutaway view of a tank wall.

FIG. 2 is a cross-sectional view illustrating a groove formed in the main panel, a weld attachment support placed in the groove, and strips welded to the weld support.

FIG. 3 is a perspective view of the main panel according to the first embodiment.

FIG. 4 is a detailed perspective view illustrating a main insulation barrier at a joint between two adjacent main insulation panels in accordance with the first embodiment.

FIG. 5 is a detailed view of a recess at the transverse edge of the main insulation panel according to the first embodiment.

FIG. 6 is a schematic sectional view of the groove and recess.

FIG. 7 is a perspective view of a main insulation panel according to a second embodiment.

FIG. 8 is a schematic cross-sectional view illustrating a main insulation barrier at a junction between two adjacent main insulation panels in accordance with a second embodiment.

FIG. 9 is a schematic sectional view illustrating a main insulation barrier at a junction between two adjacent main insulation panels in accordance with an alternative embodiment of the second embodiment.

FIG. 10 is a schematic sectional view illustrating a main insulation barrier at a junction between two adjacent main insulation panels in accordance with another alternative of the second embodiment.

FIG. 11 is a perspective view of a main insulation panel according to a third embodiment.

FIG. 12 is a schematic cross-sectional view illustrating a main insulation barrier at a junction between two adjacent main insulation panels in accordance with a third embodiment.

FIG. 13 is a schematic cutaway view of the tank of a methane tanker and a terminal for loading / unloading this tank.

DETAILED DESCRIPTION OF IMPLEMENTATION OPTIONS

Conventionally, in the description, a two-dimensional orthonormal coordinate system defined by two axes x and y is used to describe the elements of the wall 1 of a sealed and heat-insulating tank. The x-axis corresponds to the longitudinal direction and the y-axis corresponds to the transverse direction. The longitudinal direction corresponds to the direction in which the strips and welding supports extend. According to a preferred embodiment, when the tank is intended to be built into a double hull of a ship, the x-axis also corresponds to the longitudinal direction of the ship.

FIG. 1 illustrates the multilayer structure of the wall 1 of a sealed and insulating tank for storing a liquefied fluid such as liquefied natural gas (LNG). Each wall 1 of the tank contains in series in the direction of thickness from the outer side to the inner side of the tank an auxiliary heat-insulating barrier 2, held on the supporting structure 3, an auxiliary sealing membrane 4 resting on an auxiliary heat-insulating barrier 2, a main heat-insulating barrier 5 resting on an auxiliary sealing membrane 4 , and a main sealing membrane 6 for contact with the liquefied natural gas contained in the tank.

The supporting structure 3, in particular, can be formed by the hull or the double hull of the ship. The supporting structure 3 contains a plurality of walls defining the general shape of the tank, usually a multifaceted shape.

The auxiliary insulating barrier 2 comprises a plurality of auxiliary insulating panels 7, which are fixed to the supporting structure 3 by means of fastening devices, for example described in WO 2014096600. The auxiliary insulating panels 7 have a general parallelepiped shape and are arranged in parallel rows.

In the embodiment illustrated in FIG. 1, each auxiliary insulation panel 7 comprises three sheets, namely a bottom sheet 8, an intermediate sheet 9 and a top sheet 10, which forms a support surface for the auxiliary sealing membrane 4. The bottom sheet 8, the intermediate sheet 9 and the top sheet 10 are formed, for example, from plywood. Each auxiliary insulation panel 7 also comprises a first insulation foam layer 11 located between the backsheet 8 and the intermediate sheet 9, and a second insulation foam layer 12 located between the intermediate sheet 9 and the topsheet 10. The first and second layers 11, 12 of the insulating plastic foam are respectively adhered to the bottom sheet 8 and the intermediate sheet 9, as well as to the intermediate sheet 9 and the top sheet 10. The insulation foam, in particular, can be a polyurethane foam, optionally reinforced with fibers.

In another embodiment, the auxiliary insulation panels 7 may have a different general design, for example, as described in document WO 2012/127141. In this case, the auxiliary insulating panels 7 are made in the form of a box-like structure containing a bottom sheet, a top sheet and load-bearing partitions extending in the direction of the thickness of the tank wall 1 between the bottom sheet and the top sheet and delimiting a plurality of compartments filled with insulating filler, for example, perlite, glass wool or stone wool.

In another embodiment, the auxiliary insulating barrier 2 comprises auxiliary insulating blocks 7 having structures of at least two different types, for example the two above-mentioned structures, depending on the position in which they are installed in the tank.

By way of example, the auxiliary insulating panels 7 have dimensions of the order of 1130 mm × 1000 mm. The auxiliary insulating panels 7 are spaced relative to each other in the transverse direction y by a functional installation gap, for example, of the order of 1 mm. In addition, the auxiliary insulating panels 7 are spaced apart from each other in the longitudinal direction x with a gap having a width of, for example, about 60 mm. Also located in the gap formed between the transverse edges of the auxiliary insulation panels 7 is an insulating filler, which is not illustrated, such as rock wool or glass wool.

The auxiliary sealing membrane 4 comprises a continuous layer of metal strips 13 with folded edges, which are attached to the auxiliary insulation panels 7, as will be described in detail below.

The main insulating barrier 5 comprises a plurality of main insulating panels 14, which are fixed to the supporting structure 3 with the aforementioned anchoring devices. The main insulating panels 14 have a general parallelepiped shape. Each of the primary insulation panels 14 is aligned with one of the secondary insulation panels 7. The primary panels 14 have a length in the longitudinal direction x that exceeds the length of the secondary insulation panels 7, thereby reducing the size of the gap formed between the transverse edges 32 of the primary insulation panels 14. The gap between the transverse edges of the main insulation panels 14 has a width in the longitudinal direction x of less than 20 mm, preferably less than 10 mm, for example of the order of 8 mm. The distance between the main insulation panels 14 in the transverse direction y is identical to the distance between the auxiliary insulation panels 7 and corresponds to a functional installation gap of the order of 1 mm.

The structure of the main insulation panel 14 according to the first embodiment is discussed with reference to FIG. 3. The main insulation panel 14 has a multi-layer structure similar to that of the auxiliary insulation panel 7 described above. Thus, the main insulation panel 14 comprises in succession a backsheet 15, a first insulation foam layer 16, an interlayer 17, a second insulation foam layer 18 and a topsheet 19. The topsheet 19 forms a support surface 36 for the main sealing membrane 6. The insulating polymeric foam can in particular be a polyurethane-based foam that can be additionally reinforced with fibers. The top sheet 19 is made of plywood, for example. In accordance with one embodiment, the topsheet has a thickness of 9 to 15 mm.

The bottom sheet 15 contains grooves 20 for receiving the folded edges of the strips of the auxiliary sealing membrane 4. The top sheet 19 also contains grooves 21 for receiving welding supports for welded connection, intended for welding the main sealing membrane 6.

The structure of the main insulation panel 14 has been described above by way of example. Thus, in another embodiment, the main insulation panels 14 may have a different general design, such as described in document WO2012 / 127141. In another embodiment, the primary thermal barrier 5 comprises primary thermal insulation panels 14 having structures of at least two different types, for example the two above-mentioned structures, depending on the position in which they are installed in the tank.

Referring to FIG. 1, which shows that the main sealing membrane 6 comprises a continuous layer of metal strips 22 with folded edges that extend in the longitudinal direction x. The strips 22 are welded with their folded edges to welding supports 23 which run parallel to each other in the longitudinal direction x and which are fixed in grooves 21 formed in the top sheets 19 of the main insulation panels 14.

The attachment of the weld attachment support 23 to the top sheet 19 of the main insulation panel 14 and the attachment of the strips 22 of the main sealing membrane 6 to the said weld attachment support 23 is described below with reference to FIG. 2. It should be noted that the attachment of the auxiliary sealing membrane 4 to the auxiliary insulation panels 7 is performed in a similar manner.

In the embodiment shown, the weld attachment support 23 has an L-shaped cross-section and is held in the groove 21. The groove 21 in this case has an inverted T-cross-section, but may also have an L-shaped cross-section. However, the T-shaped section is preferable because it can be obtained in a simpler manner during milling operations. As an example, the groove has a depth of about 6 mm.

The support for connection by welding 23 has a welding flange 24 and a fastening flange 25, which are angled relative to each other. In this case, the welding flange 24 and the mounting flange 25 are perpendicular to each other, forming an L-shape.

The slot 21 has a portion 26 extending substantially in the direction of the thickness of the wall 1 of the tank and protruding at the support surface 36 of the topsheet 19, and at least one branch 27 that extends in a plane orthogonal to the direction of the thickness of the wall 1 of the tank. Thus, the branch 27 forms a retaining portion 28 in the topsheet 19 between the support surface 36 and the branch 27. The fastening flange 25 of the support for attachment by welding is inserted into the branch 27 of the groove 21, while the welding flange 24 extends through the portion 26 extending in the wall thickness direction 1 of the reservoir, projecting towards the interior of the reservoir beyond the top sheet 19. Thus, the fastening flange 25 is held by the holding portion 28, which allows the attachment support 23 to be welded to the main insulation panel 14.

The grooves 21 of the main insulation panels 14 are aligned one after the other in the longitudinal direction. Also, the weld attachment support 23 extends in the longitudinal direction x from substantially one end of the tank wall 1 to the other, passing along the slots 21 of a plurality of main insulation panels 14 aligned one behind the other.

The planks 22 have a middle section 29 resting on a support surface 36 of the top sheets 19 and two folded edges 30 which extend longitudinally and project from the middle section 29 towards the inside of the reservoir. The folded edges 30 of the two strips 22, which extend on both sides of the support 23 for welding attachment, are welded to a welding flange 24 of said welding support 23 for welding attachment. Sealed welds between the folded edges 30 and the welding flanges 23 are obtained, for example, using the welding machine described in the application FR 2172837 or FR2140716.

The strips 22 and supports 23 for connection by welding are made, for example, of Invar®: that is, of an alloy of iron and nickel, the coefficient of expansion of which is usually from 1.2 × 10 ^-6 to 2 × 10 ^-6 K ^-1 , of an alloy of iron with a high content of manganese, the coefficient of expansion of which is usually in the order of 7 × 10 ^-6 K ^-1 , or stainless steel.

As illustrated in FIG. 4, the main insulation panels 14 are spaced apart in the longitudinal direction x with a gap 31 of a small width. The width of the gap 31 is less than 20 mm, preferably less than 10 mm and, for example, on the order of 8 mm.

Also, to limit the mechanical stresses that can be applied to the welded mounts 23, the folded edges 30, and the welds between the welded mounts 23 and the folded edges 30 when a level difference occurs between two adjacent main insulation panels 14, the slots 21 extend through the transverse edges 32 of the main insulation panels 14 with recesses 33, one of which is illustrated in detail in FIGS. 5 and 6.

The recess 33 protrudes on the support surface 36 and is located in the extension in the longitudinal direction x of the groove 21 and the holding portion 28, so that the fastening flange 25 of the support 23 for welding attachment is not retained on the main insulation panel 14 in the region of said recess 33. This makes it possible to reduce stresses, acting on the supports 23 for welding and the folded edges 30 of the strips 22 when a level difference occurs between adjacent main insulation panels 14. As a result, the influence of the level difference in terms of fatigue characteristics of the main sealing membrane 6 and the supports 23 for welding in the area of the gaps 31 formed between the transverse edges 32 of the main insulation panels 14 decreases.

The recess 33 has a bottom 34 and two side walls 35 connecting the bottom 34 to a support surface 36. Preferably, the recess 33 has a depth p (illustrated in FIG. 6) in the direction of the thickness of the tank wall 1, which is greater than the depth of the groove 21. In particular, as shown in fig. 5, the bottom 34 is inclined so that the depth p of the recess 33 decreases from the transverse edge 32 of the main insulating panel 14 towards the groove 21. This makes it possible to limit the stresses acting on the support 23 for welding attachment and the folded edges 30 of the strips 22 on the side of the main insulating a panel 14 that rises from an adjacent main insulation panel 14 when a level difference occurs between two adjacent main insulation panels 14.

In addition, the dimension m shown in FIG. 6, the recesses 33 in the transverse direction y are greater than or equal to the size of the groove 21 in the said transverse direction y. Also, each side wall 35 of the recess 33 is located in the transverse direction y outside one end of the horizontal portion of the groove 21. In addition, each of the side walls 35 of the recess 33 is connected to the edges of the groove 21 by means of a chamfer or fillet 37. The chamfer or fillet 37 is configured to guide the weld-on flange 24 of the support 23 for welding to the vertical portion 26 of the groove 21 during the installation of the support 23 for sliding welded connection into the groove 21. Thus, this arrangement also has the advantage of facilitating the insertion of the welded support 23 into the groove 21.

In particular, in the embodiment shown, the side walls have a flat portion and are connected to the groove 21 by means of a cylindrical portion 37.

In other embodiments that are not shown, the recess 33 has a general trapezoidal or triangular shape that is oriented such that the recess expands as the distance from the slot 21 increases.

The dimension n shown in FIG. 5, the recesses 33 in the longitudinal direction are preferably determined in accordance with the size of the gap 31 formed between the transverse edges 32 of the main insulation panels 14. In fact, it has been found that the length of the region in which the support 23 for welding attachment is not held on two adjacent main insulation panels 14 , that is, corresponding to the size of the gap i shown in FIG. 4, between two successive grooves 21, should preferably be between 20 and 70 mm, preferably between 25 and 45 mm and in particular between 30 and 40 mm. This makes it possible, on the one hand, to limit the stresses that can act on the support 23 for welded attachment and the main sealing membrane 6 within the permissible range, and, on the other hand, to properly hold the main sealing membrane 6 on the main insulation panels 14, preventing it separation.

Also as an example, the dimension n of the recesses 33 in the longitudinal direction is 5 mm to 30 mm. The dimension n is, for example, of the order of 13 mm when the gap 31 has a width of the order of 8 mm.

A main insulation panel 14 according to another embodiment is described below with reference to FIGS. 7 and 8. This embodiment is preferred in that the gap 31 formed between the main insulation panels 14 in the longitudinal direction x can be further reduced. The gap 31 illustrated in FIG. 8 is preferably less than 5 mm wide, for example of the order of 1 mm. As a result, in the case of a 1 mm gap 31 between the transverse edges 32 of the main insulation panels 14, there is no insulation filler. Thus, this improves the thermal insulation characteristics of the main thermal insulation barrier 5 while simplifying its installation.

To prevent shear deformation of the strips 22 at the level of the gaps 31 between the transverse edges 32 of the main insulating panels 14 in the case of a small gap 31, the top sheet 19 of the main insulating panels 14 has, in addition to the aforementioned recesses 33, recesses 38. The recess 38 is formed along each of the transverse edges 32 and extends laterally from one end of the main insulation panel 14 to the other. The recesses 38 divide the abutment surface 36 so that the main sealing membrane 6 is not supported in the region of said recess 38. As a result, as shown in FIG. 8, the longitudinal length l of the region in which the main sealing membrane 6 is not supported is the sum of the longitudinal dimension of the recess 38 of each of the main insulation panels 14 and the width of the gap 31.

Consequently, the recesses 38 have the effect of limiting the angular deformation of the main sealing membrane 6 at the level of the gap 31 between the transverse edges 32 of the main insulation panels 14 in the event of a level difference between adjacent main insulation panels 14. Thus, the deformations of the main sealing membrane 6 remain in the elastic region and do not lead to irreversible deformations of the main sealing membrane 6 at the level of the gap 31 in the case of pressures usually characteristic of reservoirs.

Preferably, the length l, that is, the sum of the longitudinal dimension of the recess 38 of each of the adjacent main insulation panels and the width of the gap 31, is from 7 to 25 mm, and preferably from 8 to 12 mm. Also as an example, in the case of a gap 31 with a width of about 1 mm, the size of the recess 38 in the longitudinal direction is 3 to 12 mm.

The depressions 38 illustrated in FIG. 8 are cutouts. The bottom 39 of the cutout has a surface parallel to the support surface 36 and is connected to said support surface 36 by a wall that extends substantially in the direction of the thickness of the tank wall 1. The cutout has a width of, for example, 3 to 12 mm. The depth of the recess 38 in the direction of the tank wall thickness is greater than or equal to the depth of the groove 21, that is, about 6 mm. The depth of the recess 38 is preferably 8 to 10 mm.

It should be noted that in this embodiment, as in the embodiments described below with reference to Figures 9 and 10, recesses 33, as described above, are formed in the topsheet 19 so that the recesses 21 protrude into the recesses 38 through said recesses 33 ...

Figures 9 and 10 illustrate alternatives to the second embodiment shown in Figures 7 and 8. These alternatives differ from the embodiment illustrated in Figs. 8, the shape of the recess 38.

In an alternative embodiment illustrated in FIG. 9, recesses 38 are chamfered in the top sheet 19 along the transverse edges 32 of the main insulation panels 14.

In an alternative embodiment illustrated in FIG. 10, each of the recesses 38 is defined by a fillet formed in the topsheet 19 along the transverse edges 32 of the main insulation panels 14.

For these two alternative embodiments, the length l, that is, the sum of the longitudinal dimension of the recess 28 of each of the adjacent main insulation panels 14 and the width of the gap 31, is 7 to 25 mm, as in the embodiment shown in Figures 7 and 8.

Preferably, regardless of shape, the recess 38 is designed such that the topsheet 19 is recessed at least in a certain region above a plane that is inclined at an angle of 55 ° with respect to the support surface 36 and that intersects the transverse edge 32 of the main insulation panel 14 at a distance of the direction of the thickness of the reservoir relative to the plane of the support surface 36.

Figures 11 and 12 illustrate a third embodiment. This embodiment differs from the embodiments described above with reference to Figures 7-10 in that the top sheets 19 of the main insulation panels 14 no longer have recesses 33 formed in continuation of the grooves 21. Thus, in this embodiment, the grooves 21 protrude directly into the depressions 38 formed in the top sheet 19 along the transverse edges 32. Also, the size of the depressions 38 in the longitudinal direction is chosen such that the size of the gap i in the longitudinal direction between two successive grooves 21 is preferably 20 to 70 mm, preferably 25 to 45 mm and in particular from 30 to 40 mm.

Also by way of example, in the embodiment illustrated in FIG. 12, the width of the gap 31 formed between the transverse edges 32 of two adjacent main insulation panels 14 is in the order of 1 mm, while the size of the recess 38 in the longitudinal direction x is between 14.5 mm and 29.5 mm, for example, in the order of 24.5 mm.

It should be noted that in the embodiments described above, only the main insulation panels 14 are provided with structures (recesses 33 and / or recesses 38) to limit the degradation of the fatigue characteristics of the main sealing membrane 6, since the main insulation panels 14 are subject to a much more significant level difference. than the auxiliary insulation panels 7. However, alternatively or additionally, the auxiliary insulation panels 7 can also have such structures, namely the grooves formed in the top sheet, which are extended by recesses and / or recesses formed in the top sheet along the transverse edges of the auxiliary insulation panels 7.

With reference to FIG. 13 is a cutaway view of a methane tanker 70 illustrates a sealed and insulated tank 71 having a prismatic overall shape, mounted in a double hull 72 of a vessel. The tank wall 71 comprises a primary containment barrier for contact with the LNG contained in the tank, an auxiliary containment barrier located between the main containment barrier and the double hull 72 of the vessel, and two thermal insulation barriers located respectively between the main containment barrier and the secondary containment barrier and between secondary containment barrier and double casing 72.

As is known, the loading / unloading lines 73 located on the upper deck of the ship can be connected by suitable connectors to a marine or port terminal for transferring LNG to or from the tank 71.

FIG. 13 illustrates an example of a marine terminal comprising loading and unloading station 75, subsea pipeline 76, and onshore facility 77. Loading and unloading station 75 is a stationary offshore facility having a movable boom 74 and a tower 78 supporting movable boom 74. Movable boom 74 holds the bundle insulated flexible hoses 79 that can be connected to the loading / unloading lines 73. The orientable boom 74 can be adapted to fit all methane tanker sizes. A connecting conduit (not shown) extends inside tower 78. Loading and unloading station 75 allows loading and unloading of methane carrier 70 from onshore facility 77 and vice versa. The latter has reservoirs 80 for storing liquefied gas and connecting pipelines 81 connected to the loading or unloading station 75 by a subsea pipeline 76. The subsea pipeline 76 allows the transfer of liquefied gas between the loading or unloading station 75 and the onshore structure 77 over a long distance, for example 5 km. which makes it possible to stop the methane tanker 70 at a great distance from the coast during loading and unloading operations.

Pumps installed on board vessel 70 and / or pumps installed at onshore facility 77 and / or pumps installed at loading and unloading station 75 are used to generate the pressure required for the transfer of liquefied gas.

Although the invention has been described with reference to several specific embodiments, it is clear that it is in no way limited thereto, and that it includes all technical equivalents of the described means and combinations thereof so long as they fall within the scope of the invention.

The use of verbs such as "have", "contain" or "include" and derived forms does not exclude the presence of elements or steps other than those specified in the claim.

In the claims, any reference position in parentheses should not be interpreted as limiting the claim.

Claims (15)

1. A sealed and heat-insulating tank for storing liquefied gas, containing a wall (1) having in series in the direction of the wall thickness (1) from the outside to the inside of the tank a heat-insulating barrier (5) and a sealing membrane (6) resting on the said heat-insulating barrier (5); the thermal insulating barrier (5) comprises at least two insulating panels (14), each of which has a top sheet (19) forming a supporting surface (36) on which the sealing membrane (6) rests, said insulating panels (14) being aligned in the longitudinal direction, and each of them has two transverse edges (32), which are perpendicular to the longitudinal direction; the sealing membrane (6) contains at least two metal strips (22) that extend parallel to the longitudinal direction on both sides of the support (23) for welding connection, said support (23) for welding connection is extended parallel to the longitudinal direction and is held on the top sheet (19) insulating panels (14), while the strips (22) have a middle section (29) resting on the supporting surfaces (36), and two folded edges (30) that extend parallel to the longitudinal direction, with one of the folded edges ( 30) each of the two strips (22) is welded to the support (23) for welding; at least the top sheet (19) of one of the two insulating panels (14) comprises, along the transverse edge (32) of said insulating panel (14), which faces the other insulating panel (14), a recess (38), and the recess (38) runs perpendicular to the longitudinal direction from one end of the top sheet (19) of said insulation panel (14) to the other, so that the strips (22) are not supported by the supporting surface (36) of said insulation panel (14) along said transverse edge (32) of the insulation panel ( 14), while the planks (22) are not supported at the level of the recess (38). 2. A sealed and heat-insulating tank according to claim 1, wherein the top sheet (19) of each of the insulating panels (14) comprises, along the transverse edge (32) of said insulating panel (14), which faces the other insulating panel (14), a recess (38), wherein the recess (38) extends perpendicular to the longitudinal direction from one end of said insulating panel (14) to the other, so that the strips (22) are not supported by the supporting surface (36) of said insulating panel (14) along said transverse edge (32 ). 3. A sealed and heat-insulating tank according to claim 1 or 2, in which one or each recess (38) is made in such a way that the top sheet (19) of the insulating panel (14) is recessed, at least in a certain area above the plane, which inclined at an angle of 55 ° with respect to the support surface (36) and which intersects the transverse edge (32) of the insulating panel (14) at a distance of 6 mm from the support surface (36) in the direction of the wall thickness. 4. Sealed and heat-insulating tank according to any one of paragraphs. 1-3, in which one or each recess (38) is formed by a cut, beveled cut or fillet formed in the top sheet (19) along the transverse edge (32) of the insulating panel (14). 5. Sealed and heat-insulating tank according to any one of paragraphs. 1-4, in which the support for connection by welding (23) is extended in the longitudinal direction and contains a welding flange (24) and a fastening flange (25), which is located at an angle relative to the welding flange (24), each of the top sheets (19) of two insulating panels (14) has a groove (21) in which a support is installed for connection by welding (23), while each groove (21) protrudes onto the supporting surface (36) and has a branch (27) in which a fastening flange ( 25) supports (23) for connection by welding, whereby the branch (27) forms in the corresponding insulating panel (14) between the branch (27) and the supporting surface (36) a holding section (28), for which the fastening flange (25) is held, for holding the support (23) for welding on said insulating panel (14). 6. Sealed and heat-insulating tank according to PP. 2 and 3, considered in combination, in which each groove (21) extends into one of the recesses (38), so that the support (23) for welding is not held on the heat-insulating barrier (5) in the region of the said recess (38). 7. A sealed and heat-insulating tank according to claim. 4, in which the groove (21) of each of the insulating panels (14) has one end facing the other insulating panel (14), which is continued by a recess (33) protruding on the support surface (36 ), each recess (33) being formed at least in the longitudinal direction of said groove (21) and retaining portion (28), so that the support (23) for attachment by welding is not held on said insulating panel (14) in the area of the said recess (33). 8. Sealed and heat-insulating tank according to any one of paragraphs. 1-7, in which the adjacent transverse edges (32) of the insulating panels (14) are spaced apart from each other with a gap (31) that has a width in the longitudinal direction of less than 5 mm. 9. A sealed and insulating tank according to claim 8, taken in conjunction with claim 2, wherein the sum of the longitudinal dimension of the recess (38) of each of the two insulating panels (14) and the width of the gap (31) formed between the insulating panels (14) , ranges from 7 to 70 mm. 10. Vessel (70) for transporting a fluid containing a double hull (72) and a reservoir (71) according to any one of claims. 1-9 located in the double casing (72). 11. A fluid transmission system comprising a vessel (70) according to claim 10, insulated pipelines (73, 79, 76, 81) located so as to connect a reservoir (71) installed in the ship's hull with an offshore or onshore storage ( 77), and a pump for supplying fluid through insulated pipelines from an offshore or onshore storage facility to a ship's tank or from a ship's tank to an offshore or onshore storage facility. 12. The method of loading or unloading a ship (70) according to claim 10, in which the fluid is fed through insulated pipelines (73, 79, 76, 81) from the offshore or onshore storage (77) to the tank (71) of the ship or from the tank of the ship to offshore or onshore storage.

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