The invention relates to the field of sealed and thermally insulating tanks for storing and/or transporting fluid, such as cryogenic fluid.
The invention relates more particularly to the field of tanks, the sealing thereof being implemented by metal membranes having corrugations which provide said metal membranes with a flexibility and a capacity for elongation in one or more directions of a plane.
Such tanks are used, in particular, for the transport or storage of liquefied natural gas (LNG) which is stored at atmospheric pressure at approximately −162° C.
Sealed and thermally insulating tanks for transporting and/or storing cryogenic fluid are known from the patent application FR 2 861 060, said tanks comprising heat-insulating panels covered by a corrugated sealing membrane. The sealing membrane comprises an inner face which is designed to be in contact with the fluid contained in the tank and an outer face which is anchored to the inner face of the heat-insulating panel. The sealing membrane consists of a plurality of metal plates which are made of stainless steel and have series of perpendicular corrugations which enable the forces to be absorbed. The corrugated plates are welded to one another along the edges thereof and are anchored to the panels by welding the edges of the plates to strips which are also made of stainless steel and riveted to said heat-insulating panels.
The inner face of the heat-insulating panels has slots extending in the transverse direction relative to the length of the vessel, over the entire length of the heat-insulating panels. Such slots permit a deformation of the corrugations, without the heat-insulating panels becoming cracked when the tank is subjected to cold temperatures.
One idea on which the invention is based is to propose a sealed and thermally insulating wall having a corrugated membrane which is resistant to low temperatures and has limited flexion when subjected to cold temperatures.
According to one embodiment, the invention provides a sealed and thermally insulating wall for a tank for storing fluid, comprising:
Thus, the corrugation provides the sealing membrane with a flexibility which enables it to deform, in particular under the action of the flexion of the heat-insulating panels and the thermal contraction of the sealing membrane.
Moreover, the stress-relieving slot makes it possible to exploit fully this corrugation since it permits a deformation of the sealing membrane without imposing mechanical stresses which are too great on the heat-insulating panel.
Moreover, when a tank is filled with a cryogenic fluid, such as liquefied natural gas, the difference in temperature between the outside of the tank and the inside generates a thermal gradient within the heat-insulating panels. This thermal gradient may cause the flexion of the heat-insulating panels and thus the flexion of the sealing membrane. In contrast to a slot extending on either side of a heat-insulating panel, a stress-relieving slot which does not extend over the entire width or length of the panel makes it possible for the panel to preserve a certain degree of rigidity and thus limits the impact of a stress-relieving slot on the flexibility of the heat-insulating panel under thermal load.
According to the embodiments, such a sealed and thermally insulating wall may comprise one or more of the following features:
According to one embodiment, the invention also provides a fluid storage tank comprising a load-bearing structure and at least one wall as mentioned above which is fixed to the load-bearing structure.
Such a tank may form part of a land-based storage installation, for example to store LNG, or may be installed in a floating structure which is inshore or offshore, in particular an LNG carrier, a floating storage and regasification unit (FSRU), a floating production, storage and offloading unit (FPSO) and the like.
According to one embodiment, a vessel for the transport of a fluid comprises a double hull forming the load-bearing structure and a tank as mentioned above and arranged in the double hull.
According to one embodiment, the invention also provides a use of a vessel as mentioned above and in which a fluid is conducted through insulated pipelines from or toward a floating or land-based storage installation toward or from the tank of the vessel in order to load or unload the vessel.
According to one embodiment, the invention also provides a system for the transfer of a fluid, the system comprising the aforementioned vessel, insulated pipelines being arranged so as to connect the tank installed in the hull of the vessel to a floating or land-based storage installation and a pump to drive a flow of fluid through the insulated pipelines from or toward the floating or land-based storage installation toward or from the tank of the vessel.
According to one embodiment, the invention is particularly advantageous when the means for fastening the heat-insulating panels to the load-bearing structure are not capable of absorbing the flexural stresses of the heat-insulating element, for example when the heat-insulating panel is not fixed in its peripheral area but solely in the region of a central area of its external surface.
According to one embodiment, the invention also makes it possible to obtain improved behavior relative to the ageing of the insulating foam of the heat-insulating panels. More specifically, the stress-relieving slots do not extend over the entire length or width of the heat-insulating panels, the exchange surface between the insulating foam and the ambient air being restricted such that the diffusion of the expansion gas outside the cells of the foam and the migration of air therein are limited.
The invention will be understood, and further objects, details, features and advantages thereof, will appear more clearly from the following description of several particular embodiments of the invention provided solely by way of illustrative and non-limiting example with reference to the accompanying drawings, in which:
Conventionally, the terms “external” and “internal” are used to define the relative position of one element relative to another, with reference to the inside and outside of the tank.
Each tank wall in the thickness direction, successively from the inside to the outside of the tank, has at least one sealing membrane in contact with the fluid contained in the tank, a thermally insulating barrier and a load-bearing structure, not shown. In one particular embodiment, not illustrated, a wall may also comprise two levels of sealing and thermal insulation.
By way of example, the panel 1 has a length of 3 meters by a width of 1 meter. The internal sheet of plywood 3 may have a thickness of 12 mm; the external sheet of plywood 4: a thickness of 9 mm and the layer of insulating foam 2: a thickness of 200 mm. Naturally, the dimensions and thicknesses are provided by way of indication and vary according to the desired applications and thermal insulating performance.
The internal surface of the panel 1 comprises metal anchoring plates 5, 6 designed to anchor the metal plates 7, one example thereof being illustrated in
The sealing membrane is obtained by assembling multiple metal plates 7 welded to one another along their edges. As illustrated in
The metal plate 7 is produced from stainless steel or aluminum sheet, shaped by folding or stamping. Further metals or alloys are also possible. By way of example, the metal plate 7 has a thickness of approximately 1.2 mm. Further thicknesses are also conceivable, given that a thickening of the metal plate 7 results in an increase in its cost and generally increases the rigidity of the corrugations.
In the region of one of the two transverse edges 13 and in the region of one of the two longitudinal edges 12, the metal plate 7 has a stamped strip, not shown, which is inwardly offset in the thickness direction relative to the plane of the plate 7 in order to cover the edge of an adjacent metal plate 7.
A relative positioning of a metal plate 7 in relation to a heat-insulating panel 1 is illustrated in
One of the longitudinal edges 12 of the metal plate 7 is anchored to the heat-insulating panel 1 by welding said longitudinal edge 12 to the metal anchoring plates 5. Similarly, one of the transverse edges 13 is anchored to the heat-insulating panel 1 by welding said transverse edge 13 to the metal anchoring plates 6. The anchoring areas 14 between the metal plate 7 and the heat-insulating panel 1 are located on either side of the corrugations 8, 9. In other words, the anchoring areas 14 are formed at the interface between the planar portions 11 of the edges 12, 13 of the metal plates 7 extending on either side of the corrugations 8, 9 and the metal anchoring plates 5, 6.
It is noteworthy that the central corrugation of each of the series of corrugations 8, 9 advantageously extends opposite the join between two adjacent heat-insulating panels 1.
The internal surface of the heat-insulating panel 1 is provided with a plurality of stress-relieving slots 15, 16. A first series of stress-relieving slots 15 extends in the direction y of the corrugations 8. A second series of stress-relieving slots 16 extends in the direction x of the corrugations 9.
In
The stress-relieving slots 15, 16 have lengths which are shorter than the dimension of the heat-insulating panel 1 along their axis. In other words, the stress-relieving slots 15, 16 do not extend as far as the periphery of the heat-insulating panel 1. Advantageously, the length of a stress-relieving slot 15, 16 substantially corresponds to the spacing between two intersections 10 of corrugations in the direction of the slot 15, 16.
In one embodiment shown in
In a further embodiment shown in
In the embodiments of
In the embodiment of
The manufacture of the heat-insulating panels 1 may be carried out according to various embodiments. According to one embodiment, the internal plate 3 and external plate 4 are, for example, bonded on either side of the layer of insulating polymer foam 2 and then the stress-relieving slots 15, 16 are cut out. Finally, when the stress-relieving slots 15, 16 have been cut out, the metal anchoring plates 5, 6 are fixed, for example, by riveting to the internal rigid plate 3.
Alternatively, it is also possible to cut out previously the internal rigid plate 3, the layer of insulating polymer foam 2 and optionally the external rigid plate 4 and then to bond the internal rigid plate 3 and external rigid plate 4 to the layer of insulating polymer foam 2 by adjusting the slots formed in the internal plate 3 and in the layer of insulating polymer foam 2.
The slots 15, 16 may be cut out by means of a device of the slotting machine type or any other appropriate device such as by means of a water jet, laser cutting, jigsaw, fret saw, milling, circular saw, or the like.
A sealed and thermally insulating tank may comprise one or more walls as disclosed above. Such a tank may form part of a land-based storage installation, for example to store LNG, or may be installed in a floating structure, onshore or offshore, in particular an LNG carrier, a floating storage and regasification unit (FSRU), a floating production, storage and offloading unit (FPSO) and the like.
With reference to
In the manner known per se, supply/discharge pipelines 73 arranged on the upper bridge of the vessel may be connected by means of appropriate connectors to a marine or harbor terminal to transfer an LNG cargo from or toward the tank 71.
To create the pressure necessary for the transfer of the liquefied gas, pumps mounted on board the vessel 70 and/or pumps provided on the land-based installation 77 and/or pumps provided at the supply and discharge station 75 are used.
Although the invention has been described in connection with several particular embodiments, it is obvious that it is not limited thereby in any respect and it comprises all the technical equivalents of the means disclosed, in addition to combinations thereof if they fall within the scope of the invention.
The use of the verbs “to consist of” “to comprise” or “to include” and their conjugated forms does not exclude the presence of other elements or other steps from those cited in a claim. The use of the indefinite article “a” or “an” for an element or a step does not exclude, unless indicated to the contrary, the presence of a plurality of such elements or steps.
In the claims, any reference between parentheses should not be interpreted as a limitation to the claim.
Number | Date | Country | Kind |
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13 51263 | Feb 2013 | FR | national |
Filing Document | Filing Date | Country | Kind |
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PCT/FR2014/050169 | 1/30/2014 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
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WO2014/125186 | 8/21/2014 | WO | A |
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20140299038 | Shin | Oct 2014 | A1 |
Number | Date | Country |
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2412624 | Feb 2012 | EP |
2781557 | Jan 2000 | FR |
48-34268 | Oct 1973 | JP |
2007-155065 | Jun 2007 | JP |
2009059617 | May 2009 | WO |
WO 2012072906 | Jun 2012 | WO |
Entry |
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English machine translation of Hayashi JP 2007-155065. |
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Number | Date | Country | |
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20150354756 A1 | Dec 2015 | US |