Thermally Insulating Sealed Tank

Abstract

A sealed and thermally insulating tank incorporated in a supporting structure (2), the tank including at least one inclined tank wall (1) forming an angle with a horizontal direction and fixed to a supporting wall of the supporting structure (2) is disclosed. The tank wall (1) has a multilayer structure including successively, in the direction of thickness from the outside to the inside of the tank, a thermally insulating barrier (3) held against the corresponding supporting wall and a sealed membrane (4) carried by the thermally insulating barrier (3). The tank includes sealed strips (15) in the space formed between the thermally insulating barrier (3) and the supporting wall.

Claims

1. A sealed and thermally insulating tank (71) incorporated in a supporting structure (2), the tank including at least one inclined tank wall (1) forming an angle with a horizontal direction and fixed to a supporting wall of the supporting structure (2), the tank wall (1) having a multilayer structure including successively, in the direction of the thickness (52) from the outside to the inside of the tank, a thermally insulating barrier (3) held against the corresponding supporting wall and a sealed membrane (4) carried by the thermally insulating barrier (3), the tank comprising sealed or substantially sealed strips (15) in the space formed between the thermally insulating barrier (3) and the supporting wall, wherein the sealed strips (15) segment the space between the thermally insulating barrier (3) and the supporting wall in a plurality of successive zones (14) in a direction of greatest slope (51) of the wall, the zones (14) extending over an entire transverse dimension of the tank wall (1) in a transverse direction (50) inclined relative to the direction of greatest slope.

2. The tank as claimed in claim 1, in which at least one of the sealed strips (15) is extended over all the transverse dimension of the tank wall (1).

3. The tank as claimed in claim 1, in which at least one of the sealed strips is formed of a polymer material, for example a mastic or a closed cell foam, for example a closed cell polyurethane foam, or the combination of an EPDM rubber strip with a polyester foam strip.

4. The tank as claimed in claim 1, in which at least one of the sealed strips (15) includes a plurality of strip portions (16) connected to one another in sealed manner by at least one fishplate (18), the fishplate (18) being disposed between two adjacent strip portions (16).

5. The tank as claimed in claim 4, in which the fishplate (18) has a first end situated in a first strip portion (16) and a second end situated in a second strip portion (16), the second strip portion (16) being adjacent to the first strip portion (16).

6. The tank as claimed in claim 4, in which the thermally insulating barrier (3) comprises a plurality of insulating blocks (5) juxtaposed to one another in the direction of greatest slope and in the transverse direction, at least one of the sealed strips (15) being interrupted at the level of an interface or an interstice between two adjacent insulating blocks (5), the fishplate (18) being disposed between two adjacent insulating blocks (5) so as to connect two adjacent strip portions (16) in sealed manner.

7. The tank as claimed in claim 1, in which at least one of the substantially sealed strips ( 15) is traversed by a high head loss communication channel (17) so that the zones (14) separated by said at least one substantially sealed strip (15) are in slow fluidic communication enabling the pressure to be balanced between the two zones without allowing significant convective flow.

8. The tank as claimed in claim 7, in which each zone (14) is in fluidic communication with an adjacent zone (14) via at least high head loss communication channel (17).

9. The tank as claimed in claim 7, in which the head loss of a communication channel (17) is greater than or equal to , where ΔP is the minimum head loss of the communication channel, PG the driving pressure of the gas situated in the space between the thermally insulating barrier (3) and the supporting structure (2) of the tank wall (1) under normal conditions of use of the tank, and n representing the number of zones (14) segmented by the substantially sealed strips (15).

10. The tank as claimed in claim 9, in which the high head loss communication channel (17) includes a porous material filling the communication channel (17), the porous material having a porosity configured to result in a head loss greater than or equal to the minimum head loss ΔP.

11. The tank as claimed in claim 10, in which the porous material of the communication channel is chosen from melamine foam, open cell polyurethane (PU) foam and fiber braids.

12. The tank as claimed in claim 7, in which at least one of the substantially sealed strips is discontinuous only at the level of the communication channel or channels.

13. The tank as claimed in claim 7, in which a plurality of substantially sealed strips are traversed by a communication channel, the communication channel of a substantially sealed strip being offset from the communication channel of an adjacent substantially sealed strip in the transverse direction so as to form a network of communication channels in a quincunx arrangement.

14. The tank as claimed in claim 1, in which the thermally insulating barrier comprises a plurality of rows of insulating blocks extending in the transverse direction, the insulating blocks having a longitudinal dimension in the direction of greatest slope, two adjacent sealed or substantially sealed strips being spaced from one another in the direction of greatest slope by a dimension equal or substantially equal to the longitudinal dimension of the insulating blocks.

15. The tank as claimed in claim 1, in which the sealed membrane (4) consists of a corrugated sealed membrane (4) including a plurality of corrugated metal plates (9) welded to one another.

16. The tank as claimed in claim 1, in which the tank comprises a single sealed membrane (4) and a single thermally insulating barrier (3).

17. The tank as claimed in claim 1, in which the sealed membrane (4) is a secondary sealed membrane and the thermally insulating barrier (3) is a secondary thermally insulating barrier, the tank including a primary thermally insulating barrier carried by the secondary sealed membrane and a primary sealed membrane carried by the primary thermally insulating barrier.

18. A ship (70) for the transport of a cold liquid product, the ship including a double hull (72) and a tank (71) as claimed in claim 1, disposed in the double hull.

19. A transfer system for a cold liquid product, the system including a ship (70) as claimed in claim 18, insulated pipes (73, 79, 76, 81) arranged in such a manner as to connect the tank (71) installed in the hull of the ship to a floating or terrestrial storage unit (77) and a pump for driving a flow of cold liquid product through the insulated pipes from or to the floating or terrestrial storage installation to or from the tank of the ship.

20. A method of loading or offloading a ship (70) as claimed in claim 18, in which a cold liquid product is routed through insulated pipes (73, 79, 76, 81) from or to a floating or terrestrial storage installation (77) to or from the tank (71) of the ship.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0054] The invention will be better understood and better aims, details, features and advantages thereof will become more clearly apparent during the following description of a plurality of particular embodiments of the invention given by way of nonlimiting illustration only with reference to the appended drawings.

[0055] FIG. 1 is a cutaway perspective view of a tank wall in accordance with a first embodiment.

[0056] FIG. 2 is a view in section in the transverse direction of a tank wall in accordance with the first embodiment.

[0057] FIG. 3 is a schematic front view from inside the tank of a tank wall in accordance with a second embodiment with the sealed membrane omitted.

[0058] FIG. 4 is a schematic front view from inside the tank of a tank wall in accordance with a third embodiment with the sealed membrane omitted.

[0059] FIG. 5 is a schematic front view from outside the tank of a tank wall in accordance with a fourth embodiment.

[0060] FIG. 6 is a schematic cutaway representation of a methane tanker ship tank and a terminal for loading/offloading that tank.

DESCRIPTION OF EMBODIMENTS

[0061] In the description hereinafter there will be describe a sealed and thermally insulating tank 71 comprising at least one inclined tank wall 1 forming an angle with a horizontal direction and fixed to a supporting wall of the supporting structure 2. The particular case of a vertical wall will be described hereinafter. However, the invention is not limited to the particular case of a vertical wall.

[0062] In the case of a vertical wall, the direction of greatest slope 51 of that wall is therefore the vertical direction. Here the term “vertical” means extending in the direction of the terrestrial gravity field. Here the term “horizontal” means extending in a direction perpendicular to the vertical direction.

[0063] As represented in FIG. 1, the tank wall 1 has a multilayer structure including successively, in the direction 52 of thickness from the outside to the inside of the tank 71, a thermally insulating barrier 3 retained against the supporting wall 2 and a sealed membrane 4 carried by the thermally insulating barrier 3.

[0064] In the embodiment represented the thermally insulating barrier 3 includes a plurality of insulating blocks 5 that are anchored to the supporting wall 2 by means of retaining devices or couplers (not represented). The insulating blocks 5 have a parallelepipedal general shape and are disposed in parallel rows. The insulating blocks 5 may be produced with various structures.

[0065] An insulating block 5 may be produced in the form of a box including a bottom plate, a cover plate and supporting webs extending in the direction of thickness of the tank wall between the bottom plate and the cover plate and delimiting a plurality of compartments filled with an insulating packing such as perlite, glass wool or rock wool. A general structure of this kind is described for example in WO2012/127141 or WO2017/103500.

[0066] An insulating block 5 may also be produced with a bottom plate 7, a cover plate 6 and possibly an intermediate plate, for example made of plywood. The insulating block 5 also includes one or more layers of insulating polymer foam 8 sandwiched between the bottom plate 7, the cover plate 6 and the possible intermediate plate and stuck thereto. The polymer insulating foam 8 may in particular be a foam based on polyurethane, optionally reinforced by fibers. A general structure of this kind is for example described in WO2017/006044.

[0067] The sealed membrane 4 may consist of a continuous layer of metal plates 9 welded edge to edge in sealed manner that includes two mutually perpendicular series of corrugations 10,11. The two series of corrugations 10, 11 may have a regular spacing or an irregular periodic spacing. The corrugations 10, 11 may be continuous and form intersections between the two series of corrugations 10, 11. Otherwise, the corrugations 10, 11 may feature discontinuities of some corrugations at the level of the intersections between the two series. The corrugated metal plates 9 are made of stainless steel.

[0068] In order to block the thermosiphon effect of circulation of gas in the space 12 between the thermally insulating barrier 3 and the supporting structure 2, hereinafter referred to as the barrier/support space 12, there is provision for segmenting that barrier/support space 12 so as to form zones 14 in succession in the direction of greatest slope of the tank wall 1.

[0069] FIGS. 1 and 2 show a first embodiment in which sealed strips 15 segment the space between the thermally insulating barrier and the supporting wall in the direction 51 of greatest slope into a plurality of zones 14. In this embodiment the sealed strips 15 are placed at the junction between two rows of insulating blocks 5 extending in a transverse direction 50 inclined relative to the direction 51 of greatest slope. In the embodiment represented the transverse direction 50 corresponds to the horizontal direction i.e. the direction at an angle of 90° to the direction 51 of greatest slope of a vertical wall. The sealed strips 15 therefore extend over the entire transverse dimension of the tank wall 1 with no discontinuity. The sealed strips 15 are therefore rectilinear here. The sealed strips 15 may for example be formed of mastic or of closed cell polymer foam. In an embodiment not represented the transverse direction 50 may form a non-zero angle with the horizontal direction, for example between −20° and 20°.

[0070] As can be seen in FIG. 2, an insulating seal 19 is placed between two adjacent insulating blocks 5 in the direction of thickness of the tank wall 1. The insulating seal 19 enables filling of the spaces of the insulating blocks 5 in the direction of thickness so as to improve the thermal insulation of the thermally insulating barrier 3. The insulating seal 19 may for example consist of glass wool or of a sprayed polymer foam.

[0071] In FIGS. 3 and 4 elements illustrated in dashed line are drawn thus to represent their place between the insulating blocks 5 of the thermally insulating barrier 3 and the supporting structure 2.

[0072] FIG. 3 represents a second embodiment of segmentation of the barrier/support space 12 in the direction of greatest slope. In this illustration, for greater clarity, only the thermally insulating barrier 3 with some of the insulating blocks 5 and the supporting structure 2 are illustrated. In this embodiment, and in contrast to the first embodiment, the sealed strips 15 are distributed regularly or irregularly under the thermally insulating barrier 3 in the direction of greatest slope. Thus in the example illustrated a plurality of sealed strips 15 extend under each insulating block 5 of the thermally insulating barrier 3 in the transverse direction. Here the sealed strip 15 consists of beads of mastic placed on the supporting structure before positioning the insulating blocks 5.

[0073] Moreover, in this embodiment illustrated in FIG. 3 each sealed strip 15 is traversed in the direction of greatest slope by a communication channel 17 which therefore weakens the sealing property of the substantially sealed strip 15 without eliminating it completely. The communication channel 17 is for example formed by a porous material, for example by one or more braids of fibers, inserted in the sealed strip 15 so that the braids extend substantially in the direction of greatest slope and traverse the sealed strip 15 completely. The communication channel 17 is therefore a high head loss communication channel 17 because its represents for a flow of fluid in the barrier/support space 12 a singular head loss by the sudden change of section and/or by the porous material used.

[0074] Moreover, to accentuate the head loss generated by the communication channels 17 in the flow of fluid, the communication channels 17 of adjacent sealed strips 15 in the direction of greatest slope are positioned in a quincunx arrangement so that each zone 14 represents a channel for the flow extending in the transverse direction and the communication channel 17 represents for the flow a bend section between two adjacent zones 14.

[0075] FIG. 4 represents a third embodiment of the segmentation of the barrier/support space 12 in the direction of greatest slope. In this illustration, for greater clarity, only the thermally insulating barrier 3 with some of the insulating blocks 5 and the supporting structure 2 are illustrated. In this embodiment the segmentation is also effected with the aid of sealed strips 15. However, each sealed strip 15 is formed by a plurality of strip portions 16 connected to one another in the transverse direction by a fishplate 18, the fishplate 18 therefore being disposed between two adjacent strip portions 16.

[0076] As illustrated in FIG. 4, one of the strip portions 16 is placed on the lower surface of each insulating block 5, thus forming a pattern, so that the strip portions 15 are situated after installing the insulating blocks 5 in the barrier/support space 12. This pattern may be produced in various ways. In the embodiment represented this patterns forms a closed contour of the insulating block 5 and a plurality of rows spaced from the closed contour, extending in the transverse direction and distributed in the direction of greatest slope. Here the strip portions 16 are formed as before by beads of mastic.

[0077] A fishplate 18 is placed at the junction between two adjacent insulating blocks 5. It may also be disposed between other fishplates 18 regularly disposed at the junction between two adjacent insulating blocks 5. The fishplate 18 has a first end situated in the closed contour of the strip portion 16 of a first insulating block 5 and includes a second end situated in the closed contour of the pattern of the strip portions 16 of a second insulating block 5 adjacent to the first insulating block in the transverse direction. For a transverse row of insulating blocks 5 the sealed strip 15 is therefore formed by the strip portions 16 situated under each of these insulating blocks 5 and connected to one another by the fishplates 18 placed between these insulating blocks 5.

[0078] The fishplates 18 may have varying thicknesses so as to form so-called reference fishplates 18. In this case, the fishplates 18 also have a function of ensuring the flatness of the thermally insulating barrier 3 by compensating by means of their thickness the flatness defects of the supporting structure 2.

[0079] Moreover, communication channels 17 are formed in the closed contour of each insulating block 5 so that no pocket of fluid remains trapped under an insulating block 5. These communication channels 17 may be formed in the same manner as in the second embodiment or differently. As represented in FIG. 4, under the same insulating block 5 are placed two communication channels 17 disposed in a quincunx arrangement in the direction of greatest slope.

[0080] FIG. 5 represents a fourth embodiment of the segmentation of the barrier/support space 12 in the direction of greatest slope. In this illustration, for greater clarity, only the thermally insulating barrier 3 with some of the insulating blocks 5 and the supporting structure 2 are illustrated. Moreover, in this illustration the supporting structure 2 is omitted (or represented as if transparent) and the point of view is from outside the tank so that the elements situated between the supporting structure 2 and the insulating blocks 5 are in the foreground. In this embodiment and in the same manner as in the third embodiment each sealed strip 15 is formed by a plurality of strip portions 16 connected to one another in the transverse direction by a fishplate 18, the fishplate 18 therefore being disposed between two adjacent strip portions 16.

[0081] However, in contrast to the third embodiment, here the strip portions 16 are placed at the junction between two adjacent insulating blocks 5 in the direction of greatest slope and optionally at the junction between two adjacent insulating blocks 5 in the transverse direction. Each strip portion 16 therefore extends at the level of the junction between two insulating blocks 5. The adjacent strip portions 16 in the transverse direction or the direction of greatest slope are connected to one another in sealed manner by a fishplate 18. Here the strip portions 16 are formed by a closed cell polymer foam.

[0082] As illustrated in FIG. 5, communication channels 17 traverse the strip portions 16 so that the spaces situated under the insulating blocks 5 of the same row in the direction of greatest slope are in fluidic communication thanks to the communication channels 17. These communication channels 17 may be formed in the same manner as in the second embodiment or differently. Moreover, under the same insulating block 5 are placed at least two communication channels 17 disposed in a quincunx arrangement in the direction of greatest slope. The fishplates 18 of the fourth embodiment may also be reference fishplates 18.

[0083] In the various embodiments described hereinabove a sealed membrane 4 and a thermally insulating barrier 3 have been illustrated and described. The tank wall 1 may thus consist only of only one sealed membrane 4 and only one thermally insulating barrier 3.

[0084] However, the tank wall 1 may also comprise a so-called dual membrane structure. In this case the thermally insulating barrier 3 described is a secondary thermally insulating barrier and the sealed membrane 4 is a secondary sealed membrane. The tank wall 1 therefore also includes a primary thermally insulating barrier carried by the secondary sealed membrane 4 and a primary sealed membrane carried by the primary thermally insulating barrier.

[0085] Referring to FIG. 6, a cutaway of a methane tanker ship 70 shows a sealed and insulated tank 71 of prismatic general shape mounted in the double hull 72 of the ship. The wall of the tank 71 includes a primary sealed barrier intended to be in contact with the LNG contained in the tank, a secondary sealed barrier arranged between the primary sealed barrier and the double hull 72 of the ship, and two insulating barriers respectively arranged between the primary sealed barrier and the secondary sealed barrier and between the secondary sealed barrier and the double hull 72.

[0086] In a manner known in itself loading/offloading pipes 73 disposed on the top deck of the ship may be connected by means of appropriate connectors to a maritime or harbor terminal to transfer a cargo of LNG from or to the tank 71.

[0087] FIG. 6 shows an example of a maritime terminal including a loading and offloading station 75, an underwater pipe 76 and a terrestrial installation 77. The loading and offloading station 75 is a fixed off-shore installation including a mobile arm 74 and a tower 78 that supports the mobile arm 74. The mobile arm 74 carries a bundle of insulated flexible tubes 79 that can be connected to the loading/offloading pipes 73. The orientable mobile arm 74 adapts to all methane tanker loading gauges. A connecting pipe that is not shown extends inside the tower 78. The loading and offloading station 75 enables loading and offloading of the methane tanker 70 from or to the terrestrial installation 77. The latter includes liquefied gas tanks storage 80 and connecting pipes 81 connected via the underwater pipe 76 to the loading or offloading station 75. The underwater pipe 76 enables transfer of the liquefied gas between the loading or offloading station 75 and the terrestrial installation 77 over a great distance, for example 5 km, which enables the methane tanker ship 70 to remain at a great distance from the coast during loading and offloading operations.

[0088] Pumps onboard the ship 70 and/or pumps equipping the terrestrial installation 77 and/or pumps equipping the loading and offloading station 75 are used to generate the pressure necessary to transfer the liquefied gas.

[0089] Although the invention has been described in connection with a plurality of particular embodiments, it is obvious that it is in no way limited to them and that it encompasses all technical equivalents and combinations of the means described if the latter fall within the scope of the invention.

[0090] The use of the verb “to include” or “to comprise” and conjugate forms thereof does not exclude the presence of elements or steps other than those stated in a claim.

[0091] In the claims, any reference sign between parentheses should not be interpreted as a limitation of the claim.