Double-walled liquefied gas storage tank

Abstract

The invention relates to a double-walled storage tank for liquefied gas, in particular cryogenic fluid, comprising an inner wall (2) and an outer wall (3) which is arranged around the inner wall with a thermally insulated gap (4), wherein the inner wall (2) is suspended in the outer wall (3) at at least one of its ends via a tensioned-cable(s) suspension system between the inner wall (2) and the outer wall (3), the suspension system comprising the one same cable (5) passing back and forth more than once between the inner wall (2) and the outer wall (3) via respective guide passages (7), the cable (5) forming a plurality of connections between the inner wall (2) and the outer wall (3) in different directions, one end of the cable (5) being secured to one of the walls (3) and configured to place the cable (5) under tension.

Description

Double-walled liquefied gas storage tank

[0001] The invention relates to a double-walled liquefied gas storage tank, in particular cryogenic fluids.

[0002] The invention relates more particularly to a double-walled liquefied gas storage tank, in particular for cryogenic fluids, comprising an inner wall delimiting a storage volume for the fluid and an outer wall arranged around the inner wall with a thermally insulated spacing, in which the inner wall is suspended in the outer wall at at least one of its ends via a suspension system with cable(s) stretched between the inner wall and the outer wall.

[0003] Cryogenic tanks (for storing, for example, liquefied hydrogen, liquefied nitrogen, liquefied natural gas or other) generally consist of two walls or envelopes assembled one inside the other, with an inter-wall space allowing thermal insulation.

[0004] This inter-wall space is generally filled with thermal insulating material (foam, multi-layer, etc.) and possibly placed under vacuum.

[0005] The fluid is stored in the inner casing. The mechanical connection between the outer casing and the inner casing must fulfill two roles: limit thermal inputs by conduction and ensure sufficient mechanical strength to meet different load cases.

[0006] The supports or connections must therefore be sized to limit conduction while resisting load cases. The supports used today in trailers transporting cryogenic fluids are generally made of steel, in the form of a neck (sliding or not) and tie rods.

[0007] These geometries have disadvantages. The use of metal necks results in heat inputs that can be significant, as well as assembly difficulties (particularly in weld controls for use with hydrogen).

[0008] To replace these collars, suspension systems using strips or cables mounted on the dome of the internal envelope are known. However, the known solutions are bulky, complex and hinder the installation of thermal insulation in the inter-wall space.

[0009] Documents US2007068954 and FR1604703 describe other solutions for suspension by bands. However, these solutions are complex and unsatisfactory. In particular, each of the bands requires its own mechanism and the adjustment of the different bands is complex for the centering of the inner envelope in the outer envelope.

[0010] An aim of the present invention is to overcome all or part of the drawbacks of the prior art noted above.

[0011] An aim of the invention may thus be to propose a more suitable architecture which minimizes heat transfer, makes it possible to respond to load cases and simplifies manufacturing, if possible by avoiding welding.

[0012] To this end, the tank according to the invention, moreover in accordance with the generic definition given in the preamble above, is essentially characterized in that the suspension system comprises the same cable forming more than one round trip between the internal wall and the external wall via respective guide passages, the cable forming a plurality of connections between the internal wall and the external wall in distinct directions and in that one end of said cable is secured to one of the walls and configured to tension the cable.

[0013] Furthermore, embodiments of the invention may include one or more of the following features: the plurality of connections formed by the cable between the inner wall and the outer wall are located between two respective ends of the inner wall and the outer wall, the tank has a generally symmetrical shape of revolution around a central axis, the connections of the cable between the inner wall and the outer wall are arranged around said central axis and in a plane substantially perpendicular to this central axis, the cable guide passages at the level of the inner and outer walls are formed by rings or orifices carried respectively by the inner and outer walls, the cable guide passages are carried by a plate and / or a ring secured to one end of the wall in question, the two ends of the cable are fixed to the same connection point adjustable in position,the connection point is movable in a determined direction and acted upon by a return member such as a spring to tension the cable, the tank comprises a mechanism for adjusting the tension exerted by the return member on the cable, the tank has a generally cylindrical shape with a circular section and extending in a longitudinal direction, the tank is of the horizontal type, i.e. the longitudinal direction is horizontal in the tank's operating configuration, the cable is composed of at least one of the following materials: polymer, polymer and / or composite fiber(s), kevlar, epoxy, carbon, glass fibers.,

[0014] The invention may also relate to any alternative device or method comprising any combination of the above or below features within the scope of the claims.

[0015] Other features and advantages will appear on reading the description below, made with reference to the figures in which: Brief description of the figures

[0016] The invention will be better understood on reading the following description, given solely by way of example and with reference to the appended drawings in which:

[0017] is a schematic and partial view in longitudinal and vertical section of an example of a tank according to a possible embodiment of the invention,

[0018] is a schematic and transparent perspective view of one end of a tank according to another embodiment of the invention,

[0019] is a schematic perspective view of a detail of the,

[0020] is a sectional view of a detail of the,

[0021] is a sectional view of an enlarged detail of the. Detailed description

[0022] The illustrated double-walled liquefied gas storage tank 1 comprises an inner wall 2 or casing delimiting a sealed storage volume for the fluid and an outer wall 3 or casing arranged around the inner wall with a spacing 4 between these two walls 2, 3. This spacing is thermally insulated, for example via one or more layers of thermal insulating materials. Where appropriate, this spacing is under vacuum.

[0023] The inner wall 2 is suspended in the outer wall 3 at at least one of its ends, for example a longitudinal end via a suspension system with cable(s) stretched between the inner wall 2 and the outer wall 3 and described in more detail below.

[0024] The other end (opposite end) of the inner wall 2 is preferably also suspended in the outer wall 3 via the same suspension system with cable(s) stretched between the inner wall 2 and the outer wall 3. However, the other end may be suspended via another connecting structure, for example a fixed or sliding collar, a set of tie rods, etc.

[0025] As illustrated, the tank 1 may have a generally cylindrical shape with a circular section and extending in a longitudinal direction. The tank has, for example, a generally symmetrical shape of revolution around a central axis 6. In addition, the tank 1 is preferably of the horizontal type, that is to say that the longitudinal direction is horizontal in the configuration of use of the tank as illustrated in the (horizontal central axis 6).

[0026] The illustrated suspension system comprises a single cable 5 forming more than one round trip between the inner wall 2 and the outer wall 3 via respective guide passages 7 at the inner wall 2 and the outer wall 3. That is to say that the cable 5 defines at least three taut portions between the inner wall 2 and the outer wall 3, the cable 5 passing through at least two guide passages allowing a change of direction (return from one wall to the other). This forms a plurality of tensile connections between the inner wall 2 and the outer wall 3 in distinct directions with a single cable.

[0027] In addition, at least one end of the cable 3 is secured to one of the walls 3 and configured to tension the cable 5 in each of its portions forming a connection between the internal wall 2 and the external wall 3.

[0028] Thus, the two walls 2, 3 are easily centered relative to each other and the adjustment of the cable tension can be carried out at a single location for all the connections ensuring tensile forces in different directions around the central axis 6.

[0029] The plurality of connections formed by the cable 5 between the inner wall 2 and the outer wall 3 are preferably located between two respective ends of the inner wall 2 and the outer wall 3. That is to say that this connection system is put in place at the neck of the tank, in the vicinity of the tops of the ends of the two walls 2, 3 (between the outer face of the inner wall 2 and the inner face of the outer wall 3).

[0030] As illustrated, preferably the connections of the cable 5 between the internal wall 2 and the external wall 3 are arranged around the longitudinal central axis and in a plane substantially perpendicular to this central axis 6.

[0031] As illustrated, the cable may form a plurality of star connections over 360 degrees around this central axis 6.

[0032] As illustrated, the two ends of the cable 3 can be fixed to the same connection point 8 adjustable in position. These two ends of the cable 5 can be connected together at a determined location and configured to allow adjustment, possibly with a return member 9, of the tension in this cable and therefore to adjust both the relative axial and longitudinal position of the two walls 2, 3. For example, the device comprises a mechanism 10 for adjusting the tension exerted by the return member 9 on the cable 5.

[0033] For example, at least one of the ends of the cable 5 is fixed to a support whose position can be adjusted by screwing, for example an axis or a movable inner sheath in a fixed outer sheath 80, the position of the axis or of the inner sheath relative to the fixed outer sheath 80 is adjustable via a mechanical system, for example a nut 10.

[0034] In the examples illustrated, the cable guide passages 7 at the level of the internal 2 and external 3 walls are formed by loops or eyelets fixed respectively by the internal 2 and external 3 walls (preferably fixed on a support itself fixed to the wall 2, 3 concerned).

[0035] For example, and as illustrated, the passages 7 for guiding the cable 5 are defined by rings or eyelets fixed respectively by a plate 11 secured to an external end of the internal wall 2 and on a ring 12 or plate secured to an internal end of the external wall 3.

[0036] The rings can thus be fixed by screwing, welding or other means.

[0037] Of course, this embodiment is not limiting, thus, all or part of the loops could be replaced by simple passage holes provided in the plate 11 or ring 11 allowing the passage and guidance of the cable 5.

[0038] The cable 5 is composed, for example, of at least one of the following materials: polymer, polymer fiber(s) and / or composite fibers, Kevlar carbon, epoxy, glass fibers, etc. This type of polymer / composite fiber is very strong (high Young's modulus and fracture toughness) and has low thermal conduction.

[0039] Thus, at at least one end a single cable 5 and a single system for adjusting its tension can be provided to ensure the suspension (and its adjustment) of the internal wall 2 in the external wall 3.

[0040] The suspension system is compact, has low thermal conductivity, is mechanically robust and is easier to manufacture than known solutions (no or minimal welding, easy access, low interaction with inter-wall insulation). This solution is particularly suitable for on-board solutions (transported mobile tanks) of small volume (approximately 1 m3) for which size and thermal performance are critical (typically for liquid hydrogen).

Claims

A double-walled liquefied gas storage tank, in particular for cryogenic fluids, comprising an inner wall (2) delimiting a storage volume for the fluid and an outer wall (3) arranged around the inner wall with a thermally insulated spacing (4), wherein the inner wall (2) is suspended in the outer wall (3) at at least one of its ends via a suspension system with tensioned cable(s) between the inner wall (2) and the outer wall (3), characterized in that the suspension system comprises a single cable (5) forming more than one round trip between the inner wall (2) and the outer wall (3) via respective guide passages (7), the cable (5) forming a plurality of links between the inner wall (2) and the outer wall (3) in distinct directions and in that one end of said cable (3) is attached to one of the walls (3) and configured to tension the cable (3). Tank according to claim 1, characterized in that the plurality of links formed by the cable (5) between the inner wall (2) and the outer wall (3) are located between two respective ends of the inner wall (2) and the outer wall (3). Tank according to claim 1 or 2, characterized in that the tank has a general symmetrical shape of revolution about a central axis (6) and in that the connections of the cable (5) between the inner wall (2) and the outer wall (3) are arranged around said central axis (6) and in a plane substantially perpendicular to this central axis (6). Reservoir according to any one of claims 1 to 3, characterized in that the cable guidance passages (7) at the level of the internal (2) and external (3) walls are formed by rings or orifices carried respectively by the internal (2) and external (3) walls. Reservoir according to claim 4, characterized in that the cable (5) guide passages (7) are carried by a plate (11) and / or a ring (12) integral with one end of the wall (2, 3) considered. Reservoir according to any one of claims 1 to 5, characterized in that the two ends of the cable (3) are fixed to the same attachment point (8) which is adjustable in position. Reservoir according to claim 6, characterized in that the connection point (8) is movable in a determined direction and stressed by a return member (9) such as a spring to put the cable under tension. Reservoir according to claim 7, characterized in that it comprises a mechanism (10) for adjusting the tension exerted by the return member (9) on the cable (5). Tank according to any one of claims 1 to 8, characterized in that the tank has a general cylindrical shape with a circular cross-section and extending in a longitudinal direction. Tank according to claim 9, characterized in that the tank (1) is of the horizontal type, i.e. that the longitudinal direction is horizontal in the tank's operating configuration. Reservoir according to any one of claims 1 to 10, characterized in that the cable (5) is composed of at least one of the following materials: polymer, polymer fiber(s) and / or composite, Kevlar, epoxy, carbon, glass fibers. Tank according to any one of claims 1 to 11, characterized in that it comprises such a cable suspension system (5) at only one of its ends or at each of two distinct ends of the tank (1).

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