System for storing and / or transporting natural gas in liquid state

Abstract

System for storing and / or transporting a natural gas in the liquid state The present invention relates to a system for storing and / or transporting (30) a gas in the liquid state comprising at least one tank (3) which delimits a main space (20) containing a gas in the liquid state. The tank (3) comprises at least a first space (21), a second space (22) and at least one sealing membrane (10, 10a, 10b) interposed between the first space (21) and the second space (22). The first space (21) constitutes a thermal insulation space of the second space (22).The storage and / or transport system (30) comprises a safety device (12) which maintains a seal between the first space (21) and the second space (22) when a first pressure (P1) prevailing inside the first space (21) is lower than a second pressure (P2) prevailing inside the second space (22), and which puts the first space (21) into fluidic connection with the second space (22) when the first pressure (P1) is higher than the second pressure (P2). Figure for abstract: FIGURE 6.

Description

Title of the invention: System for storing and / or transporting natural gas in liquid state

[0001] The present invention relates to the field of systems for storing and / or transporting a gas maintained in the liquid state at low temperature and atmospheric pressure, said system comprising at least one tank arranged inside a transport vessel. Its subject is such a storage and / or transport system.

[0002] Liquefied natural gas, commonly known by the acronym "LNG", or by the acronym "LNG" for "Liquefied Natural Gas", is frequently transported by sea in a transport vessel comprising at least one tank housed inside the transport vessel and designed to contain the liquefied natural gas. The LNG is kept in liquid form inside the tank to increase the quantity of gas transported, the LNG then occupying 1 / 600th of the volume that it would occupy in the gaseous state, thus facilitating its transport from one site to another. The tank is also capable of maintaining the LNG in the liquid state at very low temperatures, in particular at a temperature below -163°C, the temperature at which LNG is in liquid form at atmospheric pressure.

[0003] Such an LNG tank can also be used as a fuel tank for certain ships. In other words, these ships load and store LNG in a tank, and then use the LNG as fuel.

[0004] Each tank delimits a main space which is intended to contain the LNG. The tank comprises at least a first space and a second space between which a sealing membrane is interposed. The first space forms a thermal insulation space for the second space. In other words, starting from the outside of the tank towards the inside of the tank, we encounter at least the first space, which forms a thermally insulating layer for the second space, then the sealing membrane which is intended to ensure a seal between the first space and the second space, then the second space.

[0005] It is noted that the tank is likely to comprise two sealing membranes, including a primary sealing membrane housed inside a secondary sealing membrane.

[0006] Once the membrane has been manufactured, it is known to check the tightness of this membrane to guarantee the absence of leakage from the main volume containing the liquefied natural gas to the insulation layer which surrounds this main volume.

[0007] Also, it is common to carry out a pressure test during which the waterproofing membrane is subjected to a test pressure of the order of 20 mbarg during which observes the behavior, pressure resistance of the waterproofing membrane and any leaks.

[0008] However, such a method proves to be risky and is likely to cause considerable damage to the entire tank, in the event of incorrect operation during the test mentioned above. Indeed, a handling error can lead to an increase in the pressure in the layer surrounding the main volume, which can lead to a partial or even total rupture of the sealing membrane. The consequences are even more significant in the frequent case where the tank has a primary sealing membrane and a secondary sealing membrane, both of which surround the main volume containing the liquefied natural gas.

[0009] Also, there is a need to have a storage and / or transport system comprising the tank of the transport vessel, the storage and / or transport system being capable of protecting the sealing membrane, whether single, primary and / or secondary.

[0010] The present invention falls within this context and proposes a system for storing and / or transporting a gas in the liquid state comprising at least one tank which delimits a main space intended to contain a gas in the liquid state, for example liquefied natural gas. The tank comprises at least a first space, a second space and at least one sealing membrane interposed between the first space and the second space, the first space constituting a space for thermal insulation of the second space.

[0011] According to the present invention, the storage and / or transport system comprises a safety device which maintains a seal between the first space and the second space when a first pressure prevailing inside the first space is lower than a second pressure prevailing inside the second space, and which puts the first space into fluidic connection with the second space when the first pressure is higher than the second pressure.

[0012] The safety device is designed to withstand a pressure present in the second space when this is greater than the pressure prevailing in the first space. On the other hand, the safety device puts the two spaces into fluidic connection when the pressure in the second space is lower than the pressure in the first space, in particular by a value at least equal to 35 mbarg. This prevents any detachment or tearing of the sealing membrane, the latter ensuring a separation between a volume of the first space and a volume of the second space.

[0013] According to an optional characteristic of the invention, the safety device places the first space in fluidic connection with the second space when the first pressure is greater than the second pressure by a value at least equal to 35 mbarg, possibly 50 mbarg.

[0014] According to one feature, the main space constitutes the second space, the first space being a thermally insulating layer surrounding the second space. In such a case, the tank is provided with a single thermally insulating layer which forms the first space, the second space then being the internal volume of the tank, i.e. the one which receives the fluid to be transported and / or stored.

[0015] According to another example, the storage and / or transport system comprises a second thermally insulating layer which surrounds the first space, i.e. the thermally insulating layer surrounding the main space.

[0016] According to another characteristic, the second space is a first thermally insulating layer surrounding the main space, the first space being a second thermally insulating layer surrounding the second space. In such a case, the tank is provided with two thermal insulation layers superimposed on each other and which both surround the main space intended to contain and / or store the fluid.

[0017] In both cases mentioned above, each layer is formed from an insulating mass.

[0018] According to a first exemplary embodiment, the safety device comprises a pipe fluidly connecting the first space and the second space. Such a solution allows the elements of the safety device to be installed or relocated, so as to make them accessible. For example, they can be accessible from the ship's deck or from a room dedicated to this purpose.

[0019] According to this exemplary embodiment, the safety device comprises at least one seal which is capable of breaking as soon as the first pressure exceeds the second pressure, for example by a value at least equal to 35 mbarg.

[0020] In such a case, the safety device comprises a first flange and a second flange connected to each other by assembly means, the cover being interposed between the first flange and the second flange, the first flange and the second flange jointly delimiting a channel which at least partially houses the cover.

[0021] According to one aspect of this exemplary embodiment, the first flange is housed inside the first space and the second flange is arranged inside the second space.

[0022] According to a second alternative or complementary embodiment of the first embodiment, the safety device comprises at least a plurality of plates connected to each other and forming at least a part of the sealing membrane, the safety device comprising at least one rupture member intended to break the seal of the sealing membrane so as to put the first space into fluidic communication with the second space.

[0023] According to one feature, the plurality of plates comprises at least one central plate and at least two side plates welded to the central plate by means of side welds, the rupture member comprising at least one of the side welds. According to this embodiment, the connection between the first space and the second space is created by breaking at least one of the side welds.

[0024] More particularly, a central weld can connect the central plate to an insulating block constituting the first space or the second space. The central weld then forms a point of attachment of the plates, the latter having a tendency to deform around this point of attachment, until the lateral weld breaks.

[0025] Alternatively or additionally, the plurality of plates comprises at least one central plate and at least two side plates welded to the central plate by means of side welds, each side plate consisting of two elementary plates connected to each other by an upper plate by means of upper welds, the rupture member comprising at least one of the upper welds.

[0026] Here too, a central weld connects the central plate to an insulating block constituting the first space or the second space.

[0027] The rupture member can thus be produced only by the lateral weld, only by the upper weld, or by a combination of these two welds.

[0028] According to another alternative or complementary embodiment of the embodiments described above, the rupture member comprises at least one thinning zone provided in at least one of the plates of the plurality of plates.

[0029] The thinning zone comprises a groove provided on an upper face and / or on a lower face of at least one of the plates of the plurality of plates, for example one of the side plates.

[0030] The present invention also relates to a transport vessel comprising at least one such storage and / or transport system, i.e. which comprises at least one tank and a safety device as set out in the present document.

[0031] The present invention also relates to a method for securing at least one tank of a transport vessel implemented by such a storage and / or transport system, the securing method comprising a step of maintaining a seal between the first space and the second space when a first pressure prevailing inside the first space is lower than a second pressure prevailing inside the second space, the securing method comprising a step of putting the first space into fluidic connection with the second space via the safety device when the first pressure is higher than the second pressure, for example by a value at least equal to 35 mbarg.

[0032] Other characteristics, details and advantages of the invention will emerge more clearly on reading the description which follows on the one hand, and several exemplary embodiments given for informational and non-limiting purposes with reference to the appended schematic drawings on the other hand, in which:

[0033] [Fig-1] is a side view of a transport vessel intended to be equipped with a system for storing and / or transporting a gas in the liquid state according to the present invention;

[0034] [Fig.2] is a schematic sectional view of a first variant embodiment of the storage and / or transport system equipping the transport vessel shown in [Fig.l].

[0035] [Fig.3] is a schematic sectional view of a second variant embodiment of the storage and / or transport system equipping the transport vessel shown in [Fig.l].

[0036] [Fig.4] is a schematic sectional view of a third variant embodiment of the storage and / or transport system equipping the transport vessel shown in [Fig.l].

[0037] [Fig.5] is a schematic sectional view of a fourth variant embodiment of the storage and / or transport system equipping the transport vessel shown in [Fig.l].

[0038] [Fig.6] is a schematic sectional view of a fifth variant embodiment of the storage and / or transport system equipping the transport vessel shown in [Fig.l].

[0039] [Fig.7] is a schematic sectional view of a sixth variant embodiment of the storage and / or transport system equipping the transport vessel shown in [Fig.l].

[0040] [Fig.8] is a sectional and perspective view of a first embodiment of a safety device constituting one of the storage and / or transport systems shown in Figures 2 to 7.

[0041] [Fig.9] is a sectional view of the safety device illustrated in [Fig.8].

[0042] [Fig. 10] is a schematic view of a section of a first variant of a second embodiment of a safety device constituting one of the storage and / or transport systems shown in Figures 2 to 7.

[0043] [Fig. 11] is a schematic view of a section of a second variant of the second embodiment of the safety device illustrated in [Fig. 10].

[0044] [Fig. 12] is a schematic view of a section of a third variant of the second embodiment of the safety device illustrated in [Fig. 10].

[0045] [Fig. 13] is a schematic view of a section of a fourth variant of the second embodiment of the safety device illustrated in [Fig. 10].

[0046] [Fig. 14] is a schematic view of a section of a fifth variant of the second embodiment of the safety device illustrated in [Fig. 10].

[0047] [Fig. 15] is a schematic view of a section of a sixth variant of the second embodiment of the safety device illustrated in [Fig. 10].

[0048] The features, variants and different embodiments of the invention may be combined with each other, in various combinations, provided that they are not incompatible or mutually exclusive. In particular, variants of the invention may be imagined comprising only a selection of features described below in isolation from the other features, if this selection of features is sufficient to confer a technical advantage and / or to differentiate the invention from the prior art.

[0049] In [Fig. 1] is shown a transport vessel 1, such as a LNG carrier or the like, which comprises four tanks 3, one of these tanks 3 being made visible here to facilitate understanding. The tanks 3 are sealed and thermally insulating and are configured for the transport and / or storage of liquefied natural gas. The transport vessel 1 may be arranged to only store and transport the liquefied natural gas, or to use it as fuel for the operation of the transport vessel 1. It is understood that the present invention applies to a transport vessel 1 which comprises an indifferent number of tanks 3, either a single tank 3 or a plurality of tanks 3.

[0050] The transport vessel 1 comprises a hull 2 ​​comprising at least one outer hull 4 and one inner hull 6, between which a plurality of stiffeners 8 extend. The outer hull 4 is in contact with the external environment of the transport vessel 1, generally a maritime and / or river environment. The inner hull 6 extends at a distance from this outer hull 4 and houses the tank 3 or the tanks 3. Each tank 3 comprises a main space 20 which is intended to contain the liquefied natural gas.

[0051] According to the present invention, the transport vessel 1 is equipped with a storage and / or transport system 30 for liquefied natural gas which comprises the tank 3 and a safety device 12 configured to protect the tank 3 against any detachment or tearing of the membrane. In other words, the safety device 12 is arranged to avoid any damage in the event that at least one safety condition relating to one or more pressure states inside the tank 3 is not or no longer met.

[0052] In Figures 2 to 7, the tank 3 comprises at least one sealing membrane 10, 10a, 10b which is interposed between a first space 21 and a second space 22, the first space 21 housing the second space 22. Thus, the first space 21 is located closer to the internal shell 6 of the tank 3 than the second space 22.

[0053] According to the invention, the tank 3 is equipped with the safety device 12 capable of protecting the sealing membrane 10, 10a, 10b that the tank 3 comprises against any pressure differential that would involve deformation of the membrane in the direction of the main space 20 of the tank 3.

[0054] In its generality, the safety device 12 maintains a seal between the first space 21 and the second space 22 when a first pressure P1 prevailing inside the first space 21 is lower than a second pressure P2 prevailing inside the second space 22, and the safety device 12 places the first space 21 in fluidic connection with the second space 22 when the first pressure P1 is higher than the second pressure P2. Such a fluidic connection occurs by triggering the safety device 12, for example following the rupture of a rupture member of the safety device 12. Such a rupture occurs when the first pressure P1 is higher than the second pressure P2 by a value at least equal to 35mbarg, and for example 50mbarg.

[0055] In other words, as soon as the first pressure PI prevailing outside a volume delimited by the sealing membrane 10, 10a, 10b exceeds by a value at least equal to 35 mbarg the second pressure P2 prevailing inside a volume delimited by the sealing membrane 10, 10a, 10b, then the safety device 12 acts as a fuse by authorizing fluid communication between the first space 21 and the second space 22. In other words again, as soon as the sealing membrane 10, 10a, 10b undergoes an external overpressure relative to the main volume which receives the gas in the liquid state, the seal provided by the sealing membrane 10, 10a, 10b is broken, to release this overpressure and evacuate it towards the second space 22, which makes it possible to balance the pressures on both sides. other side of the membrane and therefore guarantee the absence of deformation.

[0056] Depending on the type of transport vessel 1, or more precisely the type of tank 3 that the transport vessel 1 comprises, the safety device 12 is arranged in separate locations, while ensuring the function described above in all of the variants of arrangement and layout of the safety device 12 described below.

[0057] In Figures 2 and 3, the tank 3 comprises a single sealing membrane 10 which separates and delimits the first space 21 with respect to the second space 22. In other words, starting from the outside of the tank 3 towards the inside of the tank 3, we encounter the first space 21, which forms a thermally insulating layer of the main space 20, then the single sealing membrane 10, which is provided to ensure a perfect seal between the first space 21 and the second space 22, then the second space 22 which is made up of the main space 20 containing the liquefied natural gas. The first space 21 comprises an insulating block formed of thermally insulating panels.

[0058] In [Fig.2], the safety device 12 equips the single sealing membrane 10. In other words, the safety device 12 is provided directly on the single sealing membrane 10 and is therefore part of this single sealing membrane 10. The safety device is here in the plane of one of the walls which constitute the waterproofing membrane.

[0059] In [Fig. 3], the safety device 12 equips a first pipe 13a which fluidically connects the first space 21 and the second space 22. In other words, the first pipe 13a extends between a first inlet mouth 14a housed inside the first space 21 and a first outlet mouth 14b housed inside the second space 22, and the safety device 12 equips the first pipe 13a between the first inlet mouth 14a and the first outlet mouth 14b. In such a case, the safety device 12 can be placed on the deck of the ship.

[0060] In Figures 4 to 7, the tank 3 comprises a primary sealing membrane 10a housed at a distance from a secondary sealing membrane 10b. Starting from the outside of the tank 3 towards the inside of the tank 3, there is a thermally insulating layer of the main space 20, then the secondary sealing membrane 10b, then another thermally insulating layer of the main space 20, then the primary sealing membrane 10a delimiting the main space 20 containing the liquefied natural gas.

[0061] The thermally insulating layer of the main space 20, located between the internal shell 6 and the secondary sealing membrane 10b will subsequently be called the secondary thermally insulating layer 48 and the other thermally insulating layer located between the secondary sealing membrane 10b and the primary sealing membrane 10a will subsequently be called the primary thermally insulating layer 49.

[0062] Each layer comprises an insulating block formed of thermally insulating panels.

[0063] In [Fig.4], the safety device 12 equips the primary sealing membrane 10a. In other words, the safety device 12 is arranged directly on the primary sealing membrane 10a. The safety device is here in the plane of one of the walls which constitute the primary sealing membrane 10a. In this example, the secondary sealing membrane 10b is devoid of safety device 12. In such a case, it is thus understood that the first space 21 is interposed between the secondary sealing membrane 10b and the primary sealing membrane 10a. The second space 22 consists of the main space 20 containing the liquefied natural gas.

[0064] In [Fig.5], the safety device 12 equips the secondary sealing membrane 10b. In other words, the safety device 12 is provided directly on the secondary sealing membrane 10b. The safety device is here in the plane of one of the walls which constitute the secondary sealing membrane 10b. In this example, the primary sealing membrane 10a is without a safety device 12.

[0065] In such a case, it is understood that the first space 21 is interposed between the hull internal 6 and the secondary sealing membrane 10b. The second space 22 consists of the space located between the secondary sealing membrane 10b and the primary sealing membrane 10a.

[0066] Of course, the invention covers the case of a double membrane tank comprising both a first safety device 12 arranged on the primary sealing membrane 10a, the latter being interposed between the main space 20 and the primary thermally insulating layer 49, and a second safety device 12 arranged on the secondary sealing membrane 10b, the latter being interposed between the primary thermally insulating layer 49 and the secondary thermally insulating layer 48.

[0067] In Figures 6 and 7, the safety device 12 equips a second pipe 13b which fluidically connects adjacent spaces, the second pipe 13b extending between a second inlet mouth 15a and a second outlet mouth 15b, the safety device 12 equipping the second pipe 13b between the second inlet mouth 15a and the second outlet mouth 15b.

[0068] More particularly in [Fig.6], the second intake mouth 15a is arranged inside the first space 21, formed by the secondary thermally insulating layer and the second discharge mouth 15b is arranged inside the second space 22, formed by the primary thermally insulating layer. In this example, no safety device is provided between the main space 20 and the second space 22.

[0069] In [Fig.7], the second intake mouth 15a is arranged inside the primary thermally insulating layer 49 and the second discharge mouth 15b is housed inside the main space 20. In this example, no safety device is provided between the primary thermally insulating layer 49 and the secondary thermally insulating layer 48.

[0070] The invention also covers the case of a double membrane tank equipped with two safety devices 12 as shown in [Fig.6] and [Fig.7].

[0071] In Figures 8 and 9, a first embodiment of the safety device 12 is illustrated. According to this embodiment, the safety device 12 comprises a breaking device 16 interposed between a first flange 17a and a second flange 17b connected to each other by assembly means 18. The assembly means are for example bolts.

[0072] Preferably, the rupture device 16 comprises at least one seal 16a which is capable of breaking as soon as the first pressure P1 exceeds the second pressure P2. For this purpose, the first flange 17a and the second flange 17b jointly delimit a channel 19 which extends between a first outlet 31 delimited by the first flange 17a and a second outlet 32 ​​delimited by the second flange 17b. It is understood that the first outlet 31 is intended to extend inside the first space 21 and that the second outlet 32 ​​is intended to extend inside the second space 22, the cover 16a forming for example a part of the sealing membrane. It is also noted that the channel 19 at least partially houses the cover 16a and that the flanges 17a, 17b are removable to allow the cover 16a to be replaced when it is broken and thus restore the seal between the first space 21 and the second space 22.

[0073] In Figures 10 to 15, a second embodiment of the safety device 12 is illustrated, the safety device 12 comprising a plurality of plates 19a, 19b, 19', 19” welded together and arranged along respective planes parallel to each other, or even merged. These plates are part of the sealing membrane which is equipped with the safety device 12.

[0074] Figures 10 to 15 each include a diagram on the left which shows the state of the membrane when the second pressure P2 is greater than the first pressure PI, i.e. when the safety device 12 maintains the seal between the first space 21 and the second space 22, and a diagram on the right which shows the state of the membrane when the second pressure P2 is less than the first pressure PI, i.e. when the membrane tends to deform by swelling towards the inside of the tank. Such a state is immediately prior to the establishment of fluidic connection between the volume of the first space 21 and the volume of the second space 22. Once this state has been exceeded, the safety device 12 places the first space 21 in fluidic connection with the second space 22, so as to balance the pressures between these spaces.

[0075] According to a first variant embodiment of this embodiment illustrated in [Fig. 10], the safety device 12 comprises at least one central plate 19a and two side plates 19b, which are welded to the central plate 19a by means of side welds 41b. A central weld 41a secures the central plate 19a to a connecting plate 46 which is itself secured to the insulating block of the first space 21.

[0076] In the examples illustrated in Figures 10 to 15, the side plates 19b are not mechanically connected to the connecting plate 46, so as to allow their movement.

[0077] It is noted that the two side plates 19b extend in the same plane. One end of each side plate 19b locally overlaps the central plate 19a, in a state before rupture of the safety device 12.

[0078] It is also noted that the insulating block comprises a cavity formed in its thickness and facing the main space. This cavity receives at least the connecting plate 46 and the central plate(s) 19a.

[0079] The safety device 12 comprises a rupture member 44 which here takes the form of a side weld 41b. By deforming as illustrated in the right diagram of [Fig. 10], the side plate 19b pivots around the side weld 41b under the effect of the pressure differential between the first space 21 and the second space 22, which causes a rupture of this side weld 41b. Such pivoting is facilitated by the fact that the central plate 19a is firmly attached to the connecting plate 46 by the central weld 41a.

[0080] According to a second variant embodiment of this embodiment illustrated in [Fig. 11], the safety device 12 comprises at least two central plates 19a and two side plates 19b which are each welded to an adjacent central plate 19a, by means of side welds 41b. Two central welds 41a each connect a central plate 19a to the connecting plate 46 of the insulating block of the first space 21.

[0081] According to this exemplary embodiment, the two side plates 19b extend in the same first plane, while the two central plates 19a extend in the same second plane, this first plane and this second plane being parallel but distinct in a state before rupture of the safety device 12. It is noted that each central plate 19a is connected to the connecting plate 46 by central welds 41a arranged opposite one another.

[0082] The safety device 12 comprises the rupture member 44 which here takes the form of one or more lateral welds 41b. By deforming as illustrated in the diagram on the right of [Fig.l 1], the lateral plate(s) 19b pivot around the lateral weld 41b under the effect of the pressure differential between the first space 21 and the second space 22, which causes a rupture of this or these lateral welds 41b. Such pivoting is facilitated by the fact that each central plate 19a is individually and securely attached to the connecting plate 46 by central welds 41a.

[0083] According to a third variant embodiment of this embodiment illustrated in [Fig. 12], the safety device 12 comprises a single central plate 19a and two side plates 19b, which are welded to the central plate 19a by means of side welds 41b. A central weld 41a secures the single central plate 19a to the connecting plate 46 secured to the insulating block of the first space 21. Each side plate 19b is made up of two elementary plates 19' connected to each other by an upper plate 19”. The upper plate 19” is connected to each of the elementary plates 19' by means of upper welds referenced 41'. Thus, on either side of the central plate 19a, one of the elementary plates 19' is fixed to the upper plate 19” by means of an upper weld 41' and to the central plate 19a by means of a lateral weld 41b.

[0084] According to this embodiment, the four elementary plates 19' extend in the same first plane, while the two upper plates 19” extend in the same third plane, this first plane and this third plane being parallel but distinct in a state before rupture of the safety device 12. The first plane is thus interposed between this third plane and the second plane in which the single central plate 19a extends.

[0085] One of the elementary plates 19' comprises a lateral weld 41b which connects an edge of this elementary plate 19' to the central plate 19a and an opposite edge covered by the upper plate 19”. This upper plate 19” comprises a first edge and the latter is connected to a face of the elementary plate 19' by the upper weld 41'.

[0086] Another of the elementary plates 19' comprises a first edge and another edge fixed to the upper plate 19” by an upper weld 41', the latter extending between a second edge of the upper plate 19” and a surface of the elementary plate 19'.

[0087] As is the case in [Fig. 10], the single central plate 19a is connected to the connecting plate 46 by a single central weld 41a.

[0088] The safety device 12 comprises the rupture member 44 which here takes the form of one or more lateral welds 41b and / or one or more upper welds 41', whether the latter is provided between an elementary plate 19' and the central plate 19a or between the upper plate 19” and one and / or the other of the elementary plates 19' adjacent to the upper plate 19”.

[0089] By deforming as illustrated in the right diagram of [Fig. 12], each assembly consisting of the elementary plates 19' and the upper plate 19” pivots around its lateral weld 41b, connecting an elementary plate 19' to the central plate 19a under the effect of the pressure differential between the first space 21 and the second space 22, which causes a rupture of this or these lateral welds 41b and / or of the upper weld(s) 41'. Such pivoting is facilitated by the fact that the central plate 19a is firmly attached to the connecting plate 46 by the central weld 41a.

[0090] According to a fourth variant embodiment of this embodiment illustrated in [Fig. 13], each side plate 19b is provided with a thinning arranged on an upper face 43 of the side plate 19b, the upper face 43 being the face of the side plate 19b which faces the second space 22. Such local thinning forms a rupture member 44 which functionally meets the same criterion as the welds mentioned above. According to an exemplary embodiment, the thinning takes the form of a groove 42.

[0091] It is understood that such a groove 42 constitutes a zone of material fragility which may break upon deformation of the side plate 19b as may one of the side welds 41b, as illustrated in the right diagram of [Fig. 13].

[0092] As regards the shape and arrangement of the central plate 19a, the side plates and the welds, reference is made to the description in [Fig. 10].

[0093] According to a fifth variant embodiment of this embodiment illustrated in [Fig. 14], the thinning which forms the rupture member is provided on a lower face 45 of the side plate 19b, the lower face 45 being the face of the side plate 19b which is placed opposite the insulating block. Thus, this variant embodiment differs from [Fig. 13] only by the location of the thinning.

[0094] It is also noted that such a groove 42, whether it is formed on the upper face 43 or on the lower face 45 of the side wall 19b, is obtained indifferently by stamping or by removing material.

[0095] As regards the shape and arrangement of the central plate 19a, the side plates and the welds, reference is made to the description in [Fig. 13].

[0096] A sixth embodiment variant is illustrated in [Fig. 15]. For identical elements, reference will be made to the description in [Fig. 12]. In this example, each upper plate 19” is provided with a thinning, for example produced in the form of a groove 42 arranged on a lower face 47 of the upper plate 19”, the lower face 47 being the face of the upper plate 19” which is opposite the insulating block. It is understood that such a thinning constitutes a zone of material fragility which breaks during deformation of the side plate 19b.

[0097] Of course, the invention is not limited to the examples which have just been described and numerous adjustments can be made to these examples without departing from the scope of the invention.

[0098] The invention, as just described, achieves the aim it set itself, and makes it possible to avoid any blowing of the membrane, that is to say any deformation of the plates which constitute it due to a handling error during pressure resistance tests of the insulation spaces of an LNG storage and / or transport tank. Variants not described here could be implemented without departing from the context of the invention, since, in accordance with the invention, they comprise a system for storing and / or transporting a gas in the liquid state which comprises at least one tank and at least one safety device intended to protect a sealing membrane of such a tank.

Claims

Claims

1. Storage and / or transport system (30) for a gas in the liquid state comprising at least one tank (3) which delimits a main space (20) intended to contain a gas in the liquid state and comprising at least a first space (21), a second space (22) and at least one sealing membrane (10, 10a, 10b) interposed between the first space (21) and the second space (22), the first space (21) constituting a thermal insulation space of the second space (22), characterized in that the storage and / or transport system (30) comprises a safety device (12) which maintains a seal between the first space (21) and the second space (22) when a first pressure (PI) prevailing inside the first space (21) is lower than a second pressure (P2) prevailing inside the second space (22),and in that the safety device (12) places the first space (21) in fluidic connection with the second space (22) when the first pressure (PI) is greater than the second pressure (P2), the safety device (12) comprising at least one seal (16a) which is capable of breaking as soon as the first pressure (PI) exceeds the second pressure (P2), as well as a first flange (17a) and a second flange (17b) jointly delimiting a channel (19) which extends between a first outlet (31) delimited by the first flange (17a) and a second outlet (32) delimited by the second flange (17b), the flanges (17a, 17b) being removable to allow the seal (16a) to be replaced when it is broken.,

2. Storage and / or transport system (30) according to claim 1, wherein the first flange (17a) and the second flange (17b) are connected to each other by assembly means (18), the cover (16a) being interposed between the first flange (17a) and the second flange (17b), the first flange (17a) and the second flange (17b) jointly delimiting the channel (19) which at least partially houses the cover (16a).

3. Storage and / or transport system (30) for a gas in the liquid state comprising at least one tank (3) which delimits a main space (20) intended to contain a gas in the liquid state and comprising at least a first space (21), a second space (22) and at least one sealing membrane (10, 10a, 10b) interposed between the first space (21) and the second space (22), the first space (21) being constitutive of a thermal insulation space of the second space (22), characterized in that the storage and / or transport system (30) comprises a safety device (12) which maintains a seal between the first space (21) and the second space (22) when a first pressure (PI) prevailing inside the first space (21) is lower than a second pressure (P2) prevailing inside the second space (22), and in that the safety device (12) puts the first space (21) into fluidic connection with the second space (22) when the first pressure (PI) is higher than the second pressure (P2), the safety device (12) comprising at least a plurality of plates (19a, 19b, 19', 19”) connected to each other and forming at least part of the sealing membrane,the safety device (12) comprising at least one rupture member (44) intended to break the seal of the sealing membrane so as to put the first space (21) into fluidic communication with the second space (22).,

4. Storage and / or transport system (30) according to the preceding claim, wherein the plurality of plates (19a, 19b, 19', 19”) comprises at least one central plate (19a) and at least two side plates (19b) welded to the central plate (19a) by means of side welds (41b), the rupture member (44) comprising at least one of the side welds (41b).

5. Storage and / or transport system (30) according to claim 3 or 4, wherein the plurality of plates (19a, 19b, 19', 19”) comprises at least one central plate (19a) and at least two side plates (19b) welded to the central plate (19a) by means of side welds (41b), each side plate (19b) consisting of two elementary plates (19') connected to each other by an upper plate (19”) by means of upper welds (41'), the rupture member (44) comprising at least one of the upper welds (41').

6. Storage and / or transport system (30) according to any one of claims 3 to 5, wherein the rupture member (44) comprises at least one thinning zone (42) provided in at least one of the plates of the plurality of plates (19a, 19b, 19', 19”).

7. Storage and / or transport system (30) according to the preceding claim, in which the thinning zone (42) comprises a groove provided on an upper face (43) and / or on a lower face (45) of at least one of the plates of the plurality of plates (19a, 19b, 19', 19”).

8. Storage and / or transport system (30) according to any one of the preceding claims, in which the safety device (12) puts the first space (21) into fluidic connection with the second space (22) when the first pressure (PI) is greater than the second pressure (P2) by a value at least equal to 35 mbarg.

9. A storage and / or transport system (30) according to any preceding claim, wherein the main space (20) constitutes the second space (22), the first space (21) being a thermally insulating layer surrounding the second space (22).

10. Storage and / or transport system (30) according to the preceding claim, comprising a second thermally insulating layer which surrounds the first space (21).

11. A storage and / or transport system (30) according to any one of claims 1 to 8, wherein the second space (22) is a first thermally insulating layer surrounding the main space (20), the first space (21) being a second thermally insulating layer surrounding the second space (22).

12. Storage and / or transport system (30) according to any one of the preceding claims, wherein the safety device (12) comprises a conduit (13a, 13b) fluidly connecting the first space (21) and the second space (22).

13. Transport vessel (1) comprising at least one storage and / or transport system (30) according to any one of claims 1 to 12.

14. Method for securing at least one tank (3) of a transport vessel (1) implemented by a storage and / or transport system (30) for a gas in the liquid state according to any one of claims 1 to 12, characterized in that the securing method comprises a step of maintaining a seal between the first space (21) and the second space (22) when a first pressure (PI) prevailing inside the first space (21) is lower than a second pressure (P2) prevailing inside the second space (22), and in that the securing method comprises a step of placing the first space (21) in fluidic connection with the second space (22) via the safety device (12) when the first pressure (PI) is greater than the second pressure (P2), for example by a value at least equal to 35 mbarg.

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