GUIDE STRUCTURE FOR A LOADING / UNLOADING TOWER OF A TANK INTENDED FOR THE STORAGE AND / OR TRANSPORT OF LIQUEFIED GAS
Patent Information
- Application Number
- MX2023000432
- Authority / Receiving Office
- MX · MX
- Patent Type
- Patents
- Current Assignee / Owner
- Priority Date
- 2020-07-09
- Filing Date
- 2023-01-06
- Publication Date
- 2026-06-12
- Estimated Expiration
- 2041-07-06
Smart Images
Figure MX435422B0
Abstract
Description
GUIDE STRUCTURE FOR A LOADING / UNLOADING TOWER OF A TANK INTENDED FOR THE STORAGE AND / OR TRANSPORT OF LIQUEFIED GAS zrfrnnn / rznz / e / YiAi FIELD OF INVENTION The present invention relates to the field of tanks adapted to contain a liquefied gas. More particularly, the invention relates to a lower wall of a tank, for example, of a gravity platform or an onshore depot, for storing a liquefied gas, such as liquefied natural gas (LNG) or liquefied petroleum gas (LPG). BACKGROUND OF THE INVENTION Sealed, thermally insulated tanks for storing liquefied gas on a gravity platform or vessel are known in the prior art. They are typically equipped with a tower for loading and unloading the liquefied gas. The loading / unloading tower is generally suspended from the upper wall of a support structure, which represents the basic structure of the gravity platform or the vessel's inner hull. The tank may also include a guide structure attached to the support structure, a lower wall of the tank, and / or a sump. The guide structure is configured to maintain the lower portion of the loading / unloading tower in a given position relative to a horizontal plane while allowing vertical translational movement of the tower. The guide structure is submerged in the liquefied gas when the tank contains it. Therefore, it is necessary to provide thermal insulation for the guide structure and thermal continuity with the lower wall of the tank through which the guide structure passes. However, the technical characteristics of the guide structure sometimes make it difficult to achieve both thermal insulation of the guide structure and thermal continuity with the lower wall. Furthermore, gravity platform tanks have a much larger volume than shipboard tanks and offer only limited resistance to operational loads and the point loads involved in loading or unloading the tank with liquefied gas. In addition, the guide structure is subjected to high mechanical and thermal stresses, particularly from the loading / unloading tower, resulting in premature fatigue of both the guide structure and the bottom wall. BRIEF DESCRIPTION OF THE INVENTION A primary objective of the present invention is to alleviate at least one of the disadvantages mentioned above and further confer additional advantages by proposing a new type of wall for a liquefied gas storage and / or transport tank, particularly for a gravity platform. zrfrnnn / rznz / B / YiAi A second objective of the invention is to increase the mechanical strength of the guide structure joint at the lower wall level. A third objective of the invention is to obtain better thermal insulation of the joint of the guide structure at the level of the lower wall. A fourth objective of the invention is to minimize structural deformations of the guide structure. Therefore, the present invention proposes a tank for the transport and / or storage of a liquefied gas, comprising a support structure, a plurality of tank walls, each of which includes, in one wall thickness direction, at least one layer of thermal insulation bearing against the support structure and at least one sealed membrane bearing on the thermal insulation layer, the plurality of tank walls including at least one bottom wall, a guide structure configured to receive a tower for loading and / or unloading liquefied gas contained in the tank, the guide structure being positioned against the support structure and extending at least partly into the tank, the guide structure including a base support against the support structure, the thermal insulation layer including at least one self-supporting heat-proof panel that is at least partly positioned around the guide structure,characterized in that the thermal insulation layer includes a free space delimited in the direction of the thickness of the lower wall by a portion of the self-supporting heat-proof panel and by the support structure, the free space being configured to accommodate at least part of the base of the guide structure. By self-supporting it should be understood here, as well as in the rest of the application, that the heat-proof self-supporting panel is able to support the weight of something placed on top of it, for example, liquefied natural gas, without deforming significantly and within the limit of its mechanical strength. The free space provided in the thermal insulation layer made of self-supporting, heat-resistant panels can accommodate a portion of the guide structure's base. Therefore, the self-supporting, heat-resistant panels can be positioned as close as possible to the guide structure, thus contributing to its thermal insulation. According to one design, the clearance space has a thickness between 25 mm and 70 mm inclusive. The thickness is measured from an inner face of the supporting structure to an outer face of the heat-resistant self-supporting panel portion in a direction parallel to the thickness direction. According to one modality, the portion of the heat-resistant self-supporting panel that delimits the free space in the thickness direction includes a plywood or composite board. According to one modality, a portion of the heat-proof self-supporting panel rests on the base of the guide structure, in particular on the plate of that base. According to one embodiment, a separating device is placed between the base of the guide structure, in particular on the plate of that base, and the portion of the heat-proof self-supporting panel that rests on the base of the guide structure. According to one modality, the separator device is an insert or a mask bead or a combination of the two. According to one embodiment, the tank includes at least one locking device configured to immobilize the guide structure in at least one direction perpendicular to the direction of the bottom wall thickness. According to one method, the locking device fits into the free space. According to one model, the locking device is made of metal. According to one modality, another part of the heat-proof self-supporting panel portion rests on the locking device. According to one modality, a locking member is positioned between the locking device and the other portion of the self-supporting panel. According to one modality, the locking member is an insert or a putty bead or a combination of the two. According to one modality, the free space is delimited in a direction perpendicular to the thickness direction by an edge of the heat-proof self-supporting panel that extends between an outer face of the portion of the heat-proof self-supporting panel and an inner face of the support structure and by the guide structure. According to one modality, the locking device is positioned between the edge of the heat-proof self-supporting panel and the base of the guide structure. In one configuration, a thermal insulation member is placed between the base of the guide structure and the support structure. This thermal insulation member also serves to adjust the position along the vertical axis of the guide structure. According to one modality, the thermal insulation layer is a secondary thermal insulation layer and the sealed membrane is a primary sealed membrane, and the tank that includes a primary thermal insulation layer and a secondary sealed membrane, the secondary sealed membrane rests against the secondary thermal insulation layer, the primary thermal insulation layer rests against the secondary sealed membrane, and the primary sealed membrane rests against the primary thermal insulation layer. zrfrnnn / rznz / B / YiAi zpfrnnn / rznz / B / viAi According to one embodiment, the primary thermal insulation layer and / or the secondary thermal insulation layer includes a plurality of self-supporting heat-proof panels, each self-supporting heat-proof panel including a polyurethane foam block against which at least one plywood or composite board is placed. According to one modality, the support structure is made of a material chosen from the group comprising a metal, a metal alloy, concrete, and mixtures thereof. The invention further provides a transport and / or storage unit that includes at least one tank according to the invention, the transport and / or storage unit being selected from the group that includes a methane tank, a liquefied petroleum gas tank, a barge, a reliquefaction unit, a gasification unit, an onshore structure, for example, an onshore depot, and a gravity platform. According to one modality, the transport and / or storage unit includes a base structure to which the tank is anchored according to the invention; the base structure is made of concrete. The invention also proposes a transfer system for a liquefied gas, the system including a gravity platform according to the invention, insulated pipes arranged so as to connect the tank installed on the base structure of the gravity platform to a vessel, and a pump to propel a flow of liquefied gas through the insulated pipes from the tank on the gravity platform to the vessel. The invention further provides a method for loading or unloading a gravity platform according to the invention in which a liquefied gas is directed through insulated pipes from the gravity platform tank to a vessel. The description also includes a tank for transporting and / or storing a liquefied gas comprising a support structure, a plurality of tank walls comprising, in a wall thickness direction, at least one layer of thermal insulation abutting the support structure and at least one sealed membrane abutting the thermal insulation layer and intended to be in contact with the liquefied gas inside the tank, the plurality of tank walls comprising at least one bottom wall, and a guide structure configured to receive a loading and / or unloading tower disposed against the support structure, characterized in that the tank comprises a plurality of locking devices secured to the support structure and in contact with a base of the guide structure such that they block movement of the guide structure in a direction perpendicular to the thickness direction of the bottom wall. BRIEF DESCRIPTION OF THE FIGURES Other features and advantages of the invention will become more evident in the course of the following description, on the one hand, and from a plurality of embodiments described by way of non-limiting illustration with reference to the attached schematic figures, on the other hand, in which the figures: FIGURE 1 is a schematic perspective view of a tank according to the invention; FIGURE 2 is a schematic cross-sectional view in a vertical transverse plane of the tank in FIGURE 1; FIGURE 3 is a schematic view of a tank wall structure from FIGURE 2 viewed in one wall thickness direction; FIGURE 4 is a detailed cross-sectional view in a vertical transverse plane of a guide structure of FIGURE 1 intended to guide the loading / unloading tower of FIGURE 1 in vertical translation; FIGURE 5 is a detailed view of a locking device of the guide structure illustrated in FIGURE 4; FIGURE 6 is a schematic representation of a methane tank and a gravity loading / unloading platform including the tank according to the invention. DETAILED DESCRIPTION OF THE INVENTION It should be noted first that, while the figures describe the invention in detail for its execution, they can certainly serve to further define the invention if necessary. It should also be noted that in all the figures, elements that are similar and / or have the same function are indicated with the same numbers. In the following description, a direction of a longitudinal axis L, a direction of a transverse axis T, and a direction of a vertical axis V are represented by a trihedron (L, V, T) in FIGURES 1 and 2 and FIGURES 4 and 5. A horizontal plane is defined as a plane perpendicular to the vertical axis, a longitudinal plane as a plane perpendicular to the transverse axis, and a transverse plane as a plane perpendicular to the longitudinal axis. The terms “external” and “internal” are used to define the relative position of one element with respect to another with reference to the inside and outside of the tank. With reference to FIGURE 1, a sealed, thermally insulated liquefied gas storage tank 21 is anchored to a concrete support structure 3. The support structure 3 is formed, for example, by a base structure of a gravity platform 1. Hereafter, the expressions “base structure” and “support structure” are used interchangeably and with the same reference number. In a configuration not shown, support structure 3 is formed by the double hull of a vessel. The vessel may be a methane tank or a liquefied petroleum gas tank. Support structure 3 may also be formed by a double-retention structure, for example, of a barge, a reliquefaction unit, a gasification unit, or an onshore structure such as an onshore storage tank. To be more precise, with reference to FIGURE 2, which is a cross-sectional view of tank 21 from FIGURE 1 in section plane 150, the support structure 3 comprises a lower double partition wall 5, an upper partition wall 9, and double side partition walls Ί connecting the lower double partition wall 5 to the upper partition wall 9. Each double partition wall 5, 7 includes an external partition wall 11 and an internal partition wall 13 made of concrete. The internal partition walls 13 and the upper partition wall 9 define the overall shape of tank 21. The external partition walls 11 and the internal partition walls 13 are connected to each other by concrete spacers 15. A lower portion of the base structure 3 includes ballast compartments 17. Ballast compartments 17 are located between the inner partition wall 13 and the outer partition wall 11 of the lower double partition wall 5. Ballast compartments 17 are filled with seawater when gravity platform 1 is positioned in its operating location, submerging gravity platform 1 under ballast. As a result, gravity platform 1 is partially supported on the seabed. It should be noted that the base structure 3 also includes an insert, for example, a metal insert, embedded in the concrete of the base structure. Such an insert extends horizontally, positioned vertically beneath the guide structure 77, which will be described below, between the latter and the concrete. With reference to FIGURE 2 and FIGURE 3, tank 21 includes a plurality of walls 23, 25, and 27, each of which is positioned against an internal partition wall 13 and the upper partition wall 9 of the base structure 3. Accordingly, tank 21 includes an upper wall 23 positioned on an inner face of the upper partition wall 7 and a lower wall 27 positioned on an inner face of the internal partition wall 13. The upper partition wall 23 and the lower wall 27 extend in a principal plane substantially parallel to the horizontal plane as defined above. The upper wall 23 is substantially parallel to, and does not intersect, the lower wall 27. Here and throughout what follows, "substantially" is understood to mean that manufacturing tolerances and any assembly tolerances must be taken into account. The upper wall 23 and the lower wall 27 are connected to each other by means of side walls 25 placed on an inner face of the other internal dividing walls 13. Each of the side walls 25 extends in a plane substantially perpendicular to the horizontal plane from an edge of the lower wall 27 to an edge of the upper wall 23. The tank 21 has a general rectangular parallelepiped shape. With reference to FIGURE 3, each wall 23, 25, 27 includes in a zrfrnnn / rznz / B / YiAi direction thickness E of wall 23, 25, 27 a secondary thermal insulation layer 41 retained in the respective partition wall of the base structure 3, a secondary sealed membrane 51 supported against the secondary thermal insulation layer 41, a primary thermal insulation layer 61 supported against the secondary sealed membrane 51, and a primary sealed membrane 71 intended to be in contact with the liquefied natural gas contained in the tank 21 and supported against the primary thermal insulation layer 61. The secondary thermal insulation layers 41 of the walls 23, 25, and 27 of tank 21 communicate with each other in such a way that they form a continuous, sealed secondary thermal insulation space between the base structure 3 and the secondary sealed membrane 51. Likewise, the primary thermal insulation layers 61 of the walls 23, 25, and 27 of tank 21 communicate with each other in such a way that they form a continuous, sealed primary thermal insulation space between the secondary sealed membrane 51 and the primary membrane 71. The secondary thermal insulation layer 41 includes a plurality of self-supporting heat-resistant panels 43. The self-supporting heat-resistant panels 43 have a substantially rectangular parallelepiped shape. The self-supporting heat-resistant panels 43 may have other shapes, such as, for example, a parallelepiped shape, particularly with a square or rectangular base, or a right prism shape with a hexagonal base. The self-supporting heat-resistant panels 43 are juxtaposed in parallel rows. Each of the self-supporting, heat-resistant panels 43 includes a heat-resistant polymer foam block 45 supported on a rigid outer board 47. The rigid outer board 47 is, for example, a plywood board. The rigid outer board 47 is bonded to this heat-resistant polymer foam block 45. The heat-resistant polymer foam can be, in particular, a rigid polyurethane-based foam. Glass fibers can be embedded in the polyurethane foam for reinforcement. In an embodiment not shown, the rigid outer board 47 is made of at least one composite material. Due to manufacturing inaccuracies, for example, the inner face of the internal partition walls 13 and the inner face of the upper partition wall 9 may differ significantly from the theoretical area provided for the base structure. These differences are compensated for by bracing the self-supporting, heat-resistant panels 41 against the base structure using polymerizable resin beads 40 or putty. The self-supporting heat-proof panels 41 are anchored to the internal partition walls 13 and the upper partition wall 9 by means of bolts, not shown, welded to the inner face of the internal partition walls 13. The secondary sealed membrane 51 includes a plurality of rigid sealed layers 53 made of 0.07 mm thick aluminum foil sandwiched between two fiberglass mats impregnated with a polyamide resin. The rigid sealed layers 53 are bonded to the polymer foam blocks 45 of the self-supporting heat-resistant panels 43, for example, by means of a two-component polyurethane adhesive. To impart some flexibility to the secondary membrane and ensure its continuity between two adjacent rigid sealed layers 53, a flexible sealed layer 55 is bonded to the adjacent peripheral edges of the two adjacent rigid sealed layers 53. The flexible sealed layer 65 consists of a composite material comprising three layers: the two outer layers are fiberglass mats, and the middle layer is a thin metal foil, for example, an aluminum foil approximately 0.1 mm thick. This metal foil ensures the continuity of the secondary sealed membrane. The primary thermal insulation layer 61 includes a plurality of substantially rectangular, parallelepiped-shaped, heat-resistant self-supporting panels 63. The heat-resistant self-supporting panels 63 of the primary thermal insulation layer 61 may have other shapes, such as a cubic shape, for example. In the embodiment shown in FIGURE 3, the heat-resistant self-supporting panels 63 of the primary thermal insulation layer 61 are offset relative to the heat-resistant self-supporting panels 43 of the secondary thermal insulation layer 41 such that each primary insulation panel 63 of the primary thermal insulation layer 61 spans over four heat-resistant self-supporting panels 43 of the secondary thermal insulation layer 41. Each self-supporting heat-resistant panel 63 of the primary thermal insulation layer 61 includes a heat-resistant polymer foam block 65, for example, one based on rigid polyurethane. A first side of this polymer foam block 65 is bonded to the secondary sealed membrane 51, and a second side, opposite the first side, is covered by a rigid inner board 69. Glass fibers can be embedded in the polymer foam for reinforcement. The rigid inner board 69 of the self-supporting heat-resistant panel 63 of the primary thermal insulation layer 61 is made, for example, of plywood or composite material. The primary sealed membrane 71 includes a plurality of metal plates welded together. In the embodiment illustrated in FIGURE 3, the primary sealed membranes 71 include corrugations 75 in the metal plates that allow them to deform under the effect of thermal and mechanical loads generated by the liquefied gas in the tank 21. The primary sealed membrane 71 includes two sets of mutually perpendicular corrugations 75. The corrugations 75 project into the interior of the tank 21. The rigid inner board 69 of each self-supporting heat-resistant panel 63 of the primary thermal insulation layer 61 is fitted with metal mounting plates (not shown) for anchoring the corrugated metal sheets of the primary sealed membranes 71. The mounting plates can be assembled together, for example, by welding. With reference to FIGURE 1, tank 21 includes a guide structure 77 arranged against the support structure 3. The guide structure 77 is configured to receive a tower 29 for loading and / or unloading liquefied gas contained in tank 21. The loading / unloading tower 29 extends substantially the entire height of the tank 21, i.e., from the lower wall to the upper wall from which its upper portion 33 is suspended. The loading / unloading tower 29 includes three vertical masts 31 connected to each other by crossbeams (not shown) that define a prismatic shape with a triangular cross-section. The vertical masts 31 are hollow to allow the passage of electrical power supply cables (not shown) that provide, in particular, an electrical power supply to the pumps for unloading the tank 21 (not shown) via discharge lines (not shown) from the loading / unloading tower 29. In an embodiment not shown, the loading / unloading tower 29 may include two vertical masts or four vertical masts. The loading / unloading tower 29 includes at its lower part 35 a guide device 37 that cooperates with the guide structure 77 of the tank 21. The guide device 37 is intended to allow relative movement of the loading / unloading tower 29 with respect to the guide structure 77 in the direction of the height of the tank 21 to allow the loading / unloading tower 29 to contract or expand depending on the temperatures to which it is subjected while preventing horizontal movement of the lower part 31 of the loading / unloading tower 29. The guide structure 77 located in an area of the lower wall 27 of the tank 21 in front of a central axis of the loading / unloading tower 29 will now be described in more detail with reference to FIGURE 4, which is a view of the guide structure in the section plane 200 indicated in FIGURE 1. To simplify FIGURE 4, the primary sealed membrane 71 and the secondary sealed membrane 51 have not been shown. Guide structure 77 includes a base support against support structure 3. The guide structure 77 includes a hollow lower portion 79, which is, for example, frustoconical, and connects to a right-hand cylindrical upper portion 78. This lower portion 79 is similar to the base of the guide structure 77 mentioned earlier herein. The upper portion 78 projects into the tank 21 in such a way as to cooperate with the guide device 37 of the loading / unloading tower 29. The lower portion 79 extends through the thickness of the lower wall 27 of the tank 21 to the primary sealed membrane 71. The lower part 79 or base includes at least one plate 93 that rests against the support structure 3, the plane in which most of the plate 93 extends is a plane perpendicular to the thickness direction E of the lower wall 27. This plate 93 is the base part that extends into a free space 151 formed in the thermal insulation layer 41. zpfrnnn / rznz / B / YiAi The lower portion or frustoconical base 79 includes a small circular base 80 and a large circular base 81. The small base 80 and the large base 81 each develop in a plane perpendicular to the thickness direction E of the lower wall 27. The small base 80 has a smaller diameter than the large base 81. The upper portion 78 has a diameter substantially equal to the diameter of the small base 80. Furthermore, the large base 81 is closer to the support structure 3 than the small base 80. The lower portion 79 includes a radial wall 88 that extends from a contour of the small base 80 to a contour of the large base 81. In other words, the radial wall 88 connects the small base 80 to the large base 81, forming a cone. The radial wall 88 extends circumferentially around the small base 80 and circumferentially around the large base 81.The small base 80 is mounted to the upper part 78 of the guide structure 77 by means of a first plate 82 that extends in a plane perpendicular to the thickness direction E of the lower wall 27. The first plate 82 can have various shapes. In the example shown, the first plate 82 is circular when viewed in a plane perpendicular to the thickness direction E of the lower wall 27. The first plate 82 has a larger diameter than the diameter of the small base 80. Consequently, an outer portion 83 of the first plate 82 extends from the small base 80 in the direction of the primary sealing membrane 71 to connect with it. This outer portion 83 of the first plate 82 is continuous with the primary sealing membrane and contributes to its sealing and insulation. An inner portion 84 of the first plate 82 extends in line with the outer portion 83 into the lower part 79 of the guide structure 77. The guide structure 77 includes a second plate 85 arranged between the small base 80 and the second base 81 of the lower part 79 of the guide structure 77. The second plate 85 extends in a plane perpendicular to the thickness direction E of the lower wall 27. The second plate 85 can have various shapes. In the example shown, the second plate 85 has a circular shape when viewed in a plane perpendicular to the thickness direction E of the lower wall 27. The second plate 85 is positioned so that it is in line with the secondary sealing membrane 51 and connected to it. Therefore, the second plate 85 is substantially at the same level as the secondary sealing membrane 51. An outer portion 86 of the second plate 85 extends around the lower portion 73 of the guide structure 77. This outer portion 86 of the second plate 85 is continuous with the secondary sealing membrane and contributes to its sealing and insulation. The outer portion 86 of the second plate 85 extends circumferentially from the radial wall 88 of the lower portion 79 of the guide structure 77. The outer portion 86 of the second plate 85 is intended to connect to the secondary sealing membrane 41. zrfrnnn / rznz / B / YiAi An inner portion 87 of the second plate 85 extends into the lower portion 79 of the guide structure 77. Consequently, an interior space of the lower portion 79 is divided into a secondary portion 90 and a primary portion 91. The primary portion 91 is bounded by the first plate 82, the second plate 85, and the radial wall 88 of the lower portion 79. The secondary portion 90 is bounded by the second plate 85, the lower double partition wall 5 of the base structure 3, and the radial wall 88 of the lower portion 79 of the guide structure 77. Non-structural insulating packing (not shown) is provided in the primary portion 91 and / or the secondary portion 90. The non-structural insulating packing is, for example, glass wool, mineral wool, or a mixture thereof. Therefore, thermal conduction in the guide structure 77 is limited. Self-supporting heat-resistant panels 63 of the primary thermal insulation layer 61 adjacent to the guide structure 77 support at least one self-supporting heat-resistant panel 43 of the secondary thermal insulation layer 41 and on the outside 86 of the second plate 85. Self-supporting heat-resistant panels 63 of the primary thermal insulation layer 61 adjacent to the guide structure 77 are also supported on the outside 86 of the second plate 85. A side face of the self-supporting heat-resistant panels 63 of the primary thermal insulation layer 61 adjacent to the guide structure 77 is disposed against an edge of the outside 84 of the first plate 82.In order to improve thermal insulation, a non-structural insulation packing 92 is placed between the self-supporting heat-proof panels 63 of the primary layer of thermal insulation 61 adjacent to the guide structure 77 and the radial wall 88 of the lower part 79 of the guide structure 77. The non-structural insulation packing 92 placed in this way is, for example, glass wool, mineral wool, or a mixture thereof. The radial wall 88 of the lower section 79 includes passage holes 89. Some of the holes 89 in the radial wall 88 are arranged to establish air communication between the secondary thermal insulation space and the secondary portion 90 of the interior space of the lower section 79. This facilitates the circulation of an inert gas, such as nitrogen or argon, for example, between the secondary thermal insulation space and the secondary portion 90. Some other holes 89 in the radial wall 88 are arranged to establish air communication between the primary thermal insulation space and the primary portion 91 of the interior space of the lower section 79. This also facilitates the circulation of an inert gas, such as nitrogen or argon, for example, between the primary thermal insulation space and the primary portion 91. The guide structure 77 includes a plate 93 arranged circumferentially around the large base 81 of the lower part 79 of the guide structure 77. The plate 93 extends in a plane perpendicular to the thickness direction E of the lower wall 27. The plate 93 has a square perimeter as seen in a plane perpendicular to the thickness direction E. The plate 93 rests against the inner partition wall 13 of the lower double partition wall 5 of the support structure 3. In other words, the guide structure 77 rests on the base formed at least in part by the plate 93, which is in plane-on-plane contact with the support structure 3. The plate 93 is attached to the support structure 3 by a system of nuts and bolts (not shown). A thermal insulation member 94 is inserted between the inner face of the internal partition wall 13 and the plate 93 in such a way as to break the thermal bridge between the support structure 3 and the guide structure 77. The thermal insulation member 94 is, for example, a plywood board or composite material. The thickness of this insulation member also contributes to adjusting the height of the guide structure 77 in the vertical direction. For the arrangement as close as possible to the self-supporting heat-resistant panels of the secondary thermal insulation layer 41, which is permitted by the guide structure plate 93 77, each self-supporting heat-resistant panel 43 of the secondary thermal insulation layer 41 adjacent to plate 93 includes a cut 95. The cut 95 has a rectangular shape as seen in the projection onto a plane containing the thickness direction E of the lower wall 27. The cut 95 is made in a lower portion of the self-supporting heat-resistant panel 43 of the secondary thermal insulation layer 41 adjacent to plate 93. The cut 95 is bounded by an upper intermediate portion 96 of the self-supporting heat-resistant panel 43 of the secondary thermal insulation layer 41 adjacent to plate 93 and by an intermediate side edge 99 of the self-supporting heat-resistant panel 43 of the secondary thermal insulation layer 41 adjacent to plate 93.The lateral intermediate edge 99 extends between an external intermediate face 97 of the upper intermediate portion 96 of the heat-proof self-supporting panel 43 of the secondary thermal insulation layer 41 adjacent to plate 93 and an internal face of the internal partition wall 13 of the lower double wall 5 of the support structure 3. The upper intermediate portion 96 of the self-supporting heat-proof panel 43 of the secondary thermal insulation layer 41 adjacent to the plate 93 includes a plywood plate 98 or a composite material plate arranged at the level of the external intermediate face 97. This makes it possible to reinforce the mechanical strength of the self-supporting heat-proof panel 43 of the secondary thermal insulation layer 41 adjacent to the plate 93. Accordingly, the secondary thermal insulation layer 41 includes a free space 151 bounded in the thickness direction E of the lower wall 27 by the external intermediate face 97 of the upper intermediate portion 96 of the self-supporting heat-proof panel of the secondary thermal insulation layer 41 adjacent to plate 93 and by the inner face of the internal partition wall 13 of the lower double wall 5 of the support structure 3. In other words, the free space 151 is bounded in the thickness direction E of the lower wall 27 by a portion of the self-supporting heat-proof panel 43 of the secondary thermal insulation layer 41 adjacent to plate 93 and by the support structure 3. Therefore, the free space 151 accommodates at least part of the base, in particular plate 93 of the guide structure 77, in a direction parallel to the thickness direction E of the lower wall 27. The free space 151 has a thickness H between 25 mm and 70 mm inclusive. The thickness H is measured in a direction parallel to the thickness direction E from the inner face of the inner partition wall 13 of the lower double partition wall 5 of the support structure 3 to the outer intermediate face 97 of the upper intermediate portion 96 of the self-supporting heat-resistant panel 43 of the secondary thermal insulation layer 41 adjacent to the plate 93. The thickness H of the free space 151 is greater than or equal to a thickness of the plate 93 measured in a direction parallel to the thickness direction E of the lower wall 27. The clearance space 151 is bounded in a direction perpendicular to the thickness direction E of the lower wall 27 by the lateral intermediate edge 99 of the self-supporting heat-proof panel 43 of the secondary thermal insulation layer 41 adjacent to the plate 93 and by the guide structure 77. In other words, a length of the clearance space 151 is greater than a length of the plate 93, the length being measured in the direction perpendicular to the thickness direction E of the lower wall 27. The clearance space 151 accommodates at least a portion of the plate 93 in a direction perpendicular to the thickness direction E of the lower wall 27. The self-supporting heat-resistant panels 43 of the secondary thermal insulation layer 41 adjacent to the guide structure 77 are partly in contact with an edge of the outer part 86 of the second plate 85. In order to improve thermal insulation, a non-structural insulation packing 92 is placed between the self-supporting heat-resistant panel 43 of the secondary thermal insulation layer 41 adjacent to the guide structure 77 and the radial wall 88 of the lower part 79 of the guide structure 77. A portion 97a of the outer intermediate face 97 of the upper intermediate portion 96 of the self-supporting heat-resistant panel 43 of the secondary thermal insulation layer 41 adjacent to the plate 93 is stopped at the portion of the plate 93 accommodated in the clearance 151.In order to conform at least in part to the manufacturing tolerances of plate 93 and / or the self-supporting heat-resistant panel 43 of the secondary thermal insulation layer 41 adjacent to plate 93, a spacer device 153 is provided between plate 93 and the portion of the external intermediate face 97 that rests on the portion of plate 93 accommodated in the clearance 151. The spacer device 153 is an insert or a putty bead or a combination of the two. The insert can be made of plywood and / or at least one composite material. The separator device 153 is one of the components that contributes to controlling the vertical position of the guide structure 77. Specifically, it is necessary to align the outer part 83 of the first plate 82 with the primary sealing membrane in the same plane. It is equally necessary to align the outer part 86 of the second plate 85 in the same plane as the secondary sealing membrane. The separator device 153 plays a role in performing this function. With reference to FIGURE 4 and FIGURE 5, the tank 21 comprises at least one locking device 155 configured to immobilize the guide structure 77 in at least one direction perpendicular to the thickness direction E of the lower wall 27. The locking device 155 described hereafter may be independent of the fact that the thermal insulation layer 41 includes the free space 151 bounded in the thickness direction E of the lower wall 27 by portion 96 of the self-supporting heat-proof panel 43 and by the support structure 3, the free space 151 being configured to accommodate at least partly the base of the guide structure 77.Alternatively, the locking device 155 described below can be intimately combined with the thermal insulation layer 41 which includes the free space 151 bounded in the thickness direction E of the bottom wall 27 by part 96 of the heat-proof self-supporting panel 43 and by the support structure 3, the free space 151 being configured to accommodate at least partly the base of the guide structure 77. The locking device 155 is arranged on the inner face of the inner partition wall of the lower double partition wall such that the locking device 155 fits into the free space 151. The locking device 155 is positioned between the lateral intermediate edge 99 of the heat-resistant self-supporting panel 43 and the guide structure 77, in particular its plate 93. A plurality of locking devices 155 as described below are positioned peripherally around the guide structure. In this embodiment, the locking device 155 includes an iron angle 157 reinforced by a plurality of reinforcements 163. The iron angle 157 has an L-shaped profile, i.e., the iron angle 157 includes a first section 159 and a second section 161 perpendicular or substantially perpendicular to the first section 159. The first section 159 extends in a plane that includes the thickness direction E of the lower wall 27. In other words, the first section 159 extends in a plane perpendicular to the plane in which the plate 93 extends. The second section 161 extends in a plane perpendicular to the thickness direction E of the lower wall 27. In other words, the second section 161 extends in a plane parallel to the plane in which the plate 93 extends. The first section 159 is arranged against one of the peripheries of the guide structure, in particular plate 93, while the second section 161 is arranged against the inner face of the inner partition wall 13 of the lower double partition wall 5 while extending in a direction away from the periphery of the guide structure, for example, plate zrfrnnn / rznz / e / YiAi 93. The iron angle 157 is fixed to the inner face of the inner dividing wall 13 of the double lower wall 5 by welding it to it. Each reinforcement 163 has a rectangular parallelepiped shape. For each reinforcement 163, one face of the reinforcement 163 is positioned against the first section 159, and another face is positioned against the second section 161. The reinforcements 163 are evenly spaced along the angle iron 157. Therefore, two adjacent reinforcements 163 are at a non-zero distance from each other. The second section 161 is interrupted between two adjacent reinforcements 163. In other words, the second section 161 is formed from a plurality of legs. Each reinforcement 163 is attached to the first section 159 and to a leg of the second section 161 by welding it to the first section 159. Tank 21 includes a plurality of locking devices 155 that abut each edge of the guide structure, in particular plate 93, to immobilize the guide structure in all directions perpendicular to the thickness direction E of the lower wall 27. In other words, the locking devices 155 prevent movement of the guide structure in directions contained in the plane in which the internal dividing wall 13 of plate 93 extends. A locking element 165 can be positioned against an edge of the guide structure, specifically plate 93, and the first section 159 of the iron angle 157 of the locking device 155. The locking element 165 thus eliminates any play between the iron angle 157 and the guide structure, in this case plate 93, while simultaneously reinforcing the mechanical strength of the guide structure. The locking element 165 is in the form of a plate, specifically a wedge, with an acute angle along a longitudinal edge. The acute angle of the locking element 165 is forcibly inserted after the guide structure 77 is fixed to the support structure 3 and the locking device 155 is secured around the guide structure, in this case plate 93. The locking element 165 is welded to the first section 159 of the locking device 155 to prevent any vertical movement. When the tank 21 is mounted, the locking device 155 is located in the clearance 151. Another portion 97b of the outer intermediate face 97 of the upper intermediate portion 96 of the self-supporting heat-proof panel 43 of the secondary thermal insulation layer 41 adjacent to the plate 93 stops at the reinforcements 163 of the locking device 155. To prevent any overhang of the self-supporting heat-resistant panel 43 from bearing on both the guide structure 77 and the locking device 155, a locking member 167, 169 is disposed between the locking device 155 and the plywood or composite board 98 disposed at the level of the outer intermediate face 97 of the upper intermediate portion 96 of the self-supporting heat-resistant panel 43 of the secondary thermal insulation layer 41, which is stopped by the reinforcements 163 of the locking device 155. In the embodiment illustrated in FIGURES 4 and 5, a first locking member 167 is a plywood insert and a second locking member 169 is a putty bead. The putty bead 169 is one of the elements that contributes to the correct vertical placement of the heat-proof self-supporting panel 43 and, consequently, defines the free space 151.Therefore, the 169 putty count ensures a locking function and a flatness function for the components that rest on it. It should be noted that board 98 includes a notch 97c into which at least the first section 159 of the locking device 155 extends. The vertical position of the guide structure 77 varies depending on its manufacturing tolerances; the notch 97c prevents any mechanical interference between the locking device 155 and the self-supporting heat-proof panel 43, regardless of the vertical position of that panel. The self-supporting heat-proof panel 43 can also be prevented from protruding by producing the notch 97c in the board 98 arranged at the level of the external intermediate face 97 of the self-supporting heat-proof panel 43 of the secondary layer of thermal insulation 41 adjacent to the plate 93. This notch 97c makes it possible to accommodate a vertical edge of the first section 159 of the iron angle 157 of the locking device 155. FIGURE 5 also illustrates the composition of the internal partition wall 13, which includes the metal insert 117 to which the locking device 155 is welded. The guide structure also rests on this metal insert 117. Here, the concrete part of the internal partition wall 13 is referred to as 116. FIGURE 6 shows the generally parallelepiped-shaped transport and / or storage tank 21 mounted on the base structure 3 of a gravity platform 1. Gravity platforms 1 are generally marine structures used in the context of oil or gas exploitation. These structures often have a concrete base structure known as a gravity-based structure (GBS); the term steel gravity structure (SGS) is also used for a base structure made of steel, to which the invention also applies. Gravity 1 platforms can simultaneously function as a dam, storage facility, a platform to receive a liquefaction plant, and a loading dock in the context of the exploitation of a liquefied gas such as, for example, liquefied natural gas or ethane. The wall of tank 21 includes a primary sealed membrane intended to be in contact with the LNG contained in tank 21, a secondary sealed membrane disposed between the primary sealed membrane and the base structure 3 of the gravity platform 1, and two layers of thermal insulation disposed respectively between the primary sealed membrane zrfrnnn / rznz / B / YiAi and the secondary sealed membrane and between the second sealed membrane and the base structure 3. In a manner known in itself, the loading / unloading pipes 103 placed on the top deck of a methane tank 100 can be connected by means of appropriate connectors to the gravity platform 1 to transfer a load of LNG from or to tank 21. FIGURE 6 represents the gravity platform 1, which includes a loading and unloading station 105, a subsea pipeline 107, and a gravity platform 1. The loading and unloading station 105 is a fixed marine installation that includes a mobile alarm 111 and a tower 113 that supports the mobile arm 111. The mobile arm 111 carries an assembly of insulated flexible tubes 115 that can be connected to the loading / unloading pipelines 103. The swiveling mobile arm 111 accommodates all methane tanker loading gauges. A connecting pipe, not shown, extends into the tower 113. The loading and unloading station 105 allows the loading and unloading of at least one tank 22 from the methane tank 100 to or from the gravity platform 1. The tank 22 from the methane tank 100 can be a tank according to the invention.The gravity platform 1 includes at least one liquefied gas storage tank 21 according to the invention and connecting pipes 109 connected by the subsea pipeline 107 to the loading or unloading station 105. The subsea pipeline 107 allows the transfer of liquefied gas between the loading or unloading station 105 and the gravity platform 1 over a long distance, for example 5 km, enabling the methane tank 100 to remain a considerable distance from the shore during loading and unloading operations. Pumps on board the methane tank 100 and / or pumps equipping the gravity platform 1 and / or pumps equipping the loading and unloading station 105 are used to generate the pressure required for the transfer of the liquefied gas. Of course, the invention is not limited to the examples just described, and numerous adaptations can be applied to these examples without departing from the scope of the invention. Therefore, a transport and / or storage unit may include a tank 1, for example. These transport and / or storage units may be a liquefied petroleum gas tank, a barge, a reliquefaction unit, a gasification unit, or an onshore structure, for example, an onshore reservoir. The invention, as just described, achieves its stated objective and allows for the proposal of a tank that includes a guide structure for a liquefied gas loading / unloading tower, whose thermal insulation is improved, as well as its mechanical resistance to operating and accidental loads. Variations not described herein can be obtained without departing from the scope of the invention.
Claims
1. A tank (21) for the transport and / or storage of a liquefied gas, comprising a support structure (3), a plurality of walls (23, 25, 27) each including in one wall thickness direction (E) (23, 25, 27) at least one layer of thermal insulation (41) bearing against the support structure (3) and at least one sealed membrane (71) bearing on the thermal insulation layer (41), the plurality of walls (23, 25, 27) including at least one bottom wall (27), a guide structure (77) configured to receive a tower (29) for loading and / or unloading liquefied gas contained in the tank (21), the guide structure (77) being arranged against the support structure (3) and extending at least partly into the tank (21), the guide structure (77) including a base bearing against the support structure (3),The thermal insulation layer (41) includes at least one self-supporting heat-resistant panel (43) that is arranged at least partly around the guide structure (77), characterized in that the thermal insulation layer (41) includes a free space (151) bounded in the thickness direction (E) of the lower wall (27) by a portion (96) of the self-supporting heat-resistant panel (43) and by the support structure (3), the free space (151) being configured to accommodate at least partly the base of the guide structure (77).
2. The tank (21) according to the preceding claim, characterized in that the base includes at least one plate (93) that rests against the support structure (3), the plate (93) extending into the free space (151) and in a plane perpendicular to the thickness direction (E) of the lower wall (27).
3. The tank (21) in accordance with any of the preceding claims, characterized in that the free space (151) has a thickness (H) between 25 mm and 70 mm inclusive.
4. The tank (21) according to any of the preceding claims, characterized in that the portion (96) of the heat-proof self-supporting panel (43) that delimits the free space (151) in the thickness direction (E) includes a plywood or composite material board (98).
5. The tank (21) according to any of the preceding claims, characterized in that a part (97a) of the portion (96) of the heat-proof self-supporting panel (43) rests on the base of the guide structure (77).
6. The tank (21) according to the preceding claim, characterized in that a separator device (153) is arranged between the base of the guide structure (77) and the zrfrnnn / rznz / B / YiAi part (97a) of the portion (96) of the heat-proof self-supporting panel (43) that rests on the base of the guide structure (77).
7. The tank (21) according to the preceding claim, characterized in that the separator device (153) is an insert or a putty bead or a combination of the two.
8. The tank (21) according to any of the preceding claims, characterized in that the free space (151) is delimited in a direction perpendicular to the thickness direction (E) by an edge (99) of the heat-proof self-supporting panel (43) extending between an outer face (97) of the portion (96) of the heat-proof self-supporting panel (43) and an inner face of the support structure (3) and by the guide structure (77).
9. The tank (21) in accordance with any of the preceding claims, characterized in that a thermal insulation member (94) is disposed between the base of the guide structure (77) and the support structure (3).
10. The tank (21) according to any of the preceding claims, characterized in that it includes at least one locking device (155) located in the free space (151) and configured to immobilize the guide structure (77) in at least one direction perpendicular to the thickness direction (E) of the lower wall (27).
11. The tank (21) according to any of the preceding claims, characterized in that the thermal insulation layer (41) is a secondary thermal insulation layer and the sealed membrane (71) is a primary sealed membrane, and the tank (21) including a primary thermal insulation layer (61) and a secondary sealed membrane (51), the secondary sealed membrane (51) rests against the secondary thermal insulation layer (41), the primary thermal insulation layer (61) rests against the secondary sealed membrane (51), and the primary sealed membrane (71) rests against the primary thermal insulation layer (61).
12. A gravity platform (1) including a liquefied gas storage tank (21) according to any of the preceding claims and a tower (29) for loading / unloading liquefied gas contained in the tank, characterized in that the loading / unloading tower (29) is configured to cooperate with the guide structure (77) of the tank (21).
13. The gravity platform (1) according to the preceding claim, characterized in that it includes a base structure (3) to which the tank (21) is anchored, wherein the base structure (3) is made of concrete.
14. A transfer system for a liquefied gas, the system characterized in that it includes a gravity platform (1) according to any of claims 12 or 13, insulated pipes (103, 107, 109, 115) arranged so as to connect the tank (21) installed in the base structure (3) of the gravity platform (1) to a vessel (100), and a pump for conveying a flow of liquefied gas through the insulated pipes (103, 107, 109, 115) from the tank (21) of the gravity platform (1) to the vessel (100).
15. A method for loading or unloading a gravity platform (1) according to any of claims 12 or 13, characterized in that a liquefied gas is directed through insulated pipes (103, 107, 109, 115) from the tank (21) of the gravity platform (1) to a vessel (100).