Liquefied gas storage device comprising dome structure supporting lance

Abstract

The present invention relates to a liquefied gas storage device having a dome structure (25) comprising an outer cylinder (26), an inner cylinder (29) welded to a sealing membrane (17), a support tube (33) passing through the inner cylinder (29), and a crown ring (38) supporting a lance (34) comprising a plurality of nozzles (45) and fixed to a bottom portion of the support tube (33), the crown ring (38) having a diameter (d1) greater than a diameter (d2) of the inner cylinder (29).

Description

Technical Field

[0001] The present invention relates to the field of sealed insulated tanks for storing and / or transporting liquefied gases, such as tanks for transporting liquefied petroleum gas (also known as LPG) at a temperature between -50°C and 0°C, or tanks for transporting liquefied natural gas (LNG) at a temperature of about -162°C at atmospheric pressure.

[0002] These tanks may be installed on land or on a floating structure. In the case of a floating structure, the tanks may be used to transport liquefied gas or to receive liquefied gas for use as fuel to propel the floating structure.

[0003] The invention more particularly relates to a tank comprising a dome structure passing through a hole created in the top wall of the tank and equipped with a spray bar for spraying liquefied gas inside the tank. Background Art

[0004] Document KR20140088975 discloses a dome structure of a sealed and insulated storage tank for storing liquefied gas. The dome structure comprises:

[0005] An inner cylinder, the inner cylinder passes through a hole formed in the support structure of the top wall, passes through the top wall of the tank, and is tightly welded to the primary sealing membrane of the top wall;

[0006] an outer cylinder, disposed around the inner cylinder and welded to the support structure around the hole through which the inner cylinder passes;

[0007] a support pipe for discharging gas passing through the inner cylinder; and

[0008] The spray rod is used to spray the liquefied gas into the support pipe and is installed on the crown ring fixed at the bottom end of the support pipe.

[0009] This dome structure is not entirely satisfactory. In particular, the diameter of the inner cylinder is of particular importance. In fact, the diameter of the inner cylinder must be greater than the diameter of the boom and the crown supporting the boom in order to allow the boom and the crown supporting the boom to pass through the inner cylinder when the support tube is lowered into the boom during installation of the dome structure. Now, since the primary sealing membrane is welded to the inner cylinder, the diameter of the inner cylinder should be limited in order to limit the loss of elasticity of the primary sealing membrane in the area welded to the inner cylinder.

[0010] Furthermore, the interior of the inner cylinder may be subject to dynamic pressure due to the "sloshing" effect, i.e. due to the movement of the cargo in the tank. The movement of the cargo may also generate the undesirable presence of liquefied gas in the dome structure and in the gas extraction pipes present in the dome structure. Now, such gas extraction pipes may obviously be equipped with compressors which may be damaged by the presence of liquefied gas. Summary of the invention

[0011] One idea underlying the present invention is to design a liquefied gas storage device comprising a dome structure of the above-mentioned type which is able to resolve the above-mentioned drawbacks and in particular to limit the loss of elasticity of the sealing membrane due to welding the sealing membrane to the inner cylinder of the dome structure.

[0012] According to one embodiment, the present invention relates to a liquefied gas storage device, the device comprising: a support structure, the support structure defining an internal space and comprising a top support wall having a hole; a sealed insulated storage tank, the sealed insulated storage tank comprising a top wall and a sealing membrane, the top wall comprising at least one insulating barrier fixed to the top support wall, the sealing membrane being intended to be in contact with the liquefied gas, the device comprising a dome structure, the dome structure comprising:

[0013] - an outer cylinder extending outside the support structure and comprising a bottom end welded around the hole of the support structure;

[0014] - an inner cylinder, which passes through the holes of the support structure and the top wall, extends to the inside of the outer cylinder and comprises a bottom end welded to the sealing membrane;

[0015] - a support tube passing through the inner barrel and comprising a bottom portion extending beyond the bottom end of the inner barrel;

[0016] - a supply pipe for supplying liquefied gas, said supply pipe being fixed to said support pipe;

[0017] - A crown ring supporting a boom comprising a plurality of nozzles and being fixed to the bottom portion of the support tube, the boom comprising a plurality of nozzles and being coupled to the supply duct, the diameter of the crown ring being greater than the diameter of the inner cylinder.

[0018] According to one embodiment, the present invention also provides a method for installing a dome structure of a liquefied gas storage device, the method comprising:

[0019] - providing a support structure defining an interior space and comprising a top support wall for receiving a top wall of the sealed insulated tank, the top support wall comprising an aperture;

[0020] -Providing a gas dome structure, the dome structure comprising:

[0021] - an outer cylinder extending outside the support structure and comprising a bottom end welded around the hole of the support structure;

[0022] - an inner cylinder which passes through the hole of the support structure, extends into the interior of the outer cylinder and is anchored to the outer cylinder;

[0023] - a support tube passing through the inner barrel and comprising a bottom portion extending beyond the bottom end of the inner barrel;

[0024] - a supply pipe for supplying liquefied gas, said supply pipe being fixed to said support pipe;

[0025] - providing a crown ring supporting a spray bar, said spray bar comprising a plurality of nozzles; said crown ring having a diameter greater than that of said inner cylinder;

[0026] - displacing the crown ring from the inner space until the crown ring is in contact with the support tube;

[0027] - securing said crown ring to said support tube; and

[0028] - Closely coupling the upstream end of the spray boom to the downstream end of the supply pipe.

[0029] This installation and this method are therefore particularly advantageous, since for a given boom installation diameter the diameter of the inner barrel is smaller, which in particular makes it possible to limit the elasticity loss of the sealing membrane. Furthermore, the crown ring thus makes it possible to protect the interior of the inner barrel from the effects of the movement of liquefied gas in the tank. More specifically, the crown ring makes it possible to avoid the presence of liquefied gas in the gas extraction pipeline comprising the compressor.

[0030] Depending on the implementation, such apparatus and methods may include one or more of the following features.

[0031] According to one embodiment, the support tube comprises a fixing collar extending radially around the support tube, and the crown ring comprises an annular bottom fixed against the bottom surface of the fixing collar. This arrangement allows the crown ring to be simply fixed to the support tube through the inner space.

[0032] According to one embodiment, the annular bottom of the crown ring comprises openings distributed around the support tube, the edges of which are welded to the fixing collar. This also facilitates fixing the crown ring to the support tube through the inner space.

[0033] According to one embodiment, the fixing collar and the annular bottom comprise apertures configured to allow a fixing member to pass through the fixing collar and the annular bottom.

[0034] According to one embodiment, the fixing collar and the annular bottom each comprise a hole, located facing each other and passed through by a supply duct.

[0035] According to one embodiment, the spray bar is coupled to the supply duct in a welding zone located below the annular bottom.

[0036] According to one embodiment, the bottom part of the support tube comprises a bottom wall closing the bottom end of the support tube and windows formed in the cylindrical wall of the bottom part of the support tube, and the welding zone is positioned facing one of the windows. This facilitates the welding operation, in particular the operation of the welding gun.

[0037] According to one embodiment, the support tube comprises a fixing collar extending radially around the support tube, and the crown ring comprises an annular bottom, and in order to fix the crown ring to the support tube, the annular bottom of the crown ring is welded against the bottom surface of the fixing collar.

[0038] According to one embodiment, before welding the annular bottom of the crown ring against the bottom surface of the fixing collar, the fixing collar and the annular bottom are fixed to each other by a fixing member.

[0039] According to one embodiment, the fixing member is a temporary fixing member.

[0040] According to one embodiment, the temporary fixing member is removed after the operation of welding the annular bottom of the crown ring against the bottom surface of the fixing collar. This prevents the fixing member from being separated from the bottom wall of the tank, thereby damaging the bottom wall of the tank, especially its primary sealing membrane.

[0041] According to one embodiment, the annular bottom of the crown ring comprises openings distributed around the support tube, the edges of the openings being welded to the fixing collar.

[0042] According to one embodiment, the bottom of the support tube comprises a bottom wall closing the bottom end of the support tube and a window formed in the cylindrical wall of the bottom portion of the support tube, and the upstream end of the spray bar is welded to the downstream end of the supply pipe in a welding zone positioned facing one of the windows.

[0043] According to one embodiment, the dome structure comprises a protection plate fixed to the bottom end of the support tube, the protection plate covering the crown ring and having a plurality of holes.

[0044] According to one embodiment, the inner cylinder is anchored to the outer cylinder.

[0045] According to one embodiment, the inner cylinder is anchored to the outer cylinder by top anchoring means and bottom anchoring means.

[0046] According to one embodiment, the inner cylinder is anchored to the outer cylinder by a bottom anchoring device, the bottom anchoring device is located at a distance h from the bottom end of the inner cylinder, and the distance h is determined so that when the tank is cooled, the distance h shrinks by Δh between 90% and 110% Δl, wherein:

[0047] Δl is the vertical displacement of the sealing membrane 17 caused by the contraction of the primary insulation barrier 15 and the secondary insulation barrier 12 when the tank is cooled.

[0048] Such units may form part of onshore storage, e.g. for LNG storage, or be installed in floating, coastal or deepwater structures, in particular methane carriers, floating storage and regasification units (FSRU), floating offshore production and storage (FPSO) units, etc. Such tanks may also be used as fuel storage for any type of vessel.

[0049] According to one embodiment, a ship for transporting liquefied gas comprises a liquefied gas storage device of the above-described type.

[0050] According to one embodiment, the present invention also provides a liquefied gas transportation system, which includes the above-mentioned ship, an insulating pipeline arranged to connect the storage tank of the liquefied gas storage device of the ship to the floating or onshore storage device, and a pump for driving the flow of liquefied gas through the insulating pipeline from the floating or onshore storage device to the liquefied gas storage device of the ship, or from the liquefied gas storage device of the ship to the storage tank of the floating or onshore storage device.

[0051] According to one embodiment, the present invention also provides a method for loading or unloading such a ship, wherein liquefied gas is transferred from a floating or onshore storage device to a liquefied gas storage device of the ship, or from a floating or onshore storage device to a liquefied gas storage device of the ship through an insulated pipeline. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The invention will be better understood and other objects, details, features and advantages of the invention will become more apparent from the following description of several particular embodiments of the invention, which description is given in a purely illustrative and non-limiting manner with reference to the accompanying drawings.

[0053] Figure 1 is a schematic perspective view of a support structure for supporting a sealed, insulated liquefied gas storage tank, without showing the dome structure.

[0054] Figure 2 It is a schematic diagram of the multi-layer structure of the tank wall.

[0055] Figure 3 is a cross-sectional view of a dome structure extending through a top wall of a sealed, insulated storage tank according to one embodiment.

[0056] Figure 4 yes Figure 3 Another cross-section of the dome structure.

[0057] Figure 5 yes Figure 2Cross-section and perspective view of a dome structure that passes through the top wall of a sealed, insulated storage tank.

[0058] Figure 6 yes Figure 2 and Figure 3 Detailed view of the dome structure showing in particular the boom and support crowns that secure the boom to the support tubes.

[0059] Figure 7 is a bottom view of the support crown ring and spray boom.

[0060] Figure 8 is a bottom perspective view of the support crown ring and spray boom.

[0061] Fig. 9 is a bottom perspective view showing another embodiment in which a protective plate is located below the support crown ring.

[0062] Fig.10 is a schematic cross-sectional view of a vessel including liquefied natural gas storage tanks and a dock for loading / unloading the tanks. DETAILED DESCRIPTION

[0063] about Figure 1 , describes a support structure 1, intended to fix a sealed and insulated liquefied gas storage tank against said support structure 1. The support structure 1 is formed, for example, by a 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 support structure 1 is generally in the form of a polyhedron. It has two front and rear support walls, here in the form of an octagon, Figure 1 Only the rear support wall 2 is shown. The front support wall and the rear support wall 2 are, for example, ship cofferdam walls extending transversely with respect to the longitudinal direction of the ship. The support structure 1 also includes a top support wall 3, a bottom support wall 4 and transverse support walls 5, 6, 7, 8, 9, 10. The sealed insulated liquefied gas storage tank includes a plurality of tank walls, each of which is anchored to one of the support walls 2, 3, 5, 6, 7, 8, 9, 10 of the support structure 1, thereby defining an internal space for containing liquefied gas.

[0064] like Figure 2 As shown, each wall of the tank has, from the outside to the inside, the following in the thickness direction of the wall:

[0065] a secondary insulation barrier 12 comprising an insulating element 13 fixed to the supporting structure 1;

[0066] a secondary sealing membrane 14 anchored to the insulating element 13 of the secondary thermal insulation barrier 12;

[0067] a primary insulating barrier 15 comprising an insulating element 16 fixed to the insulating element 13 of the secondary insulating barrier 12 or to the support structure 1 and resting against the secondary sealing membrane 14; and

[0068] A primary sealing membrane 17 , which is anchored to the insulating element 16 of the primary thermal insulation barrier 15 and is intended to be in contact with the liquefied gas in the tank.

[0069] The liquefied gas intended to be stored in tanks may in particular be ethane; liquefied natural gas (LNG), ie a gas mixture comprising mainly methane and one or more other hydrocarbons; or liquefied petroleum gas (LPG), ie a hydrocarbon mixture derived from oil refining comprising mainly propane and butane.

[0070] exist Figure 3 and Figure 4 In the embodiment shown, the insulating element 13 of the secondary insulation barrier 12 is a secondary insulation panel 20 comprising a layer of insulating polymer foam 21, for example made of polyurethane, sandwiched between a cover panel 22 and a bottom panel 23, which are rigid, for example made of plywood.

[0071] The secondary sealing membrane 14 is formed of a continuous strip sheet with raised edges. Each strip has a flat central portion located on the cover plate of the secondary insulation board 20 and two raised edges protruding toward the inside of the tank. The strip is welded by its raised edges to a welding support, which is fixed in a groove formed in the cover plate of the secondary insulation board 20. For example, the strip is made of Made of iron and nickel alloys, the expansion coefficient is usually 1.2x 10 -6 K -1 and 2.0x 10 -6 K -1 Iron and manganese alloys can also be used, and their expansion coefficients are usually 7x 10 -6 K -1 Up to 10x 10 -6 K -1 .

[0072] The insulating element 16 of the primary insulating barrier 15 is a primary insulating panel 24 comprising an insulating polymer foam layer, for example made of polyurethane, sandwiched between a cover panel and a bottom panel which are rigid, for example made of plywood.

[0073] The primary sealing membrane 17 is obtained by assembling a plurality of corrugated metal sheets which are welded to each other along their edges. The corrugations protrude towards the inside of the tank. The corrugated metal sheets are fixed on anchoring strips which are fixed in countersunk holes formed in the cover plate of the primary insulation panel 24. For example, the corrugated metal sheets are made of stainless steel or aluminum.

[0074] Alternatively, the Mark V, Mark V and Mark V developed by the applicant may be used according to the patent applications WO14057221, FR2691520 and FR2877638. and Product Description Technology for producing tank walls.

[0075] about Figure 3 and Figure 4 , the dome structure 25 is described below according to one embodiment. The dome structure 25 includes a cylindrical outer cylinder 26 extending in the thickness direction of the top wall of the tank. The outer cylinder 26 passes through a hole formed in the outer hull 19. The bottom end of the outer cylinder 26 is tightly welded to the inner hull 18 around a hole 27 formed in the inner hull 18. The top end of the outer cylinder 26 is tightly closed by a removable cover 28.

[0076] The dome structure 25 also includes an inner cylinder 29, which is arranged inside the outer cylinder 26. The inner cylinder 29 is concentric with the outer cylinder 26 and passes through a hole 27 formed in the inner hull 18. The inner cylinder 29 also passes through the top wall of the tank. The inner cylinder 29 includes a bottom end tightly welded to the primary sealing membrane 17 to ensure the sealing of the primary insulation barrier 15 relative to the internal space of the tank. The inner cylinder 29 includes a compensation device 30, which is formed by a series of bellows so that it can be flexible in its longitudinal direction, thereby allowing it to shrink and expand. The outer cylinder 26 and the inner cylinder 29 are anchored to each other by a top anchoring device 31 and a bottom anchoring device 32, which will be described later. The inner cylinder 29 is open at each of its two ends.

[0077] The dome structure 25 also includes a support pipe 33 which is concentric with the inner cylinder 29 and passes through the inner cylinder 29. The support pipe 33 has two main functions, namely to ensure support for the spraying bar 34 for spraying the liquefied gas in the tank and to guide the gas phase of the gas from the internal space of the tank to the collection area 35 located at the top of the dome structure 25.

[0078] The support tube 33 includes a support collar 36 which is welded to the top end of the support tube 33 and protrudes radially outward. The support collar 36 abuts against an annular flange 37 which is welded to the outer cylinder 26 and protrudes radially inward. The support collar 36 and the annular flange 37 are tightly welded to each other.

[0079] The dome structure 25 further comprises a crown ring 38 which supports the spray bar 34 and is fixed to the bottom end of the support tube 33. In the embodiment represented, the crown ring 38 comprises an annular bottom 39 which extends around the support tube 33 in a plane orthogonal to the thickness direction of the top wall. The crown ring 38 further comprises a cylindrical edge 40 which protrudes downwardly from the radially outer edge of the annular bottom 33. In the embodiment represented, the annular bottom 39 and the cylindrical edge 40 are fixed to each other by a plurality of cleats welded to the annular bottom 39 and the cylindrical edge 40.

[0080] The annular bottom 39 is welded to a fixing collar 41 which is welded to the support tube 33 and extends radially around the support tube 33. The fixing collar 41 is located at a distance from the bottom end of the support tube 33 so that the bottom part of the support tube 33 extends below the annular bottom 39 of the crown ring 38.

[0081] The bottom of the support tube 33 includes a bottom wall 42 closing the bottom end of the support tube 33 and windows 43 formed in the bottom cylindrical wall. There are at least two windows 43, and in the embodiment shown there are four of them. The windows 43 are regularly distributed around the axis of the support tube 33. Such a structure prevents the gas in the liquid phase from being introduced into the support tube 33.

[0082] The spray bar 34 comprises one or more rings 44 arranged around the crown ring 38, in particular around the cylindrical edge 40. Each ring 44 comprises a plurality of nozzles 45 regularly distributed around the central axis of the crown ring 38. Each ring 44 is fixed to the crown ring 38 by any suitable means, for example a fixing clip 46 (in particular in Figure 7 In addition, the cylindrical edge 40 has grooves that allow the curved portion of the spray bar 34 to pass through the cylindrical edge 40 in order to connect each ring 44 to the supply pipe 47.

[0083] In addition, if Figures 6 to 8 As shown, each ring 44 of the spray bar 34 is connected to a supply pipe 47 for supplying liquefied gas to the spray bar 34. Figure 3 As shown, the supply pipe 47 passes through the inner cylinder 29 and the outer cylinder 26 from one end to the other end. The supply pipe 47 is connected to a pump (not shown) configured to pump the liquefied gas into, for example, a storage tank or a dedicated storage device. Figure 3 As can be seen in FIG. 4 , each supply pipe 47 has a spiral zone 48 wound around the support pipe 33, thereby allowing thermal contraction and expansion of the supply pipe 47. In addition, the supply pipe 47 is fixed to the support pipe 33 by an anchoring device 49, in particular as shown in FIG. Figure 3 The anchoring devices 49 are regularly distributed along the support tube 33. Advantageously, the anchoring devices 49 ensure sliding anchoring of the supply pipe 47, that is, they allow a relative displacement of the supply pipe 47 with respect to the support tube 33, so as to allow the supply pipe 47 to contract and expand.

[0084] like Figure 3As shown, the diameter d2 of the inner cylinder 29 is smaller than the diameter d1 of the crown ring 38. Similarly, the diameter d3 of the hole 27 formed in the inner hull 18 is preferably smaller than the diameter d2 of the crown ring 38. Compared with the arrangement according to the prior art, in which the diameter d2 of the inner cylinder 29 is larger than the diameter d2 of the crown ring 38, this arrangement provides several advantages. On the one hand, for a determined installation diameter of the boom 34, the diameter d2 of the inner cylinder 29 is smaller, which in particular allows a more limited number of corrugations of the primary sealing membrane 17 to be interrupted, thereby limiting the elasticity loss of said primary sealing membrane 17 due to these interruptions. On the other hand, the crown ring 38 makes it possible to protect the interior of the inner cylinder 29 from the movement of the liquefied gas in the tank. More specifically, the crown ring 38 makes it possible to avoid the presence of liquefied gas in the gas extraction pipeline including the compressor. As will be described below, to allow the installation of such a dome structure 25 , the assembly comprising the crown ring 38 and the boom 34 is fixed to the support pipe 33 from the interior space of the tank and after said support pipe 33 has been lowered through the inner cylinder 29 .

[0085] Back to Figure 3 , it is possible to observe the top anchoring means 31 and the bottom anchoring means 32, which ensure that the inner cylinder 29 is fixed to the outer cylinder 26. The top anchoring means 31 comprises a supporting collar 50, which is welded to the inner cylinder 29 and projects radially outwards around the inner cylinder 29, and an annular flange 51, which is welded to the outer cylinder 26 and projects radially inwards thereof. The supporting collar 50 rests on the annular flange 51. The supporting collar 50 and the annular flange 51 are tightly welded to each other. Thus, below the supporting collar 50 and the annular flange 51, a secondary sealing space 52 is formed between the outer cylinder 26 and the inner cylinder 29. According to an advantageous embodiment, by Figure 3 and Figure 4 The insulating layer 65 indicated by the dotted line in FIG. 1 is evenly distributed on the outer range of the inner cylinder 29 .

[0086] Furthermore, the bottom anchor 32 comprises a conical support element 53 which flares out downwards and is welded to the inner cylinder 29 around it. It also comprises a support ring which is welded to the radially outer edge of the conical support element 53 and comprises a support collar 54 which protrudes radially outwards. The bottom anchor 32 also comprises an annular flange 55 which is welded to the outer cylinder 26 and protrudes radially inwards thereof. The support collar 54 rests on the annular flange 55 directly or indirectly by means of a filling block 56 inserted between the support collar 54 and the annular flange 55, as shown in the embodiment. The filling block 56 is made of wood, for example, and is bonded to the support collar 54 and the annular flange 55, for example, by resin. Advantageously, the thickness of the filling block 56 is determined so as to withstand the manufacturing and / or positioning tolerances of the inner cylinder 29 relative to the outer cylinder 26 in the thickness direction of the tank top wall.

[0087] The inner cylinder 29 is anchored to the outer cylinder 26 at a distance h from the bottom end. According to an advantageous embodiment, the distance h is determined so that its contraction Δh when the tank cools is substantially equal to the vertical displacement Δl of the primary sealing membrane 17 due to the contraction of the primary thermal insulation barrier 15 and the secondary thermal insulation barrier 12. This prevents or at least limits any step effect between the primary sealing membrane 17 and the bottom end of the inner cylinder 29.

[0088] In addition, the dome structure 25 also includes a sheath 57, such as Figure 3 and Figure 4 As shown, the jacket is concentric with the outer cylinder 26 and is radially disposed between the outer cylinder 26 and the inner cylinder 29. The jacket 57 also passes through the hole 27 formed in the inner hull 18. A primary sealed space 58 connected to the primary insulation barrier 15 is formed between the jacket 57 and the inner cylinder 29.

[0089] like Figure 4 As shown, the dome structure 25 comprises an exhaust pipe 59, which emerges inside the primary sealed space 58. The exhaust pipe 59 is connected to a valve, not shown, which is closed by default and opens when the pressure in the primary thermal insulation barrier 15 exceeds a predetermined threshold pressure. The exhaust pipe 59 is therefore intended to protect the primary sealing membrane 17 from overpressures that may occur in the primary thermal insulation barrier 15. Advantageously, the exhaust pipe 59 comprises a spiral zone wound around the inner cylinder 29, thereby allowing thermal contraction and expansion of the exhaust pipe 59.

[0090] The dome structure 25 also comprises an inerting pipe 60, which also emerges in the primary sealed space 58. The inerting pipe 60 is connected to a storage device for an inert gas (for example nitrogen) by means of a pump, which allows the inert gas to circulate in the primary insulating barrier 15.

[0091] In addition, if Figure 4 As shown, the jacket 57 is not welded to the inner hull 18 of the double hull, thereby forming an annular channel between the jacket 57 and the inner hull 18. Figure 4 The exhaust pipe 61 and the inerting pipe 62 shown are closely passed through the outer cylinder 26 and enter the secondary sealed space 52. The exhaust pipe 61 is connected to a valve, which is closed by default and opens when the pressure in the secondary insulation barrier 12 exceeds a predetermined threshold. Therefore, the secondary sealing membrane 14 can be protected from overpressure that may occur in the secondary insulation barrier 12. The inerting pipe 62 is connected to a storage device of an inert gas (e.g., nitrogen) through a pump, which allows the inert gas to circulate in the secondary insulation barrier 12.

[0092] Furthermore, the dome structure 25 comprises at least one steam collecting pipe 63, 64 which passes closely through the wall of the outer cylinder 26 and emerges in the collecting area 35 located at the top end of the dome structure 25. Thus, the steam collecting pipes 63, 64 are able to conduct steam between the collecting area 35 and a steam collector (not shown) arranged outside the dome structure 25.

[0093] The method of installing the dome structure 25 as described above is now described. First, the first part of the dome structure 25 without the crown ring 38 and the spray bar 34 is installed and fixed to the support structure 1. To this end, the outer cylinder 26 is tightly welded to the inner hull 18 around the hole 27. The inner cylinder 29 is lowered into the outer cylinder 26 via the top end of the outer cylinder 26. In order to allow this movement, the inner diameter of the annular flange 37 is larger than the outer diameter of the support collars 50, 54, and the inner diameter of the annular flange 51 is larger than the outer diameter of the support collar 54. The support pipe 33 is also lowered through the outer cylinder 26 and the inner cylinder 29 until the support collar 36 welded to the support pipe 33 rests on the annular flange 37.

[0094] Next, the crown ring 38 and the spray rod 34 fixed to the crown ring 38 pass through the inner space of the tank close to the support pipe 33 and are fixed thereto. Figure 8 As shown, the fixing collar 41 and the crown ring 38 comprise orifices 66 configured to be positioned facing each other, thereby allowing a temporary fixing member 67 to pass through said orifices 66. For example, the temporary fixing member 67 comprises a screw-nut assembly. In addition, the crown ring 38, more specifically the annular bottom 39, comprises openings 68 that are regularly distributed around the support tube 33 and that enable the crown ring 38 to be welded to the fixing collar 41 from below. Thus, the edges of the openings 68 are welded to the fixing collar 41. After the operation of welding the crown ring 38 to the fixing collar 41, the temporary fixing members 67 can be removed, thereby preventing them from subsequently falling into the tank and damaging the primary sealing membrane 17.

[0095] The spray bar 34 is also connected to one or more supply pipes 47. To this end, Figure 7 As shown, the annular base 39 of the crown ring 38 and the fixing collar 41 each comprise a hole 69 allowing the supply pipe 47 to pass through the fixing collar 41 and the annular base 39 of the crown ring 38. To ensure the tightness of the connection, the spray bar 34 is welded to the supply pipe 47 in the welding zone 82, one of which is Figure 8 In order to facilitate the welding operation, in particular the operation of the welding gun, the welding zone 82 is preferably radially facing one of the windows 43 formed in the bottom portion of the support tube 33 .

[0096] Fig. 9 A dome structure 25 according to another embodiment is shown. This embodiment differs from the above Figures 3 to 8The embodiment of the invention is different in that the dome structure further comprises a protection plate 83 fixed to the bottom end of the support tube 33. The protection plate 83 covers the crown ring 38. The protection plate has a plurality of holes 84, allowing the gas phase to enter the support tube through the window 43. Such a protection plate 83 makes it possible in particular to protect the crown ring 38 from the movement of the liquid phase liquefied gas in the tank and to prevent even more liquid phase liquefied gas from reaching the inside of the support tube 33 and the gas extraction pipeline including the compressor.

[0097] refer to Fig.10 , a cross-sectional view of a methane carrier 70 shows a generally prismatic sealed insulated storage tank 71 installed in a double hull 72 of the vessel. The wall of the storage tank 71 includes: a primary sealing membrane intended to be in contact with the LNG contained in the storage tank, a secondary sealing membrane arranged between the primary sealing membrane and the double hull 72 of the vessel, and two insulating barriers arranged between the primary sealing membrane and the secondary sealing membrane and between the secondary sealing membrane and the double hull 72, respectively.

[0098] As known per se, the loading / unloading pipeline 73 disposed on the top deck of the vessel may be connected to a marine or port terminal through an appropriate connector to transfer the LNG cargo from or to the storage tank 71 .

[0099] Fig.10 An example of a marine terminal is shown, including a loading and unloading station 75, a submarine pipeline 76 and an onshore device 77. The loading and unloading station 75 is a fixed offshore device, including a movable arm 74 and a tower 78 supporting the movable arm 74. The movable arm 74 supports a bundle of insulated flexible pipes 79 that can be connected to the loading / unloading pipeline 73. The orientable movable arm 74 is suitable for all methane carrier templates. The connecting pipe not shown extends to the inside of the tower 78. The loading and unloading station 75 enables the methane carrier 70 to be loaded from and unloaded to the onshore device 77. The onshore device 77 includes a liquefied gas storage tank 80 and a connecting pipeline 81 connected to the loading and unloading station 75 by a submarine pipeline 76. The submarine pipeline 76 allows the long-distance (e.g., 5 km) transmission of liquefied gas between the loading and unloading station 75 and the onshore device 77, which makes it possible for the methane carrier 70 to maintain a large distance from the coast during the loading and unloading operation.

[0100] To generate the pressure required for the liquefied gas transport, a pump embedded in the vessel 70 and / or a pump equipped with the shore installation 77 and / or a pump equipped with the loading and unloading station 75 is implemented.

[0101] Although the invention has been described in connection with several specific embodiments, it is obvious that the invention is not restricted thereto and that the invention comprises all technical equivalents of the described means and their combinations if they fall within the framework of the invention as defined by the claims.

[0102] Use of the verb "comprise" or "include" does not exclude the presence of elements or steps other than those stated in a claim.

[0103] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

Claims

1. A liquefied gas storage device, comprising: A support structure (1) defining an interior space and comprising a top support wall (3) having an aperture (27); A sealed insulated tank comprising a top wall comprising at least one insulating barrier (12, 15) fixed to the top support wall (3) and a sealing membrane (17), the sealing membrane being intended to be in contact with the liquefied gas, the device comprising a dome structure (25) comprising: - an outer cylinder (26) extending outside the support structure (1) and comprising a bottom end welded around the hole (27) of the support structure (1); - an inner cylinder (29) which passes through the support structure (1) and the hole (27) of the top wall, extends inside the outer cylinder (26) and comprises a bottom end welded to the sealing membrane (17); - a support tube (33) passing through the inner cylinder (29) and comprising a bottom portion extending beyond the bottom end of the inner cylinder (29); - a supply pipe (47) for supplying liquefied gas, said supply pipe being fixed to said support pipe (33); - a crown ring (38) supporting a spray bar (34) comprising a plurality of nozzles (45) and connected to the supply pipe (47) and fixed to the bottom portion of the support tube (33), the crown ring (38) having a diameter (d1) greater than the diameter (d2) of the inner cylinder (29).

2. The liquefied gas storage device according to claim 1, wherein the support tube (33) includes a fixed shaft ring (41) extending radially around the support tube (33), and the crown ring (38) includes an annular bottom (39) fixed closely to the bottom surface of the fixed shaft ring (41).

3. The liquefied gas storage device according to claim 2, wherein the annular bottom (39) of the crown ring (38) comprises openings (68) distributed around the support tube (33), and the edges of the openings are welded to the fixed collar (41).

4. A liquefied gas storage device according to claim 2 or 3, wherein the fixing collar (41) and the annular bottom (39) comprise apertures configured to allow a fixing member (67) to pass through the fixing collar (41) and the annular bottom (39).

5. A liquefied gas storage device according to any one of claims 2 to 4, wherein the fixing collar (41) and the annular bottom (39) each comprise a hole (69) which is located facing each other and through which the supply pipe (47) passes.

6. The liquefied gas storage device according to any one of claims 1 to 5, wherein: The spray bar (34) is coupled to the supply conduit (47) in a welding area (82) located below the annular bottom (39).

7. A liquefied gas storage device as described in claim 6, wherein the bottom part of the support tube (33) includes a bottom wall (42) and a window (43), the bottom wall closing the bottom end of the support tube (33), and the window (43) is formed in the cylindrical wall of the bottom part of the support tube (33), wherein the welding area (82) is positioned facing one of the windows (43).

8. The liquefied gas storage device according to any one of claims 1 to 7, wherein a protection plate (83) is fixed to the bottom end of the support tube (33), the protection plate (83) covering the crown ring (38) and having a plurality of holes (84).

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

10. A liquefied gas delivery system, comprising: A ship (70) as claimed in claim 9; an insulating pipe (73, 79, 76, 81) arranged to connect the tank (71) of the liquefied gas storage device of the ship to a floating or onshore storage device (77); and a pump for driving the liquefied gas to flow from the floating or onshore storage device to the tank of the liquefied gas storage device of the ship through the insulating pipe, or from the tank of the liquefied gas storage device of the ship to the floating or onshore storage device.

11. A method for loading or unloading a vessel (70) as claimed in claim 9, wherein liquefied gas is transferred from a floating or onshore storage device (77) to the storage tank (71) of the liquefied gas storage device of the vessel or from the storage tank (71) of the liquefied gas storage device of the vessel to the floating or onshore storage device (77) via an insulated pipeline (73, 79, 76, 81).

12. A method for installing a dome structure of a liquefied gas storage device, the method comprising: - providing a support structure (1) defining an interior space and comprising a top support wall (3) for receiving a top wall of a sealed insulated tank, said top support wall (3) comprising an aperture (27); -Providing a gas dome structure, the dome structure comprising: - an outer cylinder (26) extending outside the support structure (1) and comprising a bottom end welded around the hole (27) of the support structure (1); - an inner cylinder (29) which passes through the hole (27) of the support structure (1) and extends into the interior of the outer cylinder (26); - a support tube (33) passing through the inner cylinder (29) and comprising a bottom portion extending beyond the bottom end of the inner cylinder (29); - a supply pipe (47) for supplying liquefied gas, said supply pipe being fixed to said support pipe (33); - providing a crown ring (38) supporting a spray bar (34) comprising a plurality of nozzles (45); the diameter (d1) of the crown ring (38) being greater than the diameter (d2) of the inner cylinder (29); - displacing the crown ring (38) from the inner space until the crown ring (38) comes into contact with the support tube (33); - fixing the crown ring (38) to the support tube (33); and - Closely coupling the upstream end of the spray bar (34) to the downstream end of the supply pipe (47).

13. The mounting method according to claim 12, wherein the support tube (33) comprises a fixing collar (41) extending radially around the support tube (33), and the crown ring (38) comprises an annular bottom (39), wherein: In order to fix the crown ring (38) to the support tube (33), the annular bottom (39) of the crown ring (38) is welded against the bottom surface of the fixing collar (41).

14. The installation method according to claim 13, wherein: Before the annular bottom (39) of the crown ring (38) is welded against the bottom surface of the fixing collar (41), the fixing collar (41) and the annular bottom (39) are fixed to each other by a temporary fixing member (67).

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

16. The mounting method according to any one of claims 12 to 15, wherein the bottom portion of the support tube (33) comprises a bottom wall (42) and a window (43), the bottom wall closing the bottom end of the support tube (33), the window (43) being formed in a cylindrical wall of the bottom portion of the support tube (33), and wherein the upstream end of the spray bar (34) is welded to the downstream end of the supply pipe (47) in a welding zone (82), the welding zone (82) being positioned facing one of the windows (43).

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