Airtight insulated tank

Abstract

The present invention relates to a sealed insulated tank including a tank wall, a sealed membrane (4) comprising a plurality of membrane sections separated by a polygonal perimeter, said plurality of membrane sections comprising at least one regular membrane section (17), said regular membrane section (17) comprising a first regular series of corrugations, said first regular series of corrugations consisting of parallel first corrugations (12) spaced from one another by a first corrugation interval (20), said plurality of membrane sections comprising at least one singular membrane section (18), said singular membrane section (18) comprising a first series of singular corrugations, planar sections comprising singular planar sections (24) having a dimension in a second direction strictly greater than N times said first corrugation interval (20), N being a natural number, said first series of singular corrugations comprising at least two first corrugations each located on either side of said singular planar section (24).

Description

[Technical field]

[0001] The present invention relates to the field of sealed, insulated tanks of the membrane type. In particular, the invention relates to the field of sealed, insulated tanks for storing and / or transporting liquefied gases at low temperatures, such as tanks for transporting liquefied petroleum gas (also called LPG) at temperatures of, for example, -50°C to 0°C, or tanks for transporting liquefied natural gas (LNG) at atmospheric pressure at about -162°C. These tanks can be installed on land or on floating structures. In the case of floating structures, the tanks are intended to transport liquefied gases or to contain liquefied gases to be used as fuel for propulsion of the floating structure. [Background technology]

[0002] Sealed, insulated tanks for storing and / or transporting liquefied gas, comprising at least one sealing membrane in contact with the liquefied gas, are known from WO 2011 / 157915. These tanks are equipped with load / unload columns, or more simply, load and unload pipes, which penetrate the roof of the tank and reach the interior space of the tank, for loading and unloading the liquefied gas into and from the tank.

[0003] The load / unload column is composed of a structure in which multiple masts are connected to each other at their lower ends via a base. The load / unload column further comprises a guide device fixed to the underside of the base and cooperating with a support leg fixed to the support structure by penetrating the bottom wall of the tank.

[0004] The pump, especially the unloading pump, is fixed to a load / unload column in the tank, to load and unload pipes, or to a support leg. In order to limit the amount of liquid that cannot be unloaded from the tank, the lower end of the unloading pump is located as close as possible to the sealing membrane, at a predetermined distance of a few centimeters.

[0005] Furthermore, in WO 2011 / 157915 the sealing membrane in contact with the liquefied gas is a corrugated metal sealing membrane having a first series of parallel corrugations in a first direction and a second series of parallel corrugations in a second direction. Summary of the Invention

[0006] The inventors have confirmed that the pump is fixed in the tank at a certain distance from the sealing membrane of the bottom wall so as not to damage the sealing membrane, but such an installation method does not allow the pump to be as close as possible to the bottom wall, which limits the volume of the cargo that can be pumped by the pump.

[0007] Specifically, the sealing membrane has corrugations that protrude towards the inside of the tank, which must be taken into account when installing the pump.

[0008] The idea behind the present invention is to reconfigure the area of ​​the membrane near the pump.

[0009] According to one embodiment, the present invention comprises: A sealed insulated tank incorporated into a support structure including a support wall, the tank includes a tank wall secured to the support wall of the support structure; The tank wall is At least one insulating barrier in a thickness direction from the exterior to the interior of the tank; at least one sealing membrane supported by said insulating barrier and intended to be in contact with a fluid in said tank; Equipped with the sealing membrane comprises a plurality of membrane sections juxtaposed and welded to one another, each membrane section being bounded by a polygonal perimeter; the plurality of membrane portions includes at least one regular membrane portion, the regular membrane portion including a first regular series of corrugations; the first regular series of corrugations comprises parallel first corrugations extending in a first direction, the first corrugations being spaced apart from one another in a second direction perpendicular to the first direction by first corrugation intervals; the regular membrane portion includes a regular planar portion located between first corrugations of the first regular series of corrugations and resting on the insulating barrier, the regular planar portion having a dimension in the second direction that is smaller than the first corrugation spacing; the plurality of membrane portions includes at least one singular membrane portion, the singular membrane portion including a first series of singular corrugations, the first series of singular corrugations consisting of first parallel corrugations extending in the first direction, the singular membrane portion including a singular planar portion having a dimension in the second direction strictly greater than N times the first corrugation spacing, N being a natural number; the regular membrane portion is adjacent to the singular membrane portion in the second direction; The first series of singular corrugations provides a sealed, insulated tank, including at least two first corrugations each located on either side of the singular planar portion in the second direction.

[0010] These features enable the singular planar portion of the singular membrane section to have an area free of the first corrugations over a larger dimension than a regular membrane section, while still maintaining sufficient flexibility using corrugations located on both sides of the singular planar portion.

[0011] Thus, when the planar portion of this singular is aligned with the internal element close to the sealing membrane, the absence of a first corrugation in this region means that the separation between the sealing membrane and the internal element can be adapted in such a way as to optimize the volume pumped.

[0012] According to other embodiments, such a tank may have one or more of the following features:

[0013] In one embodiment, the majority of the sealing membrane is made up of regular membrane portions.

[0014] According to one embodiment, the first series of singular corrugations includes two groups located on either side of the singular planar portion in the second direction, each group including at least N first corrugations spaced apart from each other in the second direction by the first corrugation interval, N being preferably a natural number equal to or greater than 2, and the singular menbrane portion includes a regular planar portion located between the first corrugations of one and the same group.

[0015] Thus, the sealed membrane of the singular membrane portion remains flexible to thermal expansion / contraction in the second direction despite having a larger singular planar portion than the regular membrane portion or the sealed membrane portion.

[0016] According to one embodiment, said natural number N is preferably equal to or greater than 2.

[0017] The natural number N may be equal to 1, 2, or 3.

[0018] According to one embodiment, the regular membrane portion is adjacent to the singular membrane portion in the second direction, and one first corrugation of the regular membrane portion adjacent to the outer periphery is separated from one first corrugation of the singular membrane portion in the second direction by a dimension equal to the first corrugation interval.

[0019] According to one embodiment, the tank comprises an interior space bounded by the sealing membrane, the tank comprises an internal element located in the interior space of the tank, The singular planar portion of the singular menbrane section is aligned with and spaced some distance from the inner element in the thickness direction of the tank wall.

[0020] Thus, if the sealing membrane has only one series of corrugations, it is possible to increase the spacing between the sealing membrane and the internal element by a dimension equal to the height of the corrugations considered in the thickness direction by eliminating the corrugations below the internal element.

[0021] According to one embodiment, the internal element has a dimension in the second direction that is greater than the first corrugation spacing, and preferably less than the dimension of the singular planar portion in the second direction, for example, if the dimension of the singular planar portion is three times the first corrugation spacing in the second direction, the dimension of the internal element in the second direction is less than three times the first corrugation spacing, and preferably between two and three times the first corrugation spacing.

[0022] According to one embodiment, the internal element is disposed in the thickness direction of the tank wall at a predetermined distance from the singular plane portion, the predetermined distance being less than 200 mm, preferably between 30 and 150 mm, for example between 95 and 105 mm, measured when the tank is empty.

[0023] Specifically, the distance is measured only when the tank is empty of its contents, such as liquefied gas, etc. If the tank is on board a ship, the measurement is performed in port or in a dry dock.

[0024] According to one embodiment, the sealing membrane comprises a second series of corrugations; the second series of corrugations includes second parallel corrugations extending in a second direction; the regular planar portion and the singular planar portion are located between the second corrugations; The singular menbrane portion includes at least two singular planar portions located on either side of one of the second corrugations.

[0025] According to one embodiment, the second corrugations of the second series of corrugations are spaced apart from each other in the first direction by a second corrugation interval, which is preferably the same between the regular planar portion and the singular planar portion.

[0026] According to one embodiment, the second corrugation has a height in the thickness direction of the tank wall that is smaller than a height of the first corrugation in the thickness direction of the tank wall.

[0027] Thus, despite the presence of the second corrugations between the singular planar portions, the absence of the first corrugations in this region allows for an increase in the separation between the sealing membrane and the internal element by a dimension equal to the difference in height between the first and second corrugations.

[0028] According to one embodiment, the sealing membrane comprises corrugated nodes, each of which is formed at an intersection of the first corrugation and the second corrugation and has a height in the thickness direction of the tank wall that is greater than the height of the first corrugation.

[0029] Thus, despite the presence of the second corrugations between the singular planar portions, the absence of the first corrugations in this region allows for an increase in the separation between the sealing membrane and the internal element by a dimension equal to the difference in height between the corrugation nodes and the second corrugations.

[0030] According to one embodiment, the singular menbrane portion comprises an opening bounded by a polygonal inner perimeter, the tank includes support legs secured to the support structure and extending through the tank wall and the opening; the singular menbrane portion includes at least one anchor to the support leg on at least one side of an inner periphery of the polygon; The anchors to the support legs are preferably provided on each side of the inner periphery of the polygon.

[0031] According to one embodiment, the tank comprises a loading / unloading column, the loading / unloading column comprising a number of masts connected to each other at their lower ends using a base, the base comprising a guide device cooperating with a support leg, the support leg being configured to guide the vertical movement of the loading / unloading column, the tank comprising at least one unloading pump arranged in the interior space and fixed to the loading / unloading column, and the internal element being formed by the unloading pump.

[0032] According to one embodiment, the inner element is connected to the support legs.

[0033] According to one embodiment, at least one of the number of first waveforms and the number of second waveforms provided in the singular lens blend portion between any side of the inner circumference and any side of the outer circumference of the singular lens blend portion is 3 or less.

[0034] According to one embodiment, at least one of the total number of the first waveforms included in the singular menbrane portion and the total number of the second waveforms included in the singular menbrane portion is 3 or less.

[0035] According to one embodiment, at least one of the total number of the first corrugations in the regular membrane portion and the total number of the second corrugations in the regular membrane portion is 3 or less.

[0036] These criteria therefore make it possible to limit the maximum distance between the two sides of the membrane part which are fixed to the insulating barrier in at least one direction, thereby ensuring that the membrane part is able to adequately withstand the stresses, in particular overpressures, to which it is subjected during use, by setting a maximum limit on the maximum distance between the anchors to the insulating barrier in at least one direction.

[0037] According to one embodiment, the thermal barrier comprises a plurality of cuboid thermal insulation blocks arranged side by side, Each insulation block comprises an insulation material and a cover panel facing the inside of the tank; A metal anchor plate is attached to the upper surface of the cover panel opposite the insulation material, The upper surfaces of the cover panels collectively form a support surface for the sealing membrane.

[0038] According to one embodiment, the anchor plate includes a first anchor plate extending in a first direction and a second anchor plate extending in a second direction.

[0039] According to one embodiment, the sealing membrane comprises a plurality of rectangular corrugated metal sheets welded together, Each corrugated metal sheet has two edges parallel to the first direction and two edges parallel to the second direction; Each regular or singular membrane section comprises one or more of said corrugated metal sheets.

[0040] According to one embodiment, each singular membrane portion and / or each regular membrane portion comprises at least one anchor to said insulating barrier on each side of the periphery of said polygon.

[0041] According to one embodiment, each anchor to the insulating barrier is disposed consecutively along the entire circumference of the polygon.

[0042] Such tanks may form part of an onshore storage facility, for example for storing LNG, or may be installed on floating structures, either onshore or offshore, such as methane carriers, Floating Storage and Regasification Units (FSRUs), Floating Production Storage and Offloading (FPSOs) or others. Such tanks may also be used as fuel tanks on ships of any type.

[0043] According to one embodiment, a vessel for transporting cryogenic liquid products comprises a double hull and the aforementioned tank arranged within said double hull.

[0044] According to one embodiment, the invention provides a system for transferring a cryogenic liquid product comprising a vessel as described above, an insulated pipe arranged to connect the tank installed in said vessel to a floating or land-based storage facility, and a pump for conveying a flow of said cryogenic liquid product through said insulated pipe from said floating or land-based storage facility to said tank of said vessel or from said tank of said vessel to said floating or land-based storage facility.

[0045] According to one embodiment, the invention provides a method for loading or unloading such a vessel, transporting cryogenic liquid product through insulated pipes from a floating or land-based storage facility to the tanks of the vessel or from the tanks of the vessel to the floating or land-based storage facility.

[0046] The invention will be better understood and other objects, details, features and advantages of the invention will become more apparent from the following description, in which several particular embodiments of the invention are described, by way of non-limiting examples only, with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0047] [Figure 1] FIG. 1 is a schematic, partial cross-sectional view of a sealed, insulated tank in the region of the support legs. [Diagram 2] FIG. 2 is a view of detail II of FIG. 1 of a prior art tank. [Diagram 3] FIG. 3 is a view of detail II of FIG. 1 of a tank according to the invention. [Figure 4] FIG. 4 shows a schematic partial view from above of the bottom wall in the region of the support feet according to a first embodiment. [Diagram 5] FIG. 5 shows a schematic partial view from above of the bottom wall in the region of the support feet according to a second embodiment. [Figure 6]FIG. 6 shows a schematic partial view from above of the bottom wall in the region of the support feet according to a third embodiment. [Figure 7] FIG. 7 is a schematic diagram showing a cross-section of a methane carrier equipped with a sealed, insulated tank and a terminal for loading and unloading the tank. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0048] FIG. 1 partially shows a sealed, insulated tank 71 for storing and / or transporting liquefied gas, which consists of a bottom wall 1 fixed to the inner surface of a support structure 2. The support structure 2 is, for example, the inner hull of a double-hulled ship or a land-based structure. To contain a cold liquid such as LNG, the tank wall consists of at least one sealing membrane 4 and at least one insulating barrier 3 arranged between the sealing membrane 4 and the support structure 2. As a safety measure, it is also possible to provide a secondary sealing membrane and a secondary insulating barrier, not shown, between the support structure and the insulating barrier 3. In such a case it is called a primary insulating barrier.

[0049] The liquefied gas stored in the tank 71 is in particular liquefied natural gas (LNG), i.e. a gas mixture containing mainly methane and one or more other hydrocarbons, ethane or liquefied petroleum gas (LPG), i.e. a mixture of hydrocarbons obtained from the refining of crude oil and essentially containing propane and butane.

[0050] The tank 71 can be manufactured according to various known shapes, such as a prismatic shape for ships, a cylindrical shape for land, etc. Furthermore, there are many ways to create the insulating barrier and sealing membrane, for example using prefabricated elements.

[0051] On the bottom wall 1 of the tank are depicted elongated rigid elements constituting the support legs 5, which extend through the insulating barrier 3 and the sealing membrane 4, with a part of the support legs 5 abutting the support structure 2 and another part protruding into the tank at a certain distance from the sealing membrane 4. The support legs 5 serve, for example, to support equipment 7 that is immersed in the tank. For example, to support an unloading pump 7, a load / unload column 6 can be arranged in the tank, as shown diagrammatically in FIG. 1. Instead of the load / unload column 6, the tank 71 may also be provided with load and unload pipes that are not connected to each other and are guided using the support legs 5.

[0052] The load / unload column 6 has a structure in which the lower ends of multiple masts are connected to each other via a base. Furthermore, the load / unload column 6 has a guide device fixed to the lower surface of the base and cooperating with the support legs 5.

[0053] The support legs 5 are configured to provide a vertical movement guide for the load / unload column 6 (or simply the load and unload pipes), and the unload pump 7 is fixed to the load / unload column 6 or directly to the support legs 5.

[0054] Here, the support leg 5 has a shape of revolution with a circular cross section, with a frustoconical lower part 8 connected at its smallest diameter end to a cylindrical upper part 9. The larger diameter base of the frustoconical part 8 abuts the support structure 2. The frustoconical part 8 extends beyond the sealing membrane 4 and through the thickness of the bottom wall 1.

[0055] The thermal barrier 3 is made up of a number of rectangular insulating blocks (not shown) arranged side by side. Each insulating block consists of an insulating material and a cover panel facing the inside of the tank, the upper surface of which is attached with a metal anchor plate, opposite the insulating material. Such insulating blocks are described, for example, in US Pat. No. 6,035,795. The upper surfaces of the cover panels collectively form the support surface for the sealing membrane 4.

[0056] With particular reference to figures 3 and 4, the sealing membrane 4 consists of a number of corrugated metal sheets 10, the faces of which, called inner faces, are intended to be in contact with the fluid in the tank. The metal sheets 10 are in particular made of stainless steel or of an iron-nickel alloy known as Invar® and are welded in the overlapping areas 11. The welds are of the lap weld joint type. The metal sheets 10 can be designed in different ways with regard to their shape and dimensions, so that the welded areas can be located in different positions.

[0057] The metal sheet 10 is provided on its inner surface with a first series of corrugations 12 extending in a first direction and a second series of corrugations 13 extending in a second direction perpendicular to the first direction.

[0058] Thus, the first series of corrugations 12 comprises a plurality of first corrugations 12 parallel to and spaced apart from one another in the second direction, and the second series of corrugations 13 comprises a plurality of second corrugations 13 parallel to and spaced apart from one another in the first direction. The sealing membrane 4 comprises planar portions 14 located between the first corrugations 12 and between the second corrugations 13, the planar portions 14 being in contact with the insulating barrier 3.

[0059] The first corrugations 12 have a height greater than the second corrugations 13. The height of the corrugations is measured between the peak of the corrugation and the height of the flat portion 14. The sealing membrane 4 further comprises corrugation nodes 15 formed at the intersections of the first corrugations 12 and the second corrugations 13. The height of each corrugation node 15 is greater than the height of the first corrugations 12. The corrugations 12, 13 protrude towards the inside of the tank 71.

[0060] As best seen in FIG. 4, the corrugated metal sheets are rectangular in shape and welded together, with each corrugated metal sheet having two edges parallel to a first direction and two edges parallel to a second direction.

[0061] Furthermore, in order to fasten the sealing membrane 4 to the thermal insulation barrier 3 , a specific metal sheet 10 is welded to the metallic anchor plate of the thermal insulation block of the thermal insulation barrier 3 , particularly in the overlapping area 11 .

[0062] In order to limit the amount of liquid that cannot be discharged from the tank 71, the lower end of the unloading pump 7 is placed as close as possible to the sealing membrane 4, at a predetermined distance of the order of a few centimetres.

[0063] 2 and 3 show in particular an enlarged view of the area located between the unloading pump 7 and the bottom wall 1, with FIG. 2 showing this area according to the prior art and FIG. 3 showing this area according to the invention.

[0064] 2, the spacing between the unloading pump 7 and the sealing membrane 4 is minimum at the corrugation node 15. This spacing is hereinafter referred to as the initial spacing 22. The inventors have now discovered that this predetermined distance tends to change significantly as the tank is in use.

[0065] To overcome the above observations, the invention shown in figure 3 proposes to reconfigure the area under the unloading pump 7. In this area, the sealing membrane 4 is therefore devoid of the first corrugations 12, in particular the corrugation nodes 15. According to the invention, therefore, only the second corrugations 13 are present under the pump 7, which means that the spacing between the unloading pump 7 and the sealing membrane 4 is minimal at the apex of the second corrugations 13. The increase in the spacing 23 compared to the initial spacing 22 is therefore equal to the difference in height between the corrugation nodes 15 and the second corrugations 13, which is for example about 33 mm when the height of the first corrugations is about 55 mm and the height of the second corrugations is about 37 mm.

[0066] According to a variant not shown but included in the invention, the sealing membrane 4 below the unloading pump 7 has neither the second corrugations 13 nor the first corrugations 12. The sealing membrane 4 is therefore flat below the pump 7. The increase in spacing is therefore equal to the height of the corrugation nodes, for example of the order of 69 mm.

[0067] 4 to 6 show more specifically the arrangement of the sealing membrane 4 and the pump 7 in the bottom wall 1 near the support legs 5 according to various embodiments of the bottom wall 1. In FIG.

[0068] Figure 4 shows a bottom wall 1 according to a first embodiment with a support leg 5 with two pumps 7. Figure 5 shows a bottom wall 1 according to a second embodiment with a support leg 5 with two pumps 7 and a sump 27 aligned with the support leg 5 in the first direction. Figure 6 shows a bottom wall 1 according to a third embodiment with a support leg 5 with two pumps 7 and two sumps 27 located on either side of the support leg 5 in the first direction.

[0069] The sealing membrane 4 comprises a number of membrane parts 17, 18 juxtaposed and welded to one another. Each membrane part 17, 18 is composed of one or more metal sheets 10 welded to one another. Each membrane part 17, 18 is delimited here by a rectangular perimeter and comprises anchors 19 for fixing the metal sheets 10 to the thermal barrier 3 along the four sides of the rectangular perimeter. The anchors 19 for fixing the membrane parts 17, 18 to the thermal barrier 3 are for example realized by welding together the metal sheets 10 and anchor plates supported by thermal insulation blocks. These anchors 19 are indicated by bold lines in Figs. 4-6 and, in the illustrated embodiment, are arranged continuously along the four sides of the rectangular perimeter of each membrane part 17 or 18. In the illustrated embodiment, these anchors 19 are formed in the overlapping areas 11 between the metal sheets 10.

[0070] 4-6, the first corrugation 12 and the second corrugation 13 are shown as dotted lines, and the intersections of these lines indicate the corrugation nodes 15. The position of each pump 7 along the sealing membrane 4 is indicated by a circle.

[0071] The sealing membrane 4 in Fig. 4 is more specifically composed of a regular membrane portion 17 and three singular membrane portions 18. The singular membrane portions 18 are portions of the tank interior where the elements are located close to the sealing membrane 4 and where the first corrugations 12 are partially removed or interrupted (see Fig.). The regular membrane portions 17 thus combine with each other and with the three singular membrane portions 18 to form the sealing membrane 4.

[0072] Thus, the regular membrane portion 17 has first corrugations 12 spaced apart by a first corrugation spacing 20, second corrugations 13 spaced apart by a second corrugation spacing 21, and regular planar portions 14 between the corrugations having a dimension in the second direction less than the first corrugation spacing 20 and a dimension in the first direction less than the second corrugation spacing 21. The first corrugation spacing 20 and the second corrugation spacing 21 are measured from peak to peak. The first corrugation spacing 20 and the second corrugation spacing 21 may be equal as shown.

[0073] As can be seen in Figures 4 to 6, the singular menbrane section 18 has first corrugations 12 and second corrugations 13 that form a first series of singular corrugations. However, along each unloading pump 7, the first corrugations 12 (here there are two) are interrupted to create areas without first corrugations 12, and the second corrugations 13 delimit a singular planar section 24 whose dimension in the second direction is between two and three times the first corrugation spacing 20.

[0074] As particularly shown in FIG. 4, the first series of singular corrugations of each singular menbrane section 18 is organized into two groups, one on each side of the singular planar section 24 in the second direction. Each group includes a plurality of first corrugations 12 spaced apart from one another by a first corrugation interval 20, i.e., For parts 18A and 18C: four first waveforms 12 in the right group and three first waveforms 12 in the left group; - for part 18B: 2 waveforms 12 in the right group, 3 waveforms 12 in the left group, is defined as follows:

[0075] In the three illustrated embodiments, in order to advantageously obtain flexibility against thermal expansion / contraction in the second direction, care is taken that each group, located respectively on either side of the singular planar portion 24, includes at least the number of interrupted first corrugations 12 in the singular planar portion 24, i.e. in this example two interrupted first corrugations 12. In this embodiment, the second corrugations 13 are not interrupted along each unloading pump 7, which means that there are multiple singular planar portions 24 for each pump 7 (four in FIG. 4).

[0076] Just prior to the singular planar portion 24 , the interrupted first corrugations 12 are closed by a corrugation cap 26 that is welded to the metal sheet 10 to enclose the interrupted first corrugations 12 .

[0077] To allow the passage of the support legs 5 and to connect the support legs 5 to the support structure, the corrugated metal sheet 10 forming the sealing membrane 4 is cut to delimit an octagonal opening 25 around the support legs 5. To ensure the continuity of the sealing membrane 4 at the opening 25, a sealed assembly of connecting parts is created between the support legs 5 and the adjacent metal sheet 10.

[0078] In the same manner used to interrupt the corrugations at the singular planar portion 24, the first corrugations 12 and second corrugations 13 are interrupted at the edges of the opening 25 using corrugated caps 26 and hermetically closed.

[0079] Due to the proximity of the support legs 5 and the pump 7, an opening 25 is provided in the singular menbrane section 18B. The edges of the opening 25 form the inner periphery of the singular menbrane section 18B. The inner periphery is octagonal, each side of which is provided with anchors 19 that secure the metal sheet 10 to the support legs 5. These anchors 19 are shown in bold in Figures 4 to 6 and, in the embodiment shown, are arranged consecutively along the eight sides of the inner periphery of the octagon.

[0080] For the singular membrane section 18B including the opening 25, the distance measured in the first and second directions between any edge of the opening 25 and the side of the outer periphery of the singular membrane section 18B closest to this edge is not more than three corrugation intervals 20 or 21. In other words, a maximum of three corrugations 12 or 13 can be counted between the side of the outer periphery and the side of the inner periphery closest to the side of the outer periphery. Taking FIG. 4 as an example, the singular membrane section 18B including the opening 25 has two first corrugations 12 on the left side of the support leg 5, three first corrugations 12 on the right side of the support leg 5, three second corrugations on the top of the support leg 5, and three second corrugations 13 on the bottom of the support leg 5. Thus, by limiting the number of corrugations 12, 13 per singular membrane section 18 in one direction, it is possible to set an upper limit on the maximum distance between the anchor 19 and the insulating barrier 3 or the support leg 5, so that the membrane section can adequately withstand the stresses to which it is subjected during use, in particular overpressures.

[0081] As in the case of singular menbrane portions 18A and 18C without openings 25, an upper limit is applied to the maximum distance between anchors 19 by ensuring that at least one of the total number of first corrugations 12 in the singular menbrane portion 18 and the total number of second corrugations 13 in the singular menbrane portion 18 is three or less.

[0082] Finally, for the same reason, now with regard to the regular membrane portion 17, at least one of the total number of first corrugations 12 that the regular membrane portion 17 comprises and the total number of second corrugations 13 that the regular membrane portion 17 comprises is less than or equal to 3.

[0083] 4, the singular membrane sections 18A-C and the regular membrane section 17 preferably have anchors 19 to the insulating barrier 3 arranged continuously along the entire periphery. Furthermore, the singular membrane section 18B preferably has anchors 19 to the support legs 5 arranged continuously along the entire inner periphery.

[0084] In FIG. 4, only the anchors 19 of three singular membrane sections 18A-C and one regular membrane section 17 are depicted. Thus, as can be seen in this figure, the assembly of three singular membrane sections 18A-C and regular membrane section 17 with the anchors 19 depicted are adjacent to each other and together form a rectangle including the support leg 5 and are aligned with the two mounting locations of the pumps 7. In this embodiment, the length of the singular membrane section 18B and the length of the regular membrane section 17 extend in the first direction and are continuous so that they can be welded together. Furthermore, as shown, each pump 7 is located at the interface between two singular membrane sections 18A-C. Thus, one of the pumps straddles the singular membrane sections 18A and 18B, and the other pump straddles the singular membrane sections 18B and 18C.

[0085] However, in another embodiment, the singular membrane sections 18A-C and the regular membrane section 17 of Figure 4 are provided with anchors 19 to the insulating barrier 3 that are not arranged continuously along the entire perimeter. Preferably, there is at least one anchor on each side.

[0086] Figure 5 relates to a second embodiment which differs from the first by the presence of a sump 27. Elements identical or similar to those in figure 4 are provided with the same reference numbers and will not be described again.

[0087] To get the best possible use out of the tanks, it is desirable to optimise the effective volume of cargo that can be loaded into and unloaded from the tank 71. The use of pumps that pull liquid towards the top of the tank means that a constant liquid head must be maintained at the bottom of the tank, otherwise the pump's suction will communicate with the gas phase and the pump will lose its prime or be damaged. For this reason, it is known to create a sump 27 in the bottom wall 1 of such a tank, which partially blocks the sealing membrane 4 and also forms another opening 25. The sump 27 consists of a vessel that penetrates the bottom wall 1 of the tank 71 and sinks downwards, the liquid in the vessel being at the lowest level of the tank.

[0088] The sealing membrane 4 is therefore interrupted around the sump 27 as well as around the support legs 5. In the embodiment of Figure 5, the sump 27 is arranged in line with the support legs 5 in a first direction and together with the support legs sandwiches one of the pumps 7, the latter being laterally offset in a second direction relative to the support legs 5 and the sump.

[0089] Thus, the three singular menbrane sections 18A, 18B, 18C are also separated. Section 18C includes an opening 25 that accommodates a sump 27. Section 18B still includes an opening 25 that accommodates a support leg 5. As in the embodiment of FIG. 4, one of the pumps 7 is disposed along the interface between the singular menbrane section 18A and the singular menbrane section 18B, and is located above the singular planar section 24, the area where the first corrugations 12 are interrupted. Similarly, another of the pumps 7 is disposed along the interface between the singular menbrane section 18B and the singular menbrane section 18C.

[0090] These singular menbrane portions 18A-18C are represented as dotted rectangles in Figures 4-6.

[0091] FIG. 6 relates to a third embodiment, which, unlike the second embodiment, has a second sump 27 arranged symmetrically to the first sump with respect to the support leg 5, so that the sump 27 is arranged on both sides of the support leg 5 in the first direction. Elements identical or similar to those in FIG. 5 are given the same reference numbers and will not be described again. Thus, three separate membrane parts 18A, 18B, 18C are also delimited. Parts 18A and 18C each include an opening 25 for accommodating a sump 27, while part 18B still includes an opening 25 for accommodating the support leg 5. As in the embodiment of FIG. 5, one of the pumps 7 is arranged along the interface between the singular membrane part 18A and the singular membrane part 18B, and is located above the planar part 24 of the singular. Similarly, another of the pumps 7 is arranged along the interface between the singular membrane part 18B and the singular membrane part 18C.

[0092] In Fig. 5 and Fig. 6, only the anchors 19 of the three singular menbrane parts 18A, 18B, 18C are shown. Moreover, in these embodiments, the singular menbrane parts 18A-C are provided with anchors 19 to the insulating barrier 3, which are not arranged continuously along the entire periphery. Preferably, there is at least one anchor on one side. In addition to the anchors 19 on the periphery and the inner periphery of the opening 25, the three singular menbrane parts 18A, 18B, 18C are also provided with discontinuous anchors 19 arranged between the inner and outer periphery. Thus, as shown for example in Fig. 5 or 6, the discontinuous anchors can extend from the periphery, either at the interface between two singular menbrane parts 18 or at one of the singular menbrane parts 18. The discontinuous anchors can also extend parallel to one side of the periphery and at some distance from the side of the periphery and the side of the inner periphery.

[0093] In the embodiment of Figure 3, the first waveform 12 is higher than the second waveform 13 and is selected to keep only the lower waveform, the second waveform 13, below the pump 7. In another embodiment of the invention not shown, the first waveform 12 may be lower than the second waveform 13. In such a case, it is the higher waveform that is kept below the pump 7.

[0094] The present invention achieves the desired objective because by removing the first corrugations 12 under the unloaded pump 7 in each singular membrane section, whatever the height of said corrugations, a gain in spacing 23 is created by removing the corrugation nodes 15 under the unloaded pump 7. Thus, even if there are still higher corrugations under the pump 7, the spacing between the unloaded pump 7 and the sealing membrane 4 is enlarged compared to the prior art. This spacing is still measured at the apex of the second corrugation 13. Thus, the spacing gain is equal to the difference in height between the corrugation nodes 15 and the second corrugation 13, e.g., about 15 mm when the height of the first corrugation is about 37 mm, the height of the second corrugation is about 55 mm, and the height of the nodes 15 is about 70 mm.

[0095] Although the invention has been described in relation to the unloading pump 7, it naturally applies to any element located inside the tank 71 and close to the sealing membrane 4.

[0096] The corrugations of the membrane may be formed in different ways, for example as described in Korean Patent Publication No. 2005-0050170. Thus, the corrugation nodes 15 and corrugations 12, 13 may have shapes different from those specifically shown in FIG.

[0097] Referring to Figure 7, a cross-sectional view of a methane carrier 70 shows a generally prismatic sealed and insulated tank 71 mounted within the vessel's double hull 72. The walls of the tank 71 consist of a primary sealing membrane intended to be in contact with the LNG in the tank, a secondary sealing membrane disposed between the primary sealing membrane and the vessel's double hull 72, and two insulating barriers disposed between the primary sealing membrane and the secondary sealing membrane and between the secondary sealing membrane and the double hull 72.

[0098] As is known per se, a load / unload pipe 73 located on the upper deck of the ship is connected by suitable connectors to an offshore or port terminal and enables the transfer of a cargo of LNG to or from the tanks 71.

[0099] FIG. 7 shows an example of a marine terminal including a loading and unloading station 75, submerged pipes 76, and onshore facilities 77. The loading and unloading station 75 is a fixed offshore installation including a moving arm 74 and a column 78 supporting the moving arm 74. The moving arm 74 supports a bundle of flexible insulated pipes 79 that can be connected to the load / unload pipes 73. The rotatable moving arm 74 adjusts to fit any size methane tanker. A connecting pipe, not shown, extends into the column 78. The loading and unloading station 75 allows the methane carrier 70 to be loaded and unloaded from the onshore facilities 77. The onshore facilities 77 consist of a liquefied gas storage tank 80 and a connecting pipe 81 connected to the loading and unloading station 75 by a submerged pipe 76. The underwater pipes 76 allow the liquefied gas to be transported long distances, e.g. 5 km, between the loading and unloading station 75 and the onshore facility 77, allowing the methane carrier 70 to be anchored quite far from shore during loading and unloading operations.

[0100] Pumps on board the ship 70 and / or pumps provided at the onshore facility 77 and / or pumps provided at the unloading station 75 are used to generate the pressure required to transport the liquefied gas.

[0101] Although the present invention has been described with reference to some specific embodiments, it is clear that the invention is in no way limited thereto, but includes all technical equivalents of the described means and combinations thereof, provided they fall within the scope of the invention.

[0102] Use of the verbs "have", "comprise" or "include" and their conjugations does not exclude the presence of elements or steps other than those stated in a claim.

[0103] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

Claims

1. A sealed, insulated tank (71) incorporated into a support structure (2) including a support wall, The tank comprises a tank wall (1) fixed to the support wall of the support structure (2), The tank wall (1) At least one insulating barrier (3) in the thickness direction from the outside to the inside of the tank; at least one sealing membrane (4) supported by said insulating barrier (3) and intended to be in contact with the fluid in said tank; Equipped with the sealing membrane (4) comprises a plurality of membrane sections juxtaposed and welded together, each membrane section being bounded by a polygonal periphery; the plurality of membrane portions includes at least one regular membrane portion (17), the regular membrane portion (17) including a first regular series of corrugations; the first regular series of corrugations comprises parallel first corrugations (12) extending in a first direction, the first corrugations (12) being spaced apart from one another in a second direction perpendicular to the first direction by first corrugation intervals (20); the regular membrane portion (17) is located between first corrugations (12) of the first regular series of corrugations and includes regular planar portions (14) resting on the thermal insulating barrier (3), the regular planar portions having a dimension in the second direction that is smaller than the first corrugation spacing (20); the plurality of membrane portions includes at least one singular membrane portion (18), the singular membrane portion (18) including a first series of singular corrugations, the first series of singular corrugations consisting of parallel first corrugations (12) extending in the first direction, the singular membrane portion (18) including a singular planar portion (24) having a dimension in the second direction strictly greater than N times the first corrugation spacing (20), N being a natural number, the natural number N being preferably 2 or greater; The regular membrane portion (17) is adjacent to the singular membrane portion (18) in the second direction; the first series of singular corrugations includes at least two first corrugations located on either side of the singular planar portion (24) in the second direction; The tank has an internal space bounded by the sealing membrane (4), and the tank has an internal element (7) located in the internal space of the tank; The singular planar portion (24) of the singular menbrane portion (18) is aligned with the internal element (7) in the thickness direction of the tank wall (1) and is positioned at a certain distance from the internal element (7).

2. 2. The sealed insulated tank (71) according to claim 1, wherein the first series of singular corrugations includes two groups located on either side of the singular planar portion (24) in the second direction, each group including at least N first corrugations (12) spaced apart from each other by the first corrugation interval (20) in the second direction, N being preferably a natural number greater than or equal to 2, and the singular menbrane portion (18) includes regular planar portions (14) located between the first corrugations (12) of the same group.

3. 3. The sealed insulated tank (71) according to claim 1 or 2, wherein the regular membrane portion (17) is adjacent to the singular membrane portion (18) in the second direction, whereby one first corrugation of the regular membrane portion (17) adjacent to the outer periphery is spaced apart from one first corrugation of the singular membrane portion (18) in the second direction by a dimension equal to the first corrugation spacing (20).

4. 3. The sealed insulated tank (71) according to claim 1 or 2, wherein the internal element (7) is arranged at a predetermined distance from the singular plane portion (24) in the thickness direction of the tank wall (1), the predetermined distance being less than 200 mm and being measured when the tank is empty.

5. The sealing membrane (4) includes a second series of corrugations; the second series of corrugations includes parallel second corrugations (13) extending in the second direction; the regular planar portion and the singular planar portion are located between the second corrugations (13); 3. The sealed insulated tank (71) according to claim 1 or 2, wherein the singular menbrane portion (18) includes at least two singular flat portions (24) located on either side of one of the second corrugations.

6. 6. The sealed insulated tank (71) of claim 5, wherein the second corrugations (13) of the second series of corrugations are spaced apart from one another in the first direction by a second corrugation spacing, and the second corrugation spacing is preferably the same between the regular planar portion and the singular planar portion.

7. 6. The sealed insulated tank (71) according to claim 5, wherein the height of the second corrugations (13) in the thickness direction of the tank wall (1) is smaller than the height of the first corrugations (12) in the thickness direction of the tank wall (1).

8. 6. The sealed insulated tank (71) according to claim 5, wherein the sealing membrane (4) comprises corrugated nodes, each of which is formed at an intersection of the first corrugation and the second corrugation and has a height in the thickness direction of the tank wall (1) greater than a height of the first corrugation (12).

9. The singular menbrane portion (18) comprises an opening (25) bounded by a polygonal inner periphery; The tank comprises support legs (5) fixed to the support structure (2) and passing through the tank wall (1) and the opening (25); The singular menbrane portion (18) has at least one anchor (19) to the support leg (5) on at least one side of the inner periphery of the polygon; 3. The sealed, insulated tank (71) according to claim 1 or 2, wherein the anchors (19) to the support legs are preferably provided on each side of the inner periphery of the polygon.

10. 10. The sealed, insulated tank (71) according to claim 9, wherein the internal element (7) is connected to the support legs (5).

11. The sealing membrane (4) includes a second series of corrugations; the second series of corrugations includes parallel second corrugations (13) extending in the second direction; the regular planar portion and the singular planar portion are located between the second corrugations (13); The singular menbrane portion (18) includes at least two singular planar portions (24) located on either side of one of the second corrugations, 10. The sealed insulated tank (71) according to claim 9, wherein at least one of the number of first corrugations (12) and the number of second corrugations (13) provided in the singular menbrane portion (18) between any side of the inner circumference and any side of the outer circumference of the singular menbrane portion (18) is 3 or less.

12. 6. The sealed insulated tank (71) according to claim 5, wherein at least one of the total number of the first corrugations (12) included in the singular menbrane portion (18) and the total number of the second corrugations (13) included in the singular menbrane portion (18) is 3 or less.

13. The thermal insulation barrier (3) comprises a plurality of rectangular parallelepiped thermal insulation blocks arranged side by side, each insulating block comprising an insulating material and a cover panel facing the inside of the tank; A metal anchor plate is attached to the upper surface of the cover panel opposite the insulating material, 3. The sealed, insulated tank (71) of claim 1 or 2, wherein the ensemble of upper surfaces of the cover panels forms a support surface for the sealing membrane (4).

14. The sealing membrane (4) comprises a plurality of rectangular corrugated metal sheets welded together; each corrugated metal sheet having two edges parallel to the first direction and two edges parallel to the second direction; 3. The sealed, insulated tank (71) according to claim 1 or 2, wherein each regular membrane section or each singular membrane section comprises one or more of said corrugated metal sheets.

15. Each singular membrane section and / or each regular membrane section comprises at least one anchor (19) to the insulating barrier (3) on each side of the polygonal periphery, 3. The sealed insulated tank (71) according to claim 1 or 2, wherein each anchor to the insulating barrier (3) is preferably arranged continuously along the entire circumference of the polygon.

16. A vessel (70) for transporting cryogenic liquid products, comprising: Double hull (72) and a tank (71) according to claim 1 or 2 arranged within the double hull; A ship equipped with:

17. 1. A system for transferring a cryogenic liquid product, comprising: A vessel (70) according to claim 16; an insulated pipe (73, 79, 76, 81) arranged to connect the tank (71) installed in the hull of the ship to a floating or land-based storage facility (77); a pump for conveying the flow of the cryogenic liquid product through the insulated pipe from the floating or onshore storage facility to the tank on the vessel or from the tank on the vessel to the floating or onshore storage facility; A system comprising:

18. 17. A method for loading or unloading a vessel (70) according to claim 16, comprising the steps of: A method for transporting said cryogenic liquid product from a floating or land-based storage facility (77) to said tanks on said vessel (71) or from said tanks on said vessel (71) to said floating or land-based storage facility (77) through insulated pipes (73, 79, 76, 81).

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