LIQUID GAS STORAGE SYSTEM WITH POLYGONAL SUPPORT STRUCTURE

Description

technical field

[0001] The invention relates to a liquefied gas storage facility and a tracing method for constructing this facility. More particularly, the liquefied gas storage facility comprises a load-bearing structure having a regular polygonal bottom wall. Technological background

[0002] A liquefied gas storage installation comprising a load-bearing structure with an internal space delimited by a bottom load-bearing wall and a sealed, thermally insulated tank installed within the internal space of the load-bearing structure is known from document FR-A-2912385 or FR-A-3121196. The tank has a bottom wall disposed on the bottom load-bearing wall and a vertical wall disposed on the vertical load-bearing wall.

[0003] The vertical wall has a plurality of vertical faces. The background wall has a plurality of sectors that are images of each other under rotation, and where said background wall has the shape of a regular polygon, each side of which corresponds to one of said vertical faces.

[0004] The number of vertical panels is chosen to be 56, for example.

[0005] The sealed and thermally insulating tank comprises a corrugated sealed membrane intended to be in contact with a liquefied gas and a thermally insulating barrier located between the sealed membrane and the supporting structure.

[0006] The vertical wall's watertight membrane has vertical corrugations. The bottom wall's watertight membrane has initial corrugations spaced a wave pitch apart and oriented along a sector axis perpendicular to the vertical face connected to said angular sector. The corrugated watertight membrane of each angular sector of the bottom wall comprises a plurality of rectangular metal plates welded together watertight so as to be arranged to form successively juxtaposed ring segments along the sector axis. A ring segment is defined as a set of complete metal plates. In other words, the edges of the ring segments are formed by the edges of the metal plates. The ring segments located in the different angular sectors are connected to each other to form rings around a central portion of the bottom wall.

[0007] In the prior art, an angular sector arrangement strategy is applied which aims to link the wave pitch of the first undulations and the length of the metal plates, which defines a width of the portion of the crown, to the angle of the angular sector in order in particular to limit the number of different pieces on an angular sector.

[0008] However, by varying the wave pitch, and especially when it increases, the arrangement strategy no longer allows for consistent angular sector angles and / or consistent lengths of the metal plates, thus reducing the number of possible solutions. Summary of the invention

[0009] One idea underlying the invention is to improve the angular sector arrangement strategy of the bottom wall in order to maintain consistent angular sector angles and consistent sheet lengths, without complicating the arrangement.

[0010] One objective of the invention is, in particular, to achieve a membrane arrangement that allows the wave pitch to be larger than the increment in length of the outer edge of the corona portion between two successive coronas. This increment in length is close to the width of the corona portion multiplied by the sector angle.

[0011] According to one embodiment, the invention provides a liquefied gas storage installation comprising: a load-bearing structure having an internal space delimited by a bottom load-bearing wall and a vertical load-bearing wall, a contour of said bottom load-bearing wall having the shape of a regular polygon with N sides, N being an integer greater than or equal to 4, said vertical load-bearing wall being composed of N vertical load-bearing faces and forming a polygonal cylindrical surface having said regular polygon as its directrix, where each of the N sides of the polygon corresponds to an intersection of the bottom load-bearing wall with one of said vertical load-bearing faces; and a watertight tank installed in the internal space of the load-bearing structure, the watertight tank having a bottom wall disposed on the bottom load-bearing wall and a vertical wall disposed on the vertical load-bearing wall, said vertical wall being composed of N vertical faces, each vertical face of the vertical wall being fixed to one of the N vertical load-bearing faces,said bottom wall comprising a plurality of angular sectors that are images of each other under a rotation by a predetermined angle about a vertical axis, the predetermined angle being equal to k.360° / N, where k is a positive integer less than or equal to half of N, each angular sector of the bottom wall being connected to at least k of the N vertical faces of the vertical wall, the sealed tank comprising a corrugated sealed membrane intended to be in contact with a liquefied gas, in which the corrugated sealed membrane of each angular sector of the bottom wall has first undulations oriented along a sector axis, the sector axis being perpendicular to a first vertical face selected from among the N vertical faces of the vertical wall, the first undulations being spaced two by two with a regular wave pitch,in which the corrugated watertight membrane of each angular sector of the bottom wall comprises a plurality of metal plates welded together in a watertight manner, the metal plates being arranged to form successively juxtaposed crown portions along the sector axis, each crown portion being made up of a set of whole metal plates and having an inner edge and an outer edge perpendicular to the sector axis, in which the first corrugations present on the crown portions are in a total number per crown portion which increases in the direction of the first vertical face, said total number per crown portion being increased only every M successive crown portions, with M a natural number greater than or equal to 2.

[0012] In other words, the total number per portion of the crown is therefore constant per group of M successive portions of the crown.

[0013] Thanks to these characteristics, by increasing the total number of corrugations every M segments of the ring, it is possible to modulate the arrangement strategy linking the regular wave pitch of the initial corrugations and the width of the ring segments by a factor of M. Thus, depending on the value of the regular wave pitch, the factor M allows for arrangement solutions with consistent values ​​for the angular sector angle and the size of the sheets constituting each ring segment, among other things.

[0014] Indeed, in the prior art, the portion width of the corona L, the regular wave pitch P and the angular sector angle A are related by the following equation: tan A / 2 = P / L

[0015] The factor M is thus inserted into this equation in the following way: tan A / 2 = P / M * L

[0016] In this way, when for example the regular wave pitch P is increased significantly compared to the prior art wave pitch, the factor M makes it possible to keep the values ​​of the angular sector angle and the size of the metal plates within an admissible range.

[0017] According to embodiments, such a storage facility may include one or more of the following characteristics.

[0018] According to one embodiment, the waterproof membrane comprises a first portion of a crown, a second portion of a crown, and a third portion of a crown arranged successively along the sector axis and in the direction of the first vertical face, the total number of first undulations of the first portion of the crown being equal to N1, the total number of first undulations of the second portion of the crown being equal to N1, and the total number of first undulations of the third portion of the crown being equal to N2, with N1 and N2 being positive natural numbers, for example with N2 equal to N1+2. This case corresponds to the factor M equal to 2.

[0019] According to one embodiment, the waterproof membrane comprises a first ring portion, a second ring portion, a third ring portion, and a fourth ring portion arranged successively along the sector axis and in the direction of the first vertical face, the total number of first undulations of the first ring portion being equal to N1, the total number of first undulations of the second ring portion being equal to N1, the total number of first undulations of the third ring portion being equal to N1, and the total number of first undulations of the fourth ring portion being equal to N2, with N1 and N2 being positive natural numbers, for example, with N2 equal to N1+2. This case corresponds to the factor M equal to 3.

[0020] According to one embodiment, one or each portion of the crown comprises a plurality of rectangular metal plates.

[0021] According to one embodiment, the crown portions each have a width extending along the sector axis between the inner edge and the outer edge of the crown portion, said width being equal in several of said crown portions, in particular in successive crown portions along the sector axis.

[0022] According to one embodiment, the width of the portion of the crown located near a center of the bottom wall and / or the width of the portion of the crown located near the vertical wall is different from the width of the other portions of the crown, preferably the other portions of the crown being of identical width to each other.

[0023] According to one embodiment, the width of at least one of the crown portions is different from the equal width of said several crown portions, for example equal to an integer fraction of the equal width of said several crown portions.

[0024] According to one embodiment, the regular wave pitch is greater than the width of one of the crown portions multiplied by the predetermined angle.

[0025] According to one embodiment, N is even and preferably is greater than or equal to 4.

[0026] According to one particular embodiment, N is between 8 and 56. According to another particular embodiment, N is equal to 56. According to yet another particular embodiment, N is equal to 8.

[0027] The integer k is equal to the number of vertical faces of the vertical wall, divided by the number of angular sectors of the bottom wall of the tank. In one embodiment, k is equal to 1 or 2.

[0028] According to one embodiment, the regular wave pitch is greater than or equal to 400 mm, preferably greater than or equal to 800 mm, preferably between 800 and 1200 mm, for example equal to 1000 mm.

[0029] For example, when N equals 56 and the width of one of the crown portions is equal to 3000mm, the regular wave pitch can be equal to 1020mm and the natural number M can be equal to 3.

[0030] According to one embodiment, one or each portion of a ring of an angular sector comprises at least one corrugated metal connecting plate located on a lateral edge of the ring portion, the corrugated metal connecting plates being configured to connect said ring portion with a ring portion of an adjacent angular section, the corrugated metal connecting plates of the ring portions being aligned with each other in a radial direction, the radial direction being inclined with respect to the axis of sector, preferably at an angle equal to half of the predetermined angle.

[0031] According to one embodiment, the waterproof membrane of the angular sector or sectors of the bottom wall has a radial undulation located near an edge of the angular sector, the radial undulation extending in the radial direction.

[0032] According to one embodiment, the first undulations of the angular sector or of each angular sector comprise first full undulations extending from a junction between the bottom wall and the vertical wall to a portion of the central crown near a center of the bottom wall, and first partial undulations which are interrupted by a wave interruption when said first partial undulation crosses one of the corrugated metal connecting plates, the wave interruption being located at a distance from the radial undulation.

[0033] According to one embodiment, the radial undulation of the angular sector is carried out on the corrugated metal connecting plates.

[0034] According to one embodiment, the corrugated metal connecting plate of a portion of a ring of rank A is identical to the corrugated metal connecting plate of a portion of a ring of rank A+B, with for example a rank A equal to 1 for a central portion of the ring located near a center of the bottom wall, where the rank is defined as a natural number incremented by 1 when moving away along the sector axis towards the vertical wall, A being a natural number greater than or equal to 1 and B being a natural number greater than or equal to 2.

[0035] According to one embodiment, the natural number B is equal to the natural number M.

[0036] According to one embodiment, the waterproof membrane of one or each angular sector of the bottom wall comprises second corrugations spaced apart from each other and extending at least partially perpendicular to the first corrugations.

[0037] According to one embodiment, the wave interruption of the first partial undulations is located between two adjacent second undulations.

[0038] According to one embodiment, a ship for the transport of a cold liquid product comprises a double hull and the aforementioned storage facility arranged in the double hull.

[0039] According to one embodiment, the invention also provides a transfer system for a cold liquid product, the system comprising the aforementioned vessel, insulated pipes arranged to connect the tank installed in the hull of the vessel to a floating or land-based storage structure and a pump to drive a flow of cold liquid product through the insulated pipes from or to the floating or land-based storage structure to or from the vessel's tank.

[0040] According to one embodiment, the invention also provides a method for loading or unloading a ship, in which a cold liquid product is conveyed through insulated pipes from or to a floating or land-based storage structure to or from the tank of the aforementioned ship. Brief description of the figures

[0041] The invention will be better understood, and other objects, details, features and advantages thereof will become more apparent from the following description of several particular embodiments of the invention, given solely by way of illustration and not limitation, with reference to the accompanying drawings. There figure 1 This represents a partial perspective and cross-sectional view of a liquefied gas storage facility. figure 2 is a top view of the storage facility of the figure 1 allowing us to distinguish the polygonal outline of the load-bearing structure of the figure 1in an example of implementation. The figure 3 is a partial perspective view, from inside a prior art liquefied storage facility, of the outer end of an angular sector of the bottom wall and portions of the vertical wall of the tank. figure 4 is a schematic perspective view, from inside the liquefied gas storage installation, of a portion of an angular sector of the bottom wall as well as portions of the vertical wall of the tank according to a first embodiment. figure 5 is a schematic perspective view, from inside the liquefied gas storage facility, of a portion of an angular sector of the bottom wall and portions of the vertical wall of the tank according to a second embodiment. figure 6represents a top view of the sealed membrane of a section of the bottom wall of a tank installed in a liquefied gas storage facility, from inside the liquefied gas storage facility according to one embodiment. figure 7 is a view of detail VII of the figure 6 , representing more specifically a portion of a crown. The figure 8 is a schematic cutaway representation of an LNG carrier including a ship tank and a terminal for loading / unloading this tank. Description of the implementation methods

[0042] As mentioned above, the invention relates to the construction of a liquefied gas storage installation, referred to as installation 1 in the following description. Installation 1 is suitable for storing a liquefied gas, in particular liquefied natural gas (LNG) at a temperature of approximately -162°C and at atmospheric pressure, or other liquefied gases.

[0043] Installation 1 mainly comprises a load-bearing structure 10 and a sealed and thermally insulated tank 20 installed in the internal space of the load-bearing structure 10.

[0044] We first describe the load-bearing structure 10. The load-bearing structure 10 includes a bottom load-bearing wall 11 and a vertical load-bearing wall 12.

[0045] Installation 1 can be designed to be located on land. The load-bearing base wall 11 is then typically horizontal, that is, located in a plane perpendicular to the direction of gravitational acceleration, represented in the figures by a vertical axis Z, within dimensional tolerances. The load-bearing base wall 11 can be located at ground level or possibly below ground level. The load-bearing structure 10 is, for example, made of concrete.

[0046] In what follows, we consider more specifically the case of an installation 1 located on land where the load-bearing bottom wall 11 is horizontal. It is nevertheless specified that the following description applies to any orientation of the load-bearing bottom wall 11 with respect to the direction of gravitational acceleration.

[0047] The outline of the bottom load-bearing wall 11 is planned to have the shape of a regular polygon with N sides, where N is an even integer greater than or equal to 4. An installation 1 where N is equal to 8 or 56 is of particular interest.

[0048] In addition to the bottom load-bearing wall 11, the load-bearing structure 10 includes a vertical load-bearing wall 12. As is more clearly visible on the figure 1This vertical load-bearing wall 12 forms a polygonal cylindrical surface, with the polygon formed by the polygonal contour of the bottom load-bearing wall 11 as its directrix. The vertical load-bearing wall 12 extends in a vertical direction, that is, in a direction perpendicular to the plane of the bottom load-bearing wall 11, within dimensional tolerances.

[0049] By referring to figures 1 and 2 The vertical load-bearing wall 12 is composed of N vertical load-bearing panels 14. Each of the N sides of the polygonal contour of the bottom load-bearing wall 11 corresponds to an intersection of the bottom load-bearing wall 11 with one of the vertical load-bearing panels 14. The vertical load-bearing panels 14 are connected to each other by edges 13, each edge 13 corresponding to a vertex of the polygonal contour of the bottom load-bearing wall 11.

[0050] We now describe an embodiment of a sealed and thermally insulating tank 20 that can be installed in the internal space of the supporting structure 10 by referring to the figures 1 to 8 The tank 20 has a bottom wall 21 arranged on the bottom load-bearing wall 11, and a vertical wall 22 arranged on the vertical load-bearing wall 12. In the same way as the bottom load-bearing wall 11, the bottom wall 21 has a contour in the form of a regular polygon with N sides.

[0051] The vertical wall 22 is composed of N vertical panels 24. Each of the N sides of the polygonal contour of the bottom wall 21 corresponds to an intersection of the bottom wall 21 with one of the vertical panels 24. The vertical panels 24 are connected to each other by edges 23, each edge 23 corresponding to a vertex of the polygonal contour of the bottom wall 21.

[0052] The bottom wall 21 comprises a plurality of angular sectors 25. The sectors 25 are mirror images of each other under rotation about a vertical axis, that is, around an axis extending parallel to the vertical faces 24. This vertical axis passes through a point located near the geometric center of the bottom load-bearing wall 11. More precisely, the sectors 25 are mirror images of each other under rotation by an angle equal to 4x180° / N, in the case where an angular sector 25 is connected to two vertical faces 24. Thanks to this exactly repeated structure, the same parts can be used to construct each angular sector 25.

[0053] In the example shown on the figures 3 And 6 , we have N = 56 and in the one represented figure 2 , we have N = 8. Only one sector 25 is represented on the figure 6 in order not to overload the drawing.

[0054] The bottom wall 21 and the vertical wall 22 comprise, extending from the supporting structure 10 towards the interior of the tank 20, a secondary thermally insulating barrier, a secondary airtight membrane, a primary thermally insulating barrier, and a primary airtight membrane 70 intended to be in contact with the liquefied gas contained in the tank 20. The bottom wall 21 and the vertical wall 22 can be constructed using modular elements. These modular elements may correspond to the GST® technology marketed by the applicant. Reference may be made to US patent 6,035,795 for the description of certain modular elements and to WO2022200536 for other specifications of this technology not described here.

[0055] The primary waterproof membrane 70 of the bottom wall 21 is mainly composed of juxtaposed rectangular metal plates 71. On one of the lateral edges of the sectors 25, the primary waterproof membrane 70 also includes connecting metal plates 71A. The connecting metal plates 71A are generally trapezoidal in shape and allow connection between said sector 25 and an adjacent sector 25, thus completing the primary waterproof membrane 70.

[0056] The primary sealing membrane 70 is corrugated to allow it to resist thermal contraction due to contact with the liquefied gas. More specifically, at the bottom wall 21, the primary sealing membrane 70 has at least 72 radiating corrugations, that is, they are parallel to each other and extend along a sector axis X from the center of the tank 20 towards the vertical sides 24, the sector axis X being perpendicular to the vertical axis Z.

[0057] The first undulations 72 are spaced two by two with a regular wave pitch 26. In addition, the primary airtight membrane 70 typically has second undulations 73 which are perpendicular to the first undulations 72. As shown in the figures and in particular in the figure 3, plates 71, 71A each have portions of undulations which, when plates 71 and 71A are juxtaposed, together constitute undulations 72, 73.

[0058] As represented more particularly in figure 6 , the rectangular metal plates 71 are arranged to form portions of crown 75 juxtaposed successively along the axis of sector X. The connecting metal plates 71A extend each of the portions of crown 75 so as to form with all the angular sectors of crowns all around the center of the bottom wall 21.

[0059] The corrugated metal connecting plates 71A of the crown sections 75 are aligned with each other in a radial direction. The radial direction is inclined with respect to the axis of sector X at an angle equal to half the angle of angular sector 25. The watertight membrane 70 of each angular sector 25 of the bottom wall 21 has a radial corrugation 77 located near an edge of the angular sector 25. The radial corrugation 77 extends along the radial direction and is formed on the corrugated metal connecting plates 71A.

[0060] There figure 3 , representing earlier art, shows, in perspective from inside installation 1, the radially outer end of an angular sector 25 as well as portions of the vertical wall 22 of tank 20. On the figure 3 , the vertical load-bearing sections 14 of the vertical load-bearing wall 12 are not shown.

[0061] At the level of the vertical wall 22, the metallic waterproof membrane 170 is mainly made up of juxtaposed rectangular metal plates 171 and has corrugations 172 which are vertical, that is to say, which extend parallel to the vertical axis Z, parallel to the vertical load-bearing panels 14. The vertical corrugations 712 are spaced two by two at the regular wave pitch 26.

[0062] Furthermore, the metallic waterproof membrane 170 typically has horizontal corrugations 173 that are perpendicular to the vertical corrugations 172 and run all the way around the tank 20. These metal plates 171 each have portions of corrugations which, when the metal plates 171 are placed side by side, together form the corrugations 172, 173, as can be seen in figure 3 .

[0063] As illustrated in figures 3 to 5Each angular sector 25 is connected on one side to a complete vertical panel 241 from among the N vertical panels 24, and on the other side to two vertical half-panels 242, each corresponding to half of a vertical panel 24 from among the N vertical panels 24 of the vertical wall 22. The complete vertical panel 241 is centered on the angular sector 25, and the vertical half-panels 242 are located on either side of the complete vertical panel 241. The angular sectors 25 are schematically represented by dashed lines on the figure 2 . The axis of sector X is defined here for each angular sector 25 as passing through the center of the tank 20 and perpendicular to the corresponding complete vertical pane 241.

[0064] In the figure 3In the prior art, at the level of the complete vertical panel 241 and the vertical half-panels 242, the metal plates 71 and the connecting metal plates 71A are extended by connecting metal plates 74 which carry corrugated portions located in line with the corrugated portions of the metal plates 71, 71A, so as to extend the first corrugations 72 to corner connecting pieces 69. These corner connecting pieces 69 are described in more detail in document WO2022200536. Thus, in the prior art, the first corrugations 72 are extended to the complete vertical panel 241 and the vertical half-panels 242, so as to be continuously connected to the vertical corrugations 172 by means of the corner connecting pieces 69.

[0065] As explained in the introduction, with this type of prior art arrangement, which imposes continuity between the first undulations 72 of the bottom wall 21 and the vertical undulations 172 of the vertical wall 22 with a regular wave pitch 26, the diameter difference between two storage installations following this arrangement is determined by the addition or removal of a vertical undulation 172 per vertical section 24 (and therefore of the associated first undulation). The diameter difference is thus proportional to the regular wave pitch 26. The number of dimensional possibilities for such an installation is therefore limited, which is all the more problematic when the regular wave pitch 26 is large.

[0066] THE Figures 4 and 5 represent two embodiments of the storage installation 1 in which, contrary to the prior art illustrated in figure 3, by locally decoupling vertical undulations 172 from their associated first undulations 72. In these diagrams, solid lines represent the edges of plates 71, 71A, 171 and the junction 28 between the bottom wall 21 and the vertical wall 22, while dashed lines represent undulations 72, 73, 77, 172, 173. Similarly, on the figure 6 , the solid lines represent the edges of plates 71, 71A while the dotted lines represent the undulations 72, 73, 77.

[0067] As seen on these Figures 4 and 5 The continuity of the first undulations 72 with the vertical undulations 172 at the level of the complete vertical panel 241 for each angular sector 25 is maintained in a manner analogous to the prior art. However, at the level of each half-vertical panel 242, the vertical undulations 172 are discontinuous with the first undulations 72.

[0068] Indeed, for each angular sector 25, a singular wave step 27 smaller than the regular wave step 26 was introduced between each vertical half-panel 242 and the complete vertical panel 241. The two vertical undulations 172 delimiting the singular wave step 27 thus include a singular undulation 174 located on the vertical half-panel 242, as visible in Figures 4 and 5 . Thus, the singular undulation 174 as well as the other vertical undulations 172 located between the singular undulation 174 and an outer edge of the half-panel are misaligned and therefore discontinuous with the first undulations 72 of the bottom wall 21.

[0069] The presence of the singular wave step 27 thus allows the addition of intermediate dimensional solutions, which can be modulated with the value of the singular wave step 27, between two arrangements comprising only regular wave steps 26.

[0070] A sudden stop of the first undulations 72 and the vertical undulations 172 at the junction between a vertical half-panel 242 and the bottom wall 21 can affect the flexibility of the waterproof membrane at this junction.

[0071] Therefore, it is advantageous to extend some of these initial corrugations 72 or vertical corrugations 172 beyond this junction so that it extends onto the vertical wall 22 or the bottom wall 21 respectively. This extension thus locally improves the flexibility of the watertight member.

[0072] Thus, in the first embodiment illustrated in figure 4The vertical undulations 172 of each vertical half-panel 242 are extended onto the back wall 21 by a vertical undulation extension 175, such that the vertical undulations 172 extend onto the back wall 21. This extension onto the back wall 21 remains localized, however. Indeed, the vertical undulation extensions 175 are interrupted on the back wall 21 at a distance from the second undulation 73 located near the junction between the back wall 21 and the vertical wall 22.

[0073] Similarly, in the second embodiment illustrated in figure 5These are the first undulations 72, which are extended onto the vertical half-panel 242 by an extension of the first undulation 76, so that the first undulations 72 extend onto the vertical wall 22. This extension onto the vertical wall 22 remains localized, however. Indeed, the extensions of the first undulation 76 are interrupted on the vertical wall 22 at a distance from the horizontal undulation 173 located near the junction between the bottom wall 21 and the vertical wall 22.

[0074] In an unillustrated embodiment, it is also conceivable that the first undulations 72 and the vertical undulations 172 are extended respectively on the vertical wall 22 and the bottom wall 21.

[0075] There figure 6represents the primary waterproof membrane 70 of an angular sector 25 of the bottom wall 21 viewed from above, according to one embodiment. As mentioned previously, the metal plates 71 of each angular sector 25 are arranged to form successively juxtaposed ring portions 75 along the sector axis X. The width of a ring portion 75 along the X axis corresponds, for the vast majority of the metal plates 71, to the length of these plates 71.

[0076] The metal plates 71 do not all have the same dimensions. Thus, in the example of the figure 6 The 71 metal plates are distributed in four different dimensions, namely: metal plates 71 of dimension "X1" comprising a first corrugation 72 and 3 second corrugations 73, one of which crosses the middle of the metal plate 71; metal plates 71 of dimension "X2" having in the example a length along the X axis equal to the length of the plates "X1", and a width in a direction orthogonal to the X axis less than the width of the plates "X1"; metal plates 71 of dimension "X3" having a width equal to the width of the plates "X2", the length being less than half the length of the plates "X2" so that the plates "X3" comprise only one second corrugation 73; metal plates 71 of dimension "X4",presenting a width less than the width of the "X3" plates so as not to have a first corrugation 72 and a length such that the sum of the length of an "X3" plate and the length of an "X4" plate is equal to the length of an "X2" (or "X1") plate.

[0077] In the example shown in figure 6 , the angular sector 25 includes from the center of the back wall 21 towards the vertical wall 22: a first portion of a crown 75 comprising 2 metal plates of dimension "X3" side by side among the metal plates 71; a second portion of a crown 75 comprising two metal plates "X2" side by side; a third portion of a crown 75 comprising two metal plates "X1" side by side; a fourth portion of a crown 75 comprising two metal plates "X1" framed on each side by a plate "X4" followed by a plate "X3" along the X axis; a fifth portion of a crown 75 comprising two plates "X1" framed on each side by a plate "X2"; a sixth portion of a crown 75 with a pattern similar to the third portion of the crown with two additional plates "X1"; a seventh portion of a crown 75 with a pattern similar to the fourth portion of the crown 75 with two additional plates "X1".

[0078] Similarly, the 71A metal connecting plates do not all have the same dimensions. These 71A metal connecting plates also have, in the example of the figure 6 a pattern that is repeated every three crown sections 75.

[0079] As previously presented, in the prior art, an arrangement strategy using angular sectors 25 is applied, which aims to link the wave pitch 26 of the first corrugations 72 and the length of the metal plates 71, or a width of the ring portion 75, to the angle of the angular sector 25, in order to limit the number of different parts on an angular sector 25. Thus, the total number of first corrugations 72 present on the ring portions 75, which increases towards the vertical wall 22, is increased at each successive ring portion 75 by two new first corrugations 72 on either side of the angular sector 25. Indeed, in the prior art, the ring portion width L, the regular wave pitch P, and the angular sector angle A are linked by the following equation: tan A / 2 = P / L

[0080] However, in the case of a high wave pitch like the one shown in the example illustrated in figure 6namely 1020mm wave pitch for 3000 x 1000 mm plates, this arrangement strategy does not allow maintaining a coherent angular sector angle without significantly increasing the size of the plates 71.

[0081] Thus, in the embodiment represented figure 6 With a wave pitch of 1020 mm, the total number of initial undulations 72 present on the ring segments 75 increases only every three successive ring segments 75. In this example, the factor of three thus allows the values ​​of the angular sector angle 25 and the size of the metal plates 71 to remain within an admissible range.

[0082] The first 72 undulations of each angular sector 25 thus include, as visible in figure 6The first complete undulations 721 extend from a junction between the bottom wall 21 and the vertical wall 22 to a central portion of the crown 75 near a center of the bottom wall 21, and the first partial undulations 722 are interrupted by a wave interruption 723. Indeed, the first partial undulations 722 are interrupted when said first partial undulation 722 crosses a corrugated metal connecting plate 71A. Thus, the wave interruption 723 is located at a distance from the radial undulation 77 of said angular sector 25 or from a neighboring angular sector. Furthermore, the wave interruption 723 is located between two adjacent second undulations 73.

[0083] By stopping the first partial undulations 722 at the level of a corrugated metal connecting plate 71A, it is thus possible to maintain a minimum distance between the radial undulation 75 and said first partial undulation 722 while limiting the maximum wave pitch between the radial undulation 77 and the first undulation 72 located closest to the radial undulation 77.

[0084] There figure 7 represents more specifically one of the crown portions 75 of the angular sector 25 illustrated in figure 6 This figure illustrates in particular the specific assembly of the metal plates 71 with connecting metal plates 71A. In addition, on this portion of the ring 75, one of the first partial undulations 722 crosses one of the connecting metal plates 71A and thus presents a wave interruption 723.

[0085] With reference to the figure 8, a cutaway view of a methane tanker 100 shows a sealed and thermally insulated tank 112 of generally prismatic shape mounted in the double hull 102 of the ship 100. The wall of the tank comprises a primary sealed membrane intended to be in contact with the LNG contained in the tank, a secondary sealed membrane arranged between the primary sealed membrane and the double hull 102 of the ship 100, and two thermally insulating barriers arranged respectively between the primary sealed membrane and the secondary sealed membrane and between the secondary sealed membrane and the double hull 102.

[0086] As is known per se, loading / unloading pipelines 103 arranged on the upper deck of the ship can be connected, by means of suitable connectors, to a marine or port terminal to transfer a cargo of LNG to or from the tank 112.

[0087] There figure 8This represents an example of a marine terminal comprising a loading and unloading berth 105, a subsea pipeline 106 and an onshore storage facility 1. The loading and unloading berth 105 is a fixed offshore installation comprising a movable arm 104 and a tower 108 which supports the movable arm 104. The movable arm 104 carries a bundle of insulated flexible pipes 109 which can be connected to the loading / unloading pipelines 103. The steerable movable arm 104 adapts to all LNG carrier sizes. An unshown connecting pipeline extends inside tower 108. The loading and unloading station 105 allows the loading and unloading of the LNG carrier 100 from or to the land-based storage facility 1. This facility includes liquefied gas storage tanks 20 and connecting pipelines 111 linked by the subsea pipeline 106 to the loading or unloading station 105.The subsea pipeline 106 allows the transfer of liquefied gas between the loading or unloading station 105 and the land-based storage facility 1 over a long distance, for example 5 km, which allows the LNG carrier 70 to be kept a long distance from the coast during loading and unloading operations.

[0088] To generate the pressure necessary for the transfer of the liquefied gas, pumps on board the ship 100 and / or pumps equipping the land storage facility 1 and / or pumps equipping the loading and unloading station 105 are used.

[0089] Although the invention has been described in connection with several particular embodiments, it is clearly evident that it is by no means limited to them and that it includes all technical equivalents of the means described as well as their combinations if these fall within the scope of the invention.

[0090] The use of the verb "comporter", "comprendre" or "include" and its conjugated forms does not exclude the presence of other elements or steps than those stated in a claim.

[0091] In claims, any reference sign in parentheses shall not be interpreted as a limitation of the claim.

Claims

1. Liquefied gas storage facility (1) comprising: a load-bearing structure (10) having an internal space delimited by a bottom load-bearing wall (11) and a vertical load-bearing wall (12), a contour of said bottom load-bearing wall (11) having the shape of an N-sided regular polygon, N being an integer greater than or equal to 4, said vertical load-bearing wall (12) being made up of N vertical load-bearing panels (14) and forming a polygonal cylindrical surface having said regular polygon as its directrix, where each of the N sides of the polygon corresponds to an intersection between the bottom load-bearing wall (11) and one of said vertical load-bearing panels (14); and a sealed tank (20) installed in the internal space of the load-bearing structure (10), the sealed tank (20) comprising a bottom wall (21) placed on the bottom load-bearing wall (11) and a vertical wall (22) placed on the vertical load-bearing wall (12), said vertical wall (22) being made up of N vertical panels (24), each vertical panel of the vertical wall (22) being fixed to one of the N vertical load-bearing panels (14), said bottom wall (21) comprising a plurality of angular sectors that are the image of one another through rotation by a predetermined angle about a vertical axis (Z), the predetermined angle being equal to k.360° / N, where k is a positive integer less than or equal to half of N, each angular sector (25) of the bottom wall (21) being connected to at least k of the N vertical panels (24) of the vertical wall (22), the sealed tank (20) comprising a corrugated sealing membrane (70, 170) intended to be in contact with a liquefied gas, wherein the corrugated sealing membrane (70, 170) of each angular sector (25) of the bottom wall (21) has first corrugations (72) oriented along a sector axis (X), the sector axis (X) being perpendicular to a first vertical panel connected to said angular sector (25), the first corrugations (72) being spaced one from the next by a regular corrugation pitch, wherein the corrugated sealing membrane (70, 170) of each angular sector (25) of the bottom wall (21) comprises a plurality of metal plates (71) welded together in a fluidtight manner, the metal plates (71) being arranged to form ring portions (75) juxtaposed successively along the sector axis (X), each ring portion (75) consisting of a set of complete metal plates, and wherein the total number of first corrugations (72) per ring portion (75) that are present on the ring portions (75) increases in the direction of the first vertical panel, characterised in that said total number per ring portion (75) is increased only every M successive ring portion (75) where M is a natural integer greater than or equal to 2.

2. Storage facility (1) according to Claim 1, wherein the ring portions (75) have an inner edge and an outer edge which are perpendicular to the sector axis (X) and each have a width extending along the sector axis (X) between the inner edge and the outer edge of the ring portion (75), said width being equal in several of said ring portions (75).

3. Storage facility (1) according to Claim 2, wherein the width of the ring portion (75) situated close to a centre of the bottom wall (21) and / or the width of the ring portion (75) situated close to the vertical wall (22) is different from the width of the other ring portions (75), the other ring portions (75) preferably having identical widths to one another.

4. Storage facility (1) according to one of Claims 1 to 3, wherein the regular corrugation pitch is greater than or equal to 400 mm, preferably greater than or equal to 800 mm, preferentially comprised between 800 and 1200 mm, and for example equal to 1000 mm.

5. Storage facility (1) according to one of Claims 1 to 4, wherein each ring portion (75) of an angular sector (25) comprises at least one corrugated metal connecting plate (71A) situated on one lateral edge of the ring portion (75), the corrugated metal connecting plates (71A) being configured to connect said ring portion (75) to a ring portion (75) of an adjacent angular sector (25), the corrugated metal connecting plates (71A) that connect the ring portions (75) being aligned with one another in a radial direction, the radial direction being inclined with respect to the sector axis (X) preferably by an angle equal to half the predetermined angle.

6. Storage facility (1) according to Claim 5, wherein the sealing membrane of the angular sector (25) of the bottom wall (21) comprises a radial corrugation (77) situated near one edge of the angular sector (25), the radial corrugation (77) extending in the radial direction.

7. Storage facility (1) according to Claim 6, wherein the first corrugations (72) of the angular sector (25) comprise first complete corrugations (721) extending from a junction (28) between the bottom wall (21) and the vertical wall (22) as far as a central ring portion near a centre of the bottom wall (21), and first partial corrugations (722) which are interrupted by a corrugation interruption (723) where said first partial corrugation crosses one of the corrugated metal connecting plates (71A), the corrugation interruption (723) being situated some distance from the radial corrugation (77).

8. Storage facility (1) according to Claim 6 or Claim 7, wherein the radial corrugation (77) of the angular sector (25) is produced on the corrugated metal connecting plates (71A).

9. Storage facility (1) according to one of Claims 5 to 8, wherein the corrugated metal connecting plate (71A) for a ring portion (75) of row A is identical to the corrugated metal connecting plate (71A) of a ring portion (75) of row A+B, where the row is defined as being a natural integer incremented by progressing along the sector axis (X) towards the vertical wall (22), A being a natural integer greater than or equal to 1 and B being a natural integer greater than or equal to 2.

10. Storage facility (1) according to one of Claims 1 to 9, wherein the sealing membrane of an angular sector (25) of the bottom wall (21) comprises second corrugations (73) spaced apart from one another and extending at least partially perpendicular to the first corrugations (72).

11. Storage facility (1) according to Claims 7 and 10 considered in combination, wherein the corrugation interruption (723) of the first partial corrugations (722) is situated between two adjacent second corrugations (73).

12. Storage facility (1) according to one of Claims 1 to 11, wherein the storage facility (1) is an onshore storage facility.