FR3157916A1 - Tank for storing and/or transporting a cargo of liquid gas intended for a ship - Google Patents

Abstract

The invention relates to a tank for storing and/or transporting a fluid intended for a ship, the tank comprising a loading/unloading tower comprising M masts (11, 12, 13), M being an integer between 2 and 4, each extending along a vertical axis, N unloading pumps (21, 22, 23), N between 1 and 4 and less than M, and a base (100) located at a lower end of the loading/unloading tower, characterized in that each of the N pumps is arranged at the lower end of the loading/unloading tower, in line with a mast and fluidically connected to said mast, and in that the base (100) comprises an anchoring device (110) fixed to the N pumps extending along a first horizontal plane, a vertical guiding device (111) for each pump relative to the base (100), and for each mast, a first holding arm (112) extending from the anchoring device (110) towards said mast along a first axis (Z1) intersecting the first horizontal plane (P1). Figure 3

Description

Tank for storing and/or transporting a cargo of liquid gas intended for a ship

The present invention relates to the field of vessels for transporting a fluid, such as, for example, liquefied natural gas (LNG). More particularly, the present invention relates to the field of tanks equipping such vessels, in which liquefied gas, for example natural gas in the liquid state, is stored, and which comprise liquefied natural gas loading/unloading towers making it possible to load fluid into the tank and/or unload it.

Technological background

In the state of the art, sealed and thermally insulating tanks for storing liquefied gas are known, which are mounted on a ship and equipped with a loading/unloading tower. The loading/unloading tower is generally suspended from a ceiling wall of a supporting structure, the supporting structure representing the internal hull of the ship. The tank also has a support foot which is fixed to the supporting structure in an area of a bottom wall of the tank. The support foot is arranged to ensure vertical translational guidance of the loading/unloading tower.

Such a tank may include a corrugated primary sealing membrane intended to be in contact with the liquefied gas. The corrugated sealing membrane includes a plurality of corrugations in order to increase its flexibility, particularly during deformations linked to strong temperature variations.

In the following, the context of the invention and the invention itself will be described with the example of LNG. However, the invention is in no way limited thereto and can be applied to other liquefied gases, liquefied petroleum gas, hydrogen, ammonia being cited as non-limiting examples.

Such an LNG transport vessel typically has four tanks representing a total volume of 174,000 m³ of LNG cargo. In each tank, the loading/unloading tower includes two unloading pumps, each associated with a mast and allowing the unloading of LNG by pumping LNG through the mast. Each pump is generally offset from the vertical axis along which the mast to which it is associated extends. More precisely, each mast delimits, by axial projection on the bottom wall of the tank, a perimeter. The pump offset from the vertical axis of the mast means that it is entirely located outside this perimeter. The term "pump" refers to an assembly consisting of an electric motor and a pump body configured to suck a fluid, in this case to suck the LNG present in the tank.

The unloading time of the ship is generally around 12 to 14 hours.

A new generation of ship can have three tanks for the same total cargo volume. Each tank therefore has a larger volume. However, it is desirable to maintain the same unloading time as that of a four-tank ship.

It should be borne in mind that at sea, under the action of the swell, liquefied gas storage tanks are subject to cargo sloshing phenomena, called "sloshing" in English. These phenomena are likely to be very violent inside the tank and consequently generate significant forces in the tank and in particular on its equipment, such as the loading/unloading tower and the pump mounting elements.

One idea behind this invention is to add an additional unloading pump, i.e. a third unloading pump in the example mentioned, to the tank in order to increase the unloading flow rate. However, adding a third pump presents difficulties in integrating this additional pump into the tripod mast. Indeed, for the pumps to function properly, it is imperative to respect distances between the pumps, these distances being defined by the pump supplier. In addition, depending on the vessel, the position of the loading/unloading tower within the tank may be very close to a side wall of the tank, or on the contrary further from this wall. It is therefore necessary to be able to install three pumps while taking into account these arrangement constraints and the constraints associated with the sloshing phenomenon.

The invention aims to overcome all or part of the problems mentioned above by proposing a loading/unloading tower comprising two to four masts (preferably three) and one, two, three or four unloading pumps (this number of pumps being less than or equal to the number of masts), each being arranged under a mast, the loading/unloading tower being equipped with an innovative base connected to the lower end of the three masts. In addition to providing the interface between the masts, the pumps and the support foot fixed to the tank bottom wall, the innovative base prevents horizontal movement of the pumps while allowing relative vertical movement between the pumps and the base caused by the effects of thermal contraction in contact with the liquefied gas.

• une tour de chargement/déchargement comprenant M mâts s’étendant chacun selon un axe vertical, M étant un nombre entier compris entre 2 et 4 ;
• un pied de soutien fixé à une paroi de fond de la cuve ;
• N pompes de déchargement, N étant un nombre entier compris entre 1 et 4 et inférieur ou égal à M ;
• une base située à une extrémité inférieure de la tour de chargement/déchargement, connectée au pied de soutien.

To this end, the invention relates to a tank for storing and/or transporting a fluid intended for a ship, the tank comprising:

• a loading/unloading tower comprising M masts each extending along a vertical axis, M being an integer between 2 and 4;
• a support foot fixed to a bottom wall of the tank;
• N unloading pumps, N being an integer between 1 and 4 and less than or equal to M;
• a base located at a lower end of the loading/unloading tower, connected to the support leg.

• un dispositif d’ancrage fixé aux N pompes de déchargement s’étendant selon un premier plan horizontal ;
• un dispositif de guidage vertical de chaque pompe par rapport à la base ;
• pour chaque mât : un premier bras de maintien s’étendant du dispositif d’ancrage vers ledit mât selon un premier axe sécant au premier plan horizontal.

According to the invention, each of the N unloading pumps is arranged at the lower end of the loading/unloading tower, in line with a mast and fluidly connected to said mast, and the base comprises:

• an anchoring device fixed to the N unloading pumps extending along a first horizontal plane;
• a device for vertically guiding each pump relative to the base;
• for each mast: a first holding arm extending from the anchoring device towards said mast along a first axis intersecting the first horizontal plane.

Advantageously, the anchoring device comprises, for each pump, at least one collar portion fixed to an upper part of said pump and a skirt extending along an enveloping surface from the at least one collar portion to at least a first height of said pump.

Advantageously, each pump comprising at least a first guide element arranged at the first height of said pump, the vertical guide device comprises, for each pump, a second guide element fixed to the skirt and of complementary shape to the first guide element, the second guide element being movable in translation vertically relative to the first guide element.

Advantageously, the base comprises a fixing zone extending along a second horizontal plane, distinct from the first horizontal plane, connecting two by two the skirts of the three pumps.

Advantageously, the second horizontal plane is parallel to the first horizontal plane.

Advantageously, the base further comprises at least one structural connection between the fixing zone and the anchoring device.

In one embodiment of the invention, each skirt comprises at least one lateral opening opposite the at least one first guide element and the second guide element is fixed on either side of the at least one lateral opening.

In another embodiment, the at least one first guide element comprises a collar fixed around said pump at the first height, said collar having at least one protuberance extending radially towards the skirt and a pin disposed on the at least one protuberance and extending vertically, and the second guide element comprises two portions connected to each other and having a channel in which the pin is disposed.

Advantageously, at least one skirt comprises a plurality of stiffeners extending, from the wrapping surface of said skirt, preferably in a vertical direction and/or a horizontal direction.

Advantageously, the anchoring device is perforated in the first horizontal plane.

Advantageously, the base comprises, for each mast, a second holding arm extending from the anchoring device towards said mast along a second axis intersecting the first horizontal plane and distinct from the first axis.

The invention also relates to a ship comprising a hull forming a supporting structure and at least one such tank anchored on said supporting structure.

Brief description of the figures

These and other features and advantages of the present invention will become more clearly apparent from the following description, given with reference to the accompanying drawings, given as non-limiting examples, and in which:

There FIG. 1 is a schematic cutaway view of a sealed and thermally insulating tank for storing a fluid equipped with a loading/unloading tower according to the invention;

There FIG. 2 is a perspective view of a tank loading/unloading tower according to an exemplary embodiment of the present invention;

There FIG. 3 represents in perspective a first embodiment of the base according to the invention;

There FIG. 4 represents in perspective the first embodiment of the base according to the invention;

There FIG. 5 represents the guide elements of the pump of the first embodiment of the base according to the invention;

There FIG. 6 represents a guiding element of the FIG. 4 from another point of view;

There FIG. 7 is a detailed bottom view of the unloading tower illustrating the guidance of the loading/unloading tower on the support leg;

There FIG. 8 represents in perspective a second embodiment of the base according to the invention;

There FIG. 9 represents the guide elements of the pump of the second embodiment of the base according to the invention;

There FIG. 10 represents in perspective a third embodiment of the base according to the invention;

There FIG. 11 is a schematic cutaway representation of a ship tank according to the invention and of a loading/unloading terminal for this tank.

For the sake of clarity, the same elements will have the same references in the different figures.

The features, variants and different embodiments of the invention, as described or as will be presented in the detailed description which follows, may be combined with each other, in various combinations, to the extent that they are not incompatible or mutually exclusive. In particular, variants of the invention may be imagined comprising only a selection of features described below in isolation from the other features described, if this selection of features is sufficient to confer a technical advantage and/or to differentiate the invention from the prior art.

The invention relates to a sealed and thermally insulating tank for storing liquefied gas which is equipped with a loading/unloading tower for loading the liquefied gas into the tank and/or unloading it. By way of non-limiting example, the liquefied gas may in particular be liquefied natural gas (LNG).

There FIG. 1 is a schematic cutaway view of a sealed and thermally insulating tank 1 for storing a fluid equipped with a loading/unloading tower according to the invention.

The sealed and thermally insulating liquefied gas storage tank 1 is equipped with a loading/unloading tower 5 for loading the liquefied gas into the tank 1 and/or unloading it. The liquefied gas may in particular be liquefied natural gas (LNG), i.e. a gas mixture comprising mainly methane and one or more other hydrocarbons, such as ethane, propane, n-butane, i-butane, n-pentane, i-pentane, neopentane, and nitrogen in small proportions.

The tank 1 is anchored in a supporting structure 3 on board a ship. The supporting structure 3 is for example formed by the double hull of a ship but can more generally be formed from any type of rigid partition having appropriate mechanical properties. The tank 1 can be intended for the transport of liquefied gas or for receiving liquefied gas used as fuel for the propulsion of the ship.

According to one embodiment, the tank 1 is a membrane tank. In such a tank 1, each wall successively has, from the outside to the inside, along the thickness direction of the wall, a secondary thermally insulating barrier 4 comprising insulating elements resting against the supporting structure 3, a secondary sealing membrane 2 anchored to the insulating elements of the secondary thermally insulating barrier 4, a primary thermally insulating barrier 6 comprising insulating elements resting against the secondary sealing membrane 2 and a primary sealing membrane 7 anchored to the insulating elements of the primary thermally insulating barrier 6 and intended to be in contact with the fluid contained in the tank 1.

On the FIG. 1 , the loading/unloading tower 5 is installed in the vicinity of the rear wall 8 of the tank 1, which makes it possible to optimize the quantity of cargo likely to be unloaded by the loading/unloading tower 5 since the ships are generally tilted backwards using the ballasts in a particular way.

At the bottom of the loading/unloading tower is the base (references 100, 200, 300) which provides anchoring and guidance for the pumps. The base will be described later.

There FIG. 2 is a perspective view of a loading/unloading tower 5 of a tank according to an exemplary embodiment of the present invention.

The loading/unloading tower 5 is suspended from an upper wall 9 of the supporting structure 3. According to a preferred embodiment, the upper wall 9 of the supporting structure 3 comprises, near the rear wall 8, a space, of rectangular parallelepiped shape not shown, projecting upwards, called a liquid dome. The liquid dome is defined by two transverse walls, front and rear, and by two side walls which extend vertically and project upwards from the upper wall 9. The liquid dome further comprises a horizontal cover 10 from which the loading/unloading tower 5 is suspended.

The loading/unloading tower 5 extends over substantially the entire height of the tank. The loading/unloading tower 5 comprises M masts, M being an integer between 2 and 4, here 3 masts 11, 12, 13, each extending along a vertical axis, which are each fixed to each other by crosspieces 15. In other words, the loading/unloading tower comprises 2, 3 or 4 masts. When the tower 5 comprises three masts, it is referred to as a tripod structure. Each of the masts 11, 12, 13 is hollow and passes through the cover 10 of the liquid dome.

Advantageously, the masts 11, 12, 13 define with the crosspieces 15 a prism with triangular section.

The tank for storing and/or transporting a fluid according to the invention also comprises a support foot 14 fixed to a bottom wall of the tank. The storage and/or transport tank also comprises N unloading pumps 21, 22, 23, N being an integer between 1 and 4 and less than or equal to M. In other words, the tank comprises one, two, three or four unloading pumps, the number of pumps being less than or equal to the number of mast(s). Finally, the tank comprises a base (here referenced 200) located at a lower end of the loading/unloading tower 5, connected to the support foot 14. In the following, the invention is described in the case where N is equal to 3, that is to say in the case of a tank comprising three unloading pumps, each associated with a mast, and M equal to 3. The description of the invention is identical in the case where the tank comprises a single unloading pump or two unloading pumps. Similarly, the description of the invention is identical in the case where the tower comprises two masts, or three masts or four masts. In the cases with two (respectively one) unloading pump and 3 masts, one (respectively two) mast is not associated with a pump. This mast (respectively these two masts) retains a structural role, without changing the characteristics of the base which is described below. In a case where the tower comprises four masts, the person skilled in the art understands from the description of the invention that the base described below may be identical to the description which follows (i.e. with three guide devices) or it may be adapted to have four guide devices, in a manner analogous to what is described below for 3 masts. The description and the figures thus represent three pumps and three masts but the invention is not limited thereto.

According to the invention, each of the three pumps 21, 22, 23 is arranged at the lower end of the loading/unloading tower 5, in line with a mast 11, 12, 13 and fluidically connected to said mast. The physical and fluidic connection between the pump and the mast is ensured in a known manner, for example by means of flanges whose diameters are adapted to that of the outlet of the pump body and that of the mast. In the case where a mast (or two masts) is not associated with a pump, no flange is present on said mast.

The base of the invention comprises an anchoring device fixed to the three pumps extending along a first horizontal plane (the anchoring device extending between two adjacent pumps when there are at least two pumps), a device for vertically guiding each pump relative to the base and for each mast, a first holding arm extending from the anchoring device towards said mast along a first axis intersecting the first horizontal plane. The details of this innovative base are described below.

There FIG. 3 represents in perspective a first embodiment of the base 100 according to the invention. As can be seen in the FIG. 3 , each of the three pumps 21, 22, 23 is arranged at the lower end of the loading/unloading tower 5, in line with a mast 11, 12, 13 and fluidly connected to said mast. In other words, the pump 21 is positioned under the mast 11, the pump 22 is positioned under the mast 12 and the pump 23 is positioned under the mast 13. In view of what has been explained above, the person skilled in the art understands that one or two pumps can be omitted without changing the core of the invention. A flange connection connects the upper end of a pump to the lower end of the mast. In projection in the plane of the bottom wall, the three masts 11, 12, 13 and the crosspieces 15 form a triangle and the pumps 21, 22, 23 are respectively arranged at the three vertices of the triangle.

By positioning each pump under a mast, the minimum distances required between the pumps are respected, and the position of the loading/unloading tower within the tank can be close to a side wall of the tank, or much further away from this wall. The presence of three pumps in a tank makes it possible to ensure a higher unloading rate than that of the same tank with two pumps. For a larger tank, it is thus possible to maintain the same unloading time as a traditional tank of smaller volume. In addition, the addition of a third pump in the tank makes it possible to eliminate the emergency retractable pump present to compensate for the failure of one of the pumps.

According to the invention, the base 100 comprises an anchoring device 110 fixed to the three pumps 21, 22, 23 extending between two adjacent pumps along a first horizontal plane P1. More precisely, each pump is equipped with fixing lugs 31, preferably at least two, arranged at its upper end. The anchoring device 110 is fixed to the pumps by means of the fixing lugs 31. Thus, the anchoring device 110 ensures the direct connection of the pumps together two by two in the same plane P1. The anchoring device defines the upper part of the base and allows, with the lower part of the base which will be detailed below, to absorb the forces due to sloshing. Such a configuration guarantees the mechanical strength of the base despite the hydrodynamic forces due to the impacts of the sloshing of liquefied gas on the tower 5.

The base comprises a vertical guide device 111 for each pump relative to the base 100. The vertical guide device allows for relative vertical movement between the pumps and the base caused by thermal contraction effects in contact with the liquefied gas. By combining the anchoring device 110 and the vertical guide device 111, the base 100 blocks the horizontal movement of the pumps. As a result, the pumps and the tower masts do not have a degree of freedom in horizontal translation in order to maintain the assembly in position despite sloshing impacts. However, a degree of freedom in vertical translation is allowed between the pumps and the base to allow for thermal contraction of the pump body, generally made of aluminum, relative to the base, for example formed of stainless steel.

Finally, the base 100 comprises, for each mast, a first holding arm 112 extending from the anchoring device 110 towards said mast along a first axis Z1 intersecting the first horizontal plane P1. The holding arm ensures the transmission of forces from the mast to the base. As will become clear later, the base being connected to the supporting structure by the support foot 14, the holding arms constitute a path for transmitting forces between the masts and the supporting structure.

There FIG. 4 represents in perspective the first embodiment of the base according to the invention. In this figure, only the base 100 is represented (i.e. the masts, the pumps, the support foot are not illustrated).

The anchoring device 110 comprises, for each pump, at least one collar portion 113 fixed to an upper part of said pump and a skirt 114 extending along an enveloping surface 115 from the at least one collar portion to at least a first height h1 of said pump (height shown in the FIG. 3 ).

As illustrated in the FIG. 3 , the collar portion 113 is attached to the mounting tabs 31 of the pump. In the first embodiment shown in Figures 3 and 4, the skirt 114 extends vertically from the collar portion towards the lower part of the pump. As will be described later, in addition to contributing to the mechanical strength of the base, the skirt serves as a support for the vertical guide device.

The base comprises a fixing zone 118 extending along a second horizontal plane P2, distinct from the first horizontal plane P1, connecting the skirts of the three pumps in pairs. Advantageously, the second horizontal plane P2 is parallel to the first horizontal plane P1. The fixing zone 118 defines the lower part of the base and, with the upper part of the base, ensures good mechanical strength of the base in the constrained environment of liquefied gas transport.

Advantageously, the base 100 further comprises at least one structural connection 119 between the fixing zone 118 and the anchoring device 110. Although not shown, one or more other structural connections 119 may connect the fixing zone 118 and the anchoring device 110, for example at the opening present in the central part of the base. The structural connection 119 acts as a stiffener for the base between the upper part and the lower part in order to allow better distribution of the forces applied at the first horizontal plane.

There FIG. 5 represents the guide elements of the pump of the first embodiment of the base according to the invention.

In this embodiment, each pump comprises at least a first guide element 116 arranged at the first height h1 of said pump. The vertical guide device comprises, for each pump, a second guide element 117 fixed to the skirt 114 and of complementary shape to the first guide element 116. The second guide element is movable in translation vertically relative to the first guide element.

More specifically, in this embodiment, the first guide element 116 has two L-shaped ends 126. The second guide element 117 comprises two wings 127 parallel to each other and spaced apart by the width of the first guide element 116 between its two ends 126. The double L-shape formed by the two wings 127 cooperates with the ends 126 of the guide element 116. This complementarity of shape ensures a degree of freedom in vertical translation and blocks any horizontal translation movement.

Advantageously, each skirt 114 comprises at least one lateral opening 140 opposite the first guide element 116 and the second guide element 117 is fixed at its ends on either side of the lateral opening 140. The opening 140 makes it easier to position and fix the second guide element 117.

There FIG. 6 represents a guide element 117 of the FIG. 5 in another view. In position, the internal surfaces 128 are the surfaces of shapes complementary to the first guide element 116. These internal surfaces can be provided with pads 129. The pads make it possible to ensure contact and relative movement between the first and second guide elements 116, 117. The pads 129 can be made of HDPE (abbreviation of “high density polyethylene”).

There FIG. 7 is a detailed bottom view of the unloading tower illustrating the guidance of the loading/unloading tower on the support leg.

Traditionally, the tank has a support foot 14 which is fixed to the supporting structure in an area of a bottom wall of the tank. The support foot is arranged to provide vertical translational guidance of the loading/unloading tower. The support foot 14 has a circular cross-sectional shape of revolution, with a frustoconical lower part 54 which connects at its smaller diameter end to a cylindrical upper part. The larger diameter base of the frustoconical part bears against the bottom wall of the supporting structure. Typically, the frustoconical lower part 54 extends through the thickness of the bottom wall of the tank beyond the level of the primary sealing membrane. The cylindrical upper part is sealed by a circular plate. The primary and secondary sealing membranes are sealed to the frustoconical lower part 54.

The loading/unloading tower 5 comprises a guide device which is fixed against the lower face of the base 100 and which cooperates with the support foot 14 which is fixed to the bottom wall of the supporting structure. Such a guide device aims to allow the relative movements of the loading/unloading tower 5 with respect to the support foot 14 in the height direction of the tank in order to allow the loading/unloading tower 5 to contract or expand depending on the temperatures to which it is subjected while preventing horizontal movements of the base 100 of the loading/unloading tower 5 by means of guide elements 57, 59.

The base according to the invention is thus provided with an upper part (anchoring device) essentially in the plane P1 and a lower part (guiding device) essentially in the plane P2, connected to each other by the skirts and any structural connections. The upper part ensures the anchoring of the pumps and the connection with the masts while the lower part ensures the guidance of the pumps and the masts. This two-level structure allows the arrangement of three pumps in a tank and meets the mechanical strength criteria required to withstand the forces applied to the loading/unloading tower and its equipment.

There FIG. 8 represents in perspective a second embodiment of the base according to the invention. The base 200 comprises the same elements as the base 100, namely an anchoring device 120 fixed to the three pumps 21, 22, 23 extending between two adjacent pumps along a first horizontal plane P1, a vertical guiding device 121 of each pump relative to the base 200, and for each mast, a first holding arm 122 extending from the anchoring device 120 towards said mast along a first axis Z1 intersecting the first horizontal plane P1.

In this embodiment, for each of the pumps, the collar takes the form of a semicircle and surrounds the pump between its two fixing lugs 31 diametrically opposed relative to the pump body. The skirt 124 descends along the pump, at a distance, according to the enveloping surface 125. The collar 123 and the skirt 124 form a half-shell for the pump. The three half-shells connect the anchoring device extending along the horizontal plane P1 and the fixing zone extending along the plane P2, ensuring the rigidity of the base. Optionally, the base may include struts (not shown in the figure). FIG. 8 ) between the fixing zone 128 and the anchoring device 120 to reinforce the structure of the base and allow the transmission of forces from the upper part to the lower part of the base. Also optionally, the base may comprise struts (not shown) between the fixing zone and the skirts, in order to reinforce the structure of the base and allow the transmission of forces from the upper part to the lower part of the base.

In the second embodiment, the anchoring device 120 is perforated in the first horizontal plane P1. Unlike the anchoring device 110 which extends in a continuity of material in the plane P1 between the collars, the anchoring device 120 comprises at least three main struts extending in the plane P1 and connecting the collars 123 in pairs. Advantageously and as shown in the FIG. 8 , the anchoring device 120 may comprise per pump at least one additional strut extending in the plane P1 between two main struts to reinforce the structure of the anchoring device. Compared to the anchoring device 110, the anchoring device 120 thus comprises less material, resulting in a gain in terms of mass embarked in the ship.

There FIG. 9 represents the guide elements of the pump of the second embodiment of the base according to the invention.

The first guide element 136 comprises a collar 150 fixed around said pump at the first height h1. The collar 150 has at least one protuberance 151 extending radially towards the skirt 124 and a pin 152 arranged on the protuberance 151 and extending vertically. The second guide element 137 comprises two portions 153, 154 connected to each other and having a channel 155 in which the pin 152 is arranged. The channel 155 has a shape complementary to the pin 152. The portion 153 is fixed to the skirt. The two portions 153, 154 may be made of HDPE. These two portions may be fixed to each other by affixing and tightening a plate 158 against the portion 154 and a screw-nut assembly 156, 157 as shown in the FIG. 9 . Thus, the pin 152, fixed to the pump, is free to translate in the channel 155 of the second guide element 137 fixed to the base to allow relative vertical movement between the pump and the base as a function of thermal contraction.

It may be noted that the first and second guide elements 116, 117 have been described in connection with the first embodiment, and the first and second guide elements 136, 137 have been described in connection with the second embodiment. However, it does not go beyond the scope of the invention if the guide elements 116, 117 are applied to the second embodiment and the guide elements 136, 137 are applied to the first embodiment, which the person skilled in the art would be able to adapt upon reading the description of this invention.

There FIG. 10 represents in perspective a third embodiment of the base according to the invention. The base 300 comprises the same elements as the base 200, namely an anchoring device 130 fixed to the three pumps 21, 22, 23 extending between two adjacent pumps along a first horizontal plane P1, a vertical guiding device 131 of each pump relative to the base 300, and for each mast, a first holding arm 132 extending from the anchoring device 130 towards said mast along a first axis Z1 intersecting the first horizontal plane P1.

In this embodiment, for each of the pumps, the collar 133 takes the form of a circle and surrounds the pump between its three fixing lugs 31. The skirt 134 descends along the pump, at a distance, according to the enveloping surface 135. The collar 133 and the skirt 134 form a shell portion for the pump. The three shell portions connect the anchoring device extending along the horizontal plane P1 and the fixing zone extending along the plane P2, ensuring the rigidity of the base. In the case where one (or two) pumps is omitted, the base remains identical, the collar 133 and the skirt 134 form a shell portion without a pump inside it. Obviously, in such a case, there is no flange in the lower part of the mast nor fixing lugs. Optionally, the base can include struts (not shown in the figure). FIG. 10 ) between the fixing zone 138 and the anchoring device 130 to reinforce the structure of the base and allow the transmission of forces from the top to the bottom of the base. Also optionally, the base may include struts (not shown) between the fixing zone and the skirts, in order to reinforce the structure of the base and allow the transmission of forces from the upper part to the lower part of the base.

In the third embodiment, and similarly to the second embodiment, the anchoring device 130 is perforated in the first horizontal plane P1. Compared to the anchoring device 110, the anchoring device 130 thus comprises less material, resulting in a gain in terms of mass on board the ship.

For each of the embodiments of the invention, the skirt may comprise a plurality of stiffeners 160 extending, from the wrapping surface of said skirt, preferably in a vertical direction and/or a horizontal direction. These stiffeners reinforce the skirt.

In addition, the base may comprise, for each mast, a second holding arm 212; 222; 232 extending from the anchoring device towards said mast along a second axis Z2 intersecting the first horizontal plane P1 and distinct from the first axis Z1. A second holding arm per mast ensures better distribution of forces between the masts and the base.

As illustrated on the FIG. 4 , each holding arm may terminate in two hoops 165 encompassing the mast with which it is associated to ensure the mast is held. Alternatively, each holding arm may terminate in a single hoop 165. Alternatively, each holding arm may terminate in a holding cylinder intended to receive a portion of the mast.

In the case where the base comprises, for each mast, two support arms, the hoop(s), or the support cylinder, are connected to the two support arms.

Similarly, the base may also include transverse stiffeners 166 extending in a horizontal plane with the two support arms associated with a mast. These transverse stiffeners 166 provide additional rigidity to the base at the support arms.

There FIG. 11 is a cutaway schematic representation of a ship tank 70 according to the invention and of a loading/unloading terminal for this tank. The cutaway view of the ship 70 shows a sealed and insulated 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 liquefied gas contained in the tank, a secondary sealing membrane arranged between the primary sealing membrane and the double hull 72 of the ship, and two 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.

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

There FIG. 11 represents an example of a maritime terminal comprising a loading and/or unloading station 75, an underwater pipeline 76 and an onshore installation 77. The loading and/or 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 pipes 73. The orientable mobile arm 74 adapts to all vessel sizes. A connecting pipe, not shown, extends inside the tower 78. The loading and unloading station 75 allows the loading and unloading of the ship 70 from or to the shore installation 77. The latter comprises liquefied gas storage tanks 80 and connecting pipes 81 connected by the subsea pipe 76 to the loading or unloading station 75. The subsea pipe 76 allows the transfer of the liquefied gas between the loading or unloading station 75 and the shore installation 77 over a long distance, for example 5 km, which makes it possible to keep the ship 70 at a great distance from the coast during the loading and unloading operations.

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.

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

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

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

It will more generally appear to those skilled in the art that various modifications can be made to the embodiments described above, in light of the teaching just disclosed to them. In the following claims, the terms used should not be interpreted as limiting the claims to the embodiments set forth in the present description, but should be interpreted to include all equivalents that the claims are intended to cover by their wording and the prediction of which is within the reach of those skilled in the art based on their general knowledge.

Claims (12)

Tank for storing and/or transporting a fluid intended for a ship, the tank comprising:

• a loading/unloading tower (5) comprising M masts (11, 12, 13) each extending along a vertical axis, M being an integer between 2 and 4;
• a support foot (14) fixed to a bottom wall of the tank;
• N unloading pumps (21, 22, 23), N being an integer between 1 and 4 and less than or equal to M;
• a base (100, 200, 300) located at a lower end of the loading/unloading tower (5), connected to the support leg (14);

the tank being characterized in that each of the N unloading pumps (21, 22, 23) is arranged at the lower end of the loading/unloading tower (5), in line with a mast (11, 12, 13) and fluidly connected to said mast,
and in that the base (100; 200; 300) comprises:

• an anchoring device (110; 120; 130) fixed to the N unloading pumps (21, 22, 23) extending along a first horizontal plane (P1);
• a vertical guide device (111; 121; 131) for each pump relative to the base (100; 200; 300);
• for each mast: a first holding arm (112; 122; 132) extending from the anchoring device (110; 120; 130) towards said mast along a first axis (Z1) intersecting the first horizontal plane (P1).

Tank according to claim 1, in which the anchoring device (110; 120; 130) comprises, for each pump, at least one collar portion (113; 123; 133) fixed to an upper part of said pump and a skirt (114; 124; 134) extending along an enveloping surface (115; 125; 135) from the at least one collar portion to at least a first height (h1) of said pump. Tank according to claim 2, each pump comprising at least a first guide element (116; 136) arranged at the first height (h1) of said pump, in which the vertical guide device comprises, for each pump, a second guide element (117; 137) fixed to the skirt and of complementary shape to the first guide element, the second guide element being movable in translation vertically relative to the first guide element. Tank according to claim 2 or 3, in which the base comprises a fixing zone (118; 128; 138) extending along a second horizontal plane (P2), distinct from the first horizontal plane (P1), connecting two by two the skirts of the three pumps. Tank according to claim 4, in which the second horizontal plane (P2) is parallel to the first horizontal plane (P1). A tank according to claim 4 or 5, wherein the base (100; 200; 300) further comprises at least one structural connection (119; 129; 139) between the attachment zone (118; 128; 138) and the anchoring device (110; 120; 130). Tank according to any one of claims 2 to 5 in combination with claim 3, in which each skirt (114) comprises at least one lateral opening (140) opposite the at least one first guide element (116) and the second guide element (117) is fixed on either side of the at least one lateral opening (140). Tank according to any one of claims 2 to 5 in combination with claim 3, wherein the at least one first guide element (136) comprises a collar (150) fixed around said pump at the first height (h1), said collar (150) having at least one protuberance (151) extending radially towards the skirt (124) and a pin (152) arranged on the at least one protuberance (151) and extending vertically, and the second guide element (137) comprises two portions (153, 154) connected to each other and having a channel (155) in which the pin (152) is arranged. Tank according to any one of claims 2 to 8, in which at least one skirt (114; 124; 134) comprises a plurality of stiffeners (160) extending, from the enveloping surface of said skirt, preferably in a vertical direction and/or a horizontal direction. Tank according to any one of claims 1 to 9, in which the anchoring device (120; 130) is perforated in the first horizontal plane (P1). Tank according to any one of claims 1 to 10, in which the base comprises, for each mast, a second holding arm (212; 222; 232) extending from the anchoring device towards said mast along a second axis (Z2) intersecting the first horizontal plane (P1) and distinct from the first axis (Z1). Vessel comprising a hull forming a supporting structure and at least one tank according to any one of claims 1 to 11 anchored on said supporting structure.