Liquefied gas storage facility comprising a dome structure supporting a spray boom

Abstract

The invention relates to a liquefied gas storage facility with a dome structure (25) comprising an outer barrel (26), an inner barrel (29) which is welded to a sealing membrane (17), a support pipe (33) which passes through the inner barrel (29) and a crown (38) which supports a spray bar (34) and is fixed to a lower portion of the support pipe (33), the spray bar (34) comprising a plurality of spray nozzles (45), the crown (38) having a diameter (d1) greater than a diameter (d2) of the inner barrel (29). Figure to be published: 3

Description

Title of the invention: Liquefied gas storage facility comprising a dome structure supporting a spray boom Technical field

[0001] The invention relates to the field of sealed and thermally insulating tanks for the storage and / or transport of a liquefied gas, such as tanks for the transport of Liquefied Petroleum Gas (also called LPG) having, for example, a temperature between -50°C and 0°C, or for the transport of Liquefied Natural Gas (LNG) at approximately -162°C at atmospheric pressure.

[0002] These tanks can be installed on land or on a floating structure. In the case of a floating structure, the tank can be intended for the transport of liquefied gas or for receiving liquefied gas used as fuel for the propulsion of the floating structure.

[0003] The invention relates more particularly to a tank comprising a dome structure which passes through an opening made in the ceiling wall of the tank and which is equipped with a spray bar intended to spray liquefied gas inside the tank. Technological background

[0004] Document KR20140088975 discloses a dome structure for a tank waterproof and thermally insulating storage of liquefied gas. The dome structure includes: - an inner barrel which passes through an opening formed in the supporting structure of the ceiling wall, passes through the ceiling wall of the tank and is sealed to the primary waterproofing membrane of the ceiling wall; - an outer barrel which is arranged around the inner barrel and is welded to the supporting structure around the opening crossed by the inner barrel; - a support pipe intended for the evacuation of gas which passes through the inner barrel; and - a spray bar which is intended for spraying liquefied gas into the support pipe and which is mounted on a crown fixed to the lower end of the support pipe.

[0005] Such a dome structure is not entirely satisfactory. In particular, the diameter of the inner barrel is particularly important. Indeed, the diameter of the inner barrel must be greater than the diameter of the spray bar and the crown which carries it in order to allow their passage through the inner barrel when the support pipe is lowered inside the spray bar, during the assembly of the dome structure. However, since the primary waterproofing membrane is welded to the inner barrel, it is necessary to limit the diameter of the inner barrel in order to limit the loss of elasticity of the primary waterproofing membrane in the area where it is welded to the inner barrel.

[0006] In addition, the interior of the inner drum is likely to be subjected to dynamic pressures due to the phenomenon of "sloshing", i.e. the movement of the cargo in the tank. The movement of the cargo is also likely to cause the unwanted presence of liquefied gas in the dome structure and in gas extraction pipes opening into the dome structure. However, such gas extraction pipes may in particular be equipped with a compressor likely to be damaged by the presence of liquefied gas. Summary

[0007] An idea underlying the invention is to design a liquefied gas storage facility comprising a dome structure of the aforementioned type making it possible to resolve the aforementioned drawbacks and in particular to limit the losses of elasticity of the sealing membranes resulting from the welding of said sealing membranes to the inner barrel of the dome structure.

[0008] According to one embodiment, the invention relates to a liquefied gas storage facility comprising a supporting structure defining an internal space and comprising an upper supporting wall comprising an opening, a sealed and thermally insulating tank comprising a ceiling wall comprising at least one thermally insulating barrier fixed to the upper supporting wall and a sealing membrane intended to be in contact with the liquefied gas, the facility comprising a dome structure comprising: - an outer barrel extending outside the supporting structure and comprising a lower end welded around the opening of the supporting structure; - an inner shaft which passes through the opening in the supporting structure and the ceiling wall, extends inside the outer shaft and has a lower end which is welded to the waterproofing membrane; - a support pipe which passes through the inner barrel and has a lower portion extending beyond the lower end of the inner barrel; - a supply conduit intended to be supplied with liquefied gas which is fixed to the support pipe; - a crown which supports a spray bar and is fixed to the lower portion of the support pipe, the spray bar comprising a plurality of spray nozzles and being connected to said supply pipe, the crown having a diameter greater than a diameter of the inner barrel.

[0009] According to one embodiment, the invention also provides a mounting method of a dome structure of a liquefied gas storage facility, said method comprising: - provide a supporting structure defining an internal space and comprising an upper supporting wall intended to receive a ceiling wall of a sealed and thermally insulating tank, the upper supporting wall comprising an opening; - provide a gas dome structure comprising: - an outer barrel extending outside the supporting structure and comprising a lower end welded around the opening of the supporting structure; - an inner barrel which passes through the opening of the supporting structure, extends inside the outer barrel, is anchored to said outer barrel; - a support pipe which passes through the inner barrel and has a lower portion extending beyond the lower end of the inner barrel; and - a supply conduit intended to be supplied with liquefied gas which is fixed to the support pipe; - providing a crown supporting a spray bar which comprises a plurality of spray nozzles; said crown having a diameter greater than a diameter of the inner barrel; - moving the crown from the internal space until the crown comes into contact with the support pipe; - fix the crown to the support pipe; and - tightly connect an upstream end of the spray boom to a downstream end of the supply pipe.

[0010] Thus, such an installation and such a method are particularly advantageous in that, for a given installation diameter of the spray bar, the diameter of the inner barrel is smaller, which in particular makes it possible to limit the loss of elasticity of the sealing membrane. In addition, the crown thus makes it possible to protect the interior of the inner barrel against movements of liquefied gas inside the tank. More precisely, the crown makes it possible in particular to avoid the presence of liquefied gas in gas extraction pipes comprising a compressor.

[0011] According to embodiments, such an installation and such a method may comprise one or more of the following characteristics.

[0012] According to one embodiment, the support pipe comprises a fixing collar which extends radially around the support pipe and the crown comprises an annular bottom which is fixed against a lower face of the fixing collar. Such an arrangement allows the crown to be fixed in a simple manner to the support pipe via the internal space.

[0013] According to one embodiment, the annular bottom of the crown comprises lights which are distributed around the support pipe and which have edges welded to the mounting collar. This also helps to allow the crown to be fixed to the support pipe through the internal space.

[0014] According to one embodiment, the fixing collar and the annular bottom comprise orifices configured to allow the passage of fixing members through the fixing collar and the annular bottom.

[0015] According to one embodiment, the fixing collar and the annular bottom each comprise an opening, said openings being positioned opposite each other and crossed by the supply conduit.

[0016] According to one embodiment, the spray ramp is connected to said supply conduit in a welding zone positioned below the annular bottom.

[0017] According to one embodiment, the lower portion of the support pipe comprises a base wall which closes a lower end of the support pipe and windows which are provided in a cylindrical wall of the lower portion of the support pipe and the welding zone is positioned opposite one of the windows. This facilitates the welding operations, and in particular the handling of the welding torch.

[0018] According to one embodiment, the support pipe comprises a fixing collar which extends radially around the support pipe and the crown comprises an annular bottom and, to fix the crown to the support pipe, the annular bottom of the crown is welded against a lower face of the fixing collar.

[0019] According to one embodiment, prior to welding the annular bottom of the crown against the lower face of the fixing collar, the fixing collar and the annular bottom are fixed to each other by means of fixing members.

[0020] According to one embodiment, the fixing members are temporary fixing members.

[0021] According to one embodiment, the temporary fixing members are removed after the welding operations of the annular bottom of the crown against the lower face of the fixing collar. This prevents the fixing members from becoming detached and thus damaging the bottom wall of the tank and in particular its primary sealing membrane.

[0022] According to one embodiment, the annular bottom of the crown comprises openings which are distributed around the support pipe and the edges of said openings are welded to the fixing collar.

[0023] According to one embodiment, the lower portion of the support pipe comprises a base wall which closes a lower end of the support pipe and windows which are provided in a cylindrical wall of the lower portion of the support pipe and the upstream end of the pul ramp is welded verification at the downstream end of the supply duct in a welding zone which is positioned opposite one of the windows.

[0024] According to one embodiment, the dome structure comprises a protective plate fixed to the lower end of the support pipe, the protective plate covering the crown and having a plurality of holes.

[0025] According to one embodiment, the inner barrel is anchored to said outer barrel.

[0026] According to one embodiment, the inner barrel is anchored to the outer barrel by a upper anchoring device and a lower anchoring device.

[0027] According to one embodiment, the inner barrel is anchored to the outer barrel, by a lower anchoring device, which is positioned at a distance h from the end in lower than the inner barrel, the distance h is determined so that the contraction Ah of the distance h when the tank is cold is between 90 and 110% Al, with: Al the vertical displacement of the sealing membrane 17 due to the contraction of the primary 15 and secondary 12 thermally insulating barriers when the tank is cooled.

[0028] Such an installation may be part of a land-based storage facility, for example for storing LNG or be installed in a floating, coastal or deep-water structure, including an LNG carrier, a floating storage and regasification unit (FSRU), a floating production and remote storage unit (FPSO) and others. Such a tank may also serve as a fuel tank in any type of vessel.

[0029] According to one embodiment, a ship for transporting a liquefied gas comprises a storage facility for a liquefied gas of the aforementioned type.

[0030] According to one embodiment, the invention also provides a transfer system for a liquefied gas, the system comprising the aforementioned ship, insulated pipes arranged so as to connect the tank of the liquefied gas storage facility of the ship to a floating or land-based storage facility and a pump for driving a flow of liquefied gas through the insulated pipes from or to the floating or land-based storage facility to or from the tank of the liquefied gas storage facility of the ship.

[0031] According to one embodiment, the invention also provides a method for loading or unloading such a ship, in which a liquefied gas is conveyed through insulated pipes from or to a floating or land-based storage facility to or from the tank of the liquefied gas storage facility of the ship. Brief description of the figures

[0032] The invention will be better understood, and other objects, details, characteristics and advantages thereof will appear more clearly during the following description of several particular embodiments of the invention, given solely for illustrative and non-limiting purposes, with reference to the appended drawings.

[0033] [Fig. 1] [Fig.l] is a schematic perspective view of a supporting structure intended to support a sealed and thermally insulating tank for storing liquefied gas, the dome structure not being shown.

[0034] [Fig.2] [Fig.2] is a schematic view of the multi-layer structure of the tank walls.

[0035] [Fig.3] [Fig.3] is a sectional view of a dome structure, according to one embodiment, passing through a ceiling wall of a sealed and thermally insulating tank.

[0036] [Fig.4] [Fig.4] is another sectional view of the dome structure of [Fig.3].

[0037] [Fig.5] [Fig.5] is a sectional and perspective view of the dome structure of [Fig.2], passing through the ceiling wall of the sealed and thermally insulating tank.

[0038] [Fig.6] [Fig.6] is a detail view of the dome structure of Figures 2 and 3 illustrating, in particular, a spray bar and a support ring ensuring the attachment of the spray bar to a support pipe.

[0039] [Fig.7] [Fig.7] is a bottom view of the support ring and spray boom.

[0040] [Fig.8] [Fig.8] is a bottom perspective view of the support ring and the spray bar.

[0041] [Fig.9] [Fig.9] is a bottom perspective view illustrating another embodiment in which a protection plate is positioned below the support crown.

[0042] [Fig. 10] [Fig. 10] is a schematic cutaway representation of a ship comprising a liquefied natural gas storage tank and a terminal for loading / unloading this tank. Description of the embodiments

[0043] In connection with [Fig.l], a supporting structure 1 is described against which a sealed and thermally insulating tank for storing a liquefied gas is intended to be fixed. The supporting structure 1 is, for example, formed by the double hull of a ship. The double hull comprises an outer hull 19 and an inner hull 18 arranged inside the outer hull 19. The supporting structure 1 has a generally polyhedral shape. It has two front and rear supporting walls, here octagonal in shape, of which only the rear supporting wall 2 is shown in [Fig.l]. The front and rear walls 2 are, for example, cofferdam walls of the ship which extend transversely to the longitudinal direction of the ship. The structure The carrier structure 1 also comprises an upper load-bearing wall 3, a lower load-bearing wall 4 and side load-bearing walls 5, 6, 7, 8, 9, 10. The sealed and thermally insulating tank for storing liquefied gas comprises a plurality of tank walls which are each anchored against one of the load-bearing walls 2, 3, 5, 6, 7, 8, 9, 10 of the carrier structure 1 and which thus define an internal space intended to contain the liquefied gas.

[0044] As shown in [Fig.2], each wall of the tank successively presents, from the outside to the inside, according to the direction of thickness of the wall: - a secondary thermally insulating barrier 12 comprising insulating elements 13 fixed to the supporting structure 1; - a secondary sealing membrane 14 anchored to the insulating elements 13 of the secondary thermally insulating barrier 12; - a primary thermally insulating barrier 15 comprising insulating elements 16 fixed to the insulating elements 13 of the secondary thermally insulating barrier 12 or to the supporting structure 1 and resting against the secondary sealing membrane 14; and - a primary sealing membrane 17 anchored to the insulating elements 16 of the primary thermally insulating barrier 15 and intended to be in contact with the liquefied gas contained in the tank.

[0045] The liquefied gas intended to be stored in the tank may in particular be ethane, liquefied natural gas (LNG), i.e. a gas mixture comprising mainly methane and one or more other hydrocarbons, or liquefied petroleum gas (LPG), i.e. a mixture of hydrocarbons resulting from the refining of petroleum comprising essentially propane and butane.

[0046] In the embodiment shown in Figures 3 and 4, the insulating elements 13 of the secondary thermally insulating barrier 12 are secondary insulating panels 20 comprising a layer of insulating polymer foam 21, for example polyurethane, sandwiched between a cover plate 22 and a rigid base plate 23, for example plywood.

[0047] The secondary sealing membrane 14 is formed from a continuous sheet of strakes with raised edges. Each strake has a flat central portion resting on the cover plate of the secondary insulating panels 20 and two raised edges projecting towards the inside of the tank. The strakes are welded by their raised edges to welding supports which are fixed in the grooves provided on the cover plates of the secondary insulating panels 20. The strakes are, for example, made of Invar®, i.e. an alloy of iron and nickel whose coefficient of expansion is typically between 1.2 x 106 K1 and 2.0 x 106 K1. It is also possible to use iron and manganese alloys whose coefficient of expansion is typically in the order of 7 x 106 K 1 to 10 x 10 6 K *.

[0048] The insulating elements 16 of the primary thermally insulating barrier 15 are primary insulating panels 24 comprising a layer of insulating polymer foam, for example polyurethane, sandwiched between a rigid cover plate and a base plate, for example plywood.

[0049] The primary sealing membrane 17 is obtained by assembling a plurality of corrugated metal sheets, welded to each other overlapping along their edges. The corrugations project towards the inside of the tank. The corrugated metal sheets are fixed on anchoring strips which are fixed in counterbores made in the cover plates of the primary insulating panels 24. The corrugated metal sheets are, for example, made of stainless steel or aluminum.

[0050] Alternatively, the walls of the tank can also be produced according to the technologies described in patent applications WO14057221, FR2691520 and FR2877638 relating respectively to the Mark V, Mark III® and NO96® products developed by the applicant.

[0051] In connection with Figures 3 and 4, a dome structure 25 according to one embodiment is described below. The dome structure 25 comprises an outer barrel 26, of cylindrical shape which extends in the direction of thickness of the ceiling wall of the tank. The outer barrel 26 passes through an opening provided in the outer shell 19. The lower end of the outer barrel 26 is sealed welded to the inner shell 18, around an opening 27 formed in said inner shell 18. The upper end of the outer barrel 26 is sealed by a removable cover 28.

[0052] The dome structure 25 also comprises an inner barrel 29 which is arranged inside the outer barrel 26. The inner barrel 29 is concentric with the outer barrel 26 and passes through the opening 27 formed in the inner shell 18. The inner barrel 29 also passes through the upper wall of the tank. The inner barrel 29 has a lower end which is sealed to the primary sealing membrane 17 so as to seal the primary thermally insulating barrier 15 against the interior space of the tank. The inner barrel 29 comprises a compensation device 30, formed for example by a series of bellows, allowing it to be given flexibility in its longitudinal direction so as to allow its contraction and expansion. The outer barrel 26 and the inner barrel 29 are anchored to each other by an upper anchoring device 31 and a lower anchoring device 32 which will be described later.The inner barrel 29 is open at each of its two ends.

[0053] The dome structure 25 also includes a support pipe 33 which is concentric to the inner barrel 29 and passing through it. This support pipe 33 has two main functions, namely to support a spray bar 34 intended to spray liquefied gas inside the tank and to conduct the vapor phase of the gas from the internal space of the tank to a collection zone 35 positioned at the upper end of the dome structure 25.

[0054] The support pipe 33 has a support collar 36 which is welded to the upper end of the support pipe 33 and which projects radially outwards. The support collar 36 rests against an annular flange 37 which is welded to the outer barrel 26 and projects radially inwards. The support collar 36 and the annular flange 37 are welded to each other in a sealing manner.

[0055] The dome structure 25 also comprises a crown 38 which carries the spray bar 34 and which is fixed to the lower end of the support pipe 33. In the embodiment shown, the crown 38 comprises an annular bottom 39 which extends in a plane orthogonal to the thickness direction of the ceiling wall, around the support pipe 33. The crown 38 also comprises a cylindrical rim 40 which projects downwardly from the radially outer edge of the annular bottom 3. In the embodiment shown, the annular bottom 39 and the cylindrical rim 40 are fixed to each other by a plurality of gussets welded to said annular bottom 39 and to said cylindrical rim 40.

[0056] The annular bottom 39 is welded against a fixing collar 41 which is welded to the support pipe 33 and extends radially around it. The fixing collar 41 is positioned at a distance from the lower end of the support pipe 33 such that a lower portion of the support pipe 33 extends below the annular bottom 39 of the crown 38.

[0057] The lower portion of the support pipe 33 comprises a base wall 42 which closes the lower end of the support pipe 33 and windows 43 which are arranged in the cylindrical wall of the lower portion. The windows 43 are at least two in number and four in number in the embodiment shown. The windows 43 are regularly distributed around the axis of the support pipe 33. Such a structure prevents liquid phase gas from entering the support pipe 33.

[0058] The spray bar 34 comprises one or more rings 44 arranged around the crown 38 and more particularly around the cylindrical rim 40. Each ring 44 comprises a plurality of spray nozzles 45 which are regularly distributed around the central axis of the crown 38. Each ring 44 is fixed to the crown 38 by any suitable means, such as fixing collars 46, visible in particular in [Fig.7] or fixing clips, for example. In addition, the cylindrical rim 40 has a groove allowing a bent portion of the spray bar verification 34 to pass through said cylindrical rim 40 so as to connect each ring 44 to a supply conduit 47.

[0059] Furthermore, as shown for example in Figures 6 to 8, each ring 44 of the spray bar 34 is connected to a supply conduit 47 intended to supply the spray bar 34 with liquefied gas. As shown for example in [Fig. 3], the supply conduits 47 pass through the inner barrel 29 as well as the outer barrel 26 from one end to the other. The supply conduits 47 are connected to a pump, not shown, which is configured to pump liquefied gas, for example into the tank or into a dedicated reservoir. It can be seen in [Fig. 3] that the supply conduits 47 each have a helical zone 48 which winds around the support conduit 33 and thus allows thermal contractions and expansions of said supply conduits 47. Furthermore, the supply conduits 47 are fixed to the support conduit 33 by anchoring devices 49, notably visible in [Fig. 3].The anchoring devices 49 are regularly distributed along the support pipe 33. Advantageously, the anchoring devices 49 ensure sliding anchoring of the supply pipes 47, that is to say they allow the relative movement of the supply pipes 47 with respect to the support pipe 33 in order to allow them to contract and expand.

[0060] As shown in [Fig. 3], the diameter d2 of the inner barrel 29 is smaller than the diameter d1 of the crown 38. Similarly, the diameter d3 of the opening 27 formed in the inner shell 18 is preferably smaller than the diameter d2 of the crown 38. Such an arrangement has several advantages over an arrangement according to the prior art in which the diameter d2 of the inner barrel 29 is greater than that of the crown 38. On the one hand, for a given installation diameter of the spray bar 34, the diameter d2 of the inner barrel 29 is smaller, which in particular makes it possible to interrupt a smaller number of undulations of the primary sealing membrane 17, thus limiting the loss of elasticity of said primary sealing membrane 17 resulting from these interruptions. On the other hand, the crown 38 makes it possible to protect the interior of the inner barrel 29 against movements of liquefied gas inside the tank.More specifically, the crown 38 makes it possible to avoid the presence of liquefied gas in gas extraction pipes comprising a compressor. As will be described later, in order to allow the installation of such a dome structure 25, the assembly comprising the crown 38 and the spray bar 34 is fixed to the support pipe 33, from the internal space of the tank, and after said support pipe 33 has been lowered through the inner barrel 29.

[0061] Returning to [Fig. 3], we observe the upper anchoring device 31 and the lower anchoring device 32 which ensure the fixing of the inner barrel 29 to the outer barrel 26. The upper anchoring device 31 comprises a support collar 50 which is welded to the inner barrel 29 and projects radially outwards, around it as well as an annular flange 51 which is welded to the outer barrel 26 and projects radially inwards therefrom. The support collar 50 rests against the annular flange 51. The support collar 50 and the annular flange 51 are welded to each other in a sealed manner. Thus, a secondary sealed space 52 is provided between the outer barrel 26 and the inner barrel 29, below said support collar 50 and annular flange 51. According to an advantageous embodiment, an insulation layer 65, shown in dotted lines in FIGS. 3 and 4, is distributed uniformly over the outer surface of the inner barrel 29.

[0062] Furthermore, the lower anchoring device 32 comprises a frustoconical support element 53 which flares downwards and which is welded to the inner barrel 29 around the latter. It also comprises a support ring which is welded to the radially outer edge of the frustoconical support element 53 and which comprises a support collar 54 which projects radially outwards. The lower anchoring device 32 also comprises an annular flange 55 which is welded to the outer barrel 26 and projects radially inwards thereof. The support collar 54 rests on the annular flange 55 directly or indirectly via a shim 56 interposed between said support collar 54 and said annular flange 55 as in the embodiment shown. The wedge 56 is, for example, made of wood and glued, for example by means of resin, against the support collar 54 and against the annular flange 55.Advantageously, the thickness of the shim 56 is determined in order to compensate for the manufacturing and / or positioning tolerances of the inner barrel 29 relative to the outer barrel 26 according to the thickness direction of the ceiling wall of the tank.

[0063] The inner barrel 29 is anchored to the outer barrel 26 at a distance h from the lower end. According to an advantageous embodiment, the distance h is determined such that its contraction Ah when the tank is cooled is substantially equal to the vertical displacement Al of the primary sealing membrane 17 due to the contraction of the primary 15 and secondary 12 thermally insulating barriers. This avoids or at least limits any walking effect between the primary sealing membrane 17 and the lower end of the inner barrel 29.

[0064] The dome structure 25 further comprises a sheath 57, visible in FIGS. 3 and 4, which is concentric with the outer barrel 26 and which is arranged radially between the outer barrel 26 and the inner barrel 29. The sheath 57 also passes through the opening 27 formed in the inner shell 18. A primary sealed space 58 communicating with the primary thermally insulating barrier 15 is provided between the sheath 57 and the inner barrel 29.

[0065] As shown in [Fig.4], the dome structure 25 comprises an exhaust duct 59 which opens into the interior of the sealed primary space 58. The exhaust duct 59 is connected to a valve, not shown, which, by default, is closed and which opens when the pressure in the primary thermally insulating barrier 15 exceeds a predetermined threshold pressure. The exhaust duct 59 is thus intended to protect the primary sealing membrane 17 against overpressures likely to occur in the primary thermally insulating barrier 15. Advantageously, the exhaust duct 59 comprises a helical zone winding around the inner barrel 29 and thus allowing thermal contractions and expansions of said exhaust duct 59.

[0066] The dome structure 25 also comprises an inerting conduit 60 which also opens into the interior of the sealed primary space 58. The inerting conduit 60 is connected to a reservoir of inert gas, such as nitrogen, by a pump, which makes it possible to circulate inert gas in the primary thermally insulating barrier 15.

[0067] Furthermore, as shown in [Fig. 4], the sheath 57 is not welded to the inner shell 18 of the double shell so as to provide an annular passage between said sheath 57 and the inner shell 18. An exhaust duct 61 and an inerting duct 62, visible in [Fig. 4], pass in a sealed manner through the outer barrel 26 to open into the secondary sealed space 52. The exhaust duct 61 is connected to a valve which, by default, is closed and which opens when the pressure inside the secondary thermally insulating barrier 12 exceeds a predetermined threshold. It thus makes it possible to protect the secondary sealing membrane 14 against excess pressures likely to occur in the secondary thermally insulating barrier 12. The inerting conduit 62 is connected to a reservoir of inert gas, such as nitrogen, by a pump, which makes it possible to circulate the inert gas in the secondary thermally insulating barrier 12.

[0068] Furthermore, the dome structure 25 comprises at least one steam collection conduit 63, 64 which passes in a sealed manner through the wall of the outer barrel 26 and opens into the collection zone 35 positioned at the upper end of the dome structure 25. Thus, the steam collection conduit(s) 63, 64 are capable of conducting steam between the collection zone 35 and a steam collector, not shown, arranged outside the dome structure 25.

[0069] A method of mounting a dome structure 25, as described above, will now be described. First, a first part of the dome structure 25, which is devoid of the crown 38 and the spray bar 34, is mounted and fixed to the supporting structure 1. For this, the outer barrel 26 is welded in a sealed manner to the inner shell 18, around the opening 27. The inner barrel 29 is lowered inside the outer barrel 26 via the upper end of the outer barrel 26. In order to allow this movement, the internal diameter of the annular flange 37 is greater than the external diameters of the support collars 50, 54 and the internal diameter of the annular flange 51 is greater than the outer diameter of the support collar 54. The support pipe 33 is also lowered through the outer barrel 26 and the inner barrel 29 until the support collar 36 welded to the support pipe 33 rests against the annular flange 37.

[0070] In a second step, the crown 38 as well as the spray bar 34 fixed to said crown 38 are approached from the support pipe 33 by the internal space of the tank and fixed thereto. To do this, as shown in [Fig.8], the fixing collar 41 as well as the crown 8 comprises orifices 66 which are configured to be positioned opposite and thus allow the passage of temporary fixing members 67 through said orifices 67. For example, the temporary fixing members 67 comprise a screw-nut assembly. Furthermore, the crown 38 and more particularly the annular bottom 39 comprises slots 68 which are regularly distributed around the support pipe 33 and which allow the crown 38 to be welded from below to the fixing collar 41. Thus, the edges of the slots 68 are welded to the fixing collar 41.After the welding operations of the crown 38 to the fixing collar 41, the temporary fixing members 67 can then be removed, which prevents them from subsequently falling inside the tank and thus damaging the primary sealing membrane 17.

[0071] The spray bar 34 is also connected to one or more supply conduits 47. To do this, as illustrated in [Fig. 7], the annular bottom 39 of the crown 8 and the fixing collar 41 each have an opening 69 allowing the supply conduits 47 to pass through the fixing collar 41 and the annular bottom 39 of the crown 38. In order to ensure the sealing of the connection, the spray bar 34 is welded to the supply conduits 47 in welding zones 82, one of which is represented in particular by dotted lines in [Fig. 8]. In order to facilitate the welding operations and in particular the handling of the welding torch, the welding zones 82 are preferably located radially opposite one of the windows 43 formed in the lower portion of the support conduit 33.

[0072] [Fig. 9] illustrates a dome structure 25 according to another embodiment. This embodiment differs from that described above in relation to FIGS. 3 to 8 in that the dome structure further comprises a protective plate 83 which is fixed to the lower end of the support pipe 33. This protective plate 83 covers the crown 38. It has a plurality of holes 84 allowing the gas in the vapor phase to penetrate inside the support pipe via the windows 43. Such a protective plate 83 makes it possible in particular to protect the crown 38 against the movements of liquefied gas in the liquid phase inside the tank and to further prevent liquefied gas in the liquid phase from reaching the interior of the support line 33 and the gas extraction line comprising a compressor.

[0073] With reference to [Fig. 10], a cutaway view of an LNG carrier ship 70 shows a sealed and thermally insulating tank 71 of generally prismatic shape mounted in the double hull 72 of the ship. The wall of the tank 71 comprises a primary sealing membrane intended to be in contact with the LNG contained in the tank, a secondary sealing membrane arranged between the primary sealing membrane and the double hull 72 of the ship, and two thermally insulating barriers arranged respectively between the primary sealing membrane and the secondary sealing membrane and between the secondary sealing membrane and the double hull 72.

[0074] In a manner known per se, loading / unloading pipelines 73 arranged on the upper deck of the ship can be connected, by means of appropriate connectors, to a maritime or port terminal to transfer a cargo of LNG from or to the tank 71.

[0075] [Fig. 10] shows an example of a maritime terminal comprising a loading and unloading station 75, an underwater pipeline 76 and an onshore installation 77. The loading and unloading station 75 is a fixed offshore installation comprising a mobile arm 74 and a tower 78 which supports the mobile arm 74. The mobile arm 74 carries a bundle of insulated flexible pipes 79 which can be connected to the loading / unloading pipelines 73. The orientable mobile arm 74 adapts to all sizes of LNG carriers. A connecting pipe, not shown, extends inside the tower 78. The loading and unloading station 75 allows the loading and unloading of the LNG carrier 70 from or to the onshore installation 77. The latter comprises liquefied gas storage tanks 80 and connecting pipes 81 connected by the underwater pipe 76 to the loading or unloading station 75.The subsea pipeline 76 allows the transfer of liquefied gas between the loading or unloading station 75 and the onshore installation 77 over a long distance, for example 5 km, which makes it possible to keep the LNG carrier 70 at a great distance from the coast during loading and unloading operations.

[0076] To generate the pressure necessary for the transfer of the liquefied gas, pumps on board the ship 70 and / or pumps equipping the onshore installation 77 and / or pumps equipping the loading and unloading station 75 are used.

[0077] Although the invention has been described in connection with several particular embodiments, it is quite obvious that it is in no way limited thereto and that it includes all the technical equivalents of the means described as well as their combinations if these fall within the scope of the invention, as defined by the claims.

[0078] The use of the verb “comporter”, “comprendre” or “include” and its conjugated forms does not exclude the presence of other elements or other stages than those stated in a claim.

[0079] In the claims, any reference sign in parentheses cannot be interpreted as a limitation of the claim.

Claims

Claims

1. A liquefied gas storage facility comprising a supporting structure (1) defining an internal space and comprising an upper supporting wall (3) comprising an opening (27), a sealed and thermally insulating tank comprising a ceiling wall comprising at least one thermally insulating barrier (12, 15) fixed to the upper supporting wall (3) and a sealing membrane (17) intended to be in contact with the liquefied gas, the facility comprising a dome structure (25) comprising: - an outer barrel (26) extending outside the supporting structure (1) and comprising a lower end welded around the opening (27) of the supporting structure (1); - an inner barrel (29) which passes through the opening (27) of the supporting structure (1) and the ceiling wall, extends inside the outer barrel (26) and has a lower end which is welded to the waterproofing membrane (17);- a support pipe (33) which passes through the inner barrel (29) and has a lower portion extending beyond the lower end of the inner barrel (29); - a supply pipe (47) intended to be supplied with liquefied gas which is fixed to the support pipe (33); - a crown (38) which supports a spray bar (34) and is fixed to the lower portion of the support pipe (33), the spray bar (34) having a plurality of spray nozzles (45) and being connected to said supply pipe (47), the crown (38) having a diameter (dl) greater than a diameter (d2) of the inner barrel (29).;

2. A liquefied gas storage facility according to claim 1, wherein the support pipe (33) comprises a fixing collar (41) which extends radially around the support pipe (33) and the crown (38) comprises an annular bottom (39) which is fixed against a lower face of the fixing collar (41).

3. A liquefied gas storage facility according to claim 2, wherein the annular bottom (39) of the crown (38) comprises openings (68) which are distributed around the support pipe (33) and which have edges welded to the fixing collar (41).

4. A liquefied gas storage facility according to claim 2 or 3, wherein the fixing collar (41) and the annular bottom (39) comprise orifices configured to allow the passage of fixing members (67) through the fixing collar (41) and the annular bottom (39).

5. A liquefied gas storage facility according to any one of claims 2 to 4, wherein the fixing collar (41) and the annular bottom (39) each comprise an opening (69), said openings (69) being positioned opposite each other and crossed by the supply conduit (47).

6. A liquefied gas storage facility according to any one of claims 1 to 5, wherein the spray bar (34) is connected to said supply conduit (47) in a weld zone (82) positioned below the annular bottom (39).

7. A liquefied gas storage facility according to claim 6, wherein the lower portion of the support pipe (33) comprises a base wall (42) which closes a lower end of the support pipe (33) and windows (43) which are provided in a cylindrical wall of the lower portion of the support pipe (33) and in which the weld zone (82) is positioned opposite one of the windows (33).

8. A liquefied gas storage facility according to any one of claims 1 to 7, wherein a protective plate (83) is attached to the lower end of the support pipe (33), the protective plate (83) covering the crown (38) and having a plurality of holes (84).

9. A vessel (70) for transporting a liquefied gas, the vessel comprising a liquefied gas storage facility according to any one of claims 1 to 8.

10. A transfer system for a liquefied gas, the system comprising a vessel (70) according to claim 9, insulated pipes (73, 79, 76, 81) arranged to connect the tank (71) of the liquefied gas storage facility of the vessel to a floating or land-based storage facility (77) and a pump for driving a flow of liquefied gas through the insulated pipes from or to the floating or land-based storage facility to or from the tank of the liquefied gas storage facility of the vessel.

11. A method of loading or unloading a ship (70) according to claim 9, wherein a liquefied gas is conveyed through ca- isolated connections (73, 79, 76, 81) from or to a floating or land-based storage facility (77) to or from the tank (71) of the ship's liquefied gas storage facility.

12. A method of mounting a dome structure of a liquefied gas storage facility, said method comprising: - providing a supporting structure (1) defining an internal space and comprising an upper supporting wall (3) intended to receive a ceiling wall of a sealed and thermally insulating tank, the upper supporting wall (3) comprising an opening (27); - providing a gas dome structure comprising: - an outer barrel (26) extending outside the supporting structure (1) and comprising a lower end welded around the opening (27) of the supporting structure (1); - an inner barrel (29) which passes through the opening (27) of the supporting structure (1) and extends inside the outer barrel (26); - a support pipe (33) which passes through the inner barrel (29) and comprises a lower portion extending beyond the lower end of the inner barrel (29);and - a supply conduit (47) for being supplied with liquefied gas which is fixed to the support conduit (33); - providing a crown (38) supporting a spray bar (34) which comprises a plurality of spray nozzles (45); said crown (38) having a diameter (dl) greater than a diameter (d2) of the inner barrel (29); - moving the crown (38) from the internal space until the crown (38) comes into contact with the support conduit (33); - fixing the crown (38) to the support conduit (33); and - sealingly connecting an upstream end of the spray bar (34) to a downstream end of the supply conduit (47).;

13. A mounting method according to claim 12, wherein the support pipe (33) comprises a fixing collar (41) which extends radially around the support pipe (33) and the crown (38) comprises an annular bottom (39) and wherein to fix the crown (38) to the support pipe (33), the annular bottom (39) of the crown (38) is welded against a lower face of the fixing collar (41).

14. Mounting method according to claim 13, wherein prior to welding the annular bottom (39) of the crown (38) against the lower face of the fixing collar (41), the fixing collar (41) and the annular bottom (39) are fixed to each other by means of temporary fixing members (67).

15. Mounting method according to claim 12 or 13, in which the annular bottom (39) of the crown (38) comprises openings (68) which are distributed around the support pipe (33) and in which the edges of said openings are welded to the fixing collar (41).

16. A mounting method according to any one of claims 12 to 15, wherein the lower portion of the support pipe (33) comprises a base wall (42) which closes a lower end of the support pipe (33) and windows (43) which are provided in a cylindrical wall of the lower portion of the support pipe (33) and wherein the upstream end of the spray bar (34) is welded to the downstream end of the supply pipe (47) in a weld zone (82) which is positioned opposite one of the windows (33).

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