AU2013273358B2

AU2013273358B2 - Lagging element for a fluidtight and thermally insulated tank comprising a reinforced lid panel

Info

Publication number: AU2013273358B2
Application number: AU2013273358A
Authority: AU
Inventors: Florent OUVRARD
Original assignee: Gaztransport et Technigaz SA
Current assignee: Gaztransport et Technigaz SA
Priority date: 2012-06-07
Filing date: 2013-05-24
Publication date: 2017-04-06
Anticipated expiration: 2033-05-24
Also published as: AU2013273358A1; FR2991660B1; KR20150028285A; IN2014MN02337A; WO2013182776A1; FR2991660A1; CN104334956B; CN104334956A; KR102051355B1

Abstract

Fluidtight and thermally insulated tank for containing a fluid, in which a tank wall comprises: a sealing barrier, a thermal insulation barrier bearing the sealing barrier, the thermal insulation barrier being made up of a plurality of lagging elements (30) which are juxtaposed to form a support surface for the sealing barrier, a lagging element (30) having a substantially parallelepipedal shape and comprising: a lining of lagging, a plurality of pillars (33) passing through the lining of lagging, a cover panel (34) running parallel to the tank wall and supported by the pillars, the cover panel comprising: a spreader panel (36) fixed to the pillars and resting on the pillars, a spacer element comprising a plurality of beams (37) which are spaced apart and run parallel to the spreader panel, an upper panel (35) parallel to the spreader panel and fixed and supported by the spacer element.

Description

1

LAGGING ELEMENT FOR A FLUID-TIGHT AND THERMALLY INSULATED TANK COMPRISING A REINFORCED LID PANEL

The invention relates to a field of production of fluid-tight, thermally insulated tanks. In particular the present invention relates to tanks intended for storage and transport of cold or hot fluids, for example tanks for storage and/or transport of liquefied gas by sea.

Fluid-tight, thermally insulated tanks may be used in various industries for storing hot or cold products. For example in the energy sector, liquefied natural gas (LNG) is a liquid which can be stored at atmospheric pressure at around -163°C in terrestrial storage tanks or tanks on-board floating structures.

For example, FR2877638 discloses a storage tank integrated in the hull of a ship, the walls of which comprise successively - in the direction of thickness from the inside to the outside of the tank - a primary sealing barrier, a primary insulating barrier, a second sealing barrier and a second insulating barrier. The insulating barriers consist of juxtaposed lagging elements. Each lagging element comprises a lagging lining through which pass a plurality of pillars of small cross-section, and a lid panel carried by the pillars, and a base panel carrying the pillars.

However when the walls are subjected to stresses exerted by a fluid stored in the tank, for example hydrodynamic stresses, the panels and pillars tend to deform unevenly within a lagging element. These deformations lead to an irregular distribution of the load which must be transmitted by each of the pillars to the lagging element. Furthermore, this deformation may cause detachment of the parts constituting the lagging element.

According to some embodiments, the invention provides a fluid-tight, thermally insulated tank integrated in a supporting structure to contain a fluid, wherein a tank wall comprises: a carrier wall, a sealing barrier, a thermal insulation barrier held on the carrier wall and carrying the sealing barrier, the thermal insulation barrier comprising a plurality of lagging elements juxtaposed to form a support surface for the sealing barrier, a lagging element with a substantially parallelepipedic form comprising: a lagging lining, 2 a plurality of pillars through the lagging lining perpendicular to the tank wall, a lid panel extending parallel to the tank wall and carried by the pillars, the lid panel comprising: a distribution panel fixed to the pillars and resting on the pillars, a spacing element resting on and fixed to the distribution panel, an upper panel parallel to the distribution panel, fixed to and supported by the spacing element, the upper panel absorbing the compression forces exerted on the lagging element.

According to some embodiments, such a tank may comprise one or more of the following characteristics.

According to some embodiments, the spacing element comprises a plurality of parallel beams extending parallel to the distribution panel and spaced apart.

According to some embodiments, the spacing element has the form of a grille, said beams forming a first assembly of parallel beams and said grille comprising a second assembly of parallel beams, the first assembly and the second assembly crossing each other and the two beam assemblies defining a lower support surface resting on the distribution panel and an upper support surface resting on the upper panel.

According to some embodiments, the first beam assembly and the second beam assembly cross at intersections, each pillar being each time positioned below a grille intersection.

According to some embodiments, the distribution panel has a rectangular form and a beam assembly extends obliquely in relation to the sides of the rectangular distribution panel.

According to some embodiments, the pillars are arranged in pillar rows, a beam being positioned superposed over a respective pillar row.

According to some embodiments, the beams have a trapezoidal section, the bases of the trapezoidal section resting respectively on the distribution panel and the upper panel.

According to some embodiments, the beams are profiles with a U-shaped cross section, the base of the U resting on one of the two panels of the distribution panel and upper panel, the wings extending from each branch of the U towards the outside of the U and resting on the other of the two panels of the distribution panel and upper panel.

According to some embodiments, the beams are profiles with a U-shaped cross section, the base of the U extending between the upper panel and the distribution panel, a first branch resting on the upper panel and a second branch resting on the distribution panel. 3

According to some embodiments, the beams are profiles of rectangular section.

According to some embodiments, the beams have a section of width between 9 and 50mm, oriented in a direction parallel to the distribution panel.

According to some embodiments, the support element is a layer of rigid insulating foam covering most of the distribution panel.

According to some embodiments, the spacing element comprises a honeycomb structure covering the distribution panel.

According to some embodiments, the spacing element comprises a fluid circulation channel (38) extending between a first side of the lagging element and a second side of the lagging element.

According to some embodiments, the circulation channel is lined with a porous lagging lining.

According to some embodiments, the lid panel also comprises an upper spacing element resting on and fixed to the upper panel, and a second upper panel, the second upper panel being parallel to the distribution panel and fixed to and supported by the upper spacing element.

According to some embodiments, the pillars are arranged in rows of parallel pillars, the pillars of one row being positioned at regular intervals, the pillars of two adjacent rows being offset by half an interval in the direction of the pillar row.

According to some embodiments, the thickness of the distribution panel and the thickness of the upper panel lies between 6.5 and 30mm in a direction perpendicular to the distribution panel, and the thickness of the spacing element is between 6.5 and 50mm in the direction perpendicular to the distribution panel.

Such a tank may form part of a terrestrial storage installation, for example to store LNG, or be installed in a floating structure near the shore or in deep water, in particular a methane tanker, a floating storage and re-gasification unit (FSRU), a floating production and remote storage unit (FPSO) and others.

According to one embodiment, a ship for the transport of cold liquid product comprises a double hull and said tank arranged in the double hull.

According to one embodiment, the invention also provides a method for loading or unloading such a ship, wherein a cold liquid product is conducted through insulated pipelines from or to a floating or terrestrial storage insulation, to or from the tank of the ship.

According to one embodiment, the invention also provides a transfer system for a 4 cold liquid product, the system comprising said ship, insulated pipelines arranged so as to connect the tank installed in the hull of the ship to a floating or terrestrial storage installation, and a pump for driving a flow of cold liquid product through the insulated pipelines from or to the floating or terrestrial storage installation, to or from the tank of the ship. A concept on which the invention is based is also to provide a lagging element for a fluid-tight, thermally insulated tank, with better structural characteristics by reinforcing the lid panel of such a lagging element, the reinforcement being obtained by producing the lid panel from two panels held spaced apart and rigidly connected together.

Certain aspects of the invention arise from the concept of increasing the inertia and hence the rigidity of the lid by increasing the thickness of the lid panel, while providing a lagging element offering a good compromise between the rigidity of the lid panel and the weight and the thermal resistance of the lagging element.

Certain aspects of the invention arise from the concept of providing fluid circulation channels within the lid panel, in order to allow the circulation of inert gas within the lagging element and hence in a wall of the fluid-tight, thermally insulated tank.

The invention will be better understood and further aims, details, characteristics and advantages thereof will appear more clearly from the following description of several particular embodiments of the invention, which are given solely for illustration and without limitation, and with reference to the attached drawings.

In the drawings: • Figure 1 is a partial, perspective, open view of a wall of a fluid-tight, thermally insulated tank in which lagging elements according to the embodiments of the invention may be used; • Figure 2 is a diagrammatic representation from the side of a lagging element which may be included in the wall of the tank of figure 1, and the stresses and deformation to which it may be subjected; • Figure 3 is a perspective, partially transparent view of a lagging element with a reinforced lid panel; • Figures 4 to 7 are perspective views of variants of the lagging element shown in figure 3; • Figures 8a to 8c are diagrammatic representations from the side of the profiles which may be used in the variant of the reinforced lid panel in figure 6; 5 • Figure 9 is a diagrammatic side view of a particular embodiment of the lagging element shown in figure 3, in which the lagging element comprises pillars with variable section; • Figure 10 is a diagrammatic side view of a lagging element in which the reinforced lid panel comprises three spaced panels; • Figure 11 is an open, diagrammatic view of a tank of a methane tanker and a loading/unloading terminal for said tank; • Figure 12 shows diagrammatically, in side view, the enclosure from figure 3.

Figure 1 shows the fluid-tight, insulating walls of a tank integrated in a supporting structure of a ship.

The supporting structure of the tank here consists of the inner hull of a doublehulled ship, the wall of which is indicated by numeral 1.

On each wall 1 of the supporting structure, a corresponding tank wall is produced by successive superposition of a secondary insulating layer 2, a secondary sealing barrier 3, a primary insulating layer 4 and a primary sealing barrier 5.

The primary insulating layer 4 and the secondary insulating layer 2 consist of lagging elements, more particularly parallelepipedic lagging enclosures 6 and 7 juxtaposed in a regular pattern. The primary enclosures 7 and secondary enclosures 6 thus form a substantially flat surface which carries the primary sealing barrier 5 and the secondary sealing barrier 3 respectively.

The primary sealing barrier 5 and the secondary sealing barrier 3 consist of parallel, invar stakes 8 with raised edges which are arranged alternately with elongated weld supports 9, also of invar. More precisely, the weld supports 9 extend perpendicular to the wall and are each held in the underlying insulating layer 2 or 4, for example housed in inverted T- shaped grooves 10 provided in the lid panels 11 of the enclosure 6 and 7. The raised edges of the stakes 8 are welded along the weld supports 9.

The primary insulating enclosures 7 and secondary insulating enclosures 6 are held on the supporting structure via anchoring elements 12. In particular the anchoring elements 12 of the secondary insulating layer 2 are fixed to the tank wall 1 via pins 13 welded perpendicular to the wall 1.

Figure 2 shows a structure of a enclosure 15 which may be used in such a tank wall.

The enclosure 15 has a base panel 16 on which ladders 17 are placed, consisting of pillar rows 18 extending perpendicular to the base panel 16, a batten 19 and a beam 20. Each 6 pillar row 18 rests on the base panel 16 via the batten 19 and carries the beam 20 which supports the lid panel 11 and is fixed thereto. The ladders 17 are assembled and fixed to the panels using fixing elements, for example by clipping. A lagging lining 21 is arranged between the base panel 16 and the lid panel 11, and surrounds the pillars 18.

The beams 20 increase the rigidity of the lid panel 11 and distribute the load when the panel is subjected to constraints, which are for example exerted by the fluid within the interior of the tank and indicated here by arrows 22, for example these stresses may be due to the movement of the fluid in the tank.

However when the lagging element is subjected to these stresses, the lid panel 11 tends to deform and warp between two ladders 17 under the effect of pressure, following curves indicated by curves 24. This deformation tends to cause the rotation of the side beams 20 located on each side of the median plane of the enclosure 15. This rotation is illustrated by lines 23. This deformation and rotation therefore cause the flexion of the lateral pillars 18 situated on the ladders on each side of the median plane of the lagging element 15 towards the outside of the enclosure, as shown by the curve 25. The pillar then becomes fragile due to this flexion 25, which adds to the compression stresses exerted on the pillars 18.

The fixing elements between the beams and the different elements of the enclosure 15 are therefore greatly stressed, which can cause their detachment. Furthermore this deformation causes a poor distribution of load through the pillars 18. In fact as shown by arrows 26 and 27, the load 26 exerted by the pillars in the centre of the enclosure 15 is much greater than the load 27 exerted by the lateral pillars 20.

To remedy these drawbacks, the enclosure 15 may be replaced by a reinforced enclosure 30 as shown in figure 3. Such a enclosure 30 comprises a base panel 31 on which battens 32 are fixed. Each pillar row 33 is positioned and fixed above a corresponding batten 32. A reinforced lid panel 34 is attached to the pillars 33. The pillars 33 in particular allow the transmission of forces exerted on the lid panel 34 to the wall 1, and hence have a compression resistance function. A lagging lining (not shown) fills the space between the pillars and may for example consist of an insulating foam cast between the pillars 33 or a foam block machined to adapt to the pillars 33.

The successive pillar rows 33 are offset in relation to each other. In fact the pillars 33 of two successive rows 29 and 39 comprise pillars 33 spaced at regular intervals, however the two rows of pillars 33 are offset in their length direction by half an interval. Such an arrangement allows a good compromise between the number of pillars 33 in the enclosure 30 and a good load distribution. 7

The reinforced lid panel 34 comprises an upper panel 35 and a lower panel 36, each with a thickness of 15mm and spaced by a series of parallel solid beams 37. In particular the beams 37 extend parallel to the longitudinal sides of the enclosure 30. Each beam 37 is positioned along and above a pillar row 33. The beams 37 have a rectangular section and a thickness of 15mm. However these beams may also have a trapezoidal section. The beams 37 and panels 35 and 36 are rigidly connected, so when the upper panel 35 is subjected to the stresses exerted by the fluid and tries to warp, the lower panel 36 works in traction, preventing rotation of the beams 37. Also since the beams 37 are immobilized by the lower panel 36, the deformation of the upper panel 35 is reduced.

The traction work of the panel 36 is shown in figure 12. In this figure we see that the panels 35 and 36 are fixed to the beams 37 by clips 90. Two side beams 37 can be seen together with a central beam 37. Line 91 indicates the curve along which the upper panel 35 tries to warp when subjected to compression stresses 94. When the upper panel 35 tries to deform between a central beam 37 and a side beam 37 along line 91, the upper panel 35 exerts stresses on the beams 37 via the clips 90. These stresses try to cause the rotation of the beams 37, as illustrated by lines 92. The lower panel 36 is itself fixed to the beams 37, reducing the rotation of the beams 37. In fact the rotation of the beams generates stresses on the lower panel 36, causing the traction work of the lower panel 36 between said beams 37, as indicated by arrows 93. In other words, the lower panel 36 prevents the rotation of the beams via the clips 90. In this way the rotation of the beams 37 is reduced and hence the flexion of the underlying pillars 33, induced by this rotation, is reduced. Thus the compressive stresses exerted on the lagging element are better absorbed by the pillars 33.

Such a structure of the reinforced panel 35 gives a lid 35 with good rigidity which effectively distributes the load in the case of localized stress. Also such a lid panel structure panel 35 provides fluid-tight, thermally insulated tanks with a good compromise between thermomechanical performance and the cost of such a tank.

Each beam 37 is spaced from further beams 37 so as to delimit a space between two beams 37 and between the panels 35 and 36. These spaces form fluid circulation channels 38 between the sides of the lagging element. The juxtaposition of the lagging elements thus forms a circuit in the tank wall in which a neutral gas can be injected to neutralize the tank wall and thus prevent any risk of explosion in the event of a leak in the presence of oxygen. Also such a gas circuit allows detection of leaks in the sealing barriers 3 and 5.

In some cases, the beams 37 may be drilled or machined to produce the passages 8 allowing circulation of fluid between the different channels 38, and thus allow circulation of the gas in several directions within the enclosure 30.

To improve the thermal resistance capacity of the insulating enclosure 30, a porous lagging lining may be installed in the pipes 38. Such a lagging lining may for example consist of a layer of glass wool, or expanded perlite.

In a further embodiment, the space between the beams 37 may be filled with an insulating foam if no fluid circulation circuit is necessary in the reinforced panels 35.

In a further embodiment, the beams 37 may extend in a transverse direction in relation to the longitudinal direction of the lagging element.

The enclosure described above may be produced in various ways. For example in a first method, the base panel 31, battens 32 and pillars 33 are assembled by clipping. The lagging lining 21 is then inserted or injected between the pillars. The lower panel 36 is clipped to the pillars 33 in a manual or automated process, then the pillars 37 are clipped to the lower panel 36. Any porous lagging lining is inserted between the beams 37, and the upper panel 35 is finally clipped to the beams 37.

In a further method, the lagging lining 21 is a foam block which is machined to produce holes. Pillars 33 are inserted in the holes, then the battens 32 and the base panel 31 are clipped to the pillars 33. The reinforced lid panel 34 is preassembled independently and drilled at the position of the pillars 33. The reinforced lid panel 34 is then positioned on the pillars 33 and screwed to the pillars 33 through holes.

Further embodiments of the reinforced lid panel 34 will now be described with reference to figures 4 to 8.

Figures 4 and 5 each show a enclosure 40 and 41, similar to the enclosure 30, in which the space between the lower panel 36 and the upper panel 35 is ensured by a grillelike structure 42 and 46 respectively.

The structure 42 takes the form of a grid of a first beam assembly 43 and a second beam assembly 44, the beams 43 being parallel to a first side of the lower panel and the beams 44 extending perpendicular to the beams 43. The beams 44 of the second assembly extend at the level of the pillar rows 29, 39, while the beams 43 extend transversely in relation to rows 29 and 39 while extending at the level of the pillars of several non-offset rows 39. Thus the grille has intersections 45 directly above the pillars 33. The beams 44 and beams 43 each rest both on the lower panel 36 and upper panel 35.

Similarly, the grille 46 has crossings 47 located directly above the pillars 33. However in this embodiment, the elements 48 constituting the grille 46 do not extend 9 parallel to the sides of the enclosure 41. In fact they each extend above a pillar 33 of each successive offset row 39 and 29.

Grilles 40 and 41 may be produced by an assembly of elongated parts or by molding.

Other variants of the enclosure 30 are shown in figures 6 and 7.

In the enclosure 50 in figure 6, the elements spacing the lower panel 36 and upper panel 35 have been replaced by a honeycomb structure 49 which covers the lower panel 36. In a similar manner to the embodiments shown above, the honeycomb structure 49 may be drilled or machined to produce passages allowing the circulation of fluid, and thus allowing the circulation of gas within the enclosure.

Alternatively, the element holding the panels 35 and 36 spaced apart may be a layer of high density foam covering the panel 35 and glued to the lower panel 36 and upper panel 35.

Figure 7 shows a variant 51 of the enclosure 30 in which the solid beams 37 have been replaced by formed or extruded metal profiles 52. A cross-section view showing the section of the metal profile 52 is illustrated in figure 8a. The metal profile 52 has a U-shaped part 53, of which the base of the U 54 is flat and rests on the lower panel 36. Two wings 55 extend towards the outside of the branches of the U and rest on the upper panel 35.

Figures 8b and 8c show two further variants 56 and 57 of metal profiles which could be used instead of the metal profile 52. In figures 8a to 8c, the position of the pillars is shown by a line 59.

In particular the metal profile 56 is a profile with a U-shaped section, in which the branches 58 of the U rest respectively on the lower panel 35 and the upper panel 36. A profile 56 is positioned on each side of a pillar such that the branches 58 of two profiles 56 thus positioned lie opposite each other. Thus a space is provided between the two profiles 56 which allows the lower panel 36 to be fixed to the pillars 33 when the profiles 56 are already attached to the lower panel 36. The metal profile 57 itself has a substantially rectangular section.

Alternatively, the profiles may be produced using extruded or molded composite materials.

The reinforced lid panels 34 shown above may be fixed to any type of small-section pillar. For example the pillars 33 shown in figures 3 to 7 have a solid rectangular section. The section of the pillars may also be square or cylindrical. Alternatively the pillars may be hollow to increase their thermal resistance, or where applicable filled with insulating 10 material. In other embodiments, the pillars may have an H section. Such pillars may be produced by machining a pillar of rectangular section or by assembling three plywood battens to form an H section. An H section pillar offers a good compromise between rigidity, thermal resistance and weight of the pillar.

Another type of pillar is shown diagrammatically in figure 9. In fact the pillars 60 shown in this figure have a section which varies as a function of height. More precisely, the pillar 60 comprises a central cylindrical portion 61 situated between two frustoconical portions 62. The bases of the frustoconical portions 62 rest on panels 31 and 36 respectively. An increase in section at the panels 31 and 36 allows better distribution of the load between the pillars 60 and prevents the pillar 60 from becoming embedded in the lids 31 and 36. Furthermore a larger section at the level of panels 31 and 36 allows the pillar 60 to offer good resistance to the torque exerted by the lids 31 and 36 during warping, and hence has a good flexion resistance.

The pillars 60 may be obtained for example from thermoplastic or thermosetting materials, where applicable fiber-reinforced.

Naturally the distribution of the beams 37 or spacing elements in relation to the pillars 33 may be different. For example the pillars 37 are not necessarily positioned at the level of the pillar rows 29 and 39 but may be arranged between the pillar rows 29 and 39. A reinforced lid panel 34 has been described above consisting of two panels. However reinforced lid panels comprising additional panels may be used. Such a reinforced panel 63 is shown in figure 10.

The reinforced panel 63 comprises a first panel 64 resting on pillars 84 and supporting a first series of beams 65. The beams 65 carry a second panel 66 which itself carries a second series of beams 67 superposed on the first series of beams 65. The second series of beams 67 supports an upper panel 68. The beam assemblies 65 and 67, panels 64, 66 and 68, and pillars 84, are rigidly connected. As illustrated by lines 69, 82 and 83, the flexion stresses are thus progressively absorbed by the traction work of the second panel 66 and the first panel 64. This absorption of stress in several stages allows a great reduction in flexion stress at the level of the pillars 84 and a good distribution of the load exerted on the upper panel 68 to the pillar assembly 84. Naturally the distribution of beams 65 and 67 may be different. For example beams 65 and 67 are not necessarily superposed and may alternate.

Any type of lagging lining 21 may be used to create the enclosures described above. Typically such a lining may for example consist of a block of machined foam, or a 11 foam cast between the pillars. Such a foam may be reinforced or not. Alternatively the lining may consist of a material with porosity of the order of nanometers, such as an aerogel. Aerogels may take different forms, for example in the form of powder, balls, non-woven fibers, woven fabrics etc.

The pillars, panels and spacing elements between the upper and lower panels may be fixed by screws. However it is possible to create the connections by glue, clips or nails.

The panels, beams and pillars may be made from plywood or from solid wood, for example of timber, beech or pine. These elements may also be made of bamboo, composite materials, plastic or metal.

The enclosures shown above may be made in the primary insulating layer 4 and/or in the secondary insulating layer 2. The reinforced lid panels of the enclosures may for example have a thickness of 45mm.

However in certain embodiments of the tank wall, the tank wall has a primary insulating layer 4 and a secondary insulating layer 2 in which the thickness of the reinforced lid panels is greater in the primary insulating layer 4 than in the secondary insulating layer 2. In fact the forces exerted on the reinforced lid panels of the secondary insulating layer 2 are already partly distributed by the enclosures of the primary insulating layer 4. Thus it is possible to use a reinforced lid panel which is less rigid and hence thinner in the secondary insulating layer 2 than in the primary insulating layer 4.

The tanks described above may be used in various installations such as terrestrial establishments or in a floating installation such as a methane tanker or other.

With reference to figure 11, an open view of a methane tanker 70 shows a fluid-tight insulated tank 71 of generally prismatic form, mounted in the double hull 72 of the ship. The wall of the tank 71 has a primary sealing barrier intended to be in contact with the LNG contained in the tank, a secondary sealing barrier arranged between the primary sealing barrier and the double hull of the ship, and two thermally insulating barriers arranged respectively between the primary sealing barrier and the secondary sealing barrier, and between the secondary sealing barrier and the double hull 72.

In a manner known in itself, loading and unloading pipelines arranged on the upper deck of the ship may be connected via appropriate connectors to a maritime or port terminal to transfer an LNG cargo from or to the tank 71.

Figure 11 shows an example of a maritime terminal with a loading and unloading 12 station 75, an underwater pipe 76 and a terrestrial installation 77. The loading and unloading station 75 is a fixed offshore installation with a mobile arm 74 and a tower 78 supporting the mobile arm 74. The mobile arm 74 carries a bundle of insulated flexible hoses 79 which can connect to the loading and unloading pipelines 73. The orientable mobile arm 74 can adapt 5 to any tanker size. A connecting pipe (not shown) extends inside the tower 78. The loading and unloading station 75 allows loading and unloading of the methane tanker 70 from or to the terrestrial installation 77. This comprises liquefied gas storage tanks 80 and connecting pipes 81 connected by the underground pipe 76 to the loading and unloading station 75. The underground pipe 76 allows the transfer of liquefied gas between the loading and unloading 10 station 75 and the terrestrial installation 77 over a long distance, for example 5 km, which allows the methane tanker 70 to remain far from the coast during the loading and unloading operations.

To create the pressure necessary for the transfer of liquefied gas, pumps on board the ship 70 and/or pumps in the terrestrial installation 77 and/or pumps in the loading and 15 unloading station 75 are used.

Although the invention has been described in connection with several particular embodiments, it is evident that it is in no way limited to these and comprises all technical equivalents of the means described and their combinations if these fall within the scope of the invention. 20 The use of the verbs "comprise", "contain" or "include" and their conjugated forms does not exclude the presence of other elements or other steps than those stated in a claim. The use of the indefinite article "a" or "an" for an element or step does not - unless specified otherwise - exclude a plurality of such elements or steps.

In the claims, a reference numeral in brackets should not be interpreted as a 25 limitation of the claim.

Claims

1. A fluid-tight, thermally insulated tank integrated in a supporting structure to contain a fluid, wherein a tank wall comprises: a carrier wall (1), a sealing barrier (3,5), a thermal insulation barrier (2, 4) held on the carrier wall and carrying the sealing barrier, the thermal insulation barrier comprising a plurality of lagging elements (6, 7, 30, 40, 41, 50, 51) juxtaposed to form a support surface for the sealing barrier, a lagging element with a substantially parallelepipedic form comprising: a lagging lining (21), a plurality of pillars (33, 60) through the lagging lining perpendicular to the tank wall, a lid panel (34) extending parallel to the tank wall and carried by the pillars, the lid panel comprising: a distribution panel (36, 64) fixed to the pillars and resting on the pillars, a spacing element resting on and fixed to the distribution panel, the spacing element comprising a plurality of beams (37, 43, 44, 52, 56, 57, 65) spaced apart and extending parallel to the distribution panel, an upper panel (35, 36) parallel to the distribution panel, fixed to and supported by the plurality of beams, the upper panel absorbing compression forces exerted on the lagging element.

2. The tank as claimed in claim 1, wherein the beams (37, 43) of said plurality of beams are parallel.

3. The tank as claimed in claim 1 or 2, wherein the spacing element has the form of a grille (42, 46), said beams forming a first assembly of parallel beams (43) and said grille comprising a second assembly of parallel beams (44), the first assembly and the second assembly crossing each other and the two beam assemblies defining a lower support surface resting on the distribution panel (36) and an upper support surface resting on the upper panel (35).

4. The tank as claimed in claim 3, wherein the first beam assembly and the second beam assembly cross at intersections (45), each pillar (33, 60) being each time positioned below a grille intersection.

5. The tank as claimed in claim 3 or 4, wherein the distribution panel has a rectangular form having four sides, and a beam assembly (43, 44) extends obliquely in relation to the sides of the rectangular distribution panel.

6. The tank as claimed in any of claims 2 to 5, wherein the pillars are arranged in pillar rows (29, 39), a beam being positioned superposed on a respective pillar row.

7. The tank as claimed in any of claims 2 to 6, wherein the beams have a trapezoidal section having parallel bases, the bases of the trapezoidal section resting respectively on the distribution panel (36) and the upper panel (35).

8. The tank as claimed in any of claims 2 to 6, wherein the beams are profdes (52) with a U-shaped cross section, the U-shaped cross section defining a base of each beam and two branches of each beam, the base (54) resting on one of the two panels of the distribution panel and the upper panel, the beams including wings (55) extending from each branch of the beam towards the outside of the U-shaped cross section and resting on the other of the two panels of the distribution panel and the upper panel.

9. The tank as claimed in any of claims 2 to 6, wherein the beams are profdes with a U-shaped cross section (56), the U-shaped cross section defining a base of each beam and two branches of each beam, the base of the beam extending between the upper panel and the distribution panel, a first branch resting on the upper panel (35) and a second branch resting on the distribution panel (36).

10. The tank as claimed in any of claims 2 to 6, wherein the beams are profdes (57) of rectangular section.

11. The fluid-tight tank as claimed in any of claims 1 to 10, wherein the beams have a section of width between 9 and 50mm, oriented in a direction parallel to the distribution panel.

12. The tank as claimed in any of claims 1 to 11, wherein the spacing element comprises a fluid circulation channel (38) extending between a first side of the lagging element and a second side of the lagging element.

13. The tank as claimed in claim 12, wherein the circulation channel (38) is lined with a porous lagging lining.

14. The fluid-tight tank as claimed in any of claims 1 to 13, wherein the lid panel also comprises an upper spacing element (67) resting on and fixed to the upper panel (66), and a second upper panel (68), the second upper panel being parallel to the distribution panel (65) and fixed to and supported by the upper spacing element (67).

15. The fluid-tight tank as claimed in any of claims 1 to 14, wherein the pillars are arranged in rows of parallel pillars (29, 39), the rows defining a row direction, the pillars of one row being positioned at regular intervals, the pillars of two adjacent rows being offset by half an interval in the row direction.

16. The fluid-tight tank as claimed in any of the preceding claims, wherein the distribution panel and the upper panel each have a thickness, the thickness of the distribution panel and the thickness of the upper panel (35, 36, 64, 66, 68) lies between 6.5 and 30mm in a direction perpendicular to the distribution panel, and the thickness of the spacing element (37, 42, 43, 49, 52, 56, 57, 65) is between 6.5 and 50mm in a direction perpendicular to the distribution panel.

17. A ship (70) for transport of cold liquid product, the ship comprising a double hull (72) and a tank (71) as claimed in any of claims 1 to 16 arranged in the double hull.

18. A use of a ship (70) as claimed in claim 17, wherein a cold liquid product is conducted through insulated pipelines (73, 79, 76, 81) from or to a floating or terrestrial storage installation (77), to or from the tank of the ship (71), in order to perform loading or unloading of the ship.

19. A transfer system for a cold liquid product, the system comprising a ship (70) as claimed in claim 17, insulated pipelines (73, 79, 76, 81) arranged so as to connect the tank (71) installed in the hull of the ship to a floating or terrestrial storage installation (77), and a pump for driving a flow of cold liquid product through the insulated pipelines from or to the floating or terrestrial storage installation, to or from the tank of the ship.