Waterproof and thermally insulating tank including a hollow rigid sheath for the passage of electrical cables

Abstract

The invention relates to a sealed and thermally insulating tank (1) comprising a loading / unloading tower (10). The loading / unloading tower (10) comprises a first, a second and a third mast (11, 12, 13), the masts (11, 12, 13) extending vertically in an internal space (4) of the tank (1) and being spaced apart from each other, and at least one pump (20), the pump (20) being integral with the loading / unloading tower (10) and comprising an electrical power supply box (23). The tank (1) further comprises a rigid sheath (30), the rigid sheath (30) being hollow and receiving at least one electrical cable (41) connected to the electrical power supply box (23). The rigid sheath (30) comprises a plurality of sections (31) aligned vertically and fixed to the loading / unloading tower (10), each said section (31) being tubular and being separated from an adjacent section of a first set (C1). Figure for abstract: Fig. 3

Description

Title of the invention: Waterproof and thermally insulating tank comprising a hollow rigid sheath for the passage of electrical cables Technical field

[0001] The invention relates to the field of sealed and thermally insulating membrane tanks. In particular, the invention relates to the field of sealed and thermally insulating tanks for the storage and / or transport of liquefied gas at low temperature, 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] The invention relates more specifically to tanks installed on a floating structure. In the case of a floating structure, the tank may be intended for the transport of liquefied gas or for receiving liquefied gas serving as fuel for the propulsion of the floating structure. Technological background

[0003] In the case of a tank installed on a floating structure, it is necessary to provide a pump to load the tank with liquefied gas or unload the tank.

[0004] It is known to integrate the pump into a loading / unloading tower located in an internal space of the tank, the pump being supplied with electricity from an electrical power source located outside the tank. The electrical cables used to convey the electrical power to the pump are received in a rigid sheath. The sheath is made up of parallelepiped-shaped metal sections, these sections being bolted to each other.

[0005] With this solution, several hundred bolts may be required to assemble the sheath. The assembly of the sheath is then inefficient, because the bolting requires assembly precautions and long and tedious checks. The same problem arises when a maintenance operation of the sheath is necessary, since such maintenance requires undoing and then redoing at least part of the bolting.

[0006] Another disadvantage of this solution is that the assembly of the sheath by means of bolts is not very resistant to impacts, and in particular to impacts due to the sloshing of liquefied gas in the tank. In practice, it is often necessary to position the sheath in the tank in such a way that the sheath is as little exposed as possible to impacts due to sloshing, which is yet another disadvantage. Summary

[0007] One idea behind the invention is to remedy at least some of the aforementioned drawbacks.

[0008] According to one embodiment, the invention provides a sealed and thermally insulating tank, the tank being anchored in a supporting structure of a ship, the tank comprising a loading / unloading tower, the loading / unloading tower comprising a first, a second and a third mast, the masts extending vertically in an internal space of the tank and being spaced from each other, the tank further comprising at least one pump, the pump being integral with the loading / unloading tower and comprising an electrical power supply box, and a rigid sheath extending vertically, the rigid sheath being hollow and receiving at least one electrical cable connected to the electrical power supply box, the rigid sheath comprising a plurality of vertically aligned sections fixed to the loading / unloading tower, each said section being tubular and being separated from an adjacent section of a first set.

[0009] The rigid sheath is thus produced without fixing the sections to each other, and in particular without bolting, which significantly improves the resistance of the sheath to impacts due to sloshing. In addition, the assembly of the tank is advantageous from an economic and industrial point of view since it does not require fixing the sections to each other, by bolting, welding or otherwise.

[0010] By "tubular" is meant that the section has a hollow annular cross-section. Such a section can then be chosen from a standard range of pipes, which facilitates the assembly of the rigid sheath. In addition, since the external shape of the sections is circular in cross-section, the sections have a lower hydrodynamic drag coefficient than sections with a parallelepiped external shape. This further improves the resistance of the rigid sheath to impacts due to sloshing, since an identical liquefied gas impact applies less mechanical force to the rigid sheath.

[0011] The rigid sheath can thus be positioned freely in the tank, since it is no longer necessary for the rigid sheath to be in a position which tends to protect it from sloshing. This is why the rigid sheath can, for example, be arranged above the electrical power supply box as will be described below.

[0012] According to embodiments, such a sealed and thermally insulating tank may comprise one or more of the following characteristics.

[0013] According to one embodiment, the metal sections are made of a metal alloy, such as stainless steel.

[0014] According to one embodiment, the rigid sheath extends vertically above the power supply box. In other words, when viewed from above parallel to the vertical direction of the masts and the rigid sheath, the hollow annular cross-section of the sections is at least partly included in the outer contour of the power supply box. This tends to minimize the length of electrical cable required for electrical connection with the power supply box, and further tends to simplify the assembly of the tank, in particular because the rigid sheath may be free of bent portions, which might otherwise be necessary to route said at least one electrical cable to the power supply box through the rigid sheath.

[0015] According to one embodiment, the first mast and the second mast are located in a first transverse plane, and the third mast is located in a second transverse plane parallel to the first transverse plane. In other words, the masts define a prism with a triangular section.

[0016] According to one embodiment, the first transverse plane and the second transverse plane are orthogonal to a longitudinal direction of the ship.

[0017] According to one embodiment, the second transverse plane is located further forward than the first transverse plane in the longitudinal direction of the ship.

[0018] According to one embodiment, the rigid sheath is located between the first transverse plane and the second transverse plane.

[0019] As mentioned above, it is no longer necessary for the rigid sheath to be in a position that tends to shelter it from sloshing. Thus, such positioning of the rigid sheath is achievable without compromising the service life of the rigid sheath.

[0020] According to one embodiment, the loading / unloading tower further comprises crosspieces fixing the masts to each other, and each said section is fixed to at least two crosspieces.

[0021] Thus, the rigid sheath contributes to the structural rigidity of the loading / unloading tower, and in particular to the latter's resistance to impacts due to sloshing.

[0022] According to one embodiment, the first clearance is between 5 mm and 20 mm when the tank is at thermal equilibrium at 20°C.

[0023] By choosing such a value for the first set, the sections can together constitute the rigid sheath while leaving only a very small part of the electric cable exposed.

[0024] According to one embodiment, one end of the rigid sheath opposite the electrical power supply box is separated from the electrical power supply box by a second set, the second set being between 20 mm and 200 mm when the tank is at thermal equilibrium at 20°C.

[0025] Thus, it is easy to make the electrical connection with the power supply box. electrical, since there remains a free space which allows an operator to manipulate said at least one electrical cable.

[0026] According to one embodiment, the rigid sheath passes through a ceiling wall of the supporting structure and opens into a hollow connecting piece above the ceiling wall, and the rigid sheath further receives: - N spaced cable support devices, said at least one electrical cable passing through each of the N cable support devices, and each cable support device having a largest external dimension which is strictly less than a largest internal diameter of the rigid sheath; - Nl support cables hung between the N cable support devices, where N is an integer greater than or equal to 2; and - a terminal support cable stretched between a hanging point located in the hollow connecting piece and the cable support device closest to the hollow connecting piece.

[0027] According to one embodiment, the hollow connecting piece comprises a T-shaped connector, the T-shaped connector comprising a first branch in the extension of the rigid sheath and a second branch oriented perpendicularly or obliquely to the rigid sheath, the attachment point is located in the first branch, and said at least one electrical cable passes through the hollow connecting piece, exiting through the second branch.

[0028] According to one embodiment, the invention also provides an assembly method for assembling a sealed and thermally insulating tank, the assembly method comprising the steps of: A) anchor the tank in a supporting structure which is integrated into a ship; B) in an internal space of the tank, install: - a loading / unloading tower comprising a first, a second and a third mast, the masts extending vertically in an internal space of the tank and being spaced from each other, and - at least one pump, the pump being integral with the loading / unloading tower and comprising an electrical power supply box, and a rigid sheath extending vertically, the rigid sheath being hollow and receiving at least one electrical cable connected to the electrical power supply box, the rigid sheath comprising a plurality of sections aligned vertically and fixed to the loading / unloading tower, each said section being tubular and being separated from an adjacent section of a first set; C) connecting said at least one electrical cable to the electrical power supply box.

[0029] This assembly method makes it possible to obtain the sealed and thermally insulating tank described above, with the same advantages. These advantages are not repeated by for the sake of brevity. It is obvious that a characteristic described in relation to the tank is applicable to the assembly process and vice versa.

[0030] According to one embodiment, the loading / unloading tower further comprises crosspieces fixing the masts to each other, and step B) comprises fixing each section to at least two crosspieces.

[0031] According to one embodiment, step B) comprises passing the rigid sheath through a ceiling wall of the supporting structure, and causing the rigid sheath to open into a hollow connecting piece above the ceiling wall; - installing N spaced cable support devices on said at least one electrical cable, said at least one electrical cable passing through each of the N cable support devices, and each cable support device having a largest external dimension which is strictly less than a largest internal diameter of the rigid sheath, and hanging Nl support cables between the N cable support devices, where N is an integer greater than or equal to 2; - inserting said at least one electric cable provided with the N cable support devices into the rigid sheath; and - attach a terminal support cable to a hanging point located in the hollow connecting piece and to the cable support device closest to the hollow connecting piece.

[0032] Thus, it is easy to insert said at least one electrical cable into the rigid sheath. In addition, the terminal support cable is stretched between the attachment point and the cable support device closest to the hollow connecting part, under the effect of the force of gravity applied to this cable support device. This tends to better maintain said at least one electrical cable in position in the rigid sheath, in particular if the support cables are also stretched between the cable support devices.

[0033] According to one embodiment, the hollow connecting piece comprises a T-shaped connector, the T-shaped connector comprising a first branch in the extension of the rigid sheath and a second branch oriented perpendicularly or obliquely to the rigid sheath, the attachment point is located in the first branch, and in step B), said at least one electrical cable provided with the N cable support devices is inserted into the rigid sheath by the first branch, then one end of the electrical cable opposite the electrical power supply box is extracted from the hollow connecting piece by the second branch.

[0034] According to one embodiment, the assembly method further comprises closing the first branch after having inserted said at least one electrical cable provided with the N cable support devices into the rigid sheath.

[0035] This tends to better ensure the sealing of the tank, in particular by preventing leaks of the liquefied gas contained in the tank via the rigid sheath. The shutter used for closing the first branch can be removable so as to allow access to the rigid sheath for maintenance of the rigid sheath.

[0036] According to one embodiment, at the end of step B), one end of the rigid sheath opposite the electrical power supply box is separated from the electrical power supply box by a second set.

[0037] In one embodiment, the liquefied gas is LNG, namely a mixture with a high methane content stored at a temperature of approximately -162°C at atmospheric pressure. Other liquefied gases may also be considered, in particular ethane, propane, butane or ethylene, or ammonia or hydrogen. Liquefied gases may also be stored under pressure, for example at a relative pressure of between 2 and 20 bar, and in particular at a relative pressure of around 2 bar. The tank may be produced using different techniques, in particular in the form of an integrated membrane tank or a self-supporting tank.

[0038] According to one embodiment, the supporting structure of the ship is formed by a double hull of the ship. The ship may in particular be a LNG carrier, a floating storage and regasification unit (FSRU), a floating production and remote storage unit (FPSO) and others. The tank may also serve as a fuel tank in any type of ship.

[0039] According to one embodiment, a ship for transporting a liquefied gas comprises a double hull and a aforementioned tank arranged in the double hull.

[0040] According to one embodiment, the invention also provides a transfer system for a liquefied gas, the system comprising the aforementioned ship, insulated pipes arranged to connect the tank installed in the hull 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 ship.

[0041] 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 ship. Brief description of the figures

[0042] The invention will be better understood, and other aims, 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.

[0043] [Fig.l] [Fig.l] is a schematic view of a watertight and thermally insulating tank anchored in a supporting structure of a ship, in section along a plane Ion- vertical of the ship, the tank being equipped with a loading / unloading tower.

[0044] [Fig.2] [Fig.2] is a schematic top view of the loading / unloading tower.

[0045] [Fig.3] [Fig.3] is a partial perspective view of the loading / unloading tower, together with a rigid sheath integral with the loading / unloading tower.

[0046] [Fig.4] [Fig.4] is an enlarged view of detail A of [Fig.l].

[0047] [Fig.5] [Fig.5] is a perspective view of a cable support device intended to be inserted into the rigid sheath.

[0048] [Fig.6] [Fig.6] is a perspective view of the cable support device of [Fig.5], traversed by electrical cables and connected to support cables.

[0049] [Fig.7] [Fig.7] is a plan view of several cable support devices of the type shown in [Fig.6].

[0050] [Fig.8] [Fig.8] is an enlarged view of detail B of [Fig.l], illustrating the insertion of the electrical cables into the rigid sheath using the cable support devices.

[0051] [Fig.9] [Fig.9] is an enlarged view of detail C of [Fig.8].

[0052] [Fig. 10] [Fig. 10] is a schematic cutaway representation of a LNG carrier tank and a loading / unloading terminal for this tank. Description of the embodiments

[0053] In [Fig.l], a sealed and thermally insulating tank 1 is shown schematically in section. The tank 1 is anchored in a load-bearing structure of a ship. The load-bearing structure comprises in particular a bottom load-bearing wall 2 and a ceiling load-bearing wall 3. For example, the load-bearing structure is formed by the double hull of the ship.

[0054] According to one embodiment, the tank 1 is a membrane tank. In such a tank 1, each tank wall has a multi-layer structure comprising, from the outside to the inside, a secondary thermally insulating barrier comprising insulating elements resting against the supporting structure, a secondary sealing membrane resting against the secondary thermally insulating barrier, a primary thermally insulating barrier comprising insulating elements, not shown, resting against the secondary sealing membrane and a primary sealing membrane intended to be in contact with the liquefied gas contained in the tank 1. The primary sealing membrane defines an internal space 4 intended to receive a liquefied gas.By way of example, such membrane tanks are described in particular in patent applications WO14057221, FR2691520 and FR2877638 relating respectively to the Mark V, Mark III and NO96 technologies developed by the applicant.

[0055] The liquefied gas intended to be stored in the tank 1 may in particular be a gas Liquefied natural gas (LNG), i.e., a gas mixture consisting mainly of methane and one or more other hydrocarbons. Liquefied gas can also be ethane or liquefied petroleum gas (LPG), i.e., a mixture of hydrocarbons from oil refining consisting mainly of propane and butane. Liquefied gas can also be ammonia or hydrogen.

[0056] The tank 1 is equipped with a loading / unloading tower 10, hereinafter referred to as “the tower 10” for convenience. The tower 10 makes it possible in particular to load the liquefied gas into the tank 1 or to unload it. For this purpose, the tower 10 comprises at least one pump 20. The pump 20 comprises a pump body 21 connected to a pipe 22. The pipe 22 may for example extend to an upper deck 6 of the ship, the upper deck 6 being located above the ceiling wall 3. When it is desired to unload the tank 1, the pump 20 is put into operation, and the liquefied gas is sucked by the pump body 21 into the pipe 22, then transferred via the pipe 22 to a liquefied gas loading / unloading equipment.

[0057] Referring now to [Fig.l], [Fig.2] and [Fig.3], the tower 10 extends into the internal space 4 of the tank 1 over substantially the entire height of the tank 1. The tower 10 comprises a tripod structure, that is to say that the tower 10 comprises masts 11, 12, 13 spaced apart, parallel to each other, and extending vertically into the internal space 4. The masts 11, 12, 13 are connected to each other by crosspieces 19 (see [Fig.2], [Fig.3]) contributing to the mechanical rigidity of the tower 10.

[0058] The pump 20 is integral with the tower 10, for example by being integral with a base (not shown) of the tower 10, the base being located at the end of the tower 10 which is close to the bottom load-bearing wall 2. According to embodiments, the pump body 21 is received in a sump arranged in the bottom wall of the tank 1 which is supported by the bottom load-bearing wall 2.

[0059] The pump 20 is electric and comprises an electrical power supply box 23 (hereinafter referred to as “the box 23”). In operation, the pump 20 is most often immersed in the liquefied gas contained in the tank 1. To supply the pump 20 with electricity, it is therefore necessary to convey electrical power from an electrical power source located outside the tank 1 to the box 23. For this, the tower 10 comprises a rigid sheath 30 (hereinafter referred to as “the sheath 30”) which will now be described. The sheath 30 is hollow and receives electrical cables 41 connected to the box 23.

[0060] With reference to [Fig.3] and [Fig.4], the sheath 30 comprises a plurality of sections 31. Each section 31 is tubular, that is to say that the section 31 has a hollow annular cross-section. For example, the sections 31 are tubes made of a metal alloy capable of withstanding the low temperature of the liquefied gas, for example stainless steel.

[0061] The sections 31 have identical internal diameters DI (see [Fig.4]). The internal diameter DI is advantageously chosen from a standard range of pipe diameters, for example the DN range (nominal diameter) defined by the ISO 6708 standard. In one example, the sections 31 are chosen with a nominal diameter of DN 150.

[0062] Referring now to [Fig. 3], the sections 31 are aligned vertically, that is to say parallel to the masts 11, 12, 13. More concretely, each end of each section 31 is fixed to a crosspiece 19 via a fixing element 39. For example, the fixing element 39 is made of a metal alloy and is welded to the section 31 and to the crosspiece 19. Each section 31 can further be fixed to one or more other crosspieces 19 via fixing elements 38. The fixing elements 38 are analogous to the fixing elements 39. For example, the fixing elements 38 are made of a metal alloy and are each welded to a section 31 and to a crosspiece 19. The fixing elements 38, 39 can be curved as shown in [Fig. 3] or have other geometries.

[0063] The sections 31 are fixed to the crosspieces 19 in such a way that each section 31 is separated from an adjacent section 31 by a non-zero clearance C1 (see [Fig.4]). The clearance C1 is between 5 mm and 20 mm, for example equal to 10 mm, when the tank 1 is in thermal equilibrium at 20°C. By choosing such a value of the clearance C1, the sections 31 can together constitute the sheath 30 while leaving only a very small part of the electric cables 41 exposed; and it is not necessary to fix the sections 31 to each other (for example by welding or bolting) to constitute the sheath 30, which is advantageous from an economic and industrial point of view.

[0064] In the example shown in [Fig.l], [Fig.2] and [Fig.4], the sheath 30 extends vertically above the housing 23. In other words, when viewed from above parallel to the vertical direction of the masts 11, 12, 13 and the sheath 30, the hollow annular cross-section of the sections 31 is included in the outer contour of the housing 23, either entirely (as shown in [Fig.2]) or partially. This tends to minimize the length of electrical cable 41 required for electrical connection with the housing 23, and further tends to simplify the assembly of the tank 1, in particular because the sheath 30 may be free of bent portions which might otherwise be necessary to route the electrical cables 41 to the housing 23 through the sheath 30.

[0065] With reference to [Fig.4], a lower end 33 of the sheath 30 opposite the housing 23 is separated from the housing 23 by a non-zero clearance C2. The clearance C2 is between 20 mm and 200 mm when the tank 1 is in thermal equilibrium at 20°C. Thus, it is easy to make the electrical connection of the electric cables 41 with the housing 23, since there remains a free space between the lower end 33 and the housing 23 which allows an operator to handle the electrical cables 41. It is specified here that although [Fig.4] shows an electrical cable 41 connected to the housing 23 at one face of the housing 23 opposite the sheath 30, the electrical connection of the electrical cables 41 with the housing 23 can be positioned differently, in particular inside the housing 23 and / or at another face of the housing 23.

[0066] According to one embodiment, as shown in [Fig.4], the lower end 33 of the sheath 30 is materialized by a terminal section 32, of the same diameter as the sections 31 but of shorter length. The terminal section 32 is fixed at 312 to an adjacent section 31. Preferably, the fixing 312 of the terminal section 32 is removable, which makes it possible to dismantle the terminal section 32 and reveal a greater length of electric cable 41, for example for a maintenance operation of the pump 20.

[0067] With reference to [Fig. 2], the masts 11 and 12 are located in a plane Ql, and the mast 13 is located in a plane Q2 parallel and spaced from the plane Ql. According to one embodiment, the planes Ql and Q2 are orthogonal to a longitudinal direction L of the ship. More particularly, as shown in Figures 1 and 2, the plane Q2 is located closer to the bow of the ship, in other words further forward along the longitudinal direction L oriented towards the bow of the ship, than the plane Ql.

[0068] As mentioned above, the sheath 30 is made without fixing the sections 31 to each other. This very significantly improves the resistance of the sheath 30 to impacts, and in particular to impacts due to the sloshing of liquefied gas in the tank 1, since the sheath 30 is devoid of fixings between the sections 31 which would be more likely to be damaged by impacts. This makes it possible to freely position the sheath 30 on the tower 10 in the longitudinal direction L. Indeed, the constitution of the sheath 30 in the form of adjacent tubular sections 31 offers the advantages cited above. Thus, and contrary to what is done in the prior art mentioned above, it is no longer necessary for the sheath 30 to be in a position which tends to shelter the sheath 30 from the sloshing. In particular, as shown in [Fig.2], the sheath 30 can be located between the planes Ql and Q2 in the longitudinal direction L rather than between the masts 11 and 12.

[0069] As shown in [Fig.2], the mast 13 may have a larger diameter than the masts 11 and 12, for example in order to form an emergency well allowing the descent of an emergency pump and an unloading line in the event of failure of the pump 20.

[0070] Alternatively, the planes Q1 and Q2 may not be orthogonal to the longitudinal direction L. In this case also, the sheath 30 may be positioned freely on the tower 10.

[0071] A method of assembling the tank 1 equipped with the tower 10, of pump 20 and sheath 30.

[0072] First of all, the tank 1 is anchored in the supporting structure using known techniques.

[0073] Then, in the internal space 4 of the tank 1, the tower 10, the pump 20 comprising the housing 23, and the sheath 30 provided with the electric cables 41 are installed. As described above, at the end of this step, the lower end 33 of the sheath 30 opposite the housing 23 is separated from the housing 23 of the set C2.

[0074] Finally, the electrical cables 41 are connected to the housing 23.

[0075] Several different orders are possible for the installation of the tower 10, the pump 20 comprising the housing 23, and the sheath 30 provided with the electric cables 41 in the internal space 4 of the tank 1.

[0076] In one example, the tower 10 and the pump 20 comprising the housing 23 are first installed. In a second step, the sections 31 are provided, and the sections 31 are fixed to the tower 10 as described above, such that the sections 31 are aligned vertically and each section 31 is separated from an adjacent section 31 of the first set C1. The sections 31 thus aligned form at least a portion of the sheath 30. Finally, in a third step, one or more electrical cables 41 are routed through the sheath 30 to the housing 23, and the electrical cables 41 are connected to the housing 23.

[0077] In another example, the tower 10 is installed in the internal space 4 of the tank 1 after having fixed the sections 31 to the tower 10, and the electric cables 41 are routed through the sheath 30 after having installed the tower 10.

[0078] In yet another example, the tower 10 is installed in the internal space 4 after having fixed the sections 31 to the tower 10 and after having routed the electrical cables 41 through the sheath 30.

[0079] With reference to Figures 5 to 9, an advantageous way of routing the electrical cables 41 through the sheath 30 to the housing 23 is described.

[0080] In [Fig. 5], a cable support device 60 is shown in perspective. The cable support device 60 comprises a cable support assembly 65 and a frame 61.

[0081] The cable support assembly 65 comprises two cable support pieces 66. Each of the two cable support pieces 66 has a groove 66C for each electrical cable 4L. The cable support pieces 66 are fixed to each other such that the grooves 66C are opposite each other in pairs, and thereby together define a space sufficient to receive each electrical cable 41 as will be detailed below. The cable support pieces 66 are here fixed to each other by means of two bolts 67; alternatively, the cable support pieces 66 can be fixed to each other in other ways.

[0082] The frame 61 comprises two frame pieces 62. Each of the two frame pieces 62 has two slots 63A. Two bolts 63 (only one of which is visible in [Fig.5]) are received in the slots 63A and fix together the two frame pieces 62 and the two cable support pieces 66, such that the two frame pieces 62 sandwich the two cable support pieces 66.

[0083] Each of the two frame pieces 62 has a slot 64. The slots 64 are positioned such that, when the two frame pieces 62 sandwich the two cable support pieces 66, the cable support device 60 has two central spaces 81, each central space 81 being formed by a slot 64 and a facing cable support piece 66. As can be seen in particular in [Fig. 5], the central spaces 81 provide sufficient space for the bolts 67. In addition, a central space 81 receives a cable attachment piece 82, visible in [Fig. 5] and [Fig. 6].

[0084] The cable attachment piece 82 is fixed, for example added, to one of the cable support pieces 66, so as to extend on either side of the frame 61 and the cable support assembly 65. In addition, the cable attachment piece 82 has, at each of its two ends, a through hole 83 (only one of which is visible in the drawings). Each of the two through holes 83 receives a shackle 84 (only one of which is visible in [Fig. 6]). Each of the two shackles 84 allows the attachment of a support cable 42. In the example shown, the support cables 42 are stainless steel cables, and each end of a support cable 42 is wound around the shackle 84 and then receives a weld point or other attachment 42W to prevent the support cable 42 from unwinding.

[0085] With reference to Figures 6 to 9, the use of the cable support devices 60 for routing the electrical cables 41 through the sheath 30 to the housing 23 will now be described.

[0086] A desired number N of cable support devices 60 is installed on the electric cables 4L. As shown in [Fig. 6], each cable support device 60 is installed such that the electric cables 41 pass through the cable support devices 60 by being received in the grooves 66C. Furthermore, as shown in [Fig. 7], the cable support devices 60 are spaced apart on the electric cables 41, and N-1 support cables 42 are hooked between the N cable support devices 60 by means of the shackles 84.

[0087] N is an integer greater than or equal to 2. The value of N is chosen in particular as a function of the length of the sheath 30 and the desired length of the support cables 42.

[0088] With reference to Figures 4, 8 and 9, the electric cables 41 provided with the N cable support devices 60 are inserted into the sheath 30, with the N1 support cables 42 hung between the cable support devices 60.

[0089] As can be seen in particular in [Fig.4], the cable support devices 60 have a larger dimension which is strictly smaller than the diameter DI of the sections 31. This makes it possible to insert the electric cables 41 provided with the N cable support devices 60 without risking that the cable support devices 60 are stuck in the sheath 30.

[0090] The electric cables 41 provided with the N cable support devices 60 are inserted into the sheath 30 through an entry point located outside the tank 1.

[0091] In the example shown in Figures 8 and 9, the sheath 30 opens into a hollow connecting piece 50. More specifically, with reference to [Fig.8], the sheath 30 passes through the ceiling load-bearing wall 3 and the upper deck 6 located above the ceiling load-bearing wall 3. For this purpose, the sheath 30 comprises a through pipe 34, and the section 31 closest to the ceiling load-bearing wall 3 is fixed, for example welded, to the through pipe 34. The through pipe 34 passes through the ceiling tank wall 303 supported by the ceiling load-bearing wall 3, for example by passing through one or more insulating elements 303B of the ceiling tank wall 303 or a space provided between these insulating elements 303B, and passes through the ceiling load-bearing wall 3. In addition, the through pipe 34 passes through the upper deck 6 until it opens into the hollow connecting piece 50.

[0092] The through conduit 34 can be fixed to the ceiling load-bearing wall 3 on the side opposite the ceiling tank wall 303, for example by being welded to a collar 403 welded to the ceiling load-bearing wall 3. In addition, the through conduit 34 can be fixed to the upper deck 6, for example by being welded to a conduit 406 welded to the upper deck 6. The through conduit 34 can be formed in one piece or be formed by several sections similar to the sections 31 fixed to each other.

[0093] With reference to [Fig.9], the hollow connecting piece 50 comprises a T-shaped connector 51. The T-shaped connector 51 comprises a first branch 52 in the extension of the sheath 30, and a second branch 53 oriented perpendicular to the sheath 30. Alternatively, the second branch 53 may be oriented obliquely but not perpendicular to the sheath 30.

[0094] In the example shown, the through pipe 34 has an internal diameter equal to D1, the first branch 52 and the second branch 53 have an internal diameter strictly greater than D1, and the hollow connecting piece 50 comprises a reduction (or reducing connection; in English: “reducer”) 59 between the through pipe 34 and the T-connection 51. In the example shown, the reducing connection 59 is an eccentric reducer.

[0095] The first branch 52 materializes the entry point for the insertion of the electric cables 41 provided with the N cable support devices 60 into the sheath 30. In other words, with reference to [Fig.8], the electric cables 41 provided with the N cable support devices 60 are inserted into the sheath 30 passing through the first branch 52.

[0096] Furthermore, a terminal support cable 43 is hooked to the last cable support device 60 inserted into the sheath 30, that is to say to the cable support device 60 which will be closest to the T-fitting 51 after inserting the electric cables 41. The hooking of the terminal support cable 43 to this cable support device 60 can be carried out in a manner analogous to the hooking of the support cables 42 to the cable support devices 60.

[0097] After inserting the electrical cables 41 provided with the N cable support devices 60 into the sheath 30, the electrical cables 41 are routed through the sheath 30 to the housing 23, and the electrical cables 41 are connected to the housing 23. The terminal support cable 43 is then attached to a hooking point 49 located in the first branch 52. For example, the hooking point 49 is materialized by a hooking piece welded to the T-connection 51 in the first branch 52, and the terminal support cable 43 is attached to this hooking piece by means of a shackle 85 in a manner similar to the attachment of the support cables 42 by means of the shackles 84.

[0098] When the terminal support cable 43 is hooked to the hooking point 49, the terminal support cable 43 is tensioned between the hooking point 49 and the cable support device 60 (not shown in [Fig.9]) closest to the T-connection 51, under the effect of the force of gravity applied to this cable support device 60.

[0099] The length of the terminal support cable 43, the length of the support cables 42 and the spacing between the cable support devices 60 can be chosen such that the support cables 42 are then tensioned between the cable support devices 60, as can be seen in [Fig. 7]. The electrical cables 41 are compressed in the grooves 66C, within the permissible compression limit of the electrical cables 41, and where appropriate within the permissible compression limit of the cable jackets of the electrical cables 4L. The total length of the electrical cables 41 is therefore chosen such that the electrical cables 41 are not tensioned between the cable support devices 60, as shown in [Fig. 7]. This makes it possible not to overstress the electrical cables 41, which is beneficial for their mechanical integrity.

[0100] More precisely, the total length of the electric cables 41 is chosen such that the electric cables 41 are not stretched between the cable support devices 60 at ambient temperature and at the low temperature of the liquefied gas, taking into account the respective thermal contraction coefficients of the support cables 42 and the electric cables 4L. Concretely, between two given cable support devices 60, the length of electric cable 41 is chosen to be greater than the length of support cable 42. Since the cable support devices 60 have a larger dimension which is strictly smaller than the diameter DI of the sections 31, the cable support devices 60 are allowed to move in the sheath 30 when the electric cables 41 and the support cables 42 thermally contract.

[0101] Returning to [Fig.9], the ends of the electrical cables 41 thus inserted into the sheath 30 are extracted from the hollow connecting piece 50 by the second branch 53. The electrical cables 41 can then be connected as desired to electrical equipment external to the tank 1, which makes it possible to complete the electrical connection of the housing 23 and the pump 20.

[0102] Furthermore, the first branch 52 may be closed by a shutter 58, such as a hood. The shutter 58 is for example fixed to an end flange 52A of the first branch 52. The shutter 58 tends to better ensure the sealing of the tank 1, in particular by preventing leaks of the liquefied gas contained in the tank 1 via the sheath 30. The shutter 58 may be removably fixed, for example by bolting to the end flange 52A, in order to allow access to the sheath 30 for maintenance of the sheath 30.

[0103] Although the drawings show the routing of three electrical cables 41 through the sheath 30, a different number of electrical cables 41 may be employed if desired.

[0104] The grooves 66C of the cable support parts 66 may alternatively be opposite the slots 64, in particular if a large number of electric cables 41 are used. In this case, the cable support assembly 65 may comprise a single cable support part 66, counter-plates being attached to this cable support part 66 to compress the electric cables 41 in the grooves 66C as described above. The cable attachment part 82 may be attached to one of these counter-plates.

[0105] In the example shown, the cable support parts 66 and the cable attachment part 82 are flat stainless steel plates, and the reinforcement parts 62 are high-density polyethylene parts, molded or machined. Alternatively, other geometries and / or other materials are conceivable for the cable support parts 66 and / or the cable attachment part 82 and / or the reinforcement parts 62.

[0106] Up to now, embodiments have been described where the tower 10 comprises a pump 20 and a sheath 30. It is of course conceivable that the tower 10 comprises several pumps 20. In this case, each pump 20 comprises a housing 23, and each housing 23 is associated with a sheath 30. Each sheath 30 can extend vertically above the corresponding housing 23 as described above. Alternatively, a sheath 30 can be associated with two neighboring pumps 20. In this case, the sheath 30 receives a first set of electrical cables 41 for supplying electricity to a first pump 20 and a second set of electrical cables 41 for supplying electricity to a second pump 20. For example, the first set of electrical cables 41 is connected to a first housing 23 that the first pump 20 comprises, and the second set of electrical cables 41 is connected to a second housing 23 that the second pump 20 comprises. The sheath 30 may extend vertically above the first housing 23 or may extend vertically above the second housing 23 or midway between them.

[0107] 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.

[0108] In a manner known per se, loading / unloading pipes 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.

[0109] [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.

[0110] 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.

[0111] 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.

[0112] The use of the verb “comprise”, “comprise” or “include” and its conjugated forms does not exclude the presence of other elements or other steps than those stated in a claim.

[0113] In the claims, any reference sign in parentheses cannot be interpreted as a limitation of the claim.

Claims

Claims

1. A sealed and thermally insulating tank (1), the tank (1) being anchored in a supporting structure of a ship, the tank (1) comprising a loading / unloading tower (10), the loading / unloading tower (10) comprising a first, a second and a third mast (11, 12, 13), the masts (11, 12, 13) extending vertically in an internal space (4) of the tank (1) and being spaced apart from each other, the tank (1) further comprising at least one pump (20), the pump (20) being integral with the loading / unloading tower (10) and comprising an electrical power supply box (23), and a rigid sheath (30) extending vertically, the rigid sheath (30) being hollow and receiving at least one electrical cable (41) connected to the electrical power supply box (23), the rigid sheath (30) comprising a plurality of sections (31) aligned vertically and fixed to the loading / unloading tower (10),each said section (31) being tubular and being separated from an adjacent section of a first set (Cl).,

2. A sealed and thermally insulating tank (1) according to claim 1, in which the loading / unloading tower (10) further comprises crosspieces (19) fixing the masts (11, 12, 13) to each other, and in which each said section (31) is fixed to at least two crosspieces (19).

3. Sealed and thermally insulating tank (1) according to any one of claims 1 to 2, in which the first clearance (Cl) is between 5 mm and 20 mm when the tank (1) is at thermal equilibrium at 20°C.

4. A sealed and thermally insulating tank (1) according to any one of claims 1 to 3, in which one end (33) of the rigid sheath (30) opposite the electrical power supply box (23) is separated from the electrical power supply box (23) by a second set (C2), the second set (C2) being between 20 mm and 200 mm when the tank (1) is at thermal equilibrium at 20°C.

5. A sealed and thermally insulating tank (1) according to any one of claims 1 to 4, in which the rigid sheath (30) passes through a ceiling wall (3) of the supporting structure and opens into a hollow connecting piece (50) above the ceiling wall (3), and in which the rigid sheath (30) further receives: - N spaced cable support devices (60), said at least one cable electrical (41) passing through each of the N cable support devices (60), and each cable support device (60) having a largest external dimension which is strictly less than a largest internal diameter (Dl) of the rigid sheath (30); - Nl support cables (42) hooked between the N cable support devices (60), where N is an integer greater than or equal to 2; and - a terminal support cable (43) stretched between a hooking point (49) located in the hollow connecting piece (50) and the cable support device (60) closest to the hollow connecting piece (50).

6. A sealed and thermally insulating tank (1) according to claim 5, wherein the hollow connecting piece (50) comprises a T-shaped connector (51), the T-shaped connector (51) comprising a first branch (52) in the extension of the rigid sheath (30) and a second branch (53) oriented perpendicularly or obliquely to the rigid sheath (30), the attachment point (49) is located in the first branch (52), and said at least one electric cable (41) passes through the hollow connecting piece (50) exiting through the second branch (53).

7. An assembly method for assembling a sealed and thermally insulating tank (1), the assembly method comprising the steps of: A) anchoring the tank (1) in a supporting structure which is integrated into a ship;B) in an internal space (4) of the tank (1), installing: - a loading / unloading tower (10) comprising a first, a second and a third mast (11, 12, 13), the masts (11, 12, 13) extending vertically in an internal space (4) of the tank (1) and being spaced from each other, and - at least one pump (20), the pump (20) being integral with the loading / unloading tower (10) and comprising an electrical power supply box (23), and a rigid sheath (30) extending vertically, the rigid sheath (30) being hollow and receiving at least one electrical cable (41) connected to the electrical power supply box (23), the rigid sheath (30) comprising a plurality of sections (31) aligned vertically and fixed to the loading / unloading tower (10), each said section (31) being tubular and being separated from an adjacent section of a first set (Cl); C) connecting said at least one electrical cable (41) to the electrical power supply box (23).;

8. An assembly method according to claim 7, wherein the tower of loading / unloading (10) further comprises crosspieces (19) fixing the masts (11, 12, 13) to each other, and in which step B) comprises fixing each section (31) to at least two crosspieces (19).

9. An assembly method according to any one of claims 7 to 8, wherein step B) comprises: - passing the rigid sheath (30) through a ceiling wall (3) of the supporting structure, and opening the rigid sheath (30) into a hollow connecting piece (50) above the ceiling wall (3); - installing N spaced cable support devices (60) on said at least one electrical cable (41), said at least one electrical cable (41) passing through each of the N cable support devices (60), and each cable support device (60) having a largest external dimension strictly less than a largest internal diameter of the rigid sheath (30), and hanging N1 support cables (42) between the N cable support devices (60), where N is an integer greater than or equal to 2; - inserting said at least one electric cable (41) provided with the N cable support devices (60) into the rigid sheath (30);and - hanging a terminal support cable (43) to a hanging point (49) located in the hollow connecting piece (50) and to the cable support device (60) closest to the hollow connecting piece (50).;

10. An assembly method according to claim 9, wherein the hollow connecting piece (50) comprises a T-connector (51), the T-connector (51) comprising a first branch (52) in the extension of the rigid sheath (30) and a second branch (53) oriented perpendicularly or obliquely to the rigid sheath (30), the attachment point (49) is located in the first branch (52), and wherein, in step B), said at least one electric cable (41) provided with the N cable support devices (60) is inserted into the rigid sheath (30) by the first branch (52), then one end of the electric cable (41) opposite the power supply box (23) is extracted from the hollow connecting piece (50) by the second branch (53).

11. An assembly method according to claim 10, further comprising closing the first branch (52) after inserting said at least one electrical cable (41) provided with the N cable support devices (60) into the rigid sheath (30).

12. Assembly method according to any one of claims 7 to 11, in which at the end of step B), one end (33) of the rigid sheath (30) opposite the power supply box (23) is separated from the power supply box (23) of a second set (C2).

13. A vessel (70) for transporting a liquefied gas, the vessel comprising a double hull (72) and a tank (71) according to any one of claims 1 to 6 arranged in the double hull.

14. A vessel (70) according to claim 13, wherein the tank (71) is according to any one of claims 5 to 6 and wherein the hollow connecting piece (50) is arranged above a deck (6) of the vessel located above the ceiling wall (3) of the supporting structure.

15. A transfer system for a liquefied gas, the system comprising a vessel (70) according to any one of claims 13 to 14, insulated pipes (73, 79, 76, 81) arranged to connect the tank (71) installed in the hull 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 vessel tank.

16. A method of loading or unloading a vessel (70) according to any one of claims 13 to 14, wherein a liquefied gas is conveyed through insulated pipes (73, 79, 76, 81) from or to a floating or land-based storage facility (77) to or from the tank (71) of the vessel (70).

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