AU2015226021B2

AU2015226021B2 - Sealed and insulating vessel comprising a deflection element allowing the flow of gas at a corner

Info

Publication number: AU2015226021B2
Application number: AU2015226021A
Authority: AU
Inventors: Sebastien Delanoe; Bruno Deletre; Yannick DUBOIS
Original assignee: Gaztransport et Technigaz SA
Current assignee: Gaztransport et Technigaz SA
Priority date: 2014-03-04
Filing date: 2015-02-17
Publication date: 2019-03-28
Anticipated expiration: 2035-02-17
Also published as: EP3114387A1; CN106164564B; AU2015226021A1; EP3114387B1; CN106164564A; KR20160146667A; KR102285763B1; FR3018338A1; WO2015132498A1; JP6496748B2; FR3018338B1; JP2017512284A

Abstract

The invention concerns a sealed and thermally insulating vessel for storing a fluid, comprising a thermally insulating barrier comprising: a plurality of insulating elements disposed along the walls of the vessel, arranged to allow the flow of fluid, such as a gas, within said thermally insulating barrier; and a corner arrangement, disposed at the intersection between first and second walls (3, 4) of the vessel, the corner arrangement comprising: a deflection element (19) comprising a first face (20a) facing the supporting structure of the second wall (4), a second face (20b) facing the supporting structure of the first wall (3) and a plurality of curved channels (21) extending between the first face (20a) and the second face (20b) of the deflexion element (19) to allow the flow of fluid, such as a gas, through the corner arrangement, the plurality of curved channels (21) comprising at least a series of curved channels spaced apart from each other in the thickness direction of the walls (3, 4) of the vessel.

Description

Sealed and insulating vessel comprising a deflection element allowing the flow of gas at a corner

Technical field

The invention relates to the field of sealed and thermally insulating membrane vessels for the storage and/or transport of fluids, such as a cryogenic fluid.

Sealed and thermally insulated membrane vessels are in particular used for the storage of liquid natural gas (LNG), which is stored at atmospheric pressure at approximately -162°C. These vessels may be installed on shore or on floating structures. In the case of a floating structure, the vessel may be intended for the transport of liquefied natural gas or to receive liquefied natural gas acting as a fuel for propulsion of the floating structure.

Prior art

Sealed or thermally insulating vessels for the storage of liquefied natural gas comprising a plurality of walls, each wall of the vessel having a multilayer structure comprising in succession, through the thickness from the outside to the inside, a load-bearing structure comprising the double hull of a ship and defining the general shape of the vessel, a secondary thermally insulating barrier attached to the load-bearing structure, a secondary sealing membrane resting against the secondary thermally insulating barrier, a primary thermally insulating barrier resting against the secondary sealing membrane and a primary sealing membrane intended to be in contact with the liquefied natural gas present in the vessel, are known in the state of the art.

The thermally insulating barriers comprise insulating elements resting against the load-bearing structure or the secondary sealing membrane and a gas phase. It is known that the gas phase in one and/or other of the thermally insulating barriers should be held at an absolute pressure below ambient atmospheric pressure, that is to say at a negative relative pressure, to increase the insulating power of the said thermally insulating barriers. One such process is, for example, described in French patent application FR 2535831.

It is however difficult to bring the gas phase of a thermally insulating barrier to very low pressures, of the order of 100 Pa absolute, in a relatively short time, because of the major head losses generated within a thermally insulating barrier, and in particular the major local head losses in the vicinity of the corner zones of the vessel.

This problem is furthermore particularly difficult to overcome in that an increase in the cross-section of the spaces for flow of the gas phase with a view to reducing the head losses results in creating local convection zones which have an adverse effect on the effectiveness of the thermal insulation and are likely to imperil the structure of the ship by locally creating cooled zones in the load-bearing structure.

Summary

One idea underlying the invention is to provide a sealed and thermally insulating vessel comprising an insulating thermal barrier in which head losses are reduced and without any insulation defects.

According to one embodiment the invention provides a sealed and thermally insulating vessel for the storage of a fluid, the said vessel comprising a plurality of walls, each wall having in succession, through the thickness of the wall of the vessel from the outside to the inside of the vessel, an external load-bearing structure, a thermally insulating barrier attached to the load-bearing structure and a sealing membrane supported by the said thermally insulating barrier, the said thermally insulating barrier comprising:

- a plurality of lagging elements located along the walls of the vessel, arranged so as to allow a fluid, such as gas, to flow within the said thermally insulating barrier; and

- a corner arrangement located at the intersection between first and second walls of the vessel, the corner arrangement comprising:

- a deflection element comprising a first face opposing the load-bearing structure of the second wall, a second surface opposing the loadbearing structure of the first wall, and a plurality of elbow channels extending between the first surface and the second surface of the deflection element to allow fluid such as gas to flow through the corner arrangement, the plurality of elbow channels comprising at least one set of elbow channels spaced apart from each other through the thickness of the first and second walls of the vessel.

Thus, thanks to the presence of the deflection element at the intersection between two walls of the vessel, gas circulation in the corners of the vessel is encouraged. Furthermore, by distributing the elbow channels through the thickness of the walls of the vessel the elbow channels substantially follow the isothermal lines within the thermally insulating barrier in such a way that natural and forced convection within the deflection element is limited.

Hence such a deflection element makes it possible to encourage gas to flow within the thermally insulating barrier without thereby creating any local insulation defects.

Depending upon the embodiments, such a vessel may comprise one or more of the following characteristics:

- the plurality of lagging elements located along the walls of the vessel defines passages for the flow of fluid within the thermally insulating barrier, the first surface of the deflection element communicating with one or more of the passages for the flow of fluid defined by the plurality of lagging elements located along the first wall and the second surface of the deflection element communicating with one or more of the passages for the flow of fluid defined by the plurality of lagging elements located along the second wall,

- the deflection element comprises a plurality of sets of elbow channels spaced apart through the thickness of the first and second walls of the vessel, the said sets being spaced apart from each other in a direction parallel to a line of intersection between the first and second walls of the vessel,

- a set of elbow channels spaced apart through the thickness of the walls of the vessel comprises at least four elbow channels, advantageously at least ten elbow channels and preferably at least 20 elbow channels,

- the elbow channels have a cross section of less than 5 cm², preferably of the order of from 0.25 to 1 cm²,

- the cross section of the elbow channels has a larger dimension in a direction parallel to the corner of the vessel than through the thickness of a wall of the vessel,

- the elbow channels each comprise a first portion extending parallel to the first wall and a second portion extending parallel to the second wall and communicating with the first portion,

- the elbow channels have an arched shape, the elbow channels having increasing radii of curvature from the inside to the outside of the vessel,

- the deflection element further comprises a third surface parallel and opposite to the first surface, and a fourth surface parallel and opposite to the second surface, the deflection element comprising a housing lined with a lagging lining between the elbow channels of arched shape having the greatest radius of curvature and the third and fourth surfaces,

- the deflection element comprises a stack of plates stacked against each other in a direction perpendicular to the first and second surface, the plates each including a plurality of voids defining a portion of the elbow channels. The plates can in particular be obtained by the injection of polymer material,

- the deflection element comprises a stack of plates stacked against each other in a direction perpendicular to a surface of the deflection element having a common edge with the first and second surfaces, at least some of the stacked plates being provided with elbow-shaped grooves shaped to form the elbow channels on at least one of their surfaces,

- in one embodiment the stack of plates comprises a plurality of flat load-bearing plates inserted between two plates equipped with elbow grooves,

- the deflection element is in the shape of a rectangular parallelepiped,

- the deflection element in the shape of a rectangular parallelepiped is associated with at least one junction element comprising a plurality of straight channels parallel to one of the first and second walls and opening opposite elbow channels of the deflection element,

- the junction element has openings passing through the said junction element in a direction parallel to the edge formed at the intersection between the first and second walls of the vessel,

- the deflection element is of an elbow shape,

- the elbow-shaped deflection element comprises two straight parts, each having a beveled edge and connected to each other via their beveled edges,

- the corner arrangement comprises lagging corner elements and the deflection element therein is associated with the lagging corner elements,

- the deflection element is made up of polymer material selected from expanded polystyrene, polyurethane, polyurethane foam, polyethylene, polyethylene foam, polypropylene, polypropylene foam, polyamide, polycarbonate or polyetherimide. The deflection element may also be made of other thermoplastic materials, which may optionally be reinforced with fibers. Such a material must be capable of being injected when a deflection element is formed from a stack of injected plates,

- each wall of the vessel has, in succession, through the thickness of the vessel from the outside to the inside of the vessel, an outer load-bearing structure, a secondary thermally insulating barrier attached to the load-bearing structure, a secondary sealing membrane supported by the said secondary thermally insulating barrier, a primary thermally insulating barrier resting against the secondary sealing membrane and a primary sealing membrane intended to be in contact with the fluid stored in the vessel, each of the primary and secondary thermally insulating barriers comprising a corner arrangement incorporating a deflection element.

Such a vessel may form part of an onshore storage facility, for example, for storing LNG, or be installed in a floating, coastal or deep-water structure, in particular a methane tanker, a floating storage and regasification unit (FSRU), a floating production and storage offshore unit (FPSO) and other units.

According to one embodiment a ship for the transport of a fluid comprises a double hull and an aforesaid vessel located within the double hull.

According to one embodiment the invention also provides a process for loading or unloading such a ship in which a fluid is caused to pass along insulated piping from or to a floating or onshore storage facility, to or from the vessel on the ship.

According to one embodiment the invention also provides a transfer system for a fluid, the system comprising the aforesaid ship, insulated piping arranged in such a way as to connect the vessel installed within the hull of the ship to a floating or onshore storage facility and a pump to drive fluid through the insulated piping from or to the floating or onshore storage facility, to or from the vessel on the ship.

Some aspects of the invention are based on the idea of encouraging the circulation of gas between the different walls of a vessel. Some aspects of the invention are based on the idea of encouraging gas circulation between the walls of a vessel so as to facilitate the positioning of a thermally insulating barrier under particularly low negative relative pressures of the order of 10 to 1000 Pa. Some aspects of the invention are based on the idea of encouraging the circulation of inert gas within a thermally insulating barrier. Some aspects of the invention start from the idea of encouraging the pumping of a fluid present within the thermally insulating barrier in the event of a failure in the sealing of the load-bearing structure or a sealing membrane. In fact, pumping of a fluid present within the thermally insulating barrier may in particular be necessary in order to drain off water which has entered the thermally insulating barrier in the event of damage to the double hull of the ship. Some aspects of the invention are based on the idea of encouraging stages for testing the seal of a sealing membrane once gas (a mixture of nitrogen and ammonia, tracer gases such as helium, Nidron or other) has been circulated in the thermally insulating barrier in order to detect any leakage faults.

Brief description of the figures

The invention will be better understood, and other objects, details characteristics and advantages thereof will be more clearly apparent during the course of the following description of several particular embodiments of the invention provided purely by way of illustration and without being limiting, with reference to the appended drawings.

• Figures 1 and 2 are partially exploded, partial perspective views of a corner structure fitted with deflection elements according to a first embodiment for the sealed and thermally insulating vessel for the storage of a fluid.

• Figure 3 is a diagrammatical illustration of a deflection element according to one embodiment.

• Figure 4 is an exploded perspective view of a deflection element comprising a stack of plates.

• Figure 5 is a cross-sectional view of a deflection element of a corner arrangement for a primary thermally insulating barrier.

• Figure 6 is a perspective view of a deflection element.

• Figure 7 is a cross-sectional view illustrating a deflection element associated with junction elements at a corner arrangement of a secondary thermally insulating barrier.

• Figure 8 is a perspective view of a corner structure according to a second embodiment, fitted with deflection elements.

• Figures 9 and 10 are detailed views of Figure 8.

• Figure 11 is a view of the corner structure in Figure 7, in cross-section in a transverse plane passing through one deflection element of the primary thermally insulating barrier.

• Figure 12 is a view of the corner structure in Figure 7, in cross-section in a transverse plane passing through a deflection element of the secondary thermally insulating barrier.

• Figure 13 is a diagrammatical cut-away illustration of a vessel in a methane tanker and a terminal for loading/unloading that vessel.

Detailed description of embodiments

Figure 1 shows a corner structure of a sealed and thermally insulating vessel for the storage of a fluid. Such a corner structure is in particular suitable for a membrane vessel, such as for example described in document FR2683786.

The general structure of such a vessel is well known and is of polyhedral shape. From the outside to the inside of the vessel, the vessel wall comprises a load-bearing structure 1, a secondary thermally insulating barrier comprising lagging elements formed of juxtaposed insulating boxes on the load-bearing structure and anchored thereto by secondary attachment members, a secondary sealing membrane supported by the insulating boxes of the secondary thermally insulating barrier, a primary thermally insulating barrier comprising lagging elements formed of juxtaposed insulating boxes attached to the secondary sealing membrane by primary attachment members and a primary sealing membrane supported by the insulating boxes and intended to be in contact with the cryogenic fluid held in the vessel.

Load-bearing structure 1 may in particular be a self-supporting metal sheet or, more generally, any type of rigid partition having appropriate mechanical properties. The load-bearing structure may in particular be formed by the hull or double hull of the ship. The load-bearing structure comprises a plurality of walls defining the general shape of the vessel.

The primary and secondary sealing membranes are for example made of a continuous sheet of metal strakes with raised edges, the said strakes being welded together by their raised edges and parallel welding supports mounted on the insulating boxes. The metal strakes are, for example, made of Invar ®- that is an alloy of iron and nickel whose expansion coefficient typically lies between 1.2 .10 ⁶and 2 .10 ⁶ K¹, or an iron alloy having a high manganese content whose expansion coefficient is typically of the order of 7 .10 ⁶ K¹.

The insulating boxes have the general shape of a rectangular parallelepiped. The insulating boxes include parallel base and top panels spaced apart through the thickness of the insulating box. Load-bearing elements extend through the thickness of the insulating block, and are fixed to both the base panel and the top panel, and are able to take up compression forces. The base and top panels, the peripheral partitions and the load-bearing elements are, for example, made of wood or a composite thermoplastic material.

The insulating boxes have peripheral partitions. At least two opposite peripheral partitions are pierced to allow the flow of gas through the insulating boxes, so that an inert gas can be circulated through and/or the gas phase within can be placed in the thermally insulating barriers under reduced pressure, i.e. under a negative relative pressure.

A lagging lining is placed inside the insulating boxes. The lagging lining comprises, for example, glass wool, cotton wool or a polymer foam, such as polyurethane foam, polyethylene foam or polyvinyl chloride foam, or a granular or powder material, such as perlite, vermiculite, or glass wool - or a nonporous material of the aerogel type.

In Figure 1 there will be seen a connecting ring 2 which anchors the primary and secondary sealing membranes to load-bearing structure 1 at the corners between the transverse and longitudinal walls of the vessel. Connecting ring 2 here extends along an intersection between first wall 3 and second wall 4. Connecting ring 2 comprises an assembly of several welded sheets. The sheets in connecting ring 2 are for example made of Invar ®. Connecting ring 2 is fixed by means of connecting sheets 9, 10, 11, 12 to two flanges 5, 6 perpendicular to loadbearing structure 1 of first wall 3 and two flanges 7, 8 perpendicular to load-bearing structure 1 of second wall 4. Connecting ring 2 comprises primary anchoring surfaces 13, 14 intended to receive the metal strakes of the primary sealing membrane and secondary anchoring surfaces 15, 16 intended to receive the metal strakes of the secondary sealing membrane. The structure of such a connecting ring 2 is in particular described in French patent application FR2549575 or in French patent application FR2724623.

Connecting ring 2 and connecting sheets 9, 10, 11, 12 of ring 2 connecting to load-bearing structure 1 here define four spaces of parallelepiped shape in which lagging corner elements 17 are housed and ensure continuity of insulation of the primary and secondary thermally insulating barriers in the vicinity of connecting ring 2. Only lagging corner elements 17 of the primary thermally insulating barrier can be seen in Figures 1 and 2.

Lagging corner elements 17 may be formed by blocks of insulating polymer foam or be formed of insulating boxes such as described previously.

It will be noted that the sheets of connecting ring 2 have openings 18 in the vicinity of the primary thermally insulating barrier which allow gas to flow between the primary thermally insulating barrier of first wall 3 and the primary thermally insulating barrier of second wall 4. In the embodiment illustrated in Figure 1 openings 18 are of a generally rectangular shape, the corners of which are rounded off. In the embodiment in Figure 2 openings 18 are of circular geometry to limit stress concentrations and not adversely affect the fatigue strength of connecting ring 2.

As illustrated in Figures 1 and 2 the primary thermally insulating barrier incorporates deflection element 19 in the vicinity of the corner arrangement. Deflection elements 19 are housed within connecting unit 2 and located opposite openings 18 made in connecting ring 2. Deflection elements 19 are associated with lagging corner elements 17. Deflection elements 19 may be housed in a housing of matching shape made in lagging corner elements 17 or be located in the gaps extending between two adjacent lagging corner elements 17.

Deflection elements 19 are intended to direct the flow of gas across connecting ring 2 between the primary thermally insulating barriers of first and second walls 3, 4 of the vessel.

The structure of such a deflection element 19 is illustrated in particular in Figures 5 and 6. Deflection element 19 has the shape of a rectangular parallelepiped. Deflection element 19 has a first surface 20a opposite load-bearing structure 1 of second wall 4 and a second surface 20b facing load-bearing structure 1 of first wall 3. In other words first surface 20a is located opposite the primary thermally insulating barrier of first wall 3 and second surface 20b is located opposite the primary thermally insulating barrier of second wall 4. Deflection element 19 comprises a plurality of elbow channels 21 extending between first and second surfaces 20a, 20b, thus allowing gas to flow between the primary thermally insulating barriers of first and second walls 3, 4.

In a cross-sectional plane at right angles to the intersection between first and second walls 3, 4, deflection element 19 comprises a set of elbow channels 21 which are regularly spaced through the thickness of walls 3, 4 of the vessel. Elbow channels 21 are thus substantially parallel to the isothermal lines within the thermally insulating barrier. Elbow channels 21 thus create a stratified flow of gas across deflection element 19, which reduces convection. In order to achieve satisfactory thermal stratification of the gas flow each set of elbow channels 21 comprises at least four elbow channels, advantageously at least ten elbow channels, and preferably at least twenty elbow channels.

As illustrated in Figure 6, deflection element 19 comprises a system of elbow channels comprising a plurality of sets of elbow channels 21, the sets being spaced apart from each other in a direction parallel to the edge formed at the intersection between first and second walls 3, 4.

In the embodiments in Figures 5 and 6, elbow channels 21 are of an arched shape having a radius of curvature which increases from the inside to the outside of the vessel. Arched channels 21 in the same set have a common center of curvature which is located on a bisectrix of the angle formed at the intersection between first and second walls 3, 4. The center of curvature of arched channels 21 can in particular have a radius of curvature whose center corresponds to the edge between first and second surfaces 20a, 20b of deflection element 19.

In the embodiment in Figure 5, deflection element 19 has a housing 22 lined with lagging lining between arched channels 20 having the largest radius of curvature and a third surface 20c of deflection element 19, opposite first face 20a, and a fourth surface 20d opposite second face 20b. The lagging lining occupying this housing 22 is, for example, of glass wool, an aerogel or a polymer foam, such as a polyurethane or polyvinyl chloride foam.

Elbow channels 21 have a small cross-sectional area, typically less than 5 cm², generally of the order of 0.25 to 1 cm².

The cross-sections of the elbow channels may be of several shapes circular, square, rectangular, ovoid or other shapes. Advantageously, the crosssection of the elbow channels has a larger dimension in the direction parallel to the corner of the vessel than through the thickness of a wall of the vessel. Thus the largest dimension of the cross-section is orientated in the direction of the isotherms, whereas the smallest dimension is orientated along the thermal gradient.

In an alternative embodiment, illustrated diagrammatically in Figure 3, elbow channels 21 may comprise a first portion 21a parallel to first wall 3 and a second portion 21b parallel to second wall 4 and communicating with first portion 21a.

According to one embodiment, not illustrated, deflection element 19 is formed of a stack of plates stacked against each other in a direction perpendicular to first surface 20a or second surface 20b. The plates include a plurality of spaces which when the plates are stacked form elbow channels 21 described previously. The spaces may be formed during the operation of injection molding of the plates or by means of a later machining operation. Such plates can in particular be made of polymer materials having good mechanical properties and good thermal insulation properties, such as polyethylene (PE), polypropylene, (PP) or polyether-imide (PEI), for example, which may optionally be reinforced with fibers such as glass fibers.

According to another embodiment illustrated in Figure 4, deflection element 19 may comprise a stack 23 of plates stacked upon each other in a direction perpendicular to fifth and sixth surfaces 20e, 20f of deflection element 19, each having a common edge with first and second surfaces 20a, 20b of deflection element 19. At least some of the stacked plates have elbow grooves on at least one of those surfaces which form elbow channels 21 described previously when the plates are stacked. According to one embodiment, flat load-bearing plates formed of a material having greater mechanical strength than the plates forming the elbow grooves are each placed between two plates having elbow grooves. Such an embodiment is advantageous in that it makes it possible to use materials which are particularly appropriate for the construction of elbow grooves, while obtaining a deflection element 19 having good mechanical strength properties through the insertion of flat load-bearing plates.

The plates having elbow grooves are made of polymer material selected from polymers such as expanded polystyrene and thermoplastic materials, such as polyethylene (PE), polypropylene (PP) or polyether-imide (PEI), which are reinforced with fibers such as glass fibers. The elbow grooves may in particular be made by injection molding of the plates, or through subsequent stamping or machining operations.

When the deflection element comprises a stack 23 of plates, the said plates are attached to each other by any appropriate means, by adhesive bonding, thermoplastic welding, clipping or an attached mechanical connection, for example.

Furthermore it will be noted that in the embodiment illustrated in Figure 6 panels 24, 25 of insulating material may be attached to the third surface 20c of deflection element 19, opposite first surface 20a and against fourth surface 20d, opposite second surface 20b. Panels 24, 25 of insulating material may in particular be vacuum insulating panels, commonly indicated by the abbreviation, VIP, for vacuum insulating panels. Such vacuum insulating panels generally comprise a nanoporous core in an encapsulating seal and placed under negative pressure.

It should also be noted that the invention is not limited to deflection element 19 formed of a stack of plates and that it is also possible to construct such deflection elements 19 fitted with a plurality of elbow channels 21 through any other appropriate process and, in particular, by means of 3-dimensional printing processes.

In particular, in a variant embodiment, deflection element 19 is formed of an insulating polymer foam in which elbow channels 21 have been machined out of the mass. The insulating polymer foam may in particular be selected from thermoplastic foams such as polyethylene or polypropylene foams or thermohardening foams such as polyurethane. Thus deflection element 19 is formed of a material having good thermal insulation properties.

Figure 7 illustrates more particularly gas flow within the corner arrangement of the secondary thermally insulating barrier. Connecting sheets 9, 10, 11, 12 of connecting ring 2 to load-bearing structure 1 define three secondary thermally insulating barrier spaces in which lagging corner elements 28, 29, 30 are placed. In the embodiment illustrated in Figure 7, the lagging corner elements are insulating boxes comprising a peripheral partition pierced with holes 31 which allow gas to flow across the insulating boxes.

The space adjacent to the corner of the vessel is equipped with a deflection element 19 similar to the deflection element described previously. As for the other two spaces, these are equipped with junction elements, 32, 33 which have a plurality of gas flow channels 34 opening opposite elbow channels 21 of deflection element 19. Gas flow channels 34 of junction elements 32, 33 are also located opposite holes made in the peripheral partitions of the adjacent insulating boxes. Junction elements 32, 33 are incorporated in a housing of matching size made in lagging corner elements 28, 29.

In the space bordering a secondary thermally insulating barrier of first wall 3 flow channels 34 in junction element 33 extend substantially parallel to first wall 3, whereas in the space bordering the second thermally insulating barrier of second wall 4 flow channels 34 of junction element 32 extend substantially parallel to the second wall.

Furthermore, in the embodiment illustrated, junction elements 32, 33 are provided with openings 35 passing through said junction elements 32, 33 in a direction parallel to the edge formed at the intersection between the first and second walls 3, 4 so as to allow gas to flow along the corner of the vessel.

Figures 8 to 12 illustrate a corner structure which is in particular appropriate for membrane vessels of a second type, such as described for example in document FR 2691520.

In such a vessel the secondary thermally insulating barrier comprises a plurality of lagging panels attached to load-bearing structure 1 through bands of resin and studs welded onto load-bearing structure 1. Gaps between the lagging panels are lined with glass wool and provide passages for the flow of gas through the secondary thermally insulating barrier. Likewise spaces between the bands of resin, between the load-bearing structure and the lagging panel, provide spaces for the flow of gas. The lagging panels are, for example, made of a layer of insulating polymer foam sandwiched between two layers of plywood bonded onto the said foam layer. The insulating polymer foam may in particular be a polyurethane-based foam.

The lagging panels of the secondary membrane are covered by a secondary sealing membrane formed of a composite material comprising a sheet of aluminum sandwiched between two sheets of glass fiber fabric.

The primary thermally insulating barrier comprises lagging panels having a structure identical to that of the lagging panels of the secondary thermally insulating barrier. Gaps are made between the lagging panels to allow gas to flow within the primary barrier.

The primary sealing membrane is obtained by assembling a plurality of metal plates, welded to each other along their edges, and include corrugations extending in two perpendicular directions. The metal plates are, for example, made of stainless steel or aluminum, shaped by bending or pressing.

A corner structure, illustrated in Figure 8, includes two lagging panels 36, 37 having an external surface attached to the load-bearing structure. Lagging panels 36, 37 are connected to each other via their beveled lateral edges, for example, by adhesive bonding. Lagging panels 36, 37 thus form a corner of the secondary thermally insulating barrier.

A flexible sealing membrane 38 rests on lagging panels 36, 37 and ensures that the seal of the secondary sealing membrane remains continuous at the corner of the vessel.

In addition to this, the corner structure includes a plurality of insulating blocks 39, 40 of the primary thermally insulating barrier attached to flexible sealing membrane 38. Corner connections 41 of insulating material, such as polymer foam, are placed between adjacent edges of two insulating blocks 39, 40 at the angle of the vessel and thus ensure that the thermal insulation is continuous over the corner of the vessel. Likewise, joining insulating elements 42 are inserted between insulating blocks 39, 40.

Furthermore, metal angle sections 43 of the primary sealing barrier rest on insulating blocks 39, 40. Metal angle sections 43 have two flanges which are each parallel to one of the walls of the vessel. The flanges have studs 44 welded onto their inside surface. Studs 44 are used to attach welding equipment when welding the elements of the primary sealing membrane to metal angle sections 43.

At the corner structure, the primary thermally insulating barrier has deflection elements 45 which ensure that gas flows across the corner arrangement of the primary thermally insulating barrier. Deflection elements 45 are each inserted between two pairs of insulating blocks 39, 40.

Deflection element 45, illustrated in Figures 8, 10 and 11, is an elbowshaped element having a set of elbow channels 47 extending between a first surface 20a of deflection element 45 against second wall 4 at its opposite extremity, and a second surface 20b of deflection element 45 located opposite first wall 1 at its opposite extremity.

First surface 20a and second surface 20b of deflection element 45 are each located opposite a gap for the flow of gas provided between two lagging panels of the primary thermally insulating barrier.

Elbow channels 47 have a first portion 47a running parallel to first wall 3 and a second portion 47b running parallel to second wall 4. In the embodiment illustrated in Figure 11 the two portions 47a, 47b communicate with each other through an arched portion.

As in the preceding embodiments, deflection element 47 has a set of elbow channels 47 regularly spaced through the thickness of walls 3, 4 of the vessel in a cross-sectional plane at right angles to the intersection between first and second walls 3, 4, so that elbow channels 47 substantially follow the isotherms of the vessel at its corner.

Furthermore, as illustrated in Figure 8, elbow-shaped insulating elements 48 are located on either side of deflection element 47 while a third insulating element of elbow shape 49 rests on the surface of deflection element 47 facing into the vessel.

Finally, as illustrated in Figures 8 and 12, a secondary thermally insulating barrier also comprises deflection elements 46 at the corner structure, which ensure that gas flows through the corner arrangement of the secondary thermally insulating barrier. Deflection elements 46 are inserted in housings made in lagging panels 36, 37.

As in the previous embodiment, first surface 20a and second surface 20b of deflection elements 46 will be advantageously located opposite the gaps for the flow of gas formed between the lagging panels of the secondary thermally insulating barrier.

Deflection element 46, illustrated in detail in Figure 12, is formed of two straight parts 46a, 46b. Each of straight parts 46a, 46b comprises channels 50 parallel to one of walls 3, 4 of the vessel. Straight parts 46a, 46b each have a beveled edge and are abutted together via their beveled edges. Channels 50 of one of straight parts 46a, 46b open opposite channels 50 of the other straight part 46a, 46b in such a way as to form elbow channels.

In a version not illustrated, deflection element 46 can be made in a manner which fits angles other than 90°.

With reference to Figure 13, a cut-away view of a methane tanker 70 shows a sealed and insulated vessel 71 of generally prismatic shape mounted in the double hull 72 of the ship. The wall of vessel 71 comprises a primary sealing barrier intended to be in contact with the LNG present in the vessel, a secondary sealing barrier made between the primary sealing barrier and double hull 72 of the ship, and two insulating barriers located between the primary sealing barrier and the secondary sealing barrier, and between the secondary sealing barrier and the double hull 72 respectively.

In a known manner, loading/unloading piping 73 located on the upper deck of the ship may be connected by mean of appropriate connections to a maritime or port terminal to transfer a cargo of LNG to or from vessel 71.

Figure 13 shows one embodiment of a maritime terminal comprising a loading and unloading station 75, an undersea pipeline 76 and an onshore facility

77. Loading and unloading station 75 is a fixed offshore facility comprising a moving arm 74 and a tower 78 supporting moving arm 74. Moving arm 74 carries a bundle of insulated flexible pipes 79 which can be connected to loading/unloading pipes 73. Orientable moving arm 74 adjusts to all methane tanker dimensions. A connecting pipe, which is not shown, extends within tower 78. Loading and unloading station can be used to load and unload methane tankers 70 to or from onshore facility 77. This includes liquefied gas storage vessels 80 and connecting piping 81 connected by undersea pipe 76 to loading or unloading station 75. Undersea pipe is used to transfer liquefied gas between loading or unloading station 75 and onshore facility 77 over a large distance, for example, 5 km, as a result of which methane tanker 70 can be kept at a great distance from the coast during loading and unloading operations.

Pumps on board ship 70 and/or pumps in onshore facility 77 and/or pumps in loading and unloading station 75 are used to create the pressure required for the transfer of liquefied gas.

Although the invention has been described in connection with several particular embodiments it is obvious that it is not thereby in any way limited, and that it comprises all technical equivalents of the means described, together with their combinations if these fall within the scope of the invention.

Use of the verbs incorporate, comprise or include and their conjugated forms does not rule out the presence of other elements or other stages in addition to those stated in a claim. The use of the indefinite article a or an for an element or a stage does not, unless mentioned to the contrary, rule out the presence of a plurality of such elements or stages.

In the claims none of the reference numbers within brackets are to be interpreted as a limitation of the claim.

Claims

1. A sealed and insulating vessel for the storage of a fluid, the said vessel comprising a plurality of walls (3, 4), each wall having in succession, through the thickness of the wall of the vessel from the outside to the inside of the vessel, an outer load-bearing structure (1), a thermally insulating barrier attached to the load-bearing structure and a sealing membrane supported by the said thermally insulating barrier, the said thermally insulating barrier comprising:

- a plurality of lagging elements located along the walls of the vessel, arranged so as to define passages for the flow of gas within the said thermally insulating barrier; and

- a corner arrangement located at the intersection between the first and the second walls (3, 4) of the vessel, the said vessel being characterized in that the corner arrangement comprises:

- a deflection element (19, 45, 46) having a first surface (20a) opposite to the load-bearing structure of the second wall (4) and communicating with one or more of the passages for the flow of fluid defined by the plurality of lagging elements located along the first wall (3), a second surface (20b) opposite the load-bearing structure of the first wall (3) and communicating with one or more of the passages for the flow of fluid defined by the plurality of lagging elements located along the second wall (4) and a plurality of elbow channels (21,47, 50) extending between the first surface (20a) and the second surface (20b) of the deflection element (19, 45, 46) to allow fluid to flow across the corner arrangement, the plurality of elbow channels (21, 47, 50) comprising at least one set of elbow channels spaced apart from each other through the thickness of the first and second walls (3, 4) of the vessel.

2. The vessel as claimed in claim 1, in which the deflection element comprises a plurality of sets of elbow channels (21, 47, 50) spaced apart from each other through the thickness of the first and second walls (3, 4) of the vessel, the said sets being spaced apart from each other in a direction parallel to a line of intersection between the first and second walls (3, 4) of the vessel.

3. The vessel as claimed in claim 1 or 2, in which the set of elbow channels (21, 47, 50) which are spaced apart from each other through the thickness of the walls of the vessel comprise at least four elbow channels.

4. The vessel as claimed in any one of claims 1 to 3, in which the elbow channels (21,47, 50) have a cross-sectional area of less than 5 cm².

5 secondary sealing membrane and a primary sealing membrane intended to be in contact with the fluid stored in the vessel, each of the primary and secondary thermally insulating barriers incorporating a said corner arrangement comprising a deflection element (19, 45, 46).

20. A ship (70) for the transport of a fluid, the ship comprising a double hull (72) and

5. The vessel as claimed in any one of claims 1 to 4, in which the cross section of the elbow channels (21, 47, 50) has a larger dimension in a direction parallel to the corner of the vessel than along a direction of the thickness of a wall (3, 4) of the vessel.

6. The vessel as claimed in claim 1 or 5, in which the elbow channels (21, 47, 50) each comprise a first portion (21a, 47a) extending parallel to the first wall (3) and a second portion (21b, 47b) extending parallel to the second wall (4) and communicating with the first portion (21a, 47a).

7. The vessel as claimed in any one of claims 1 to 6, in which the elbow channels (21) are of arched shape, the elbow channels (21) having radii of curvature which increase from the inside to the outside of the vessel.

8. The vessel as claimed in claim 7, in which the deflection element (19) further comprises a third surface (20c), parallel and opposite to the first surface (20a), and a fourth surface (20d) parallel and opposite to the second surface (20b), and in which the deflection element (19) comprises a housing (22) lined with a lagging lining between the elbow channel of arched shape (21) having the greatest radius of curvature and the third and fourth surfaces (20c, 20d).

9. The vessel as claimed in any one of claims 1 to 8, in which the deflection element (19) comprises a stack of plates stacked against each other in a direction perpendicular to the first surface (20a) or the second surface (20b), the plates each incorporating a plurality of spaces defining a portion of the elbow channels (21).

10 a vessel (71) as claimed in any one of claims 1 to 19 located within the double hull.

21. A process for the loading or unloading of a ship (70) as claimed in claim 20, in which a fluid is passed through insulated piping (73, 79, 76, 81) to or from a floating or onshore (77) storage facility to or from the vessel (71) on the ship.

10. The vessel as claimed in any one of claims 1 to 9, in which the deflection element (19) comprises a stack (23) of plates stacked against each other in a direction perpendicular to one surface (20e, 20f) of the deflection element (19) having a common edge between the first surface (20a) and the second surface (20b), and in which at least some of the stacked plates are provided on at least one of those surfaces with elbow grooves shaped to form the elbow channels (21).

11. The vessel as claimed in claim 10, in which the stack (23) of plates comprises a plurality of flat load-bearing plates placed between two plates fitted with elbow grooves.

12. The vessel as claimed in any one of claims 1 to 11, in which the deflection element (19) is in the shape of a rectangular parallelepiped.

13. The vessel as claimed in claim 12, in which the deflection element (19) in the shape of a rectangular parallelepiped is associated with at least one junction element (32, 33) comprising a plurality of straight channels (34) parallel to one of the first and second walls (3, 4) and opening opposite the elbow channels (21) of the deflection element (19).

14. The vessel as claimed in claim 13, in which the junction element (32, 33) has openings (35) crossing the said junction element (32, 33) in a direction parallel to the edge formed at the intersection between the first and the second walls (3, 4) of the vessel.

15. The vessel as claimed in any one of claims 1 to 11, in which the deflection element (45, 46) is of an elbow shape.

16. The vessel as claimed in claim 15, in which the elbow-shaped deflection element (46) has two straight parts (46a, 46b) each having a beveled edge and connected to each other via their beveled edges.

17. The vessel as claimed in any one of claims 1 to 16, in which the corner arrangement comprises lagging corner elements (17, 28, 29, 30, 36, 37, 39, 40) and in which the deflection element (19, 45, 46) is associated with the lagging corner elements (17, 28, 29, 30, 36, 37, 39, 40).

18. The vessel as claimed in any one of claims 1 to 17, in which the deflection element (19, 45, 46) is made of a polymer material selected from expanded polystyrene, polyurethane, polyurethane foam, polyethylene, polyethylene foam, polypropylene, polypropylene foam, polyamide, polycarbonate or polyetherimide.

19. The vessel as claimed in any one of claims 1 to 18, in which each wall of the vessel (3, 4) has in succession, through the thickness of the vessel from the outside to the inside of the vessel, an outer load-bearing structure (1), a secondary thermally insulating barrier attached to the load-bearing structure (1), a secondary sealing membrane supported by the said secondary thermally insulating barrier, a primary thermally insulating barrier resting against the

15 22. A transfer system for a fluid, the system comprising a ship (70) as claimed in claim 20, insulated piping (73, 79, 76, 81) arranged in such a way as to connect the vessel (71) installed in the hull of the ship to a floating or onshore storage facility (77) and a pump to drive fluid through the insulated piping to or from the floating or onshore storage facility to or from the vessel on the ship.