WO2023118320A1 - Vessel comprising a superstructure and a tank for the storage of liquefied gas to the rear of the superstructure - Google Patents

Abstract

The invention relates to a vessel comprising a superstructure and a sealed and thermally insulating tank (2), the tank being situated to the rear of the superstructure in the longitudinal direction. The tank comprises a bottom wall (22), two longitudinal walls (24), and two chamfered lower walls (25) each connecting the bottom wall to a longitudinal wall. One of the chamfered lower walls meets the bottom wall at a lower edge (32) and meets the adjacent longitudinal wall at an intermediate edge (33). A distance (B), parallel to the transverse direction (Z' - Z), between the median line (31) of the bottom wall and the intermediate edge, and a distance (C1), parallel to the transverse direction, between the lower edge and the intermediate edge, satisfy the inequality C1>= 0.45 B. Particular application to vessels for transporting a bulk solid product.

Description

Ship comprising a cask and a tank for the storage of liquefied gas behind the cask

The invention relates to the field of ships comprising a cask and a watertight and thermally insulating tank for the storage of a low-temperature liquefied combustible gas located at the rear of the cask. The tank is intended to receive liquefied combustible gas serving as fuel for the propulsion of the ship.

In one embodiment, the liquefied combustible gas is liquefied natural gas (LNG), namely a high methane content mixture stored at a temperature of approximately -162°C at atmospheric pressure. Other liquefied combustible gases can also be considered, including ethane, propane, butane, liquefied petroleum gas (LPG), ethylene, ammonia or methanol.

It has already been proposed, in the documents CN 110789663 B, KR 10-2015-0082929 A or CN 108502102 A, ships in which a sealed and thermally insulating tank for the storage of LNG is located aft of the castle of the ship. This makes it possible to propel the ship mainly or even entirely using LNG, instead of the fuel oil usually used in the maritime sector, which has certain advantages, in particular by limiting certain discharges of atmospheric pollutants; and this without positioning the tank in a location that would otherwise have been used for the transport of the ship's cargo or payload.

However, the vessel's movements at sea, for example under the effect of climatic conditions such as the state of the sea or the wind, cause the liquid in the tank to agitate. Liquid agitation, commonly referred to as sloshing, creates stresses on the vessel walls which can adversely affect the integrity of the vessel. However, the integrity of the tank is particularly important in the context of an LNG tank due to the flammable or explosive nature of the liquid transported and the risk of cold spots on the steel hull of the ship.

On the other hand, in the context of a ship as proposed by the aforementioned documents, the risk of damage to the tank due to sloshing is increased due to two distinct factors.

First, since the LNG contained in the tank is gradually consumed during the vessel's voyage, the tank is neither completely full nor completely empty for a significant part of the voyage. However, it is known that the risk of damage due to sloshing is greater with a tank which is neither completely full nor completely empty, since in an empty tank, the residual liquid contained in the tank has a limited weight and does not generate only weak stresses on the tank walls, whereas in a full tank, the residual space not occupied by the liquid in the tank is limited, which accordingly limits the freedom of movement of the liquid in the tank and therefore the force of the impacts on the vessel walls.

Secondly, the arrangement of the tank aft of the castle, which itself is located at the rear of the ship, causes the tank to be located very far from the metacenter of the ship, which exacerbates the movements of the liquid in the tank and therefore the corresponding risk of damage to the tank due to sloshing.

Certain aspects of the invention start from the observation that if it is desirable to place the tank behind the cask, it is important to ensure that this positioning of the tank does not increase the risk of damage to the tank due to the sloshing.

One idea at the basis of the invention thus consists in proposing a ship of the aforementioned type in which the tank is able to resist damage due to sloshing despite its positioning behind the castle.

The invention thus proposes a vessel comprising:
- A hull extending in a longitudinal direction of the ship, the hull comprising a bottom and an upper deck spaced from the bottom in a vertical direction of the ship;
- a castle located in the last rear quarter of the ship in the longitudinal direction and extending above the upper deck in the vertical direction;
- a sealed and thermally insulating tank for the storage of a liquefied combustible gas, the tank being located behind the cask in the longitudinal direction,
the vessel having vessel walls including: a bottom wall; a ceiling wall spaced from the bottom wall; two longitudinal walls; two upper chamfer walls each connecting the ceiling wall to a longitudinal wall; and two lower chamfer walls each connecting the bottom wall to a longitudinal wall,
the two longitudinal walls being parallel and spaced from each other in a transverse direction of the ship, the transverse direction being perpendicular to the longitudinal direction and to the vertical direction of the ship, and the bottom wall having a center line s' extending parallel to the longitudinal direction of the vessel,
one of the lower chamfer walls joining the bottom wall at a lower edge, and joining the adjacent longitudinal wall at an intermediate edge,
in which a distance B, parallel to the transverse direction, between the center line of the bottom wall and the intermediate edge, and a distance C1, parallel to the transverse direction, between the lower edge and the intermediate edge, satisfy the inequality C1 ≥ 0.45⋅B.

It is specified that the expressions "last quarter aft" and "behind the castle" are understood in relation to the normal direction of advance of the vessel in the longitudinal direction. Similarly, the expression "ahead of" is understood in relation to this direction of advance of the vessel.

It has been observed by the applicant that with such a dimensioning of the tank, there is a tendency to limit the risk of damage to the tank due to sloshing. The tank is thus able to resist damage due to sloshing despite its positioning behind the castle.

According to embodiments, such a ship may have one or more of the following characteristics.

According to one embodiment, the distance B and the distance C1 satisfy the inequality 0.50⋅B ≥ C1 ≥ 0.45⋅B. Such sizing tends to facilitate the installation of scaffolding in the tank during the construction of the tank.

According to another embodiment, the distance B and the distance C1 satisfy the inequality C1 ≥ 0.60⋅B. It has been observed by the applicant that with such a dimensioning of the tank, the risk of damage to the tank due to sloshing is very appreciably limited. The tank is thus even better able to resist damage due to sloshing despite its positioning behind the castle.

In addition, since the bottom chamfer wall of the tank is relatively large compared to the bottom wall, a relatively large free space can be created in the hull under the bottom chamfer wall, which can accommodate other equipment of the vessel.

According to one embodiment, the two lower chamfer walls are symmetrical with respect to a plane of symmetry extending parallel to the vertical direction and including the center line of the bottom wall.

According to one embodiment, the tank is symmetrical with respect to a plane of symmetry extending parallel to the vertical direction and including the center line of the bottom wall.

According to one embodiment, the plane of symmetry coincides with a median plane of the hull, the median plane extending parallel to the longitudinal direction of the ship.

Thus, the tank is not only symmetrical with respect to the plane of symmetry, but also centered with respect to the hull of the ship, which tends to limit sloshing.

According to one embodiment, the ceiling wall of the tank has a surface greater than the surface of the bottom wall of the tank.

According to one embodiment, the lower chamfer wall joins the bottom wall at the level of the lower edge so as to form an angle equal to 45° with the bottom wall.

In this way, it is possible to make the tank walls, or at least the bottom wall and the bottom bevel wall, according to constructions known for membrane tanks which allow the realization of 45° angles. In addition, the angle equal to 45° makes it possible to clear a large free space in the shell under the lower chamfer wall. However, other values are possible for the angle.

According to one embodiment, one of the upper chamfer walls joins the ceiling wall at an upper edge so as to form an angle equal to 45° with the ceiling wall, and joins the adjacent longitudinal wall at the level of a second intermediate edge.

According to one embodiment, a distance H, parallel to the vertical direction of the ship, between the lower edge and the upper edge, and a distance C3, parallel to the vertical direction of the ship, between the second intermediate edge and the upper edge, satisfy the inequality C3 ≥ 0.17⋅H.

According to one embodiment, the distance C1 is strictly greater than the distance C3. According to another embodiment, the distance C1 is equal to the distance C3.

According to one embodiment, the vessel walls further include two parallel transverse walls spaced apart along the longitudinal direction of the ship.

According to one embodiment, each of the vessel walls comprises a multilayer structure comprising, from the exterior towards the interior of the vessel, a secondary thermally insulating barrier, a secondary sealing membrane located against the secondary thermally insulating barrier, a primary thermally insulating barrier located against the secondary sealing membrane and a primary sealing membrane located against the primary thermally insulating barrier and intended to be in contact with the liquefied gas.

According to one embodiment, the vessel further comprises a plurality of intermediate decks located between the bottom and the upper deck of the hull and including a first intermediate deck, and the tank extends, in the vertical direction, from the first deck intermediate to above the upper deck.

In this way, it is possible to vary the filling capacity of the tank, simply by modifying the height of the part of the tank which extends above the upper deck, without appreciably modifying the rest of the configuration of the vessel. . This makes it possible to adapt the ship's liquefied fuel gas carrying capacity according to the ship's needs.

According to one embodiment, the intermediate bridges further include a second intermediate bridge located above the first intermediate bridge in the vertical direction, and the intermediate edge is located, in the vertical direction, between the second intermediate bridge and the bridge superior.

According to one embodiment, the vessel further comprises a plurality of cofferdam walls surrounding the tank, and each of the tank walls is fixed to a facing cofferdam wall.

The cofferdam walls constitute a structural assembly fixed to the hull of the ship and which entirely surrounds the tank, which ensures satisfactory structural anchoring of the tank on the hull, protects the tank from external elements despite its positioning partly above the upper deck, and protects the hull against possible contact with the liquefied combustible gas in the event of an accidental leak from the tank.

According to one embodiment, the cofferdam walls include: two longitudinal cofferdam walls, each of the two longitudinal walls of the vessel being attached to a longitudinal cofferdam wall; and two cofferdam chamfer walls, each of the two bottom chamfer walls of the vessel being fixed to a cofferdam chamfer wall, and one of the cofferdam chamfer walls joining a longitudinal cofferdam wall at an edge cofferdam middleman; and the intermediate ridge is above the intermediate cofferdam ridge in the vertical direction of the ship.

According to one embodiment, the cofferdam walls further include two transverse cofferdam walls, each of the two transverse walls of the vessel being attached to a transverse cofferdam wall.

According to one embodiment, the tank comprises a pump configured to evacuate liquefied combustible gas from an interior volume of the tank.

According to one embodiment, the bottom wall comprises a sump, and the pump comprises a pump head placed in the sump.

Such a configuration makes it possible to significantly reduce the volume of liquefied combustible gas which cannot be pumped by the pump.

According to one embodiment, the ship further comprises a gas evacuation mast comprising a mast body and a mast head, a first end of the mast body being fixed to the ship aft of the castle in the longitudinal direction of the ship and above the ceiling wall of the tank in the vertical direction of the ship, the masthead being arranged at a second end of the mast body and comprising an opening allowing the fuel gas contained in the tank to be evacuated, and the mast body being inclined so that the second end is farther from the castle, in the longitudinal direction of the ship, than the first end.

Such a configuration ensures that the opening for evacuating the combustible gas contained in the tank is located as far as possible from the castle. This helps to protect the ship's crew in the event of overpressure and/or serious damage to the tank.

According to one embodiment, the ship further comprises at least one liquefied combustible gas inlet installation configured to convey liquefied combustible gas to the tank, the liquefied combustible gas inlet installation being located on the upper deck in front of the castle in the longitudinal direction of the ship, and preferably located in a side region of the upper deck in the transverse direction of the ship.

According to one embodiment, the ceiling wall of the vessel is surmounted by a vessel connection space having a dome structure through which a liquefied fuel gas charging line passes through the ceiling wall of the vessel.

According to one embodiment, the ship further comprises a propulsion system, the tank being intended to supply the combustible gas to the propulsion system.

The ship can thus be propelled mainly by burning the liquefied fuel gas contained in the tank, which limits certain releases of atmospheric pollutants associated with the combustion of marine fuel oil; and this without positioning the tank in a location that would otherwise have been used for the transport of the ship's cargo or payload.

According to one embodiment, the vessel further comprises at least one gas management system disposed above the ceiling wall of the tank and configured to supply liquefied combustible gas contained in the tank to the propulsion system.

According to one embodiment, the propulsion system comprises a main engine and at least one auxiliary engine, the main engine being located in the hull forward of the tank in the longitudinal direction of the ship, the auxiliary engine being located in the hull more laterally than the main engine following the transverse direction of the vessel.

According to one embodiment, the main engine is arranged in a main engine room arranged on the first intermediate deck and the second intermediate deck in the extension of the plane of symmetry of the tank, and the auxiliary engine is arranged in an engine room auxiliary fitted on the second intermediate deck more laterally than the main engine room following the transverse direction of the ship.

According to one embodiment, the propulsion system comprises a combustion gas evacuation pipe connected both to the main engine and to the auxiliary engine and crossing the second intermediate deck between the tank and the castle in the longitudinal direction of the ship.

This limits the total length of piping required to evacuate the combustion gases from the main engine and the auxiliary engine.

According to one embodiment, the combustion gas evacuation pipe opens into a chimney arranged between the tank and the cask in the longitudinal direction of the ship.

According to one embodiment, the liquefied combustible gas is liquefied natural gas. According to another embodiment, the liquefied combustible gas is a liquefied combustible gas taken from the group formed by ethane, propane, butane, liquefied petroleum gas (LPG), ethylene, ammonia and methanol; in particular taken from the group formed by ethane, propane, butane, liquefied petroleum gas (LPG), and ethylene.

According to one embodiment, the ship comprises, in front of the cask in the longitudinal direction of the ship, at least one hold for transporting a solid product in bulk.

According to one embodiment, the ship has a loading opening passing through the upper deck and configured to allow loading of solid product in bulk from the hold.

According to one embodiment, the ship comprises, in front of the cask in the longitudinal direction of the ship, a plurality of spaced holds along the longitudinal direction of the ship, the plurality of chocks comprising a hold closest to the cask.

According to one embodiment, the liquefied fuel gas inlet installation is located on the upper deck forward of the cask and aft of the loading opening of the hold closest to the cask, in the longitudinal direction of the ship. .

In this way, the liquefied combustible gas inlet installation is located relatively close to the cask and behind all the loading openings of the holds, which respectively makes it possible to limit the length of the pipes conveying the liquefied combustible gas to the tank. , and to limit the risk of a load falling on the liquefied combustible gas inlet installation.

According to one embodiment, the invention also provides a transfer system for a liquefied fuel gas, the system comprising an aforementioned vessel, insulated pipes arranged so as to connect the tank of the vessel to a floating or terrestrial storage installation and a pump to drive a flow of liquefied fuel gas through the insulated pipelines from the floating or onshore storage facility to the ship's tank.

According to one embodiment, the invention also provides a method for loading an aforementioned ship, in which a liquefied fuel gas is routed through insulated pipes from a floating or onshore storage facility to the tank of the ship.

Brief description of figures

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 by way of illustration and not limitation. , with reference to the accompanying drawings.

There is a sectional view of the aft part of a ship comprising a sealed and thermally insulating tank for storing a liquefied fuel gas, the tank being located aft of the castle of the ship in the longitudinal direction of the ship.

There is a sectional view of the ship from the according to II-II.

There is a sectional view of the ship from the according to III-III.

There is a schematic cross-sectional view of one half of the vessel's tank of the , used to illustrate relevant quantities for the dimensioning of the tank.

There is a sectional view of the ship from the according to plan V.

There is a sectional view of the ship from the according to plan VI.

There is a sectional view of the ship from the according to plan VII.

There is a schematic representation of a ship comprising a watertight and thermally insulating tank for storing a liquefied fuel gas, the tank being located aft of the castle of the ship, and a loading terminal for this tank.

We will describe, with reference to Figures 1 to 8, a ship 1 comprising a sealed and thermally insulating tank for the storage of a liquefied combustible gas, the tank being located behind the castle of the ship 1.

There is a sectional view of the rear part of the vessel 1. The vessel 1 is here a bulk carrier, that is to say a vessel designed for the transport of solid products in bulk. Thus, in a manner known per se, the ship 1 comprises, in front of its castle 6 in a longitudinal direction X′-X of the ship 1, one or more chocks 9 for transporting a solid product in bulk. The wedges 9 are spaced apart along the longitudinal direction X′-X of the vessel 1 in a manner known per se. It is specified that only one of these wedges 9, namely the wedge 9 closest to the castle 6, is represented schematically on the . In a manner known per se, each hold 9 is accessible from a loading opening 99 passing through the upper deck 5 and allowing the solid product to be introduced in bulk into the hold 9.

However, it should be noted that the following description is applicable to other types of ship than bulk carriers, as long as these ships include a cask 6.

As just mentioned, the ship 1 comprises a cask 6, the construction of which is known as such and which is located in a last rear quarter of the ship 1 in the longitudinal direction X′-X of the ship 1. It is specified that the expressions "last quarter aft" and "behind castle 6" are understood in relation to the normal direction of advancement F of ship 1 in the longitudinal direction X'-X. Similarly, the expression "ahead of" is understood in relation to this direction of advance F of vessel 1.

In a manner known per se, the hull 3 of the ship 1 comprises a bottom 4, optionally double-walled, and an upper deck 5 spaced from the bottom 4 in a vertical direction Y′-Y of the ship 1, the castle 6 extending to the -above the upper deck 5 in the vertical direction Y'-Y. Still in a manner known per se, the castle 6 is a structure which houses various 6D bridges for the ship's crew, and comprises at its top a 6P gangway accommodating various equipment to allow the ship's crew 1 to pilot the ship 1 .

Vessel 1 has a sealed and thermally insulating tank 2, hereinafter referred to as "tank 2" for convenience. The tank 2 is designed to allow the storage of a liquefied combustible gas. In one embodiment, the liquefied fuel gas is liquefied natural gas (LNG). Other liquefied combustible gases can also be considered, including ethane, propane, butane, liquefied petroleum gas (LPG), ethylene, ammonia or methanol. The liquefied combustible gas contained in tank 2 is intended to supply a propulsion system 80 which will be described in more detail later.

We will now describe in more detail the construction of the tank 2 and its positioning in the ship 1.

Generally, as shown in the , there , and the , the tank 2 is located behind the castle 6 in the longitudinal direction X'-X.

Coming back to the , the ship 1 further comprises a first intermediate deck 11, a second intermediate deck 12 and a third intermediate deck 13. The intermediate decks 11, 12 and 13 extend between the bottom 4 and the upper deck 5 and are spaced along the Y'-Y vertical direction.

With reference to the , there and the , the tank 2 extends, in the vertical direction Y′-Y, from the second intermediate bridge 12 to above the upper bridge 5.

There and the are respectively sectional views of the vessel 1 according to plans II-II and III-III of the , and thus show the vessel 2 in section along a transverse direction Z'-Z of the vessel 1. It is specified that the transverse direction Z'-Z is perpendicular to the longitudinal direction X'-X and to the vertical direction Y'Y.

As can be seen on the and the , the vessel 2 has vessel walls including: a bottom wall 22; a ceiling wall 23; two longitudinal walls 24; two lower chamfer walls 25; and two upper chamfer walls 26. The aforementioned vessel walls, together with two transverse walls (not shown) extending parallel to the transverse direction Z′-Z, delimit an interior volume 21 of the vessel 2 in which the liquefied fuel gas.

Each of the aforementioned vessel walls comprises a multilayer structure comprising, from the exterior towards the interior of the vessel, a secondary thermally insulating barrier, a secondary sealing membrane located against the secondary thermally insulating barrier, a primary thermally insulating barrier located against the secondary sealing membrane and a primary sealing membrane located against the primary thermally insulating barrier and intended to be in contact with the liquefied combustible gas. By way of example, such membrane tanks are described in particular in documents WO 2019/239048 A1, WO 2014/057221 A1, FR 2 691 520 A1 and FR 2 877 638 A1. Membrane tanks can in particular correspond to the GTT Next1®, Mark V®, Mark III® and NO96® products developed by the applicant.

As can be seen on the , the ceiling wall 23 of the tank 2 is surmounted by a tank connection space ("Tank Connection Space" or TCS in English) 50. The tank connection space 50 comprises in particular a dome structure 29 through which a loading pipe (not shown) passes through the ceiling wall 23 in order to fill the tank 2 with liquefied combustible gas. This tank connection space 50 is a secure space where the pipes passing through the ceiling wall 23 are connected to the other equipment of the vessel 1.

We also see on the that one or more gas management systems ("Fuel Gas Handling System" or FGHS in English) 51 are arranged above the ceiling wall 23 of the tank 2. The gas management systems 51, in a known manner per se, are configured to supply liquefied fuel gas contained in the tank 2 to the propulsion system 80, by means of a set of pipes and valves not shown in the drawings.

Still with reference to the , the tank connection space 50 is surmounted by a gas vent mast 60 which will be described in more detail below.

In a manner known per se and not shown in the drawings, the interior volume 21 of the tank 2 is provided with at least one pump configured to drive liquefied fuel gas from the interior volume 21 of the tank to the propulsion system 80, via the dome structure 29. The pump is for example supported by a tripod mast known per se and arranged in the interior volume 21 of the tank.

In one embodiment, the bottom wall 22 of the tank 2 comprises a sump 65, and the pump comprises a pump head which is arranged in this sump 65. Such a configuration is advantageous because it makes it possible to significantly reduce the volume of liquefied combustible gas that cannot be pumped by the pump. Alternatively, as shown in , the tank 2 can comprise several pumps, and several separate sumps 65 can be provided on the bottom wall 22 to each receive a pump head of a corresponding pump.

The aforementioned vessel walls are surrounded by a set of cofferdam walls generally designated by the reference 40, and more particularly visible in FIGS. 2 and 3. Each of the vessel walls is fixed to a cofferdam wall facing the set of cofferdam walls 40.

More concretely, the set of cofferdam walls 40 includes:
- a bottom cofferdam wall 42, to which the bottom wall 22 of the tank 2 is fixed;
- an upper cofferdam wall 43, to which the ceiling wall 23 of the tank is fixed;
- two longitudinal cofferdam walls 44, each of the longitudinal walls 24 of the tank 2 being fixed to a longitudinal cofferdam wall 44;
- two walls of cofferdam chamfer 45, each of the lower walls of chamfer 25 of the tank 2 being fixed to a wall of cofferdam chamfer 45; And
- two transverse cofferdam walls (not shown) extending parallel to the transverse direction Z'-Z, each of the transverse walls (not shown) of the tank 2 being fixed to a transverse cofferdam wall.

As shown in Figures 2 and 3, each of the cofferdam chamfer walls 45 joins the adjacent longitudinal cofferdam wall 44 at an intermediate cofferdam edge 49.

It is well understood that the set of cofferdam walls 40 constitutes a structural assembly fixed to the hull 3 of the ship 1 and which completely surrounds the tank 2, which ensures satisfactory structural anchoring of the tank 2 on the hull 3, protects the tank 2 from the external elements despite its positioning partly above the upper deck 5, and protects the hull 3 against possible contact with the liquefied combustible gas in the event of an accidental leak from the tank 2.

The positioning of the tank 2 behind the cask 6 in the longitudinal direction X′-X, which itself is located at the rear of the ship 1, causes the tank 2 to be located very far from the metacentre (not shown) of the ship 1. This exacerbates the movements of the liquefied combustible gas contained in the tank 2 and therefore the corresponding risk of damage to the tank 2 due to sloshing. Described below, with particular reference to the , characteristics of the tank 2 which allow the tank 2 to resist damage due to sloshing despite its positioning behind the castle in the longitudinal direction X′-X.

It is possible to define a centerline 31 of the bottom wall 22 which runs parallel to the longitudinal direction X'-X of the ship 1. By "centerline" it is meant that the centerline 31 shares the bottom wall 22 into two half-walls which have equal surfaces. In the example shown, the center line 31 corresponds to a central height axis of the tank 2. The plane 31P perpendicular to the bottom wall 22 and including the center line 31 thus divides the interior volume 21 of the tank 2 into two portions that have equal volumes.

The central axis of height of the tank 2 can optionally pass through the dome structure 29 as shown in the and the .

With reference to the , to the and at the , a lower chamfer wall 25 joins the bottom wall 22 at a lower edge 32 so as to form an angle δ (cf. ) equal to 45°. In addition, this lower chamfer wall 25 joins the adjacent longitudinal wall 24 at an intermediate edge 33.

With reference to the and at the , the intermediate edge 33 may be located, in the vertical direction Y'-Y, between the intermediate bridge 13 and the upper bridge 5, and/or the intermediate edge 33 may be located, in the vertical direction Y'-Y , above the middle cofferdam ridge 49.

With reference to the , we define :
- A distance B, parallel to the transverse direction Z'-Z, between the center line 31 and the intermediate edge 33;
- A distance C1, parallel to the transverse direction Z'-Z, between the lower edge 32 and the intermediate edge 33; And
- a distance C2, parallel to the vertical direction Y'-Y, between the lower edge 32 and the intermediate edge 33.

It is understood that the distances C1, C2 and B together define the relative dimensions of the lower bevel wall 25 and of the bottom wall 22 of the tank 2. It is further understood that since the lower bevel wall 25 joins the wall of bottom 22 at the level of a lower edge 32 so as to form an angle δ equal to 45°, we have C1=C2.

Furthermore, the distances C1 and B are chosen such that the following inequality holds: C1 ≥ 0.60⋅B.

When the tank 2 is dimensioned in the way that has just been described, the lower chamfer wall 25 is relatively large compared to the bottom wall 22 and is inclined at 45° relative to the bottom wall 22. It has It has been observed by the applicant that this makes it possible to very appreciably limit the risk of damage to the tank 2 due to sloshing, in particular by limiting the risk that a surge of the liquefied combustible gas contained in the tank 2 reaches the upper chamfer wall 26, and more generally allowing the lower chamfer wall 25 to absorb most of the impacts of the liquefied combustible gas.

Alternatively, the distances C1 and B are chosen such that the following inequality holds: C1 ≥ 0.45⋅B, for example such that 0.50⋅B ≥ C1 ≥ 0.45⋅B. Such sizing tends to limit the risk of damage to vessel 2 due to sloshing, although to a lesser degree than when C1 ≥ 0.60⋅B. In addition, such a dimensioning tends to ensure that the bottom wall 22 has a sufficient surface for the installation of a scaffolding in the tank 2 during the construction of the tank 2, and therefore tends to facilitate the installation of a such scaffolding.

As shown in the drawings, the tank 2, or at the very least the lower chamfer walls 25, can be symmetrical with respect to the plane 31P.

It is specified that the plane 31P can be confused with a median plane (not referenced) of the hull 3, this median plane extending parallel to the longitudinal direction X′-X of the ship 1. Thus, the tank 2 is not only symmetrical relative to the plane 31P, but also centered relative to the hull 3 of the ship 1, which tends to limit sloshing.

It is further specified that the angle δ formed by the lower bevel wall 25 and the bottom wall 22 at the level of the lower edge 32 may have a value different from 45°. For example, this value can be equal to approximately 135° or any other value that can be achieved in the context of a membrane tank.

With reference again to the , to the and at the , an upper chamfer wall 26 joins the ceiling wall 23 at an upper edge 35 so as to form an angle ζ (cf. ) equal to 45°. In addition, this upper chamfer wall 26 joins the adjacent longitudinal wall 24 at an intermediate edge 34.

With reference again to the , we define :
- a distance H, parallel to the vertical direction Y'-Y, between the lower edge 32 and the upper edge 35;
- A distance C3, parallel to the vertical direction Y'-Y, between the intermediate edge 34 and the upper edge 35; And
- a distance C4, parallel to the transverse direction Z'-Z, between the intermediate edge 34 and the upper edge 35.

It is understood that the distances C3, C4 and H together define the relative dimensions of the upper chamfer wall 26 and of the ceiling wall 23 of the tank 2. It is further understood that since the upper chamfer wall 26 joins the wall of ceiling 23 at an upper edge 35 so as to form an angle ζ equal to 45°, we have C3=C4.

Furthermore, the distances C3 and H are chosen such that the following inequality holds: C3 ≥ 0.17⋅H.

Furthermore, in certain embodiments, the distance C1 is strictly greater than the distance C3, and/or the ceiling wall 23 of the tank 2 has a surface which is greater than the surface of the bottom wall 22 of the tank. 2.

In other embodiments, the distance C1 is equal to the distance C3, or even C1=C2=C3=C4.

The positioning of the tank 2 which has been described above with reference to the drawings is only an example. Various other positions of the tank 2 are possible, as long as the tank 2 is located behind the castle 6 in the longitudinal direction X'-X.

As mentioned above, the tank connection space 50 is surmounted by a gas vent mast 60. In a manner known per se and as described for example in the document WO 2019/097131 A1, the mast 60 comprises a mast body 60C, and a mast head (not shown) disposed at one end 62 of the mast body 60C and comprising an opening 63 allowing the combustible gas contained in bowl 2.

Still in a manner known per se, the gas evacuation mast 60 is provided to allow the combustible gas contained in the tank 2 to be evacuated in the event of overpressure and/or serious damage to the tank 2, in order to avoid catastrophic rupture and/or explosion of the tank 2.

The end 61 of the mast body 60C which is opposite the end 62 is fixed to the ship 1 above the ceiling wall 23 of the tank 2 and behind the castle 6. For example, as shown in the figures 1 and 3, the end 61 is fixed above the tank connection space 50.

With reference to the , provision is made for the mast body 60C to be inclined so that the end 62 is farther from the castle 6, in the longitudinal direction X′-X, than the end 61. In this way, the opening 63 allowing to evacuate the combustible gas contained in the tank 2 is located as far as possible from the castle 6 and therefore from the bridges 6D and the footbridge 6P. This contributes to protecting the crew of the ship 1 in the event of overpressure and/or serious damage to the tank 2. In addition, it is understood that if the overpressure and/or serious damage to the tank 2 occurs while the ship 1 advances in the direction of advancement F, the relative wind due to the inertia of the ship 1 will tend to push the combustible gas even further from the castle 6, which further contributes to protecting the crew.

As mentioned above, the liquefied combustible gas contained in the tank 2 is intended to supply a propulsion system 80. The propulsion system 80 and its positioning in the ship 1 will now be described, with more particular reference to the and at the .

The propulsion system 80 includes a main engine 81. The main engine 81 drives a propulsion propeller 7 via a corresponding drive shaft 7A (cf. ). The main engine 81 can be of any known type, as long as it is capable of consuming liquefied combustible gas coming from the tank 2. In certain variants not shown, several main engines 81 can be provided.

The propulsion system 80 further comprises three auxiliary motors 82 (cf. ). The auxiliary motors 82 are, for example, electric generators used to power various electrical equipment of the ship 1 and/or turboelectric propulsion motors of the ship 1. The auxiliary motors 82 can be of any known type, as long as they are capable of consume liquefied fuel gas from tank 2. Alternatively, a different number of auxiliary motors 82 may be provided.

With reference to the , the main engine 81 is arranged in the hull 3 in front of the tank 2 in the longitudinal direction X′-X. For example, a central axis of the main motor 81 can be aligned with the plane 31P of the tank 2 described above. On the other hand, the auxiliary engines 82 are arranged in the hull 3 more laterally than the main engine 81 in the transverse direction Z'-Z. For example, the main engine 81 can be arranged in a main engine room 121 arranged on the intermediate decks 11 and 12 in the extension of the plane 31P of the tank 2, while the auxiliary engines 82 are arranged in an auxiliary engine room 122 arranged on the intermediate deck 12 more laterally than the main engine room 121 in the transverse direction Z'-Z.

The arrangement of the main engine 81 and the auxiliary engines 82 which has just been described makes it possible to provide that the evacuation of the combustion gases leaving the main engine 81 and the auxiliary engines 82 is done by a single gas evacuation pipe. combustion 88 (cf. ), which limits the total length of piping required to evacuate the combustion gases. With reference to the , the pipe 88 crosses the intermediate bridge 13 between the tank 2 and the cask 6 in the longitudinal direction X′-X. With reference to the , there and the , the pipe 88 opens into a chimney 8 which is arranged between the tank 2 and the castle 6 in the longitudinal direction X′-X.

With reference again to the , there may be provided a tank 89 intended to contain marine fuel ("Marine Diesel Oil" in English) laterally relative to the main engine room 121 and on the side opposite the auxiliary engine room 122 in the transverse direction Z'- Z.

With reference to the and at the , for the arrival of the liquefied combustible gas in the tank 2, the ship 1 is provided with at least one installation for the arrival of liquefied combustible gas (also known as the “bunker station” in French; “bunker station in English) 90, known as such. In the example shown, two installations 90 are provided, one on each side of the ship 1 in the transverse direction Z'-Z, more precisely in a side region of the upper deck 5 in the transverse direction Z'-Z.

The installations 90 are located on the upper deck 5 forward of the castle 6 in the longitudinal direction X′-X. More specifically, in the example shown, the installations 90 are located on the upper deck 5 forward of the castle 6 and aft of the opening 99 closest to the castle 6 in the longitudinal direction X′-X. It is understood that in this way, the length of the pipes 99C conveying the liquefied fuel gas to the tank 2 is limited; and the risk of a load falling on 90 installations is limited.

With reference to the , there is shown a ship 1 of the type described above comprising a watertight and thermally insulating tank 2 mounted in the hull 3 of the ship 1 behind the castle 6 of the ship 1. In a manner known per se, the ship's loading pipes can be connected , by means of appropriate connectors, to a maritime or port terminal to transfer an LNG cargo to tank 2.

There represents an example of a maritime terminal comprising a loading and unloading station 75, an underwater pipeline 76 and an installation on land 77. The loading and unloading station 75 is a fixed offshore installation comprising a mobile arm 74 and a tower 78 which supports the movable arm 74. The movable arm 74 carries a bundle of insulated flexible pipes 79 which can be connected to the ship's loading pipeline. The adjustable mobile arm 74 adapts to all vessel sizes. A connecting pipe, not shown, extends inside the tower 78. The loading station 75 allows the loading of the ship 1 with LNG fuel from or to the shore installation 77. This comprises storage tanks of liquefied gas 80 and connecting pipes 81 connected by the underwater pipe 76 to the loading station 75. The underwater pipe 76 allows the transfer of the liquefied gas between the loading station 75 and the shore installation 77 on a great distance, for example 5 km, which makes it possible to keep the ship 1 at a great distance from the coast during the loading operations.

To generate the pressure necessary for the transfer of the liquefied gas, pumps on board the ship 1 and/or pumps fitted to the shore installation 77 and/or pumps fitted to the loading 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 the 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 "comport", "understand" or "include" and its conjugated forms does not exclude the presence of other elements or other steps than those set out in a claim.

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

Claims (19)

1. Vessel (1) comprising:
   - a hull (3) extending in a longitudinal direction (X'-X) of the ship (1), the hull (3) comprising a bottom (4) and an upper deck (5) spaced from the bottom (4) along a vertical direction (Y'-Y) of the ship (1);
   - a castle (6) located in a last rear quarter of the ship (1) in the longitudinal direction (X'-X) and extending above the upper deck (5) in the vertical direction (Y'-Y) ;
   - a sealed and thermally insulating tank (2) for storing a liquefied combustible gas, the tank (2) being located behind the cask (6) in the longitudinal direction (X'-X),
   the vessel having vessel walls including: a bottom wall (22); a ceiling wall (23) spaced from the bottom wall (22); two longitudinal walls (24); two chamfer top walls (26) each connecting the ceiling wall (23) to a longitudinal wall (24); and two lower chamfer walls (25) each connecting the bottom wall (22) to a longitudinal wall (24),
   the two longitudinal walls (24) being parallel and spaced from each other in a transverse direction (Z'-Z) of the vessel (1), the transverse direction (Z'-Z) being perpendicular to the longitudinal direction ( X'-X) and the vertical direction (Y'-Y) of the vessel (1), and the bottom wall (22) having a center line (31) extending parallel to the longitudinal direction (X'-X ) of the vessel (1),
   one of the lower chamfer walls (25) joining the bottom wall (22) at a lower edge (32), and joining the adjacent longitudinal wall (24) at an intermediate edge (33),
   in which a distance B, parallel to the transverse direction (Z'-Z), between the center line (31) of the bottom wall (22) and the intermediate edge (33), and a distance C1, parallel to the transverse direction (Z'-Z), between the lower edge (32) and the intermediate edge (33), verify the inequality C1 ≥ 0.45⋅B.
2. Vessel (1) according to Claim 1, in which the distance B and the distance C1 satisfy the inequality C1 ≥ 0.60⋅B.
3. Vessel (1) according to any one of Claims 1 to 2, in which the tank (2) is symmetrical with respect to a plane of symmetry (31P) extending parallel to the vertical direction (Y'-Y) and including the center line (31) of the bottom wall (22).
4. Vessel (1) according to any one of claims 1 to 3, in which each of the tank walls comprises a multilayer structure comprising, from the outside towards the inside of the tank, a secondary thermally insulating barrier, a membrane of secondary sealing located against the secondary thermally insulating barrier, a primary thermally insulating barrier located against the secondary sealing membrane and a primary sealing membrane located against the primary thermally insulating barrier and intended to be in contact with the liquefied gas, and in wherein the lower chamfer wall (25) joins the bottom wall at the lower edge (32) so as to form an angle (δ) equal to 45° with the bottom wall (22).
5. Vessel (1) according to any one of claims 1 to 4, further comprising a plurality of intermediate decks located between the bottom (4) and the upper deck (5) of the hull (3) and including a first intermediate deck ( 12), and in which the tank (2) extends, in the vertical direction (Y'-Y), from the first intermediate bridge (12) to above the upper bridge (5).
6. Vessel (1) according to Claim 5, in which the intermediate decks further include a second intermediate deck (13) located above the first intermediate deck (12) in the vertical direction (Y'-Y), and in which the The intermediate edge (33) is located, in the vertical direction, between the second intermediate bridge (13) and the upper bridge (5).
7. Vessel (1) according to any one of claims 1 to 6, further comprising a plurality of cofferdam walls (40) surrounding the tank (2), and in which each of the tank walls is fixed to a cofferdam wall glance.
8. Vessel (1) according to claim 7, wherein the cofferdam walls include: two longitudinal cofferdam walls (44), each of the two longitudinal walls (24) of the tank (2) being fixed to a longitudinal cofferdam wall (44 ); and two cofferdam chamfer walls (45), each of the two lower cofferdam chamfer walls (25) of the tank (2) being attached to a cofferdam chamfer wall (45), and one of the cofferdam chamfer walls (45) joining a longitudinal cofferdam wall (44) at an intermediate cofferdam edge (49); and wherein the intermediate ridge (33) is above the intermediate cofferdam ridge (49) in the vertical direction (Y'-Y) of the vessel (1).
9. Vessel (1) according to any one of claims 1 to 8, in which the bottom wall (22) comprises a sump (65), the tank (2) comprises a pump configured to evacuate liquefied fuel gas from an interior volume (21) of the tank (2), and the pump comprises a pump head arranged in the sump (65).
10. Vessel (1) according to any one of claims 1 to 9, further comprising a gas venting mast (60) comprising a mast body (60C) and a mast head, a first end (61) of the body mast (60C) being fixed to the ship (1) behind the castle (6) in the longitudinal direction (X'-X) of the ship (1) and above the ceiling wall (23) of the next tank the vertical direction (Y'-Y) of the ship (1), the masthead being arranged at a second end (62) of the mast body (60C) and comprising an opening (63) allowing the combustible gas contained in it to be evacuated in the tank (2), and the mast body (60C) being inclined so that the second end (62) is farther from the castle (6), in the longitudinal direction (X'-X) of the ship (1 ), than the first end (61).
11. Vessel (1) according to any one of claims 1 to 10, further comprising at least one liquefied combustible gas inlet installation (90) configured to supply liquefied combustible gas to the tank (2), the installation the liquefied fuel gas inlet (90) being located on the upper deck (5) forward of the cask (6) in the longitudinal direction (X'-X) of the ship (1), and preferably located in a lateral region of the upper deck (5) in the transverse direction (Z'-Z) of the ship (1).
12. Vessel (1) according to any one of claims 1 to 11, further comprising a propulsion system (80), the tank (2) being intended to supply the fuel gas to the propulsion system (80).
13. Vessel (1) according to claim 12, in which the propulsion system (80) comprises a main engine (81) and at least one auxiliary engine (82), the main engine (81) being located in the hull (3) in forward of the tank (2) in the longitudinal direction (X'-X) of the vessel (1), the auxiliary engine (82) being located in the hull (3) more laterally than the main engine (81) in the transverse direction (Z'-Z) of the ship (1).
14. Vessel (1) according to Claim 13 taken in combination with Claim 6, in which the propulsion system (80) comprises a combustion gas evacuation conduit (88) connected both to the main engine (81) and to the auxiliary engine (82) and crossing the second intermediate bridge (13) between the tank (2) and the castle (6) in the longitudinal direction (X'-X) of the ship (1).
15. Vessel (1) according to Claim 14, in which the combustion gas evacuation pipe (88) opens into a chimney (8) arranged between the tank (2) and the castle (6) in the longitudinal direction (X' -X) of the vessel (1).
16. Vessel (1) according to any one of claims 1 to 15, in which the liquefied combustible gas is liquefied natural gas.
17. Ship (1) according to any one of claims 1 to 16, in which the ship (1) comprises, forward of the cask (6) in the longitudinal direction (X'-X) of the ship (1), at least one hold (9) for transporting a solid product in bulk.
18. Transfer system for a liquefied combustible gas, the system comprising a ship (1) according to one of Claims 1 to 17, insulated pipes (73, 79, 76, 81) arranged so as to connect the tank (2) of the vessel (1) to a floating or onshore storage facility (77) and a pump for driving a flow of liquefied combustible gas through the insulated pipes from the floating or onshore storage facility to the tank (2) of the vessel (1 ).
19. Method of loading a ship (1) according to one of Claims 1 to 17, in which a liquefied combustible gas is conveyed through insulated pipes (73, 79, 76, 81) from a floating or terrestrial storage installation (77) to the tank (2) of the ship (1).

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