EP4222406A1

EP4222406A1 - Assembly method and storage tank facility for liquefied gas

Info

Publication number: EP4222406A1
Application number: EP21786224.2A
Authority: EP
Inventors: Paul Baron; Jocelyn DESBRUGERES; Cédric FELGUEIRAS
Original assignee: Gaztransport et Technigaz SA
Current assignee: Gaztransport et Technigaz SA
Priority date: 2020-10-02
Filing date: 2021-10-01
Publication date: 2023-08-09
Also published as: CN116324258A; US20230366512A1; KR20230057457A; FR3114863A1; JP2023544598A; WO2022069751A1; FR3114863B1

Abstract

The invention relates to a storage facility for liquefied gas, comprising a support structure and a sealed and thermally insulating tank (71) arranged in the support structure, in which so-called contiguous membranes (13, 13') of the sealing membrane of the cofferdam wall of the main structure of the tank (71) protrude at least partially into the liquid dome (2), said so-called contiguous membranes being secured directly and sealingly to the so-called contiguous membranes of the liquid dome (2).

Description

Title of the invention: Assembly method and installation of storage tank for liquefied gas

[0001] The invention relates to the field of storage facilities for liquefied gas comprising a sealed and thermally insulating tank, with membranes. In particular, the invention relates to the field of sealed and thermally insulating tanks for the storage and/or transport of liquefied gas at low temperature, such as tanks for the transport of Liquefied Petroleum Gas (also called LPG) having for example a temperature between -50°C and 0°C, or for the transport of Liquefied Natural Gas (LNG) at around -162°C at atmospheric pressure. These tanks can be installed on land or on a floating structure. In the case of a floating structure, the tank may be intended for the transport of liquefied gas or to receive liquefied gas used as fuel for the propulsion of the floating structure.

[0002] The document FR2991430 describes a storage facility for liquefied gas comprising a sealed and thermally insulating tank integrated into a supporting structure consisting of the double hull of a ship. Each wall of the vessel comprises a secondary thermally insulating barrier, a secondary sealing membrane, a primary thermally insulating barrier and a metallic or metallic alloy primary sealing membrane.

[0003] The primary sealing membrane conventionally comprises waves intended to allow thermal contractions, without rupture of the membrane, these waves conventionally forming a network of small and large waves extending parallel to each other respectively so as to form a grid delimited by node zones, i.e. the generally perpendicular intersections of the small and large waves.

[0004] In an area located at the top of the tank, the tank has a protruding portion in the form of a chimney. In this zone, the support structure is locally interrupted so as to delimit a loading/unloading opening intended to be traversed by fluid loading/unloading pipes. This loading/unloading opening and this pipe in the form of a chimney, called Liquid Dome, comprise an insulation or thermally insulating barrier as well as an element forming a primary sealing membrane.

As seen in Figures 1 and 2 attached, this liquid dome is conventionally located at one longitudinal end of the tank so that one of the vertical walls of the liquid dome continues or extends, in the same plane, by a wall vertical to the main structure of the vessel (containing a cold fluid). When the tanks are present in a cold fluid transport ship such as LNG or LPG, i.e. an LNGC (“Liquid Natural Gas Carrier”), this vertical wall common to the liquid dome and to the main structure of the tank is called a cofferdam wall.

[0006] The tank is installed in a structure subjected to very high mechanical stresses, such as a ship, which bends and twists depending on the conditions of its environment. The load-bearing structure being interrupted at the level of the liquid dome, these mechanical forces are all the more important there.

The walls of the main structure of the tank are mounted and assembled/fixed on the one hand while the walls of the liquid dome are mounted and assembled/fixed on the other hand, these two parts of the storage installation being then connected to each other in a sealed manner.

[0008] However, taking into account in particular the sizing of the primary insulation membranes, the connection of the membranes and the continuity of the waves are ensured by a connecting plate, generally of small size, fixed by welding to the contiguous membranes of the liquid dome and of the main structure of the tank.

[0009] This connecting plate is not a satisfactory solution.

[0010] First of all, in order to ensure the continuity of the vertical waves between the liquid dome and the main structure of the tank, the operators are obliged to deform in situ, using striking tools, this connecting plate because the waves of the two parts - liquid dome on one side and main structure on the other - are not aligned. This operation is tedious for the operators and typically requires several hours of work.

[0011] Then, the shaping of this connecting plate at its vertical waves leads to its embrittlement. As mentioned earlier, this area of a ship is subject to high mechanical stress. This is why it is not acceptable for a portion of the primary waterproofing membrane to fail and compromise the tightness of the storage facility.

[0012] After various experiments and tests, the applicant has found that it is possible to do without this connecting piece, or portion of sheet metal, by proposing a simpler and faster assembly solution, while making it possible to make more reliable, from the point of view of mechanical strength and sealing, this connection zone between the primary membranes of the main structure of the tank and those of the liquid dome.

Thus, the present invention relates to a storage facility for liquefied gas comprising a supporting structure and a sealed and thermally insulating tank arranged in the support structure, the sealed and thermally insulating tank comprising a main structure formed by a plurality of tank walls connected to each other and fixed to the support structure, the main structure defining an internal storage space, the main structure comprising at least one sealing membrane and at least one thermally insulating barrier, the thermally insulating barrier being placed between the sealing membrane and the supporting structure; the sealing membrane, the thermally insulating barrier of the main structure and a so-called upper load-bearing wall being locally interrupted so as to delimit a pipe forming the load-bearing wall of a chimney extending along a vertical axis up to an upper end consisting in a loading/unloading opening intended to be traversed by liquefied gas loading/unloading pipes, said pipe up to said opening defining a liquid dome of the tank comprising, like the main structure of the tank, at least one membrane sealing and at least one thermally insulating barrier, the thermally insulating barrier being placed between the sealing membrane and the load-bearing wall; the liquid dome being located at one of the axial ends of the tank, a vertical wall of the main structure of the tank, called the cofferdam wall, extends from the said main structure to form, along the same plane, a wall of the conduct of the liquid dome; the sealing membrane of the main structure and of the liquid dome are composed of a plurality of flat metallic membranes, fixed together in a sealed manner, each having at least two lines of perpendicular corrugations, the shape and dimensions of these two lines of corrugations being respectively identical for all the membranes so that the juxtaposed membranes have a repeated pattern.

The invention is characterized in that so-called contiguous membranes of the sealing membrane of the cofferdam wall of the main structure of the tank are at least partly protruding into the liquid dome, said so-called contiguous membranes being directly fixed, in a sealed manner, to so-called contiguous membranes of the liquid dome.

[0015] Thus, the applicant has found after multiple tests and analyzes that it is possible to connect firmly and in a perfectly sealed manner, the main structure of the tank with the liquid dome, while optimizing the assembly time or assembly of the respective membranes of these two parts of a storage installation for liquefied gas, without using a connecting plate.

[0016] In doing so, the invention allows substantial savings in the production of the liquid dome while ensuring or maintaining a perfect seal against the liquefied gas and excellent mechanical resilience of the latter to all the stresses that this zone is conventionally subjected to.

[0017] The expression "in a sealed manner" is understood to mean in connection with the fixings, in particular between membranes, the fact that the fixing is carried out by welding, possibly supplemented by a chemical fixing, by gluing, and/or mechanical, for example using a seal.

[0018] The term “metallic” is understood to mean in particular in connection with the membranes the fact that it is a metal or a metal-based alloy, more often a metal-based alloy such as than a steel.

[0019] The term "membrane" systematically refers to the fact that it is a sealed membrane, impermeable to the fluid, whether the term is accompanied by the term "tight" or not. A membrane is qualified as such in the context of the present invention if it has, on the cofferdam wall, at least one vertical wave line, preferably a plurality of vertical waves, and at least one line of horizontal wave. In the mode of execution chosen to illustrate the invention, the vertical waves from/on the cofferdam wall are small waves while the horizontal waves are large waves.

[0020] The term "wave" or "corrugation", with or without plural, refers to the same element present on a membrane to allow its deformation, by contraction and/or stretching, under the effect of thermal expansion linked to the presence or the absence of a liquefied gas, cold or even very cold, in the tank. The two lines of waves or corrugations perpendicular to each other, defining a membrane in the context of the present invention, can be of identical or different shape. In the following, these two lines of waves or corrugations are advantageously different, with a horizontal line of large wave or corrugation and a vertical line of small wave or corrugation.

[0021] The term "contiguous" mainly in connection with the membranes, those of the liquid dome and those of the main structure of the tank, refers to the fact that these membranes are those closest to the other part of the tank, namely sometimes from the main structure for the membranes located in the liquid dome and from the liquid dome for the membranes located in the main structure. [0022] The term "pipe" means the fact that it forms the outer wall of the liquid dome, more precisely the wall of the chimney opening into the tank containing the liquefied gas, the term "chimney" referring to the general form of the liquid dome which extends vertically.

Other advantageous features of the invention are briefly presented below:

[0024] Preferably, the flat metal membranes forming the sealing membrane of the main structure and of the liquid dome have a rectangular shape with two large sides and two small ones.

[0025] Preferably, the flat metal membranes comprise an elevation extending along two contiguous sides intended to cover the contiguous side of another membrane.

[0026] Advantageously, the thermally insulating barrier of the main structure and of the liquid dome of the tank comprise metal plates on which are welded, in a discontinuous manner, the sealing membrane of the main structure and of the liquid dome.

[0027] Advantageously, the so-called contiguous membranes of the liquid dome comprise an elevation extending along the long lower side while the so-called directly contiguous membranes of the main structure of the tank comprise an elevation extending along one of the two short sides of the membrane. According to a particular example, the membranes said to be directly contiguous with the main structure of the tank have only one elevation extending along one of the two short sides of the membrane.

According to a particular embodiment, when these so-called contiguous membranes are mounted and assembled after the other membranes of the liquid dome, which is a preferred embodiment of the invention, the so-called contiguous membranes of the liquid dome comprise an elevation extending along the two opposite long sides while the so-called directly contiguous membranes of the main structure of the tank have only one elevation extending along one of the two short sides of the membrane, respectively.

[0029] According to a feature of the invention, preferably, the protruding part of the so-called contiguous membranes of the sealing membrane of the cofferdam wall (B) of the main structure of the tank are protruding by at least 30 millimeters in the liquid dome, preferably 55 mm. [0030] Storage installation according to any one of the preceding claims, in which the protruding part of the so-called contiguous membranes of the sealing membrane of the cofferdam wall (B) of the main structure of the tank are protruding by at plus 60 millimeters in the liquid dome.

[0031] It can be noted here that the expression "of the cofferdam wall", i.e. the wall referenced B or B 'in Figure 2, in connection in particular with the main structure of the tank is superfluous because the only membranes which interest the present invention in the embodiment chosen to illustrate it are the membranes of the cofferdam wall because this wall is the only one which is extended vertically, in other words without a break in the angle, in the liquid dome.

[0032] Of course, the invention would also find application if, for example, the liquid dome is located at an angle of the main structure, so that in addition to the cofferdam wall, a side wall - the wall F on the Figure 2, in the case where there would not be the chamfers E - would be extended vertically in the liquid dome. This scenario is covered by the present invention although such an arrangement of the liquid dome, in a corner of the tank, is a priori not very advantageous and practical.

Advantageously, the so-called contiguous membranes of the liquid dome have a length of between 500 millimeters and 3300 millimeters and a width of between 200 millimeters and 800 millimeters.

Advantageously, the so-called contiguous membranes of the sealing membrane of the cofferdam wall of the main structure of the vessel have a length of between 500 millimeters and 3300 millimeters and a width of between 200 millimeters and 800 millimeters.

According to yet another advantageous aspect of the invention, the so-called contiguous membranes of the sealing membrane of the cofferdam wall of the main structure of the tank are in two rows of parallel membranes, one row of membranes having a width of between 200 and 400 millimeters and the other row of membranes having a width of between 700 and 800 millimeters.

The invention also relates to a method for mounting a storage installation as described above, in which it comprises: a first step of mounting and fixing, in a sealed manner, the assembly of the sealing membrane of the cofferdam wall of the main structure of the vessel; - a second step of mounting and fixing, in a leaktight manner, the entire sealing membrane of the liquid dome with the exception of the contiguous membranes of said liquid dome; the first and second steps being executed in any order or simultaneously;

- a final step of assembly and fixing, in a sealed manner, of the so-called contiguous membranes of said liquid dome so that the entire cofferdam wall, the main structure and the liquid dome are sealed.

The invention relates to a vessel for transporting a cold liquid product, the vessel comprising a double hull and a storage facility as described above arranged in the double hull.

The invention also relates to a transfer system for a cold liquid product, the system comprising a ship as described above, insulated pipes arranged so as to connect the tank installed in the hull of the ship to an external installation floating or onshore storage facility and a pump for driving a flow of cold liquid product through the insulated pipes from or to the external floating or onshore storage facility to or from the ship's tank.

Finally, the present invention relates to a method for loading or unloading a ship as described above, in which a cold liquid product is routed through insulated pipes from or to an external floating storage installation. or land to or from the vessel's tank.

The invention will be better understood, and other aims, details, characteristics and advantages thereof will appear more clearly during the following description of several particular embodiments of the invention, given for illustrative purposes only. and non-limiting, with reference to the accompanying drawings.

[0041] [fig.1] Figure 1 is a schematic sectional and perspective view of a liquefied gas carrier ship of the LNGC type.

[0042] [fig.2] Figure 2 is a cross-section and cutaway of a tank of the ship shown in Figure 1.

Figure 3 is a schematic view illustrating a sealing membrane with three parallel rows of large wave or corrugation and nine parallel rows of small wave or corrugation, the two types of rows being mutually perpendicular. [0044] [fig .4] Figure 4 is a schematic view illustrating the arrangement of the membranes at the level of the zone of the liquid dome and of the main structure of the tank, with the indication of the covering of each membrane with respect to her neighbor.

[0045] [fig.5] Figure 5 is an enlarged view of a portion P of Figure 4.

[0046] [fig.6] Figure 6 is a detailed and dimensioned view of a contiguous membrane, called the side membrane, of the main structure of the tank.

[0047] [fig.7] Figure 7 is a view, identical to the view of Figure 4, illustrating thermal insulation blocks present under the membranes, with in particular the metal plates allowing the membranes to be fixed by welding to these thermal insulation blocks.

[0048] [fig.8] Figure 8 is a cutaway schematic representation of an LNG tanker storage facility and a loading/unloading terminal for this tank.

The term "vertical" here means extending in the direction of the earth's gravity field. The term "horizontal" here means extending in a direction perpendicular to the vertical direction.

When the storage facility is positioned on a ship 70 such as an LNG carrier, the supporting structure, not visible in the appended figures, is formed by the double hull of the ship. The outer upper load-bearing wall is called the ship's outer deck.

[0051] In the following, the present invention is illustrated with a liquefied gas carrier ship 70 of a conventional type, namely an LNGC for "Liquid Natural Gas Carrier", but it is understood that the invention can be apply to other types of tanks provided that such a tank comprises a sealing membrane, called primary due to its direct contact with a fluid contained in the tank and the possible presence of a second sealing membrane , and a liquid dome 2 or the like, that is to say a chimney and an opening for loading/unloading said fluid, having at least one continuous wall section with a wall of the main structure of the tank 71, 71 '. These two characteristics being verified, the present invention can be applied to such a fluid storage installation.

[0052] Thus, as can be seen in Figure 1, one can see the distribution of the four LNG tanks 71, 71' conventionally present in an LNGC-type LNG tanker ship 70. Thus, as we have seen previously, three of the four tanks 71 have the same dimensions while a last one, that 71 'located at the front of the ship 70, has smaller dimensions so in particular that the ballasts, arranged laterally and under the tank 71 ', have dimensions much larger than the others ballasts, located around the other three tanks 71, in order to more easily rebalance the trim of the ship 70, given the fact that most of the weight of the ship 70 is located at the rear of the latter when the tanks 71 are empty .

[0053] At the rear of the ship 70 is conventionally located the machines or engine room, not visible in the appended figure, intended to manage the whole of the ship 70, from the propulsion to all the generation circuits. and supplying the various equipment items of the ship 70. Furthermore, above the machines is the cask 31 which conventionally consists of a tower or the like where the crew accommodation and the ship's command post are located in particular.

A tank 71 comprises a main structure formed of a front wall D, a rear wall B, a ceiling wall A, a bottom wall C and two side walls F, not both visible in the attached figure 2 (one side of the tank not being visible in this figure), connecting the bottom wall C to the ceiling wall A, and finally two to four bevel walls E, G connecting the side walls F to the bottom wall C or to the ceiling wall A. The walls of the tank 71 are thus connected to each other so as to form a polyhedral structure and to delimit an internal storage space. The tank 71 'is substantially identical to a tank 71 .

In order to load and unload the tank 71 with liquefied gas, the storage installation comprises a loading/unloading opening locally interrupting the outer upper load-bearing wall, the internal upper load-bearing wall and the ceiling wall of the tank 71 of so as to allow in particular the loading/unloading pipes, not shown in the appended figures, to reach the bottom of the tank 71 by crossing this opening.

[0056] The storage installation also comprises a loading/unloading tower, not visible in the appended figures, located to the right of the opening of the liquid dome 2 and inside the tank 71 forming a support structure for the loading/unloading pipes over the entire height of the tank 71 as well as for the pumps (not shown).

[0057] The vessel 71 thus comprises a chimney, or conduit, located on or above the main structure and allowing the vessel walls to extend continuously from the internal bridge to the external bridge at the level where these are interrupted. through the loading/unloading opening. For liquefied gas storage tanks 71, 71', such a chimney, or pipe, provided with a cover closing said loading/unloading opening is called: the liquid dome 2. [0058] The loading/unloading opening as well as the chimney conventionally have a rectangular or square outline or action. The chimney thus comprises four walls, one B' being the extension of the rear wall B, also designated as the "cofferdam wall" of the main structure of the tank 71, 71', as visible in FIG. 2, while the other three are connected to the ceiling wall A forming an angle of 90° with it.

The present invention relates only to the wall B, B ', or to the two walls in a different embodiment, continuous or extension without angle break between the main structure of the tank 71, 71 'and the dome liquid 2, more precisely at the level of the sealing membrane and its junction between the main structure of the tank 71, 71' and the liquid dome 2.

[0060] Figure 3 shows such a conventional sealing membrane 3. A sealing membrane is defined, in the context of the present invention, as a sheet of metal or a metal alloy comprising at least a first wave line or corrugation 4 and at least one second line of wave or corrugation 5, the first and the second line of wave or corrugation 4, 5 extending perpendicular to one another.

[0061] According to one embodiment, the main structure of the tank 71, 71' is made using Mark III® technology which is described in particular in the document FR-A-2691520.

In such a main structure, the secondary thermally insulating barrier, the primary thermally insulating barrier and the secondary sealing membrane essentially consist of panels juxtaposed on the load-bearing structure, which may be the internal load-bearing structure or the structure connecting the inner top load-bearing wall to the outer top load-bearing wall at the opening. The secondary waterproofing membrane is made of a composite material comprising an aluminum sheet sandwiched between two sheets of fiberglass fabric. The primary waterproofing membrane is obtained by assembling a plurality of metal plates, welded to each other along their edges, and comprising undulations extending in two perpendicular directions. The metal plates are, for example, made of stainless steel or aluminum, shaped by bending or by stamping.

[0063] More particularly to illustrate an embodiment of the invention, the sealing membrane is a so-called primary sealing membrane (because in direct contact with the fluid stored in the tank 71, 71 ') is obtained by assembling a plurality of corrugated metal sheets conforming to the membrane shown in Figure 3. Each corrugated metal membrane 3 comprises a first series of parallel corrugations 5, called high or large, extending in a first direction and a second series of parallel corrugations 4, called low or small, extending in a second direction perpendicular to the first series. The node zones 6 are the crossing zones of these two types of waves 4, 5. The undulations 4, 5 protrude towards the inside of the tank 71, 71'. As mentioned above, these corrugated metal membranes 3 are, for example, made of stainless steel or aluminum.

The corrugated metal membranes 3 are fixed to insulating panels 21 by means of metal plates 20 extending in two perpendicular directions, vertically and horizontally on the cofferdam wall B, B', these plates 20 being fixed on the internal face (oriented towards the internal space of the tank) of the insulating panels 21. Thus, each insulating panel 21 having an internal face equipped with metal plates 20 on which are welded the corrugated metal membranes 3 forming the primary sealing membrane . These insulating panels 21 on which the sealing membranes 3 are fixed are visible, with the aforementioned metal plates 20, in the appended figure 7.

The metal plates 20 extend in two perpendicular directions which are each parallel to two opposite edges of the insulating panels 21. The metal plates 20 are fixed in recesses made in the internal face of the insulating panel 21 and fixed thereto. here, by screws, rivets or staples for example.

[0066] The appended figures 4 to 7 illustrate the actual arrangement of the sealing membrane 3, or primary sealing membrane, at the level of the wall B of the main structure of the tank 71, 71 'and of the wall B' continues to wall B in liquid dome 2.

The first characteristic of such an arrangement lies in the fact that only sealing membranes 3, 13, 13', 33 are used - comprising at least two wave lines 4, 5 or perpendicular corrugation between they - to achieve the continuity of the tightness of these two walls, the cofferdam wall B of the main structure of the tank 71, 71 'and the continuous wall B' of the liquid dome 2. Thus, no intermediate element is present in this zone, it being understood that an "intermediate element", such as a sheet, is not a sealing membrane 3, 13, 13', 33 according to the present invention, that is to say the definition of a membrane given previously.

The second characteristic of such an arrangement according to the invention lies in the fact that the sealing membrane 13 of the main structure of the tank 71, 71 'directly adjacent to the liquid dome 2 - i.e. the three membranes 14, 15, 16 visible in Figure 4 - is protruding in the liquid dome 2, that is to say in the space forming this dome liquid 2 from the opening present in the ceiling wall A, the insulation and sealing elements being considered here to define the location of this opening of the liquid dome 2.

As can be seen in Figure 6, the protrusion 17 of the sealing membrane 13 in the liquid dome 2 is 55 millimeters in this example. In general, this protrusion 17 is at least 30 millimeters and at most 60 millimeters. As can be seen clearly in Figure 6, to achieve this protuberance 17, either the contiguous membrane 13 is protruding over its entire width as is the case with the central membrane 15, or the contiguous membrane is protuberant over only a part of its length as is the case for the side membranes 14 and 16. For these so-called side membranes 14 and 16, a cut has been made, for example by laser or using a saw, in a conventional membrane to extract the portion not contiguous to the liquid dome 2 and which is therefore not protruding in the latter 2.

Another feature of the present invention resides in the dimensions of the contiguous membranes 13, 13′, 33 both of the liquid dome 2 and of the main structure of the tank 71, 71′. Indeed, these dimensions are not conventional and have been chosen to adjust perfectly, and as safely as possible, the connection of the membranes 13, 13 'of the main structure of the tank 71, 71' and those 33 of the liquid dome 2. Thus, a conventional membrane 3 of the main structure of the tank 71, 71' normally comprises three long wave lines 5 or corrugation, but the contiguous membranes 13, 13' of the main structure of the tank 71, 71' only comprise two long wave lines 5 or corrugation for the directly contiguous membrane 13, or even a single/single long wave line 5 for the contiguous membrane 13'. In the same way, a conventional membrane 3 of the liquid dome 2 normally comprises two lines 5 of long wave or corrugation, but the contiguous membranes 33 of the liquid dome 2 comprise only one/single line 5 of long wave.

[0071] By way of non-limiting example are given, in Figure 6, the dimensions, expressed in millimeters, of the contiguous side membrane 14 of the main structure of the tank 71, 71 ', with in particular a protrusion 17 of 55 millimeters resulting from a prior cutting of the membrane 14. Since FIGS. 4 and 5 show the membranes 13, 13' and 33 to scale, part of the main structure of the tank 71, 71' and the dome liquid 2, one can deduce the dimensions, or more exactly the domains or ranges of dimensions of each of the membranes 13, 13' and 33, knowing the dimensions precisely given for the lateral contiguous membrane 14 in FIG. is recalled here that the precise dimensions given in Figure 6 represent only one embodiment and that other embodiments of the invention can be provided, the dimensions given in Figure 6 being able to vary, with the exception of the protruding part 17, in a domain or a range of +/- 30 millimeters (mm) preferably of +/- 15 mm at most. For the protruding part 17, it will be noted that it cannot be less than 30 millimeters and greater than 60 millimeters.

Another feature of the invention lies in the fact that the contiguous membranes 33 of the liquid dome 2 have, on their two lower/upper faces 34, 35 or even the two opposite long sides, an elevation 7 extending the along said two faces or sides 34, 35 so as to cover the two lower and upper membranes to which they are fixed respectively. It should be noted here that only the lower elevation 7 is imperative in the context of the present invention where the contiguous membranes 33 of the liquid dome must be mounted and assembled after those of the main structure of the tank 71, 71 '.

This particular characteristic of these contiguous membranes 33 is justified by the assembly method specific to the storage installation according to the invention in which these contiguous membranes 33 of the liquid dome 2 are advantageously mounted last, once the sealing membranes of the liquid dome 2 mounted and fixed and the sealing membranes of the main structure of the tank 71, 71 '(or at least the membranes located near the liquid dome 2) are also mounted and fixed. In doing so, the directly adjoining membranes 13 of the main structure of the tank 71, 71 'have only a single elevation 7, more precisely on one of the short sides (width).

It should indeed be noted that a conventional membrane 3, like that shown in Figure 3, has two elevations 7 extending along two contiguous sides of the membrane 3, either one short sides defining the width of the membrane 3 and one of the long sides of the membrane 3. As can be noted in FIGS. 4 to 6, the black isosceles triangles indicate, thanks to the orientation of the tip of said triangle , the position of the elevation 7 so that the membrane on which the black isosceles triangle is located covers, at this portion of elevation 7, the adjacent membrane at the level of the small or large side considered. Thus, FIG. 4 in particular is very explicit about the mounting or the relative assembly of the various membranes, whether they are those 3, 13, 13' of the liquid dome 2 or those 3, 33 of the main structure of the tank 71 , 71'.

Figure 7 illustrates the thermal insulation blocks 21 which equip a storage facility for liquefied gas. In the context of the present invention, these thermal insulation blocks 21 are not modified with respect to the state of the art and details of such thermal insulation blocks 21 are in particular described in FR-A-2861060. Nevertheless, a particularity of this invention lies in the metal plates 20, described above, located on these thermal insulation blocks 21, opposite the membranes 3, 13, 13', 33, so as to fix by welding or welding these latter 3, 13, 14', 33 to the thermal insulation block 21 via these metal plates 21 . These metal plates 20, also called "Anchoring Strip" (AS), are here arranged in a manner suitable for the contiguous membranes 13, 13', 33, both those 13, 13' of the main structure of the tank 71, 71' and those 33 of liquid dome 2.

Thus, the contiguous membranes 33 of the liquid dome 2 are located in the immediate vicinity of metal plates 20, so that they have a discontinuous weld line extending over more than 70% of their length, whereas these membranes 33 are not wide because they have only one long wave line or corrugation. By comparison, the other membranes 3 of the liquid dome 2 have two lines 5 of large wave or corrugation and have only one discontinuous weld line on plates 20, representing more than 70% of their length. The contiguous membranes 13' of small dimensions of the main structure of the tank 71, 71' are also provided with such a discontinuous welding line whereas they also only have a single/single long wave line 5, at like membranes 33.

[0077] Referring to Figure 8, a cutaway view of an LNG carrier 70 shows a sealed and insulated tank 71 of generally prismatic shape mounted in the double hull 72 of the ship. The wall of the tank 71 comprises a primary sealing membrane intended to be in contact with the LNG contained in the tank, a secondary sealing membrane arranged between the primary sealing membrane and the double hull 72 of the ship, and two insulating barriers arranged respectively between the primary sealing membrane and the secondary sealing membrane and between the secondary sealing membrane and the double shell 72.

In a manner known per se, loading/unloading pipes 73 arranged on the upper deck of the ship can be connected, by means of appropriate connectors, to a maritime or port terminal to transfer a cargo of LNG from or to the tank. 71 .

[0079] Figure 8 shows an example of a maritime terminal comprising a loading and unloading station 75, an underwater pipe 76 and a shore installation 77. The loading and unloading station 75 is a fixed off-shore installation comprising a movable arm 74 and a tower 78 which supports the movable arm 74. The movable arm 74 carries a bundle of insulated flexible pipes 79 connectable to the pipes loading/unloading 73. The adjustable mobile arm 74 adapts to all sizes of LNG carriers. A connecting pipe, not shown, extends inside the tower 78. The loading and unloading station 75 allows the loading and unloading of the LNG carrier 70 from or to the shore installation 77. This comprises liquefied gas storage tanks 80 and connecting pipes 81 connected by the underwater pipe 76 to the loading or unloading station 75. The underwater pipe 76 allows the transfer of the liquefied gas between the loading or unloading station 75 and the shore installation 77 over a great distance, for example 5 km, which makes it possible to keep the LNG carrier 70 at a great distance from the coast during loading and unloading operations.

To generate the pressure necessary for the transfer of the liquefied gas, pumps on board the ship 70 and/or pumps fitted to the shore installation 77 and/or pumps fitted to the loading and unloading station are used. 75.

[0081] Although the invention has been described in connection with several particular embodiments, it is obvious that it is in no way limited thereto and that it includes all the technical equivalents of the means described as well as their combinations if these fall within the scope of the invention.

[0082] The use of the verb "to comprise", "to understand" or "to include" and of its conjugated forms does not exclude the presence of other elements or other steps than those set out in a claim. The use of the indefinite article “un” or “une” for an element or a step does not exclude, unless otherwise stated, the presence of a plurality of such elements or steps.

[0083] In the claims, any reference sign in parentheses cannot be interpreted as a limitation of the claim.

Claims

[Claim 1] Storage installation for liquefied gas comprising a supporting structure and a sealed and thermally insulating tank (71) arranged in the supporting structure, the sealed and thermally insulating tank (71) comprising a main structure formed by a plurality of walls of tank connected to each other and fixed to the supporting structure, the main structure defining an internal storage space, the main structure comprising at least one sealing membrane (3, 13, 13') and at least one thermally insulating barrier, the thermally insulating barrier being placed between the sealing membrane (3, 13, 13') and the supporting structure; the sealing membrane (3, 13, 13'), the thermally insulating barrier of the main structure and a so-called upper load-bearing wall being locally interrupted so as to delimit a pipe forming the load-bearing wall of a chimney extending along an axis vertical up to an upper end consisting of a loading/unloading opening intended to be traversed by pipes for loading/unloading liquefied gas, said pipe up to said opening defining a liquid dome (2) of the tank (71) comprising, like the main structure of the tank (71, 71 '), at least one sealing membrane (3, 33) and at least one thermally insulating barrier, the thermally insulating barrier being placed between the sealing membrane (3 , 33) and the bearing wall; the liquid dome (2) being located at one of the axial ends of the tank (71), a vertical wall of the main structure of the tank (71), called the cofferdam wall (B), extends from the said main structure to form, along the same plane, a wall (B') of the conduit of the liquid dome (2); the sealing membrane (3, 13, 13', 33) of the main structure and of the liquid dome (2) are composed of a plurality of flat metal membranes, fixed to each other in a sealed manner, each having at least two lines perpendicular corrugations (4, 5), the shape and dimensions of these two lines of corrugations (4, 5) being respectively identical for all the membranes so that the juxtaposed membranes have a repeated pattern; characterized in that membranes (13, 13') said to be contiguous with the sealing membrane of the cofferdam wall (B) of the main structure of the tank (71) are at least partly protruding in the liquid dome (2 ), said so-called membranes contiguous being directly fixed, in a sealed manner, to so-called contiguous membranes of the liquid dome (2).

[Claim 2] Storage installation according to claim 1, in which the flat metal membranes (3, 13, 13', 33) forming the sealing membrane of the main structure and of the liquid dome (2) have a rectangular shape with two large sides and two small ones.

[Claim 3] A storage facility according to claim 1 or 2, wherein the flat metal membranes have a raised portion (7) extending along two adjoining sides intended to cover the adjoining side with another membrane.

[Claim 4] Storage installation according to any one of the claims, in which the thermally insulating barrier of the main structure and of the liquid dome (2) of the tank (71) comprise metal plates on which are welded, in a discontinuous manner , the sealing membrane (3, 13, 13', 33) of the main structure and of the liquid dome (2).

[Claim 5] Storage installation according to at least one of Claims 2 to 4, in which the so-called contiguous membranes of the liquid dome (2) comprise an elevation (7) extending along the long lower side while the membranes said to be directly adjacent to the main structure of the tank (71, 71') comprise an elevation (7) extending along one of the two short sides of the membrane.

[Claim 6] Storage installation according to any one of the preceding claims, in which the protruding part (17) of the membranes (13) said to be contiguous to the sealing membrane of the cofferdam wall (B) of the main structure of the tank (71) protrude at least 30 millimeters into the liquid dome (2), preferably 55 millimeters.

[Claim 7] Storage installation according to any one of the preceding claims, in which the protruding part (17) of the membranes (13) said to be contiguous to the sealing membrane of the cofferdam wall (B) of the main structure of the tank (71) protrude no more than 60 millimeters into the liquid dome (2).

[Claim 8] Storage installation according to any one of the preceding claims, in which the so-called contiguous membranes of the liquid dome (2) have a length of between 500 millimeters and 3300 millimeters and a width of between 200 millimeters and 800 millimeters.

[Claim 9] Storage installation according to any one of the preceding claims, in which the membranes (13, 13') said to be contiguous with the membrane 18 sealing the cofferdam wall (B) of the main structure of the tank (71) have a length between 500 millimeters and 3300 millimeters and a width between 200 millimeters and 800 millimeters.

[Claim 10] Storage installation according to claim 9, in which the membranes (13, 13') said to be contiguous with the sealing membrane of the cofferdam wall (B) of the main structure of the tank (71, 71' ) are presented in two rows of parallel membranes, one row of membranes (13') having a width of between 200 and 400 millimeters and the other row of membranes (13) having a width of between 700 and 800 millimeters.

[Claim 11] A method of mounting a storage facility according to any preceding claim, wherein it comprises:

- a first stage of assembly and fixing, in a sealed manner, of the entire sealing membrane (3, 13, 13') of the cofferdam wall (B) of the main structure of the vessel;

- a second step of mounting and fixing, in a sealed manner, the entire sealing membrane (3) of the liquid dome (2) with the exception of the contiguous membranes of said liquid dome (2); the first and second steps being executed in any order or simultaneously;

- a final step of assembly and fixing, in a leaktight manner, of the membranes (33) said to be contiguous to the said liquid dome (2) so that the whole of the cofferdam wall (B, B'), of the structure main and the liquid dome (2), or waterproof.

[Claim 12] Vessel (70) for transporting a cold liquid product, the vessel comprising a double hull (72) and a storage installation (1) according to one of claims 1 to 10 arranged in the double hull.

[Claim 13] Transfer system for a cold liquid product, the system comprising a vessel (70) according to claim 12, insulated pipes (73, 79, 76, 81) arranged so as to connect the tank (71) installed in the ship's hull to an external floating or onshore storage facility (77) and a pump for driving a flow of cold liquid product through the insulated pipes from or to the external floating or onshore storage facility to or from the tank of the ship.

[Claim 14] A method of loading or unloading a ship (70) according to claim 12, in which a cold liquid product is conveyed through 19 insulated pipes (73, 79, 76, 81) from or to an external floating or terrestrial storage facility (77) to or from the ship's tank (71).