Float retaining device

Abstract

The invention relates to a float retaining device (1) for a sealed and insulated tank for storing liquids, the float retaining device (1) comprising: a hollow tube for receiving a float, the hollow tube comprising an opening; and a door, the door being retained on the hollow tube and being mounted to slide on the hollow tube in the longitudinal direction of the hollow tube by means of guiding and retaining means, the door having a closed position in which the door at least partially covers the opening in the hollow tube and wherein an abutting element of the door rests against an abutting element of the hollow tube under the effect of the earth's gravity.

Description

Technical Field

[0001] The present invention relates to the field of sealed and thermally insulated membrane tanks for storing and / or transporting fluids, such as cryogenic fluids. More precisely, the present invention relates to a float retaining device intended to be integrated into a tank.

[0002] Sealed and insulated membrane tanks are particularly suitable for storing liquefied natural gas (LNG), which is stored at atmospheric pressure at approximately -162°C. These tanks can be installed on land or on floating structures. In the case of floating structures, the tanks can be designed to transport LNG or to receive LNG for use as fuel to propel the floating structure. Background Art

[0003] In the prior art, sealed and insulated tanks for storing liquefied natural gas are known, said tanks being integrated into a supporting structure, such as a double hull, of a ship intended for transporting liquefied natural gas.

[0004] Storage tanks include systems for measuring liquid levels. For this purpose, known metering systems utilize floats. These systems include a float retaining tube that extends through the tank's top wall to near the tank's bottom wall, with the system's float housed within the tube.

[0005] For various reasons, such as for calibration, maintenance, inspection or updating of the hardware, the interior of the float holding tube must be accessible. Currently there is no float holding device that allows such operations to be performed in a simple and safe manner.

[0006] Furthermore, during the life of the tank, the float retaining tube is subjected to significant forces, particularly from expansion, which causes the liquid in the tank to surge. This surge is commonly known as sloshing.

[0007] This phenomenon, along with wear of the hardware and the handling of installing and removing the float retaining device, can easily damage the tank. For example, if the float retaining device door falls to the bottom of the tank and if the door or nuts and bolts move freely within the tank, severe deformation of the membrane may result. Currently, there is no float retaining device that can reliably retain the float door and improve its anti-sloshing capabilities.

[0008] Furthermore, maintenance operations on metering systems using floats are susceptible to being performed by different personnel with different skills and abilities. It is therefore necessary to simplify the device in order to prevent any difficulties or errors in installation or removal, which could easily lead to, for example, the door of the float retaining device falling onto the membrane of the tank.

[0009] In view of this, a specific float retaining device has been developed. Summary of the Invention

[0010] One idea behind the present invention is to solve some or all of the above problems.

[0011] One idea behind the present invention is to provide a float retaining device with improved resistance to sloshing, in particular a float retaining device with high resistance to the various fluid dynamic forces to which it is subject.

[0012] Another idea behind the present invention is to propose an improved float retaining device. More specifically, to provide a float retaining device in which the mechanical stresses are better distributed, thereby making it possible to limit breakage and damage to the float retaining device and surrounding hardware.

[0013] Another idea behind the present invention is to provide a float retaining device that is more reliable and that is easy to maintain. In particular, one idea behind the present invention is to provide a float retaining device that is easier to access inside.

[0014] According to one embodiment, the present invention relates to a float retaining device for a sealed and insulated storage tank for storing liquid, the float retaining device comprising:

[0015] - a hollow tube for receiving the float, the hollow tube being intended to be mounted in the tank in a configuration in which the hollow tube passes through the top wall of the tank and extends to the vicinity of the bottom wall of the tank, the hollow tube comprising an opening; - a door retained on the hollow tube and mounted so as to be movable on the hollow tube;

[0016] And wherein the float retaining device has a closed position in which the door partially covers the opening in the hollow tube such that access to the interior space of the hollow tube is formed.

[0017] Thus, at least some maintenance operations, in particular calibration, can be performed without having to remove the door.

[0018] According to one embodiment, the float retaining device comprises a float. Said float is intended to be able to measure the level of liquid present in a sealed, insulated tank.

[0019] According to one embodiment, the door is mounted so as to be movable on the hollow tube by means of guiding and retaining means and due to the effect of the earth's gravity, the abutment element of the door bears against the abutment element of the hollow tube.

[0020] According to one embodiment, the door is mounted to slide on the hollow tube in the longitudinal direction of the hollow tube.

[0021] According to one embodiment, the door is mounted so as to be movable in rotation about the hollow tube.

[0022] According to one embodiment, the door has a disengaged or removed position in which the door does not cover the opening in the hollow tube.

[0023] According to one embodiment, the hollow tube has a bottom at least partially covering the lower end of the hollow tube.

[0024] According to one embodiment, the present invention provides a float retaining device for a sealed and insulated storage tank for storing liquid, the float retaining device comprising:

[0025] - a hollow tube for receiving the float, the hollow tube having a longitudinal direction and intended to be mounted in the tank in a configuration in which the longitudinal direction of the hollow tube is parallel to the direction of the Earth's gravity, the hollow tube passing through the top wall of the tank and extending to the vicinity of the bottom wall of the tank, the hollow tube comprising an opening, and - a door retained on the hollow tube and mounted so as to be movable on the hollow tube in the longitudinal direction of the hollow tube by means of guiding and retaining means, the float retaining means having a closed position in which the door partially covers the opening in the hollow tube and in which, due to the effect of the Earth's gravity, an abutment element of the door rests on an abutment element of the hollow tube.

[0026] Therefore, in order to return the door to the disengaged position in which the opening in the hollow tube is fully exposed, the door must slide upward. Due to the above features, the door remains in the closed position under the action of gravity, thereby preventing it from falling to the bottom of the storage tank and damaging it.

[0027] According to one embodiment, the float retaining device further comprises a locking device configured to fix the door in the closed position in a locked state and to allow a sliding movement of the door in the direction of the upper end of the hollow tube in a released state.

[0028] This makes it possible to further limit the risk of the door falling to the bottom of the tank and furthermore to avoid movement of the door. For example, when the float retaining device is integrated into a tank on board a ship, the door remains in the closed position regardless of the heel and pitch angles and the movement of the liquid in the tank.

[0029] According to one embodiment, the door comprises at least two lugs protruding laterally on both sides of the door, and each lug comprises an orifice, said lugs forming an abutment element of the door, the hollow tube comprises at least two flanges protruding towards the outside of the hollow tube on both sides of the opening, said flanges forming an abutment element of the hollow tube, and said guiding and retaining device comprises at least two rods protruding from the respective flanges in the direction of the upper end of the hollow tube and parallel to the longitudinal direction of the hollow tube and extending in the orifices of one and the other of the two lugs, respectively.

[0030] Due to these features, the guiding and holding device is simple and is able to reliably guide the sliding movement of the door.

[0031] According to one embodiment, in the closed position, due to the effect of the earth's gravity, the at least two lugs rest respectively on one and the other of the flanges.

[0032] Thanks to these features, the weight of the door rests on the flanges of the hollow tube, which makes it possible to limit the stresses that could easily be exerted on the rods guiding the door.

[0033] According to one embodiment, the door comprises four lugs and the hollow tube comprises four flanges.

[0034] Thanks to these features, the door remains in the closed position. In addition, the forces are better distributed, resulting in increased resistance to swaying.

[0035] According to one embodiment, the door comprises between two and eight lugs and the hollow tube comprises between two and eight flanges.

[0036] According to one embodiment, the number of lugs and flanges is the same.

[0037] According to one embodiment, the lugs protruding laterally on both sides of the door are respectively in pairs facing each other.

[0038] According to one embodiment, the transversely protruding flanges on both sides of the orifice in the hollow tube are respectively face-to-face in pairs.

[0039] According to one embodiment, the rod of the guide and retaining means is a stud on which at least one corresponding nut is fastened, thereby locking one of the lugs on one of the flanges in order to lock the door in the closed position.

[0040] Thanks to these features, the door is securely held in the closed position and can also be easily disassembled.

[0041] According to one embodiment, the opening is formed in a lower portion of the hollow tube.

[0042] The lower portion of the hollow tube can be defined as the area located near the bottom of the tank. More precisely, the lower portion of the hollow tube is the lower half close to the bottom of the tank, that is, it extends over a length of less than 50% of the total length of the hollow tube. More precisely, the lower portion extends over a length of less than 30% and preferably less than 15% of the total length of the hollow tube.

[0043] Thanks to these features, the operator can easily enter the interior of the tube through the opening. In fact, the operator can, for example, recover, replace or repair the float and the nuts and bolts located in the hollow tube.

[0044] According to one embodiment, the door in the closed position only partially covers the opening so as to form a passage to the interior space of the hollow tube.According to one embodiment, a passage aperture is formed on the door so as to form a passage to the interior space of the hollow tube.

[0045] Thanks to these features, at least some maintenance operations, in particular calibration, can be carried out without having to remove the door. This possibility is particularly advantageous because it makes it possible to limit accidents that can easily arise from improper installation of the door.

[0046] According to one embodiment, the dimensions of the passage allowing access to the interior of the hollow tube are 20 mm to 300 mm in length (inclusive) and 10 mm to 300 mm in width (inclusive), 40 mm to 150 mm in length (inclusive) and 30 mm to 120 mm in width (inclusive), preferably 100 mm in length and 80 mm in width. These dimensions make it possible, in particular, to extract the float (for example, if it is damaged) and the nuts and bolts.

[0047] According to one embodiment, the shape of the passage enabling access to the interior space of the hollow tube is a circle, an ellipse, a parallelepiped, a rectangle, a rectangle with rounded corners, a square, a square with rounded edges.

[0048] According to one embodiment, the door has a lower edge comprising a notch. The notch particularly contributes to the formation of a passage that allows access to the interior space of the hollow tube. For example, the notch can constitute the upper part of the passage.

[0049] According to one embodiment, the opening has a lower edge comprising a notch. The notch particularly contributes to the formation of a passage that allows access to the interior of the hollow tube. For example, the notch may constitute the lower portion of the passage.

[0050] According to one embodiment, the opening has a lower edge at a distance from the bottom, such that a retention volume is defined between the lower edge of the opening and the bottom of the hollow tube.

[0051] These features keep any debris, nuts and bolts, or floats within a specific volume that might otherwise fall to the bottom of the float retaining device. This also protects the tank and surrounding components. Components contained within the retention volume are effectively prevented from freely migrating into the tank, thus limiting any impact on the tank's membrane. Furthermore, this allows at least a portion of the lower edge of the closed door to cover the area of ​​the hollow tube below the lower edge of the opening, thereby increasing the float retaining device's resistance to sloshing.

[0052] According to one embodiment, the lower edge of the opening is spaced from the bottom by a minimum distance of between 15 mm and 600 mm (inclusive). The minimum distance is preferably between 20 mm and 300 mm (inclusive), between 25 mm and 150 mm (inclusive), between 30 mm and 100 mm (inclusive), between 40 mm and 60 mm (inclusive), for example 50 mm.

[0053] According to one embodiment, the diameter of the hollow tube is between 50 mm and 500 mm, between 100 mm and 300 mm, between 200 mm and 250 mm, for example 219 mm.

[0054] According to one embodiment, the retention volume is preferably between 1.5 liters and 2.3 liters (inclusive).

[0055] According to one embodiment, the hollow tube and / or door is made of a material selected from stainless steel, high manganese steel, or any other alloy having elasticity suitable for cryogenic applications.

[0056] According to one embodiment, the thickness of the hollow tube and / or the door is between 5 mm and 30 mm inclusive.

[0057] According to an embodiment, the door has a weight between 2 kg (kilograms) and 15 kg (inclusive), such as approximately 5 kg to 10 kg.

[0058] According to one embodiment, the door comprises a peripheral area comprising a protruding portion which, in the closed position, covers an area of ​​the hollow tube adjoining the opening.

[0059] Thanks to these features, the forces exerted on the door due to the sloshing phenomenon are absorbed by the hollow tube. This makes it possible to increase the resistance of the float retaining device to the sloshing phenomenon.

[0060] According to one embodiment, the door has an upper edge, a lower edge and two longitudinal edges extending in the longitudinal direction of the hollow tube, and each longitudinal edge connects the lower edge and the upper edge, and the protrusion includes the longitudinal edges and the upper edge of the door.

[0061] According to one embodiment, the protruding portion comprises a longitudinal edge, an upper edge and a lower edge.In said embodiment, the passage aperture is formed on the door so as to form a passage to the inner space of the hollow tube.

[0062] According to one embodiment, the hollow tube has a cylindrical wall and the opening is formed in the cylindrical wall.

[0063] According to one embodiment, the hollow tube has an overall cylindrical shape, and the door comprises a segment concentric with the hollow tube and surrounding the outer surface of the hollow tube. According to one embodiment, the door surrounds the hollow tube. This makes it possible to limit the stresses exerted on the hollow tube and the door due to sloshing. These features further enable the door to slide in the longitudinal direction of the hollow tube or to rotate around the hollow tube about an axis of rotation parallel to the longitudinal direction.

[0064] According to one embodiment, the float retaining device may be used in a sealed insulated tank for storing a fluid. According to one embodiment, the fluid is selected from liquefied petroleum gas (LPG), liquefied natural gas (LNG), liquid hydrogen (LH2) or some other cryogenic fluid.

[0065] According to another embodiment, the present invention relates to a float retaining device for a sealed and insulated storage tank for storing liquid, the float retaining device comprising:

[0066] a hollow tube for receiving the float, the hollow tube being adapted to be mounted in the tank in a configuration where the hollow tube passes through the top wall of the tank and extends to near the bottom wall of the tank, the hollow tube including an opening, and

[0067] - a door held on the hollow tube, the door comprising a peripheral area including a projection which, in the closed position, covers the area of ​​the hollow tube adjacent to the opening. Forces exerted on the door due to the sloshing phenomenon are thus absorbed by the hollow tube.

[0068] One embodiment of the present invention is a sealed and insulated storage tank for storing liquid, which includes a top wall, a bottom wall and the aforementioned float retaining device, wherein the hollow tube passes through the top wall and extends to the vicinity of the bottom wall.

[0069] Such tanks may form part of an onshore storage facility for storing LNG, for example, or be installed in a floating structure either coastal or in deep water, in particular a methane carrier, a floating storage and regasification unit (FSRU), a floating production storage and offshore (FPSO) unit, etc. Such tanks may also be used as fuel tanks in any type of ship.

[0070] In one embodiment, a ship for transporting cold liquid products includes a double hull and the above-mentioned storage tank disposed in the double hull.

[0071] In one embodiment, the present invention also provides a method of loading or unloading a vessel of the above type, wherein the cold liquid product is transferred from a floating or onshore storage device to a tank of the vessel or from a tank to a floating or onshore storage device via an insulated pipeline.

[0072] In one embodiment, the present invention also provides a transportation system for cold liquid products, the system comprising: the above-mentioned ship; an insulating pipeline arranged so as to connect a storage tank installed in the hull of the ship to a floating or onshore storage device; and a pump for driving the fluid of the cold liquid product from the floating or onshore storage device to the ship's storage tank or from the storage tank to the floating or onshore storage device through the insulating pipeline. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] The present invention will be better understood and other objects, details, features and advantages thereof will become clearly apparent in the course of the following description of specific embodiments thereof, given by way of non-limiting illustration only and with reference to the accompanying drawings.

[0074] [ Figure 1 ] Figure 1 A schematic cross-sectional view of a sealed, insulated tank for storing liquid including a float retaining device is shown.

[0075] [ Figure 2 ] Figure 2 A detailed view of an area I is depicted on an enlarged scale, showing in perspective a portion of a float retaining device according to one embodiment.

[0076] [ Figure 3 ] Figure 3 Indicates that according to Figure 2 A front view of an embodiment of a float retaining device.

[0077] [ Figure 4 ] Figure 4 Indicates along Figure 3 A cross-sectional view of the float retaining device taken along line AA.

[0078] [ Figure 5 ] Figure 5 Schematic diagram showing a hollow tube of a float retaining device according to one embodiment, without the door shown to allow visibility of the float.

[0079] [ Figure 6 ] Figure 6 A perspective view showing a float retaining device according to another embodiment.

[0080] [ Figure 7 ] Figure 7 A perspective view showing a float retaining device according to another embodiment.

[0081] [ Figure 8 ] Figure 8 A perspective view showing a float retaining device in a closed position according to another embodiment.

[0082] [ Figure 9 ] Figure 9 express Figure 8 A perspective view of the float retaining device in the disengaged position.

[0083] [ Figure 10 ] Figure 10 express Figure 8 A perspective view of the float retaining device in another disengaged position.

[0084] [ Figure 11 ] Figure 11 is a schematic cross-sectional view of a methane tanker ship comprising a sealed, insulated storage tank and a terminal for loading / unloading the tank. DETAILED DESCRIPTION

[0085] By convention, the terms "lower" and "upper" define the relative positions of elements or portions of elements, with "lower" meaning near the bottom of the tank and "upper" meaning near the top of the tank.

[0086] Figure 1 The invention shows a sealed and insulated storage tank for storing liquid (such as liquefied gas). The storage tank comprises a top wall 2, a bottom wall 3 and a float retaining device 1. The float retaining device 1 passes through the top wall 2 of the storage tank and extends to the vicinity of the bottom wall 3 of the storage tank.

[0087] Examples of this type of tank are membrane tanks. These have a multilayer structure that, in the thickness direction from the outside of the tank to the inside, features: a secondary thermal insulation barrier held on a support structure; a secondary sealing membrane resting against the secondary thermal insulation barrier; a primary thermal insulation barrier resting against the secondary sealing membrane; and a primary sealing membrane resting against the primary thermal insulation barrier and intended to come into contact with the liquefied natural gas contained in the tank. Membrane tanks of this type are specifically described in, for example, patent applications WO14057221, FR2691520, and FR2877638.

[0088] However, the present invention is not limited to this particular type of tank.

[0089] like Figures 2 to 5 As shown, the float retaining device 1 comprises a hollow tube 4 intended to receive a float 9, for example a float capable of measuring the level of a liquid in a tank. The hollow tube 4 has a longitudinal direction and an opening 41, which is located at Figure 2 and Figure 3 The lower middle part of the hollow tube 4 is visible and Figure 5 The hollow tube 4 has a cylindrical overall shape. An opening 41 is formed in the lower portion of the hollow tube 4. The opening 41 has a rectangular overall shape with rounded corners and also has a notch 42 located on the lower portion of the opening 41. The size of the opening 41 is preferably larger than the diameter of the float 9 intended to be integrated into the float retaining device. Generally speaking, the diameter of the float is between 50 mm and 300 mm (inclusive). For example, Figure 5 The float 9 shown has a diameter of 127 mm.

[0090] The hollow tube 4 further comprises four flanges 43 protruding towards the outside of the hollow tube 4 on either side of the opening 41. Four studs 44 are welded to the respective flanges 43. The studs 44 protrude in the direction of the upper end of the hollow tube 4. In the embodiment shown, the studs 44 pass through the openings in the flanges 43 and are welded to said flanges 43.

[0091] Figure 2 The hollow tube 4 shown in FIG4 further comprises a bottom 45 covering the lower end of the hollow tube 4. The bottom 45 comprises an aperture 451 enabling liquid communication between the interior of the float retaining device 1 and the tank. The opening 41 has a lower edge represented by a notch 42 formed at a distance from the bottom 45 such that a retention volume is defined between the lower edge 42 of the opening 41 and the bottom 45 of the hollow tube 4. The retention volume makes it possible to retain elements that may fall into the interior of the float retaining device 1, such as the float 9, bolts, studs, etc.

[0092] The float retaining device 1 further includes a door 5. The door has a semicircular cross-section, an upper edge 52, a lower edge 53, and two longitudinal edges 54 extending in the longitudinal direction of the hollow tube 4 and each connecting the lower edge 53 and the upper edge 52. The door further includes a notch 55 on the lower edge 53. The door 5 includes four lugs 51 that protrude laterally on either side of the door 5, and each lug includes an aperture.

[0093] The door 5 is held on the hollow tube 4 and mounted so as to slide on the hollow tube 4 in the longitudinal direction of the hollow tube 4 so that the studs 44 pass through the holes in the four lugs 51. The function of the studs 44 is to guide the door 5 and to hold it against the hollow tube 4. Due to the effect of the earth's gravity, at least two lugs 51 of the door 5 abut against the corresponding flanges 43 of the hollow tube 4. Therefore, the door 5 is particularly Figures 2 to 4 , is shown in the closed position corresponding to a position of the door 5 in which it covers more of the opening than in all other positions of the door 5. This arrangement, combined with the force of gravity, enables the door 5 to be reliably held in the closed position.

[0094] Furthermore, the door 5 only partially covers the opening 41 in the hollow tube 4 so as to define a passage allowing access to the interior space of the hollow tube 4 even when the door 5 is in the closed position. Figure 1 and Figure 2 The hollow tube 4 is defined by the notch 42 and the notch 55 of the door 5. The two notches 42 and 55 are connected and form a passage to the inner space of the hollow tube 4. Figure 2In the embodiment shown, the recesses 42 , 55 have similar shapes. The shape of the recess 42 of the hollow tube 4 may also differ from the shape of the recess 55 of the door 5 .

[0095] like Figure 4 As shown, the door 5 has a section that is concentric with the hollow tube 4 and surrounds the outer surface of the hollow tube 4. In addition, the door 5 includes a peripheral area with a protrusion 6, which, in the closed position, covers the area of ​​the hollow tube 4 adjacent to the opening 42. The protrusion 6 of the peripheral area can be more or less large. For example, in a direction perpendicular to the longitudinal direction of the hollow tube 4, the protrusion can have a width between 2 mm and 20 mm (inclusive), for example a width of 13 mm.

[0096] The float retaining device 1 also includes a flat washer and a nut 8, such as an M8 HK sawtooth nut, which is fixed to the thread 441 of each stud 44 after the door 5 is inserted and then the washer is inserted. Thus, the nut 8 fixes the four lugs 51 and the four flanges 43 to lock the door 5 in the closed position. The washer is optional and its function is mainly to protect the lugs 51 from friction during the fixing with the nut 8.

[0097] The door 5, initially in the closed position, can be disengaged from the opening by removing the nut 8 and applying a force to the door in the direction opposite to the force of gravity until the opening in the lug 51 disengages from the stud 44. The direction of the force required to disengage the door is determined by Figure 2 Indicated by the arrow extending from the door 5.

[0098] exist Figure 6 , elements that are similar or identical to those of the above-described embodiments or have the same functions are denoted by 100.

[0099] Figure 6 A float retaining device according to another embodiment is shown.

[0100] The hollow tube 104 includes a plurality of holes 551 in the bottom wall 145 to allow fluid communication between the interior of the float retaining device 100 and the tank. The hollow tube 104 also includes four flanges 143 that protrude toward the exterior of the hollow tube 104 on either side of the opening, and each flange includes an orifice.

[0101] Float retaining device 100 also includes door 105, which includes a rectangular notch 155 with rounded corners located in the lower edge 153 of hollow tube 104. Door 105 also includes four lugs 151, which protrude laterally on either side of door 105 and each include an aperture. However, each pair of lugs 151 is positioned between the two flanges 134 of the hollow tube. Therefore, due to the effect of gravity, the two lower lugs 151 of door 105 abut against the corresponding lower flanges 143 of hollow tube 104. The two upper lugs 151 contact the two upper flanges 143 and do not rest on them. The four lugs 151 and the four flanges 143 are locked by a locking nut and bolt system, locking the four lugs 151 and the four flanges 143 to lock door 105 in the closed position. The four nut and bolt system must be removed to remove door 105. In this type of embodiment, if one or more of the nut and bolt systems are accidentally unscrewed, there is a risk that they may damage the tank and cause the door 105 to fall to the bottom of the tank.

[0102] Figure 7 FIG. 2 shows another embodiment of a float retaining device 200. The float retaining device 200 is different from the device shown in the above figure in that: Figure 7 The lower portion of the float retaining device 200 shown comprises an upper portion of the hollow tube 204 located above the assembly flange 24 and a lower portion of the hollow tube 204 connected to the upper portion of the hollow tube via the assembly flange 24. The lower portion of the hollow tube 204 is formed by a half-shell 304 of the hollow tube 204. A door formed by a half-shell 205 is retained on the hollow tube 204. The door comprises a channel 296 in the lower portion in the form of a rectangle with rounded corners.

[0103] The two half-shells are connected on their first side by two hinges 21. Each hinge 21 includes a first lug 22 protruding from half-shell 205 and a second lug 23 protruding from half-shell 304, each lug including an aperture. Lugs 22 and 23 are connected via a nut and bolt system that passes through holes in lugs 22 and 23, preventing longitudinal movement of half-shell 205. The second side of the two half-shells is connected and secured by a longitudinal securing system 30. The half-shells include corresponding tabs 30 that protrude from each half-shell a certain length in the longitudinal direction of hollow tube 204 and the door, facing each other and adjacent to each other. Each tab 30 includes three corresponding apertures distributed along its length and is secured via a nut and bolt system that passes through the apertures, thereby preventing longitudinal movement perpendicular to the longitudinal movement of half-shell 205. Thus, half-shell 205 is in the closed position. Said lower portion of the float retaining device 200 is integrated into the rest of the float retaining device 200 via an assembly flange 24 which can be connected to the upper portion of the hollow tube 204 .

[0104] Figure 8 、 Figure 9 and Figure 10 2 shows a float retaining device according to another embodiment. This float retaining device 300 differs from the previous embodiment in that a door 305 surrounds a hollow tube 404. Door 305 has a circular cross-section and includes an upper edge 152, a lower edge 153, and two longitudinal edges 154 extending in the longitudinal direction of hollow tube 404 and connecting lower edge 153 and upper edge 152, respectively. Door 305 also includes two extensions 251 and 252, which are joined to the two longitudinal edges 154 to surround hollow tube 404.

[0105] In the closed position, the extensions 251 , 252 are advantageously situated axially on either side of the opening 141 .

[0106] Thus, the door 305 has concentric segments that surround the hollow tube 404 and encompass the outer surface of the hollow tube 404 , which makes it possible to hold the door in place on the hollow tube 404 .

[0107] Thus, the extensions 251, 252 form guide and retaining elements for the door 305. They allow Figure 9 The sliding movement in the longitudinal direction of the hollow tube 404 shown and / or Figure 10 The door 305 is shown in FIG. 4 as a rotational movement about the longitudinal axis of the hollow tube 404 .

[0108] Due to the effect of gravity, the door 305 abuts against the abutment element 243 of the hollow tube 404. The abutment element 243 of the hollow tube 404 is formed by the bottom 245 of the hollow tube 404, the diameter of which is greater than the cross-sectional diameter of the hollow tube 404. The portion of the bottom 245 visible outside the hollow tube corresponds to the abutment element 243. Figure 8 In the closed position shown, the door rests on the abutment element 243, in particular enabling the door to sit better on the hollow tube and thus enabling the resistance of the float retaining device to sloshing effects to be increased. Figure 2 and Figure 3 A similar arrangement includes aperture 651 to allow fluid communication between the interior of the float retaining device 300 and the tank.

[0109] In a variant embodiment, the float retaining device 300 includes at least one removable retaining member (not shown) configured to maintain the door in the disengaged position, such as Figure 9 or Figure 10As shown. For example, such a retaining member can be a pin that passes through two facing apertures formed in the door and the hollow tube, respectively. The retaining member can also be a pin that passes through an aperture formed in the hollow tube and projects onto the outside of the hollow tube. In this case, the pin is positioned so that the door abuts against it during movement intended to move the door from the disengaged position to the closed position. Any other retaining member is also conceivable, in particular a fixing clip, a bolt, etc.

[0110] In another alternative embodiment, alternatively or in addition to the aforementioned embodiment, the float retaining device 300 may also include at least one removable retaining member (not shown) configured to retain the door in the closed position. For example, such a retaining member may be a pin that passes through two facing apertures formed in the door and the hollow tube, respectively.

[0111] The technology described above, featuring different float retaining devices, can be used with various types of storage tanks, such as LNG storage tanks in onshore installations or in floating structures such as methane carriers or other vessels.

[0112] In a manner known per se, a loading / unloading line 73 provided on the upper deck of the vessel can be connected to a maritime or port terminal by means of appropriate connectors in order to transport the LNG cargo from or to the storage tanks 71 .

[0113] Figure 11 An example of a marine terminal is shown, comprising a loading and unloading station 75, underwater pipelines 76, and an onshore installation 77. The loading and unloading station 75 is a fixed onshore installation comprising a mobile arm 74 and a tower 78 supporting the mobile arm 74. The mobile arm 74 carries bundled insulated flexible piping 79 that can be connected to the loading / unloading pipeline 73. The orientable mobile arm 74 is suitable for all methane tanker loading pressure gauges. Connecting pipelines (not shown) extend within the tower 78. The loading and unloading station 75 enables methane tanker vessels 70 to be loaded from and unloaded to a land-based installation 77. The land-based installation includes a liquefied gas storage tank 80 and a connecting pipeline 81, which is connected to the loading or unloading station 75 via the underwater pipeline 76. The underwater pipeline 76 enables the transport of liquefied gas between the loading or unloading station 75 and the onshore installation 77 over a considerable distance (e.g., 5 km), enabling the methane tanker 70 to remain at a considerable distance from shore during loading and unloading operations.

[0114] Pumps on board the vessel 70 and / or pumps provided with the shore installation 77 and / or pumps provided with the loading and unloading station 75 are used to generate the pressure required for transporting the liquefied gas.

[0115] Although the invention has been described in connection with a number of specific embodiments, it is obvious that the invention is in no way limited to these embodiments and that the invention comprises all technical equivalents and combinations of the described means, if they fall within the scope of the invention as defined by the claims.

Claims

1. A float retaining device (1, 100, 200, 300, 400) for a sealed and insulated storage tank for storing liquid, the float retaining device (1, 100, 200, 300, 400) comprising: a hollow tube (4, 104, 204, 404) for receiving a float (9), the hollow tube (4, 104, 204, 404) being adapted to be mounted in the tank in a configuration where the hollow tube (4, 104, 204, 404) passes through the top wall (2) of the tank and extends to near the bottom wall (3) of the tank, the hollow tube (4, 104, 204, 404) comprising an opening (41, 141), and a door (5, 105, 205, 305) held on the hollow tube (4, 104, 204, 404) and mounted so as to be movable on the hollow tube (4, 104, 204, 404), And wherein the float retaining device (1, 100, 200, 300, 400) has a closed position, in which the door (5, 105, 205, 305) partially covers the opening (41) in the hollow tube (4, 104, 204, 404) so ​​that a passage (296, 396) is formed to the interior space of the hollow tube (4, 104, 204, 404).

2. The float retaining device of claim 1 , wherein the door (5, 305) is mounted so as to be movable on the hollow tube (4, 404) by means of guiding and retaining means (441, 44, 252), and wherein due to the effect of the earth's gravity, the abutment element (51, 251) of the door (5, 305) rests against the abutment element (43, 243) of the hollow tube.

3. The float holding device according to claim 1 or 2, wherein the door (5, 305) is adapted to slide on the hollow tube (4, 404) along the longitudinal direction of the hollow tube (4, 404).

4. The float retaining device according to claim 1 or 2, wherein: The door (305) is adapted to be rotatably movable around the hollow tube (404).

5. The float retaining device according to claim 2 further comprises a locking device (8) configured to fix the door (5) in the closed position in the locked state and to allow the door (5) to slide in the direction of the upper end of the hollow tube (4) in the released state.

6. The float retaining device according to claim 2 , wherein the door ( 5 ) comprises at least two lugs ( 51 ) which project laterally on both sides of the door ( 5 ) and each lug comprises an orifice, the lugs ( 51 ) forming an abutment element ( 51 ) of the door ( 5 ), and wherein the hollow tube ( 4 ) comprises at least two flanges ( 43 ) which project towards the outside of the hollow tube ( 4 ) on both sides of the opening ( 41 ), the flanges ( 43 ) forming an abutment element ( 43 ) of the hollow tube ( 4 ), the guiding and retaining means ( 441 , 44 ) comprising at least two rods ( 441 ) which project from the respective flanges ( 43 ) in the direction of the upper end of the hollow tube ( 4 ) and parallel to the longitudinal direction of the hollow tube ( 4 ) and extend in the orifices of one lug and the other lug of the two lugs ( 51 ) respectively.

7. The float retaining device of claim 6, wherein in the closed position, due to the effect of the earth's gravity, at least two lugs (51) respectively rest against one and the other of the flanges (43).

8. The float retaining device of claim 6, wherein the door (5) comprises four lugs (51), and the hollow tube (4) comprises four flanges (43).

9. The float retaining device according to claim 6, wherein the rod of the guiding and retaining means (441, 44) is a stud (441, 44) on which at least one corresponding nut (8) is fixed, thereby locking one of the lugs (51) on one of the flanges (43) to lock the door (5) in the closed position.

10. The float retaining device according to claim 1 or 2, wherein the opening (41, 141) is formed in a lower portion of the hollow tube (4, 304, 404).

11. The float retaining device of claim 1 or 2, wherein the door (5, 105) has a lower edge (53, 153) comprising a notch (55, 155).

12. The float retaining device of claim 1 or 2, wherein the opening (41) has a lower edge comprising a notch (42).

13. The float retaining device of claim 1 or 2, wherein the hollow tube (4, 104, 204, 404) has a bottom (45, 145, 245) at least partially covering the lower end of the hollow tube (4, 104, 204, 404), and the opening (41, 141) has a lower edge at a distance from the bottom (45, 145, 245) so as to define a retention volume between the lower edge of the opening (41, 141) and the bottom (45, 145, 245) of the hollow tube (4, 104, 204, 404).

14. The float retaining device of claim 13, wherein the lower edge of the opening (41, 141) is spaced from the bottom (45, 145, 245) by a minimum distance between 15 mm and 600 mm, inclusive.

15. The float retaining device of claim 1 or 2, wherein the door (5, 105, 205, 305) comprises a peripheral area including a protruding portion (6) which, in the closed position, covers an area of ​​the hollow tube (4, 104, 204, 404) adjacent to the opening (41, 141).

16. The float retaining device of claim 15 , wherein the door ( 5 , 105 , 205 , 305 ) has an upper edge ( 52 , 152 ), a lower edge ( 53 , 153 ) and two longitudinal edges ( 54 , 154 ) extending in the longitudinal direction of the hollow tube ( 4 , 104 , 204 , 404 ) and each connecting the lower edge ( 53 ) and the upper edge ( 52 , 152 ), and wherein the protruding portion ( 6 ) includes the longitudinal edges ( 54 , 154 ) and the upper edge ( 52 , 152 ) of the door ( 5 , 105 , 205 , 305 ).

17. The float retaining device of claim 1 or 2, wherein the hollow tube (4, 104, 204, 404) has a cylindrical overall shape, and the door (5, 105, 205, 305) has a segment that is concentric with the hollow tube (4, 104, 204, 404) and surrounds the outer surface of the hollow tube (4, 104, 204, 404).

18. A sealed and insulated storage tank for storing liquid, comprising a top wall (2), a bottom wall (3) and a float retaining device (1, 100, 200, 300, 400) according to any one of claims 1 to 17, wherein the hollow tube (4) passes through the top wall (2) and extends to the vicinity of the bottom wall (3).

19. A ship (70) for transporting cold liquid products, said ship comprising a double hull (72) and a tank (71) according to claim 18, said tank being arranged in said double hull.

20. A transport system for a cold liquid product, the system comprising: The vessel (70) according to claim 19; Insulated piping (73, 79, 76, 81) arranged to connect the tanks (71) mounted in the hull of the vessel to a floating or onshore storage facility (77); and a pump for driving a flow of cold liquid product from the floating or onshore storage facility to the vessel's tanks or from the tanks to the floating or onshore storage facility through the insulated piping.

21. A method of loading or unloading a vessel (70) as claimed in claim 19, wherein the cold liquid product is driven from a floating or onshore storage device (77) to the vessel's tanks (71) or from the tanks to the floating or onshore storage device via insulated pipelines (73, 79, 76, 81).

Images