Sealed and thermally insulating tank for storing liquefied gas

Abstract

The invention relates to a tank (71) comprising a bottom wall (6) and a roof wall (4), the roof wall (4) being traversed by at least one loading / unloading pipe (9, 14), the tank comprising a tuned dynamic damping device (12) fixed in the height direction (H) to the loading / unloading pipe (9, 14), the tuned dynamic damping device (12) comprising an oscillating body (18) extending all around the loading / unloading pipe (9, 14), and a pair of spring devices (25, 27) connecting the oscillating body (18) to the loading / unloading pipe (9, 14), the spring devices (25, 27) of the pair of spring devices (25, 27) being located one on each side of the loading / unloading pipe (9, 14) in a tank longitudinal direction (L) perpendicular to the height direction (H).

Description

[0001] Description

[0002] Title of the invention: SEALED AND THERMALLY INSULATED TANK FOR STORING LIQUEFIED GAS

[0003] technical field

[0004]

[0001] The invention relates to the field of leak-proof and thermally insulated membrane tanks. In particular, the invention relates to the field of leak-proof and thermally insulated tanks for the storage and / or transport of liquefied gases at low temperatures, such as tanks for transporting Liquefied Petroleum Gas (also called LPG) at temperatures ranging, for example, from -50°C to 0°C, or for transporting Liquefied Natural Gas (LNG) at approximately -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 can be used for transporting liquefied gas or for receiving liquefied gas to serve as fuel for the propulsion of the floating structure.

[0005] Technological background

[0006] [2] It is known in particular from document WO2018203005 of sealed and thermally insulated tanks comprising a loading / unloading tower suspended from and passing through a ceiling wall. The loading / unloading tower comprises a plurality of pipes, each of which allows the loading and / or unloading of the tank.

[0007] [3] During tank operation, the loading / unloading tower piping may be subjected to external stresses, for example from the propulsion of the vessel transporting the tank. These stresses can generate dynamic vibration and resonance problems in the loading / unloading tower.

[0008] [4] At the level of the vibration antinodes of the natural modes of the pipes, significant dynamic fatigue stresses can damage them, which implies increased monitoring of this structure or strengthening of the pipes to resist these vibrations, which implies an increase in cost.

[0009] Summary of the invention [5] One idea underlying the invention is to limit the impact of vibrations on the tank loading / unloading line(s) related to external stresses.

[0010] [6] According to one embodiment, the invention provides a sealed and thermally insulated liquefied gas storage tank intended to be integrated into a load-bearing structure, the tank comprising a bottom wall and a ceiling wall opposite the bottom wall in a height direction of the tank, the bottom wall and the ceiling wall intended to be fixed to the load-bearing structure, in which the ceiling wall is traversed by at least one loading / unloading pipe, the tank comprising a guiding device fixed to the bottom wall, the loading / unloading pipe being guided in the height direction by the guiding device, in which the tank comprises at least one tuned dynamic damping device fixed in the height direction to the loading / unloading pipe,The tuned dynamic damping device comprises an oscillating body extending at least partially around the loading / unloading pipe, and spring devices connecting the oscillating body to the loading / unloading pipe, each spring device being spaced from adjacent spring devices around the loading / unloading pipe.

[0011] [7] Thanks to these characteristics, the tuned dynamic damping device limits the amplitude of vibrations perceived by the loading / unloading pipeline and thus limits the stresses and deformations undergone by the pipeline. Indeed, the oscillating body connected to the loading / unloading pipeline by the spring devices dissipates the vibrations perceived by the pipeline by oscillating around it.

[0012] [8] According to embodiments, such a tank may include one or more of the following characteristics.

[0013] [9] According to one embodiment, each spring device is separated from adjacent spring devices by an angle equal to 3607N, with N being the number of spring devices.

[0014]

[0010] According to one embodiment, the oscillating body extends all around the loading / unloading conduit.

[0011] According to one embodiment, one or each of the spring devices has a stiffness whose value is chosen to match a target vibration frequency to be dissipated.

[0015]

[0012] According to one embodiment, each spring device comprises a spring having a first end fixed to the oscillating body and a second end fixed to the loading / unloading line, the spring being configured to be elastically deformable in bending or in tension / compression in a direction perpendicular to the height direction.

[0016]

[0013] The spring may be, for example, a leaf spring, a helical spring or any other type of spring suitable for the intended use.

[0017]

[0014] According to one embodiment, each spring is made up of a single spring or the assembly of two or more springs in series.

[0018]

[0015] According to one embodiment, at least one of the spring devices or each spring device comprises a damper in parallel with the spring, the damper having a first end fixed to the oscillating body and a second end fixed to the loading / unloading line.

[0019]

[0016] According to one embodiment, each shock absorber is made up of a single shock absorber or the assembly of two or more shock absorbers in series.

[0020]

[0017] According to one embodiment, the oscillating body has a shape of revolution having an axis of revolution coinciding with an axis of revolution of the loading / unloading conduit, for example a cylindrical shape of revolution, an annular shape or a toric shape.

[0021]

[0018] According to one embodiment, the spring is a first spring, and each spring device comprises the first spring and a second spring connected in series with the first spring, the second spring being coupled to an actuator, the actuator being configured to in a locked state block the deformation of the second spring and in an unlocked state allow the deformation of the second spring to be free.

[0022]

[0019] According to one embodiment, the shock absorber is a first shock absorber, and at least one of the spring devices or each spring device comprises a second shock absorber in parallel with the second spring, the second shock absorber having a first end fixed to the first shock absorber and a second end fixed to the loading / unloading line.

[0023]

[0020] According to one embodiment, at least one of the spring devices or each spring device comprises a first spring and a second spring connected in series with the first spring, the second spring being coupled to an actuator, the actuator being configured to in a locked state block the deformation of the second spring and in an unlocked state allow the deformation of the second spring to be free.

[0024]

[0021] Thus, the spring device can exhibit two different stiffnesses depending on whether the actuator is in the locked or unlocked state. Indeed, if stiffness k1 is assigned to the first spring and stiffness k2 to the second spring, the stiffness of the spring device is equal to k1 in the locked state and to (k1 x k2) / (k1 + k2) in the unlocked state.

[0025]

[0022] According to one embodiment, the spring devices are first spring devices, the plurality of first spring devices consisting of a pair of first spring devices located on either side of the loading / unloading line in a longitudinal tank direction perpendicular to the height direction, and the tuned dynamic damping device comprises a pair of second spring devices, the pair of second spring devices being located on either side of the loading / unloading line in a transverse tank direction perpendicular to the height direction and perpendicular to the longitudinal tank direction.

[0026]

[0023] According to one embodiment, the spring devices are first spring devices, and the tuned dynamic damping device comprises second spring devices, the second spring devices being alternated with the first spring devices around the loading / unloading line.

[0027]

[0024] Thus, the tuned dynamic damping device makes it possible to absorb the vibrations of the loading / unloading line in two or more distinct directions, and at identical or different frequencies.

[0028]

[0025] The previous characteristics associated with the spring device or the first spring device are transposable to the second spring device.

[0029]

[0026] According to one embodiment, the stiffness of the first spring devices differs from that of the second spring devices.

[0027] According to one embodiment, the tuned dynamic damping device is located midway between the bottom wall and the ceiling wall in the vertical direction.

[0030]

[0028] Thus, it has been observed that an antinode of the natural mode of the vibrations experienced by the loading / unloading line is located near the middle of the line so that it is advantageous to position the dynamic damping device near this antinode.

[0031]

[0029] According to one embodiment, the tank includes a protection system configured to protect the tuned dynamic damping device, the protection system being attached to the tuned dynamic damping device or to the loading / unloading line.

[0032]

[0030] According to one embodiment, the oscillating body has an internal surface facing the loading / unloading line and an external surface opposite the internal surface, the external surface being equipped with a deflector.

[0033]

[0031] Thus, the protection system which includes the deflector makes it possible to reduce the hydrodynamic forces suffered by the tuned dynamic damping device so as to avoid its damage.

[0034]

[0032] According to one embodiment, the tank comprises a casing fixed to the loading / unloading line and surrounding the tuned dynamic damping device.

[0035]

[0033] Thus, the protection system, which includes the housing, reduces the hydrodynamic stresses experienced by the tuned dynamic damping device, thereby preventing damage to it. The housing also prevents any part of the tuned dynamic damping device from falling onto the bottom wall.

[0036]

[0034] According to one embodiment, the casing has perforated or wire-mesh walls.

[0037]

[0035] According to one embodiment, the tank includes a fastening device configured to fix the tuned dynamic damping device to the loading / unloading line. The fastening device comprises a ball-joint tie rod extending in the vertical direction and having a first end connected by a first ball joint to the oscillating body and a second end connected by a second ball joint to the loading / unloading line.

[0036] Thus, the tuned dynamic damping device is retained to the loading / unloading line while maintaining a certain freedom of movement.

[0038]

[0037] According to one embodiment, the tank includes an additional tuned dynamic damping device fixed in the height direction to the loading / unloading line, the additional tuned dynamic damping device being spaced from the tuned dynamic damping device in the height direction.

[0039]

[0038] Thus, the additional tuned dynamic damping device further limits the amplitude of vibrations perceived by the loading / unloading pipeline and therefore reduces the stresses and deformations experienced by the pipeline. The additional tuned dynamic damping device can also be adapted to dampen vibrations of different frequencies or to dampen vibration antinodes located at different points along the pipeline.

[0040]

[0039] According to one embodiment, the tank comprises a plurality of additional tuned dynamic damping devices spaced apart from each other in the height direction.

[0041]

[0040] According to one embodiment, the loading / unloading line is a first loading / unloading line and the tuned dynamic damping device is a first tuned dynamic damping device, the ceiling wall being traversed by at least a second loading / unloading line, the second loading / unloading line being guided in the height direction by the guiding device, the tank comprising a second tuned dynamic damping device fixed in the height direction to the second loading / unloading line.

[0042]

[0041] According to one embodiment, the tank comprises a plurality of loading / unloading lines, the tank comprising several tuned dynamic damping devices each fixed to a loading / unloading line of the plurality of loading / unloading lines.

[0043]

[0042] According to one embodiment, each loading / unloading line is equipped with one or more tuned dynamic damping devices.

[0044]

[0043] According to one embodiment, the tank includes a loading / unloading tower comprising at least the first loading / unloading pipe and the second loading / unloading pipe, as well as a fixing mesh securing the first loading / unloading pipe and the second loading / unloading pipe together.

[0045]

[0044] According to one embodiment, the tank includes a discharge pump fixed to a lower end of the loading / unloading tower.

[0046]

[0045] According to one embodiment, the invention also provides a vessel for the transport of a cold liquid product, the vessel extending in a longitudinal direction and comprising a double hull and the aforementioned tank disposed in the double hull.

[0047]

[0046] According to one embodiment, the longitudinal direction of the tank is parallel to the longitudinal direction of the vessel.

[0048]

[0047] According to one embodiment, the invention also provides a transfer system for a cold liquid product, the system comprising the aforementioned vessel, insulated pipes arranged to connect the tank installed in the hull of the vessel to a floating or land-based storage facility and a pump to drive a flow of cold liquid product through the insulated pipes from or to the floating or land-based storage facility to or from the vessel tank.

[0049]

[0048] According to one embodiment, the invention also provides a method for loading or unloading a ship, in which a cold liquid product is conveyed through insulated pipes from or to a floating or land-based storage facility to or from the tank of the aforementioned ship.

[0050] Brief description of the figures

[0051]

[0049] The invention will be better understood, and other objects, details, features and advantages thereof will become more apparent from the following description of several particular embodiments of the invention, given solely by way of illustration and not limitation, with reference to the accompanying drawings.

[0052]

[0050] Figure 1 represents a partial front view of the interior of a tank according to one embodiment, the tank including in particular a loading / unloading pipe and a tuned dynamic damping device.

[0053]

[0051] Figure 2 shows a partial front view of the interior of a tank according to one embodiment, the tank comprising in particular a loading / unloading tower and several tuned dynamic damping devices.

[0052] Figure 3 shows a schematic view of detail III of Figure 1, representing a tuned dynamic damping device according to a first embodiment.

[0054]

[0053] Figure 4 represents a schematic view of detail III of figure 1, representing a dynamic damping device tuned according to a second embodiment.

[0055]

[0054] Figure 5 represents a schematic top view of a dynamic damping device tuned according to a third embodiment fixed to a loading / unloading line.

[0056]

[0055] Figure 6 represents a schematic top view of a dynamic damping device tuned according to a fourth embodiment fixed to a loading / unloading line.

[0057]

[0056] Figure 7 represents a schematic top view of a dynamic damping device tuned according to a fifth embodiment fixed to a loading / unloading line.

[0058]

[0057] Figure 8 represents a schematic top view of a dynamic damping device tuned according to a sixth embodiment fixed to a loading / unloading line.

[0059]

[0058] Figure 9 represents a graph for a loading / unloading line without a dynamically tuned damping device according to the prior art, the graph showing vibration frequencies on the abscissa and displacement velocities on the ordinate, each curve representing a different height of the loading / unloading line.

[0060]

[0059] Figure 10 represents a graph for a loading / unloading line with a dynamically tuned damping device according to one embodiment, the graph showing vibration frequencies on the abscissa and displacement velocities on the ordinate, each curve representing a different height of the loading / unloading line.

[0061]

[0060] Figure 11 is a schematic cutaway view of an LNG carrier including a ship tank and a loading / unloading terminal for this tank

[0062] Description of embodiments

[0061] A sealed and thermally insulated tank 71 for the storage of liquefied gas will be described later with reference to figures 1 to 11.

[0063]

[0062] The tank 71 is a membrane tank having a multilayer structure comprising, from the outside in, a secondary thermally insulating barrier resting against a load-bearing structure 1, a secondary airtight membrane resting against the secondary thermally insulating barrier, a primary thermally insulating barrier resting against the secondary airtight membrane, and a primary airtight membrane 2 intended to be in contact with the liquefied gas contained in the tank 71. The primary airtight membrane defines an internal space 3 intended to receive the liquefied gas. By way of example, such membrane tanks are described in particular in patent applications WO2019239048, WO14057221, FR2691520, and FR2877638.

[0064]

[0063] The liquefied gas intended to be stored in tank 71 may, in particular, be liquefied natural gas (LNG), that is to say, a gaseous mixture consisting mainly of methane and one or more other hydrocarbons. The liquefied gas may also be ethane or liquefied petroleum gas (LPG), that is to say, a mixture of hydrocarbons from petroleum refining consisting essentially of propane and butane.

[0065]

[0064] The tank 71 is a polyhedral tank comprising, in particular, a ceiling wall 4 fixed to an upper load-bearing wall 5 of the load-bearing structure 1, and a bottom wall 6 fixed to a lower load-bearing wall 7 of the load-bearing structure 1, the ceiling wall 4 and the bottom wall 6 being spaced apart in a vertical direction H. The tank 71 also comprises a front wall and a rear wall (not shown), spaced apart in a longitudinal direction L. The tank 71 also comprises side walls closing the internal space 3 with the bottom wall 6, the ceiling wall 4, the front wall, and the rear wall. The side walls are arranged on either side of the bottom wall 6 in a transverse direction T perpendicular to the longitudinal direction L. When the tank 71 is arranged in a vessel 70, the longitudinal direction L corresponds to the longitudinal direction of the vessel 70.

[0066]

[0065] Figure 1 shows a portion of the tank 71, of which only a portion of the ceiling wall 4 and a corresponding portion of the bottom wall 6 are shown.

[0066] The ceiling wall 6 has an opening 8 through which a liquefied gas loading / unloading line 9 passes in a sealed manner through the ceiling wall 4.

[0067]

[0067] Thus, the loading / unloading pipe 9 opens into the internal space 3 of the tank 71 in order to load or unload it with liquefied gas. Furthermore, as can be seen in Figure 1, a support foot 10 is provided, passing through the bottom wall 6 and fixed to the lower load-bearing wall 7. The support foot 10 is equipped with a guiding device 1 configured to ensure translational guidance along the vertical direction H of the loading / unloading pipe 9 and to maintain the pipe 9 vertically in line with the axis of the opening 8. The support foot 10 is thus positioned close to the axis of the opening 8.

[0068]

[0068] During the use of the tank 71, the loading / unloading line is subjected to vibrations generated in particular by the engine or propeller of the ship transporting the tank.

[0069]

[0069] In order to limit the impact of these vibrations on the pipe 9, the tank 71 includes a tuned dynamic damping device 12 fixed in the height direction H to the loading / unloading pipe 9, as seen in Figure 1. The tuned dynamic damping device 12 will be described in more detail later with reference to Figures 3 to 8.

[0070]

[0070] Figure 2 also shows a portion of the tank 71, for which only a portion of the ceiling wall 4 and a corresponding portion of the bottom wall 6 are shown. In this embodiment, the opening 8 in the ceiling wall 4 is traversed by a loading / unloading tower 13, which includes at least one first loading / unloading pipe 9 and a second loading / unloading pipe 14. The pipes 9 and 14 of the loading / unloading tower 13 are fixed to each other by means of a fixing mesh 15. In this embodiment, the first loading / unloading pipe 9 is primarily intended for loading the tank, while the second loading / unloading pipe 14 is primarily intended for unloading the tank, with an unloading pump 16 attached to its end.

[0071]

[0071] The loading / unloading tower 13 is also subject to vibrations generated in particular by the motorization or propeller of the ship transporting the tank.

[0072] Therefore, as can be seen in figure 2, the tank 71 includes a first tuned dynamic damping device 12 fixed in the height direction H to the first loading / unloading pipe 9 and a second tuned dynamic damping device 12 fixed in the height direction H to the second loading / unloading pipe 14.

[0072]

[0073] The inventors have observed that an antinode of the natural mode of the vibrations experienced by the loading / unloading pipe(s) 9, 14 is located near the middle of the pipe.

[0073]

[0074] Thus, and as shown in figures 1 and 2, the tuned dynamic damping device 12 of each pipe 9, 14 is located midway between the bottom wall 6 and the ceiling wall 4 in the height direction H so as to be advantageously positioned at the antinode of the natural mode and thus allow optimized damping of the latter.

[0074]

[0075] Advantageously, and as seen in figure 2, one of the pipes 9, 14, and for example the loading / unloading pipe 9 can be equipped with an additional tuned dynamic damping device 17. The additional tuned dynamic damping device 17 is spaced from the tuned dynamic damping device 12 in the height direction H.

[0075]

[0076] The additional tuned dynamic damping device 17 can have various functions depending on its placement on the pipe 9, 14 and its ability to dampen vibrations. Indeed, it can be positioned at another antinode of the natural mode of the vibrations experienced by the loading / unloading pipe(s) 9, 14 in order to dampen that antinode more specifically. The additional tuned dynamic damping device 17 can also act on other vibration frequencies with spring stiffnesses, described later, adapted to these vibrations.

[0076]

[0077] Indeed, two distinct vibration frequencies can be experienced by line 9, 14 depending on whether the tank is empty or full of liquefied gas. Line 9, 14 exhibits natural vibration frequencies that vary according to the tank's fill level. Typically, the natural frequencies are lower at higher fill levels because, in this case, the modes involve more mass (the liquid mass added to the structural mass of line 9, 14).

[0077]

[0078] As an example, for a loading / unloading tower 13 with a mass of approximately 42 tonnes, the mass of liquid reacting by vibration with the tower 13 when the tank 71 is full and when the pipe 9, 14 is vibrating is approximately 11 tonnes. Thus, in this case, when the tank 71 is empty, the natural frequency of vibration is approximately 5 Hz, while when the tank 71 is full, the natural frequency of vibration is approximately 4 Hz.

[0078]

[0079] Subsequently, any characteristic described with reference to the tuned dynamic damping device 12 is applicable to the additional tuned dynamic damping device 17.

[0079]

[0080] Figures 3 and 4 represent more particularly the tuned dynamic damping device 12 according to a first embodiment and according to a second embodiment, and the means of fixing it to the loading / unloading line 9, 14.

[0080]

[0081] The tuned dynamic damping device 12 comprises an oscillating body 18 extending all around the loading / unloading pipe 9, 14. The loading / unloading pipe 9, 14 advantageously has the shape of a cylindrical pipe with a circular cross-section. The oscillating body 18 advantageously has a shape of revolution having an axis of revolution coinciding with an axis of revolution of the loading / unloading pipe 9, 14. It may be a cylindrical shape of revolution, an annular shape, or a toroidal shape.

[0081]

[0082] The tank 71 includes a fixing device 19 configured to fix the tuned dynamic damping device 12 to the loading / unloading line 9, 14.

[0082]

[0083] The fixing device 19 includes a ball joint tie rod 20 extending in the height direction H. The ball joint tie rod 20 has a first end connected by a first ball joint 21 to the oscillating body 18 and has a second end connected by a second ball joint 22 to the loading / unloading line 9, 14. This type of fixing device 19 allows the oscillating body 18 to move freely over a short distance, particularly in vibration, while keeping it fixed to the loading / unloading line 9, 14 in the useful area.

[0083]

[0084] In the first embodiment illustrated in Figure 3, the oscillating body 18 is equipped with a deflector 23 to reduce the hydrodynamic forces experienced by the tuned dynamic damping device 12. Specifically, the oscillating body 18 has an inner surface facing the loading / unloading pipe 9, 14 and an outer surface opposite the inner surface, to which the deflector 23 is attached. The deflector 23 may, for example, have an arched shape to redirect the hydrodynamic forces away from the oscillating body 18, as shown in Figure 3.

[0084]

[0085] In the second embodiment illustrated in Figure 4, the tank 71 includes a casing 24 attached to the loading / unloading line 9, 14. The casing 24 is designed to surround the tuned dynamic damping device 12 so as to completely cover it and form a box around the tuned dynamic damping device 12. The casing 24 thus offers the same advantage as the deflector 23, namely reducing hydrodynamic forces, but also prevents part of the tuned dynamic damping device 12 from falling onto the bottom wall 6. The casing 24 may advantageously have added or screened walls to allow the passage of liquefied gas into the casing 24.

[0085]

[0086] Figures 5 to 8 schematically present, from a top view, the tuned dynamic damping device 12 according to several embodiment variants.

[0086]

[0087] The tuned dynamic damping device 12 includes spring devices 25 connecting the oscillating body 18 to the loading / unloading line 9, 14. It is through the spring devices that the vibrations of the loading / unloading line 9, 14 are transmitted and damped to the oscillating body 18. In addition, by choosing the stiffness of the spring device 25, it is possible to tune the tuned dynamic damping device 12 to the main frequency of the vibrations.

[0087]

[0088] In the third embodiment illustrated in Figure 5, the tuned dynamic damping device 12 comprises a pair of spring devices 25, the two spring devices 25 being located on either side of the loading / unloading conduit 9, 14 in the longitudinal direction L. Each spring device 25 of the pair of spring devices here comprises a spring 26 having a first end fixed to the oscillating body 18 and a second end fixed to the loading / unloading conduit 9, 14. In this embodiment, the spring 26 is a leaf spring elastically deformable in bending.

[0088]

[0089] Figure 6 presents a fourth embodiment in which the tuned dynamic damping device 12 comprises a pair of first spring devices 25 in the longitudinal direction L and a pair of second spring devices 27. The pair of second spring devices 27 is located on either side of the loading / unloading line in the transverse direction T. In this embodiment, the springs 26 are helical springs working in tension / compression.

[0089]

[0090] The springs 26 of the second spring devices 27 may have a different stiffness than the springs 26 of the first spring devices 25. Indeed, vibrations in one direction may be of a different frequency than vibrations in the other direction so that the dynamic damping device 12 must be tuned accordingly.

[0090]

[0091] In the fifth embodiment illustrated in Figure 7, and compared to the fourth embodiment, each spring device 25, 27 has, in addition to the spring 26, a damper 28 mounted in parallel. Thus, the spring device 25, 27 designed in this way allows for faster damping of vibrations in the tuned dynamic damping device 12.

[0091]

[0092] Figure 8 shows a sixth embodiment in which, compared to the fourth embodiment, each spring device 25, 27 now comprises a first spring 26 and a second spring 29 connected in series with the first spring 26. Indeed, the first spring 26 has a first end fixed to the loading / unloading conduit 9, 14 and a second end fixed to a first end of the second spring 29, or to a connecting element fixed between the two springs 26, 29. The second end of the second spring 29 is fixed to the oscillating body 18.

[0092]

[0093] Furthermore, the second spring 29 is coupled to an actuator 30. The actuator 30 is configured to, in a locked state, block the deformation of the second spring 29 and, in an unlocked state, allow the deformation of the second spring 29 to proceed freely.

[0093]

[0094] Thus, the two-stage spring device 25, 27 designed in this way can exhibit two different stiffnesses depending on whether the actuator is in the locked or unlocked state. Indeed, if the stiffness k1 is assigned to the first spring 26 and the stiffness k2 to the second spring 29, the stiffness of the spring device 25, 27 is equal to k1 in the locked state and to (k1 x k2) / (k1 + k2) in the unlocked state. The two-stage spring device 25, 27 thus makes it possible, for example, to adapt the stiffness and therefore the damped vibration frequency according to the fill level of the tank 71.

[0095] The embodiments of the tuned dynamic damping device 12 presented are not limited to those shown above. Indeed, other embodiments are possible in which features of various embodiments presented above are combined. For example, the deflector 23 of the first embodiment can be combined with the two-stage spring devices 25, 27 of the sixth embodiment.

[0094]

[0096] Figure 9 represents a graph for a loading / unloading line without a tuned dynamic damping device 12 according to the prior art, while Figure 10 represents a graph for a loading / unloading line with a tuned dynamic damping device 12 according to an embodiment.

[0095]

[0097] These two graphs present vibration frequencies on the x-axis and displacement velocities of the loading / unloading pipe 9, 14 on the y-axis at a given point, each curve representing a different height of the loading / unloading pipe and therefore the velocity at that point. It can thus be observed that the vibration peak 31 of the loading / unloading pipe 9, 14 shown in Figure 9 has been significantly reduced by the presence of a tuned dynamic damping device 12 attached to it, so that only two other vibration peaks 32 remain at similar frequencies and lower velocities.

[0096]

[0098] With reference to Figure 11, a cutaway view of a LNG carrier 70 shows a sealed and thermally insulated tank 71 of generally prismatic shape mounted in the double hull 72 of the ship 70. The wall of the tank 71 comprises a primary sealed membrane intended to be in contact with the LNG contained in the tank, a secondary sealed membrane arranged between the primary sealed membrane and the double hull 72 of the ship 70, and two thermally insulating barriers arranged respectively between the primary sealed membrane and the secondary sealed membrane and between the secondary sealed membrane and the double hull 72.

[0097]

[0099] As is known per se, loading / unloading pipelines 73 arranged on the upper deck of the ship can be connected, by means of suitable connectors, to a marine or port terminal to transfer a cargo of LNG to or from the tank 71.

[0098]

[0100] Figure 11 shows an example of a marine terminal comprising a loading and unloading berth 75, a subsea pipeline 76, and an onshore facility 77. The loading and unloading berth 75 is a fixed offshore facility comprising a movable arm 74 and a tower 78 that supports the movable arm 74. The movable arm 74 carries a bundle of insulated flexible pipes 79 that can be connected to the loading / unloading pipelines 73. The steerable movable arm 74 accommodates all LNG carrier sizes. An unshown connecting pipeline extends inside tower 78. The loading and unloading station 75 allows the loading and unloading of the LNG carrier 70 from or to the onshore facility 77. This facility includes liquefied gas storage tanks 80 and connecting pipelines 81 linked by the subsea pipeline 76 to the loading or unloading station 75.The subsea pipeline 76 allows the transfer of liquefied gas between the loading or unloading station 75 and the onshore facility 77 over a long distance, for example 5 km, which allows the LNG carrier 70 to be kept a long distance from the coast during loading and unloading operations.

[0099]

[0101] To generate the pressure necessary for the transfer of the liquefied gas, pumps on board the ship 70 and / or pumps equipping the land installation 77 and / or pumps equipping the loading and unloading station 75 are used.

[0100]

[0102] Although the invention has been described in connection with several particular embodiments, it is clearly evident that it is by no means limited to them and that it includes all technical equivalents of the means described as well as their combinations if these fall within the scope of the invention.

[0101]

[0103] The use of the verb "comporter", "comprendre" or "include" and its conjugated forms does not exclude the presence of other elements or steps than those stated in a claim.

[0102]

[0104] In claims, any reference sign in parentheses shall not be interpreted as a limitation of the claim.

Claims

DEMANDS

1. A sealed and thermally insulated liquefied gas storage tank (71) intended to be integrated into a load-bearing structure, the tank (71) comprising a bottom wall (6) and a ceiling wall (4) opposite the bottom wall (6) in a height direction (H) of the tank (71), the bottom wall (6) and the ceiling wall (4) intended to be fixed to the load-bearing structure (1), in which the ceiling wall (4) is traversed by at least one loading / unloading pipe (9, 14), the tank comprising a guiding device (11) fixed to the bottom wall (6), the loading / unloading pipe (9, 14) being guided in the height direction (H) by the guiding device (11), in which the tank comprises at least one tuned dynamic damping device (12) fixed in the height direction (H) to the loading / unloading pipe (9, 14),the tuned dynamic damping device (12) comprising an oscillating body (18) extending at least partially around the loading / unloading pipe (9, 14), and spring devices (25, 27) connecting the oscillating body (18) to the loading / unloading pipe (9, 14), each spring device (25, 27) being spaced from the adjacent spring devices around the loading / unloading pipe (9, 14).

2. Tank (71) sealed and thermally insulating according to claim 1, wherein each spring device (25, 27) comprises a spring (26) having a first end fixed to the oscillating body (18) and a second end fixed to the loading / unloading line (9, 14), the spring (26) being configured to be elastically deformable in bending or in tension / compression in a direction perpendicular to the height direction (H).

3. Tank (71) sealed and thermally insulating according to claim 2, wherein each spring device (25, 27) includes a damper (28) in parallel with the spring (26), the damper (28) having a first end fixed to the oscillating body (18) and a second end fixed to the loading / unloading line (9, 14).

4. A sealed and thermally insulating tank (71) according to claim 2 or claim 3, wherein the spring (26) is a first spring, and each spring device (25, 27) comprises the first spring (26) and a second spring (29) connected in series with the first spring (26), the second spring (29) being coupled to an actuator (30), the actuator (30) being configured to be in a locked state block the deformation of the second spring (29) and in an unlocked state allow free deformation of the second spring (29). [Claims] A sealed and thermally insulating tank (71) according to any one of claims 1 to 4, wherein the spring devices are first spring devices, the first spring devices (25, 27) consisting of a pair of first spring devices located on either side of the loading / unloading line (9, 14) in a longitudinal direction (L) of the tank perpendicular to the height direction (H), and wherein the tuned dynamic damping device (12) comprises a pair of second spring devices (25, 27), the pair of second spring devices (25, 27) being located on either side of the loading / unloading line (9, 14) in a transverse direction (T) of the tank perpendicular to the height direction (H) and perpendicular to the longitudinal direction (L) of the tank.

6. A sealed and thermally insulating tank (71) according to claim 5, wherein a stiffness of the first spring devices (25, 27) is different from a stiffness of the second spring devices (25, 27).

7. A sealed and thermally insulating tank (71) according to any one of claims 1 to 6, wherein the tuned dynamic damping device (12) is located midway between the bottom wall (6) and the ceiling wall (4) in the height direction (H). [Claims] A sealed and thermally insulating tank (71) according to any one of claims 1 to 7, wherein the tank includes a protection system configured to protect the tuned dynamic damping device (12), the protection system being attached to the tuned dynamic damping device (12) or to the loading / unloading line (9, 14).

9. A sealed and thermally insulating tank (71) according to any one of claims 1 to 8, wherein the tank comprises a fastening device (19) configured to fix the tuned dynamic damping device (12) to the loading / unloading line (9, 14), the fastening device (19) comprising a ball joint tie rod (20) extending in the height direction (H) and having a first end connected by a first ball joint (21) to the oscillating body (18) and having a second end connected by a second ball joint (22) to the loading / unloading line (9, 14).

10. A sealed and thermally insulating tank (71) according to any one of claims 1 to 9, wherein the tank comprises a damping device additional tuned dynamic (17) fixed in the height direction (H) to the loading / unloading line (9, 14), the additional tuned dynamic damping device (17) being spaced from the tuned dynamic damping device (12) in the height direction (H). [Claim 1 1] A sealed and thermally insulating tank (71) according to any one of claims 1 to 10, wherein the loading / unloading pipe (9, 14) is a first loading / unloading pipe (9, 14) and the tuned dynamic damping device (12) is a first tuned dynamic damping device (12), the ceiling wall (4) being traversed by at least one second loading / unloading pipe (9, 14), the second loading / unloading pipe (9, 14) being guided in the height direction (H) by the guiding device (11), the tank comprising a second tuned dynamic damping device (12) fixed in the height direction (H) to the second loading / unloading pipe (9, 14).

12. A sealed and thermally insulating tank (71) according to any one of claims 1 to 11, wherein each spring device (25, 27) has a stiffness whose value is chosen to be tuned to a target frequency of vibrations to be dissipated.

13. Vessel (70) for the transport of a cold liquid product, the vessel extending in a longitudinal direction (L) of vessel and comprising a double hull (72) and a tank (71) according to any one of claims 1 to 12 disposed in the double hull.

14. Transfer system for a cold liquid product, the system comprising a vessel (70) according to claim 13, insulated pipes (73, 79, 76, 81) arranged to connect the tank (71) installed in the hull of the vessel to a floating or land-based storage facility (77) and a pump to drive a flow of cold liquid product through the insulated pipes from or to the floating or land-based storage facility to or from the vessel tank.

15. A method of loading or unloading a ship (70), wherein a cold liquid product is conveyed through insulated pipes (73, 79, 76, 81) from or to a floating or land-based storage facility (77) to or from the tank (71) of the ship (70) according to claim 13.

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