FLUID TRANSFER SYSTEM, SWIVEL JOINT DEVICE INCLUDING SUCH A SYSTEM, STACK OF SWIVEL JOINT DEVICES AND FLUID EXPLOITATION INSTALLATION

Fluid transfer system (100) including a liquid transfer pipe (110) and a gas transfer pipe (120) that are concentric, the gas transfer pipe (120) surrounding the liquid transfer pipe (110), and a buffer member (130), disposed between the liquid transfer pipe (110) and the gas transfer pipe (120) and surrounding at least partially the liquid transfer pipe (110), the buffer member (130) being configured to transfer an evaporated portion of the liquefied gas circulating in the liquid transfer pipe (110) from the liquid transfer pipe (110) to the gas transfer pipe (120). Swivel joint device (1000) including such a system (100), stack (1010) of swivel joint devices, and fluid exploitation installation (1).

TECHNICAL FIELD OF THE INVENTION

The invention relates to a fluid exploitation installation.

It also relates to a fluid transfer system used in such an installation.

The invention applies in particular for a fluid having at least a liquid state or a gaseous state according to a temperature to which it is brought, and the state of which, liquid or gaseous, has a strong impact on the volume occupied by the same quantity of fluid.

Such a fluid exploitation installation may be, for example, a hydrocarbon exploitation installation on an offshore type platform.

The invention may for example relate to a submerged or surface fluid transfer system, used for a hydrocarbon transfer, for example between a submerged PLEM (abbreviation of “Pipe Line End Manifold”) and any nearby moored ship, or a ship and a carrier. Such a ship includes an FPSO (“Floating Production Storage Offloading unit”), an FSO (“Floating Storage and Offloading”), an FSRU (“Floating Storage and Regasification Unit”), an FLNG (“Floating Liquified Natural Gas”) or other unit.

The invention may for example find a particular application for the transfer of liquefied gas, for example ammonia, or liquid methane (which is liquid at a temperature below approximately −160° C.) which is a main constituent of liquefied natural gas (LNG) after separation from water, CO2and the constituents of liquefied petroleum gas (LPG).

Prior Art

European patent EP 2 356 018 describes an installation for transferring fluid between an offshore natural gas extraction and liquefaction unit, and a liquefied natural gas (LNG) carrier. To perform the transfer, the installation comprises, on one side, a cryogenic LNG transfer line between the offshore unit and the carrier, and on another side, a gas return line. In a particular case of natural gas (NG) export, one problem is essentially linked with a strong dependence on a state of the natural gas (essentially gaseous or liquid) according to temperature and pressure conditions of an environment wherein the NG resides. Indeed, NG is naturally found in a gaseous state, under pressure, at a positive temperature, i.e. at least equal to 0° C. (typically about 120° C. at 300 bar in a reservoir rock), while it is in a liquid state when it is brought to a temperature below about −160° C., at 1 bar absolute, after refining. Natural gas in the liquid state is referred to as LNG (liquefied natural gas).

This change of state has a strong impact on the volume occupied by the same quantity of NG.

It is possible to store about 600 times more NG in the liquid state than in the gaseous state in the same volume. Hence, it is much more advantageous to store or transport NG in the liquid state (i.e. LNG) than in the gaseous state.

However, storing LNG requires very effective thermal insulation so that it can retain its liquid state and not return to a gaseous state because the pressure of the fluid would then be likely to increase to approximately 600 bar.

Nevertheless, when transferring NG, for example from a ship to a carrier, a buoy or even a land-based site, while the NG is initially in a liquid state, a portion of the NG evaporates.

Preferably, this evaporated portion must then be returned to a liquefaction unit, for example located on the ship, to refine it and liquefy it again to minimise any production loss and potential greenhouse gas-related pollution.

In an installation such as that described in the aforementioned patent or similar, a floating offshore unit therefore has the function of extracting, refining, converting and/or transferring crude fluids, or electricity obtained by evaporated NG combustion.

A non-limiting example of such a floating unit is known as “FPSO” (“Floating Production Storage Offloading unit”).

Such a floating unit is for example formed by a ship, which is mobile on account of its environment, around a mooring turret, which is geostationary, via a main journal bearing. The ship may be temporarily moored to the turret.

Such an installation may include pipes which form an underwater pipe network which allows fluidic communication to transfer a fluid between the seabed and the ship.

For this, the installation comprises at least one swivel joint device, or a stack of swivel joint devices known as a “swivel stack”.

To ensure the tightness between the ship and the turret and thus ensure fluid transfer integrity, the swivel joint device is provided with a first so-called fixed part, considered geostationary, secured to the turret and a second so-called mobile part, secured to the ship. The second part of the swivel joint device is therefore rotatable with respect to the first, geostationary, part of the swivel joint device.

A swivel joint device is furthermore generally provided with several dynamic sealing members, called dynamic seals, disposed in spaces, that are frequently circular, arranged between the first fixed part and the second mobile part of the swivel joint device.

In the example of the exploitation of natural gas, the latter is pumped, then generally cleared of sand, water or other gases that it may contain to limit or prevent pipe incrustation or blockage. Such a separation is performed for example by distillation for gases (ethane, propane, H2S, CO2, etc.), and by settling or other processes to remove sand and water. The NG may then be liquefied, then thrust by floating pipes, for example flexible hoses, to a storage and/or transport entity, for example an export gas carrier (for example a methane carrier), for example moored in tandem, or a mooring buoy, to subsequently be transferred to a refinery on land, or even directly to a specific site, on land.

At least a first swivel joint device may therefore be located on the ship in order to extract the NG and send it to a separation installation, whereas at least another swivel joint device may be disposed to transfer the LNG from a liquefaction unit to the storage and/or transport entity, and to reroute a gas to the liquefaction unit.

The LNG transfer thus involves a passage via at least one swivel joint device capable of withstanding the cryogenic temperature of the LNG (i.e. approximately between −160° C. and −100° C. and between 1 bar and 25 bar absolute) so that it is kept in the liquid state as much as possible.

DISCLOSURE OF THE INVENTION

The invention relates, according to a first aspect, to a fluid transfer system configured to equip a fluid exploitation installation, the fluid transfer system including:a liquid transfer pipe, configured to carry a liquefied gas, anda gas transfer pipe, configured to carry a gas in vapour form,
characterised in that the liquid transfer pipe and the gas transfer pipe are concentric, the gas transfer pipe surrounding the liquid transfer pipe,
and in that the fluid transfer system furthermore includes:a buffer member, disposed between the liquid transfer pipe and the gas transfer pipe and surrounding at least partially the liquid transfer pipe, the buffer member being configured to transfer an evaporated portion of the liquefied gas circulating in the liquid transfer pipe from the liquid transfer pipe to the gas transfer pipe.

A fluid refers here to any deformable medium, including mainly a liquid and a gas, as opposed to a solid medium. A fluid therefore refers here indifferently to a liquid or a gas, or a mixture of liquid and gas.

While the invention is applied in particular to the transfer of LNG as liquefied gas, it can nonetheless be applied to any gas or gas mixture, diphasic under so-called “normal” transfer conditions, such as for example, without being restrictive, liquefied petroleum gas (LPG), carbon dioxide (CO2), optionally under pressure, for example at a pressure at least equal to 5.11 bar and a temperature at least equal to −56° C., ammonia (NH3), liquefied nitrogen (annotated LN2), liquefied argon (ArL), liquefied helium (HeL), etc.

In a particular example implementation, the gas in vapour form circulating in the gas transfer pipe includes evaporated liquefied gas.

The fluid transfer system according to the invention makes it possible to contribute to thermal insulation of the liquid transfer pipe forming a central channel intended for liquefied gas, using the gas transfer pipe to surround it, and makes it possible to separate the two flows (liquid and gas) by an intermediate volume formed by the buffer member.

Thus, the gas transfer pipe encases the liquid transfer pipe and forms a thermal barrier and a differential pressure damper.

Evaporated gas from the liquid may thus circulate in the buffer member and escape into the gas transfer pipe.

The gas transfer pipe is then configured to recover and circulate an evaporated portion, or fraction, of the liquid.

Leaks generated in the system may then be recovered.

In an example embodiment, a gas transfer pipe is a gas return pipe, configured to carry an evaporated portion of the liquefied gas.

Such a fluid transfer system is thus capable of transferring the liquefied gas, for example to a transport and/or storage unit, and returning the evaporated fraction, for example to a liquefaction unit.

Such a fluid transfer system is applied for example to installation capable of purifying natural gas extracted from underwater petroleum and gas deposits, liquefying it and storing it to finally transfer it either via a stack of swivel joint devices, or a mooring and loading buoy—not restricted to either or to one of each—to a methane carrier transferring to a refinery or a port, or via an offloading buoy allowing a methane carrier to supply a refinery via a cryogenic underwater pipeline.

In use, a pressure in the gas transfer pipe is generally greater than that in the liquid transfer pipe.

Thanks to the buffer member, the system can thus tend towards pressure equilibrium. When liquid passes from the liquid transfer pipe to the buffer member, it will be in a hotter zone than the liquid transfer pipe and it will therefore be evaporated and automatically counterbalance the liquid pressure.

The buffer member thus includes an internal volume forming a chamber between the liquid transfer pipe and the gas transfer pipe.

For example, the buffer member includes a fluid inlet configured to introduce fluid, from the liquid transfer pipe, into the buffer member.

A wall of the liquid transfer pipe may for example include at least one orifice opening into the buffer member.

For example, the fluid inlet includes the at least one orifice of the wall of the liquid transfer pipe.

For example, the buffer member includes a fluid outlet configured to extract fluid from the buffer member to the gas transfer pipe.

A wall of the gas transfer pipe may for example include at least one orifice opening into the buffer member.

For example, the fluid outlet includes the at least one orifice of the wall of the gas transfer pipe.

In an example embodiment, the fluid transfer system includes at least one dynamic sealing member.

The dynamic sealing member may be disposed in the buffer member, for example at an interface between the buffer member and the liquid transfer pipe and/or the gas transfer pipe.

In an example embodiment, the dynamic sealing member includes a seal, a journal bearing, or a composite assembly.

In another example embodiment, in particular if the fluid has no lubricant power, the dynamic sealing member may include a journal bearing.

A journal bearing makes it possible in particular to be able to produce a natural leak.

As a general rule within the scope of the present invention, a seal may be made of ultra-high molecular weight polyethylene (generally referred to as the acronym “UHMWPE”).

As a general rule within the scope of the present invention, a journal bearing may be made of PTFE filled with carbon powder or fibres.

For example, the fluid inlet in the buffer member includes a leak passage, for example produced by a dynamic sealing member.

For example, the fluid outlet from the buffer member includes a leak passage, for example produced by a dynamic sealing member.

In an example embodiment, the fluid inlet includes at least one safety valve.

The safety valve is for example configured to balance an overpressure between the liquid transfer pipe and the buffer member.

It thus makes it possible to manage fluid leaks, from the liquid transfer pipe, into the buffer member to the gas transfer pipe.

Thus, any overpressure in the liquid transfer pipe is released in the buffer member by at least one calibrated safety valve.

For example, the at least one orifice of the wall of the liquid transfer pipe is equipped with the at least one safety valve.

In an example embodiment, the fluid outlet includes at least one exhaust valve.

The exhaust valve is for example configured to balance an overpressure between the buffer member and the gas transfer pipe.

Thus, any overpressure in the buffer member is released in the gas transfer pipe by at least one calibrated exhaust valve.

For example, the at least one orifice of the wall of the gas transfer pipe is equipped with the at least one exhaust valve.

In an example embodiment, the buffer member includes at least one inner wall forming a labyrinth for a fluidic flow in the buffer member.

In an example embodiment, the inner wall divides the internal volume of the buffer member into at least two chambers, the fluid inlet being disposed in a first of the two chambers, and the fluid outlet being disposed in a second of the two chambers.

Thus, the first of the two chambers is the innermost of the two chambers, i.e. juxtaposed to the liquid transfer pipe, and the second of the two chambers is the outermost of the two chambers, i.e. juxtaposed to the gas transfer pipe.

For example, the inner wall is configured to allow a passage of fluid from the first chamber to the second chamber.

In an example embodiment, the inner wall includes at least one fluid transmission orifice.

In an example embodiment, the inner wall includes at least one balancing valve, for example disposed in the fluid transmission orifice.

The balancing valve is for example configured to balance a pressure between the two chambers of the buffer member.

For example, the inner wall may include at least two walls, or parts, thus dividing the internal volume of the buffer member into at least a third chamber. The third chamber is thus formed between the first chamber and the second chamber.

At least one of the parts of the inner wall, or each of the parts, may then include a fluid transmission orifice.

Where applicable, a balancing valve formed in the part of the inner wall between the first chamber and the third chamber, in particular in the corresponding fluid transmission orifice, then forms a first balancing valve.

Where applicable, a balancing valve formed in the inner wall between the third chamber and the second chamber, in particular in the corresponding fluid transmission orifice, then forms a second balancing valve.

As a general rule, the at least one orifice arranged in at least one part of the inner wall, and/or a valve (also referred to a micro-valve) optionally equipping such an orifice, are sized according to the configuration of the buffer member, or more generally the fluid transfer system, and managements of fluid pressure sought in the buffer member.

Therefore, there may be several orifices, and/or several valves, disposed in one direction or another according to the pressures sought.

A valve network may therefore be configured, as desired, to manage a usable overpressure to energise the joints and for their maintenance.

According to the sought situation, each valve may therefore be disposed, in one direction or another, and sized, to control the different pressure transfers in the at least one chamber of the buffer member.

For example, a second balancing valve may be mounted in the opposite direction relative to the first balancing valve.

Mounting balancing valves in opposite directions makes it possible optionally, for example, to generate an overpressure of a valve of the calibration of the safety valve in the first chamber while allowing maintenance or setting to manual overpressure of the two other chambers, for example with a gas injection as described hereinafter.

In an example embodiment, the buffer member is annular and surrounds the liquid transfer pipe.

The buffer member thus contributes to the thermal insulation of the liquid transfer pipe and to the collection of any leaks that may arise therefrom.

Another advantage of the fluid transfer system having at least one buffer member is being able to make use of gravity.

Thus, a gaseous counterpressure helps keeping the liquid in its circuit more than the sealing produced by a dynamic sealing member.

In an example embodiment, the fluid transfer system is configured so that a liquid flow in the liquid transfer pipe is along a first direction, for example downward, i.e. according to gravity, and so that a gas flow in the gas transfer pipe is also along the first direction.

In an example embodiment, the fluid transfer system is configured so that a liquid flow in the liquid transfer pipe is along a first direction, for example downward, i.e. according to gravity, and so that a gas flow in the gas transfer pipe is along a second direction, opposite the first, for example upward.

In a particular example implementation, the fluid transfer system is configured so that a liquid flow is downward, i.e. according to gravity, and so that a gas flow is upward, i.e. against the liquid flow.

For example, the fluid inlet of the buffer member is offset relative to the fluid outlet relative to a longitudinal axis (X) of the liquid transfer pipe.

The longitudinal axis (X) of the liquid transfer pipe corresponds here to an average fluid flow line in the liquid transfer pipe.

In the case of cylindrical pipe with circular cross-section, the longitudinal axis (X) is an axis of revolution of said pipe.

In an example embodiment, at least one part of the fluid inlet in the buffer member is disposed at a lower height than a height of at least one part of the fluid outlet to ensure a low level for liquid and a high level for gas.

In an example embodiment, the fluid transfer system includes an insulating sheath.

For example, the insulating sheath surrounds at least one section of the gas transfer pipe.

The insulating sheath may surround at least one section of the liquid transfer pipe, for example a section juxtaposed to the buffer member.

For example, the insulating sheath includes a double-wall structure.

For example, the insulating sheath includes an insulating coating.

The insulation of the external structure is for example ensured at critical locations by the presence of a double wall which may include any type of insulating material and/or be put under vacuum inside the double wall.

In an example embodiment, the fluid transfer system includes a pressurisation system which includes a gas, the fluid transfer system being configured to inject gas from the pressurisation system in the internal volume of the buffer member.

The gas of the pressurisation system is for example an inert gas.

For example, the gas includes at least one gas from among: Nitrogen, Argon, Helium, or Methane, or any mixture thereof.

For example, the gas of the pressurisation system is configured to be in a gaseous state at a temperature greater than or equal to about −160° C.

For example, the gas of the pressurisation system is chosen from have a dew point below −160° C.

For example, the pressurisation system includes a pressurised dry gas cylinder.

For example, the fluid transfer system may include a pressure regulator configured to regulate a pressure in the buffer member.

By regulating the pressure in the buffer member, a gas volume in the buffer member will be pressurised according to a predefined pressure in order to maintain this pressure in the buffer member. By injecting a sufficient gas volume into the buffer member, a pressure will be established and oppose any liquid leak.

For example, for a defined pressure of 25 bar in the buffer member, and a pressure in the liquid transfer pipe varying between 10 bar and 20 bar, a calibration pressure of the safety valve is about 5 bar, as well as at least that of a balancing valve where applicable.

Thus, the buffer member makes it possible to limit or prevent liquid leaks from the liquid transfer pipe.

In an example embodiment, the buffer member includes a gas injection port configured to inject a gas, in particular a pressurised, inert and dry gas into the buffer member, for example in at least one chamber of the buffer member.

In an example embodiment, the fluid transfer system includes at least one manifold to inject gas into the buffer member via the gas injection port, referred to as overflow manifold.

The overflow manifold thus links the buffer member with the pressurisation system, which may include for example a pressurised dry gas cylinder.

Such a pressurisation system (potentially manual), with an overflow manifold, makes it possible to control leak flows, and especially purge and/or drain liquid and/or solid residues which may have been loaded, despite at least one purification of the fluid.

In such a fluid transfer system, it is therefore possible to clean at least one part of the fluid transfer system, for example the buffer member, with purges, optionally operated from outside the system, on the sealing surfaces and/or the friction surfaces: for example, journal bearings or seals according to the technique used.

This contributes to better safety of the fluid transfer system because pressurising with an inert gas may be performed without having to disassemble the system.

Moreover, limiting fouling of the fluid transfer system makes it possible to reduce its wear and therefore produce better operating reliability.

Furthermore, such a fluid transfer system makes it possible to monitor a liquid circulation pressure and contributes to quality of its sealing.

According to the type of fluid, this makes it possible to prevent atmospheric pollution and/or potential ignition of the gas in air.

Furthermore, this limits a cryopumping phenomenon, which may be risky, wherein water may frost and thus induce seal abrasion, noise, and/or also form clathrates according to the fluid used, in particular methane clathrates where applicable, i.e. compounds wherein methane molecules are trapped in a lattice of water molecules. Such clathrates form a type of wax which contributes to the wear of the system and incidentally generates undesired leaks. It is therefore preferable to be able to prevent clathrate formation.

The use of a pressurisation with an inert and dry gas as described above, even during system operation, thus makes it possible to inert, test, purge, drain and dry at least one part of the buffer member.

In another example embodiment, the buffer member may be pressurised by the gas flow.

In such an example embodiment, the overflow manifold is then fluidically connected to the gas transfer pipe, on one side, and to the gas injection port of the buffer member, on the other.

According to another example embodiment, alternatively or additionally, the fluid transfer system may include a valve sized according to a desired pressure and/or controlled according to a target pressure.

According to another advantageous option, the fluid transfer system is configured to compensate a length variation of the liquid transfer pipe.

The length variation of the liquid transfer pipe is due to an axial deformation (expansion or contraction), i.e. according to a length of the pipe.

For illustration purposes, in operation with LNG, the fluid in the liquid transfer pipe is preferably maintained at a temperature between −160° C. and −140° C., therefore the pipe is at a temperature between about −160° C. and −140° C. However, when the fluid flow is initiated in the pipe, the liquid transfer pipe is at ambient temperature at the start of the operation. On account of the substantial cooling, the liquid transfer pipe contracts, and therefore reduces in length. However, the gas transfer pipe is not subjected to the same contraction. Consequently, the liquid transfer pipe reduces in length relative to the gas transfer pipe surrounding it.

Immobilising the liquid transfer pipe relative to the gas transfer pipe would generate excessive stress to ensure pipe integrity, and/or would involve very high costs.

It is therefore advantageous that the fluid transfer system be configured to compensate such length variations.

In an example embodiment, the liquid transfer pipe includes an incident section equipped with an endpiece, and a receiving section, forming a protective sleeve, wherein the endpiece is inserted.

Thus, according to the deformation of the liquid transfer pipe, the endpiece is pushed more or less deeply into the receiving section.

In an example embodiment, the buffer member is configured to glide relative to at least one from among the incident section and the receiving section, i.e. slide relative to the incident section and/or the receiving section.

The buffer member then acts as a ring which may move (for example move up or down) relative to the incident section, while being tight in rotation.

Optionally, the buffer member is attached, fastened, to at most one from among the incident section and the receiving section.

Thus, the buffer member is configured to compensate a deformation of the liquid transfer pipe, in particular by producing a junction between the incident section and the receiving section, by longitudinal sliding.

This may simplify the design of extra-long pipes, for example a natural gas pipeline.

However, according to another embodiment, the buffer member could be an axially floating ring.

In an example embodiment, the system described here may produce reverse leaks, i.e. where gaseous fluid may be reliquefied. Such a system is then configured to withstand an overpressure in both directions.

The inlets and outlets described here then have their functions reversed. For example, the fluid inlet configured to introduce fluid, from the liquid transfer pipe, into the buffer member, then serves to extract fluid from the buffer member to the liquid transfer pipe. Likewise, the fluid outlet configured to extract fluid from the buffer member to the gas transfer pipe, then serves to introduce fluid, from the gas transfer pipe, into the buffer member.

Such a fluid transfer system including two concentric pipes makes it possible for example to offer the following options:gas transfer for loading or offloading a gaseous product;protection (inerting) of a tank, upstream or downstream from the system;insulation (“pipe in pipe”);protection (referred to as “boil off protection”), i.e. a gas is applied on the surface of a liquefied gas and thus prevents its liquefaction by creating a gaseous headspace;leak control: by applying a permanent vacuum in the gas transfer pipe, it is possible to control and/or analyse an optional introduction of gas into the buffer member and thus check whether there is a leak in the system which could come from the liquid transfer pipe.

The invention also relates, according to another aspect, to a swivel joint device which includes a fluid transfer system including all or some of the features described above.

For example, the swivel joint device includes a first, so-called fixed, annular part and a second annular part rotatable about an axis of rotation X and relative to said first fixed annular part.

The swivel joint device generally has an internal space defined by an internal surface of the first fixed annular part.

The swivel joint device includes a transfer pipe which enters via the first fixed annular part of the swivel joint device and opens out of the swivel joint device via an outlet coupling connected to the second mobile annular part.

A flow thus passes through the swivel joint device by entering the first fixed annular part via the transfer pipe and outflowing via the second mobile annular part via the outlet coupling.

Here, the transfer pipe which enters the swivel joint device includes at least the gas transfer pipe of the fluid transfer system, forming a gas inlet in the swivel joint device, and the second mobile part includes the outlet coupling which forms a gas outlet of the swivel joint device.

In an example embodiment, the liquid transfer pipe of the fluid transfer system is disposed in the internal space of the swivel joint device.

Such a swivel joint device thus simultaneously enables liquid transfer and gas transfer by ensuring the rotation along the vertical axis (X) and the sealing of said circuits.

In an example embodiment wherein the liquid transfer pipe includes an incident section and a receiving section, one of the incident section or the receiving section may be fastened to the second mobile annular part and/or the other of the incident section or the receiving section may be fastened to the first fixed annular part.

For example, the second annular part is rotatable relative to the first annular part by means of a hinge member, at least partially inserted between the first annular part and the second annular part.

For example, the hinge member includes a bearing member.

In an example embodiment, the swivel joint device includes a fluid injection port configured to inject a fluid into the hinge member.

In an example embodiment, the swivel joint device includes at least one manifold configured to inject fluid into the hinge member via the fluid injection port.

Similarly, a fluid may be injected on a barrier which is located outside the hinge member, which encompasses the hinge member, and the barrier may be pressurised, for example at a pressure of 40 bar or 50 bar, optionally thanks to a manifold, and which will for example prevent seawater from entering (sea spray, rain, waves if floating system such as a buoy, etc).

According to another advantageous option, the manifold may be a manifold for oil or other lubricant (such as for example glycols or ethers of petroleum which make it possible to lubricate at −160° C.), the oil or other lubricant being chosen so as not to set at the operating temperature (about −160° C. maximum).

According to an alternative example embodiment if a bearing member is too complex to lubricate, the hinge member may include at least one friction pad.

In an example embodiment, the swivel joint device includes an insulating sheath.

For example, the insulating sheath surrounds at least partially the first fixed annular part and/or the second mobile annular part.

For example, the insulating sheath includes a double-wall structure.

For example, the insulating sheath includes an insulating coating.

The insulation of the external structure is for example ensured at locations considered to be critical by the presence of a double wall which may include any type of insulating material and/or be put under vacuum inside the double wall.

An aim of such insulation is that of limiting heat exchanges which may cool the hinge member or promote heating of the liquid flow.

The invention also relates, according to another aspect, to a stack of swivel joint devices including at least two swivel joint devices, at least a first of the swivel joint devices of the stack of swivel joint devices being as described above.

The invention furthermore relates, according to a further aspect, to a fluid exploitation installation which includes at least:a liquefaction unit,a storage and/or transport entity,a first swivel joint device including a fluid transfer system as described above, the first swivel joint device being connected by the outlet coupling to the liquefaction unit and by the gas transfer pipe to the storage and/or transport entity, the liquid transfer pipe of the fluid transfer system connecting the liquefaction unit to the storage and/or transport entity, andat least a second swivel joint device, which includes an inlet pipe into the second swivel joint device which is connected to a pipe of an underwater pipe network to extract natural gas, and an outlet coupling which is connected to the liquefaction unit.

For example, the second swivel joint device may be a high-pressure high-temperature swivel joint device (annotated HPHTS).

In an example embodiment, the installation includes a stack of swivel joint devices including at least two swivel joint devices, the stack of swivel joint devices including at least the first swivel joint device and the second swivel joint device.

In an example embodiment, the installation furthermore includes a ship, and at least one from among the first swivel joint device or the second swivel joint device is disposed on the ship.

DETAILED DESCRIPTION

FIG.1illustrates a fluid exploitation installation1on an offshore platform, allowing the exploitation of offshore hydrocarbon fields2.

This installation1, also known as a floating production storage offloading unit (FPSO), may be provided with a ship3which is mobile, on account of its environment formed by the sea2, and a mooring turret4which is geostationary and about which the ship3is mobile.

The mooring turret4may for example be mechanically secured to the seabed2via underwater anchors5.

The ship3may be mobile relative to the turret4via a bearing mechanism7.

The installation1may be provided with pipes6which form an underwater pipe network allowing a fluidic communication for a transfer of fluid (for example: water, methanol, detergents, etc.) between the mooring turret4and the seabed.

The fluid circulating in the pipes6may also come from a subfloor of the sea2.

The fluid may then be processed and purified before the gas can be liquefied.

For this, the fluid exploitation installation1includes a liquefaction unit30, which may be located on the ship3as illustrated here, or be adjoined to it on a mooring alongside floating unit for example.

The liquefied fluid may then be pushed towards a storage and/or transport entity40, for example via a mooring buoy.

A storage and/or transport entity40is for example an export gas carrier (for example a shuttle methane carrier), which may be moored in tandem, or by a mooring buoy, to subsequently transfer the fluid to a refinery on land, or even directly to a specific site, on land.

For example, the storage and/or transport entity40may be:Either moored alongside (in tandem) or in-line (referred to as “piggy back”) and connected by floating hoses1012for LNG and floating hoses1011for gas transfer;Either moored and connected to a buoy (not illustrated) by optionally coaxial, floating or underwater hoses, which may for example be either floating between two waters, or embedded;

According to another example, the ship may also supply a refinery on land or even directly a specific site (not illustrated).

The installation1includes a swivel joint device10ensuring:sealing between the ship3and the mooring turret4, andfluid transfer integrity.

The swivel joint device10may be formed from a swivel joint or disposed in a stack of such joints.

At least one swivel joint device10, for example an HPHTS swivel joint device, may therefore be located on the ship3in order to extract the NG and send it to the liquefaction unit30, whereas at least another swivel joint device may be disposed to transfer the LNG from the liquefaction unit30to the storage and/or transport entity40, and to reroute a gas to the liquefaction unit30. The installation1may then in particular include at least one stack1010of swivel joint devices including at least two swivel joint devices.

As illustrated inFIG.2, such a swivel joint device10, for example HPHTS, is overall annular and includes a first so-called fixed annular part11, which is generally configured to be secured to the mooring turret4, and/or to the mooring anchors5, as well as a second so-called mobile annular part12, which is configured to be secured to the ship3.

In the example described here, the second annular part12is rotatable relative to the first annular part11by means of a bearing member13at least partially inserted between the first annular part11and the second annular part12.

The bearing member is for example protected by seals.

The swivel joint device10has an internal space14defined here by an internal surface15of the first annular part11.

The swivel joint device10furthermore includes a transfer pipe16connected, directly or indirectly, to at least one of the underwater pipes6.

The transfer pipe16enters the first annular part11via the internal space14and opens out of the swivel joint device10via an outlet coupling17. The outlet coupling17is for example connected to a processing and/or liquefaction unit (not shown) in order to separate and then liquefy the gas and subsequently transfer the liquefied gas to a shuttle tanker or a storage unit on land.

A flow thus passes through the swivel joint device10by entering the first fixed annular part11via the transfer pipe and outflowing via the second mobile annular part12via the outlet coupling.

FIG.3represents a fluid transfer system100according to a first embodiment of the invention.

The fluid transfer system100includes a liquid transfer pipe110, configured to carry a liquefied gas (LG).

The liquid transfer pipe110is here a pipe with a circular cross-section.

The pipe with a circular cross-section then includes a cylindrical wall delimiting an internal volume of the pipe wherein a fluid flow may flow, such as for example a liquefied gas flow represented schematically by the arrow111.

The liquid transfer pipe110includes here two sections, including an incident section112and a receiving section113.

The incident section112and the receiving section113are partially imbricated in one another, thus allowing a length variation of the liquid transfer pipe110, a length variation that may be induced according to the temperature (expansion) and the pressure (hydrostatic end force). The length represents here a dimension along a longitudinal axis X, illustrated inFIG.3. The longitudinal axis (X) corresponds here to an average fluid flow line in the liquid transfer pipe110. In the case of cylindrical pipe with circular cross-section, it consists of an axis of revolution of the pipe.

As seen more clearly inFIG.4for example, the incident section112includes an endpiece114, forming a part of reduced cross-section of the incident section112, configured to be inserted into the receiving section113, which thus forms a protective sleeve.

Such a protective sleeve may for example be configured to protect seals and/or journal bearings against erosion which may be due to turbulence of a mixture of gas bubbles and liquid in the liquid transfer pipe110. This sleeve may be for example guided by a journal bearing115disposed between the receiving section113and the endpiece114.

According to the deformation of the liquid transfer pipe, the endpiece is pushed more or less deeply into the receiving section113.

The liquid transfer pipe110is thus configured to adopt a retracted configuration wherein at least a part of the endpiece114is inserted into the receiving section113and the liquid transfer pipe110then has a first length, and a deployed configuration wherein the part of the endpiece is out of the receiving section113and the liquid transfer pipe110then has a second length, greater than the first length.

In the retracted configuration, at least half of a length of the endpiece114is preferably engaged in the receiving section113, considering for example a working temperature under most difficult conditions, such as for example about 25 bar at −100° C.

Moreover, the incident section112may rotate relative to the receiving section113, for example here along the axis X.

The fluid transfer system100also includes a gas transfer pipe120.

The gas transfer pipe120is in particular configured to carry an evaporated portion of the liquefied gas, in particular to the liquefaction unit.

The gas transfer pipe120is here a pipe with an annular cross-section.

In other words, the pipe with an annular cross-section includes an internal cylindrical wall and an external cylindrical wall which surrounds the internal cylindrical wall, and a fluid may then flow in the pipe between the internal cylindrical wall and the external cylindrical wall.

InFIG.3, a gas flow is represented by the arrow121.

The gas flow is here represented schematically in the opposite direction to that of the liquid flow represented schematically by the arrow111. However, the gas flow could be in the same direction as that of the liquid, depending on a context and/or a desired application.

In the present example embodiment, the gas transfer pipe120surrounds the liquid transfer pipe110.

Furthermore, the liquid transfer pipe110and the gas transfer pipe120are concentric.

The fluid transfer system100furthermore includes a buffer member130.

The buffer member130is in particular configured to transfer an evaporated portion of liquefied gas circulating in the liquid transfer pipe110, from the liquid transfer pipe110to the gas transfer pipe120.

The buffer member130thus makes it possible to separate gas, from liquid leaks which could be evaporated inside the liquid transfer pipe110, and return this gas to a liquefaction unit via the gas transfer pipe120.

The buffer member130is here disposed between the liquid transfer pipe110and the gas transfer pipe120and surrounds at least partially the liquid transfer pipe110.

In other words, the buffer member130is here annular and surrounds the liquid transfer pipe110.

The buffer member130thus contributes to thermal insulation of the liquid transfer pipe110and to the collection of any leaks that may arise therefrom.

The fluid transfer system100thus makes it possible to contribute to thermal insulation of the liquid transfer pipe110forming a central channel intended for liquefied gas, using the gas transfer pipe120to surround it, and makes it possible to separate the two flows (liquid and gas) by an intermediate volume formed by the buffer member130.

The gas transfer pipe120encases the liquid transfer pipe110and forms a thermal barrier and a gas/liquid differential pressure damper.

Evaporated gas from the liquid may circulate in the buffer member130and escape into the gas transfer pipe120.

The gas transfer pipe120is then configured to recover and circulate an evaporated portion, or fraction, of the liquid.

The buffer member130includes, on one hand, a fluid inlet131and, on the other, a fluid outlet132.

The fluid inlet131is configured to introduce fluid into the buffer member130, from the liquid transfer pipe110.

For example, the fluid inlet131may include at least one orifice formed in the wall of the liquid transfer pipe110and opening into the buffer member130.

The fluid inlet131may in particular include several orifices disposed around the liquid transfer pipe110.

In the present example embodiment, the fluid inlet131includes at least one safety valve141.

It may in particular include several safety valves disposed around the liquid transfer pipe110.

The safety valve141is for example configured to balance an overpressure between the liquid transfer pipe110and the buffer member130.

Thus, any overpressure in the liquid transfer pipe110is released in the buffer member130by at least one safety valve141calibrated accordingly.

Here, the safety valve141is disposed in the wall of the liquid transfer pipe110, in particular in the present example embodiment, in the incident section112, and for example in an orifice of the fluid inlet131.

Alternatively or additionally, as illustrated here, the fluid inlet131may also include a leak passage142, for example a passage bypassing a dynamic sealing member143described hereinafter.

A leak passage refers here to an interstice formed by a contact between parts.

In the present example, as seen more clearly inFIG.4, when the incident section112is inserted into the receiving section113, a contact between the endpiece114, the journal bearing115and the receiving section113may allow a fluid leak.

To nonetheless control such a leak, the fluid transfer system100includes for example a dynamic sealing member143.

In this example, the dynamic sealing member143includes a piston seal.

The dynamic sealing member143is for example here disposed in the buffer member130, and for example around a junction between the incident section112and the receiving section113, for example facing an interstice between the buffer member130and the incident section112.

The fluid outlet132is configured to extract fluid from the buffer member130, to the gas transfer pipe120.

For example, the fluid outlet132may include at least one orifice formed in the wall of the gas transfer pipe120, in particular the internal cylindrical wall, and opening into the buffer member130.

It may in particular include several orifices disposed around the gas transfer pipe120, in particular the internal cylindrical wall.

In the present example embodiment, the fluid outlet132includes at least one exhaust valve144.

It may in particular include several exhaust valves disposed around the gas transfer pipe120, in particular the internal cylindrical wall.

The exhaust valve144is for example configured to balance an overpressure between the buffer member130and the gas transfer pipe120.

Thus, any overpressure in the buffer member130is released in the gas transfer pipe120by at least one exhaust valve144calibrated accordingly.

Here, the exhaust valve144is disposed in the internal cylindrical wall of the gas transfer pipe120, in particular in an orifice of the fluid outlet132.

Alternatively or additionally, as illustrated here, the fluid outlet132may also include a leak passage145, for example a passage bypassing a dynamic sealing member146described hereinafter.

In the present example, as seen more clearly inFIG.4, the fluid transfer system100includes a separating partition151against which the buffer member130abuts.

A contact between the separation partition151and the buffer member130may allow a fluid leak to pass through.

To limit such a leak, the fluid transfer system100includes for example a dynamic sealing member146, for example here a facial seal.

The dynamic sealing member146is for example here disposed in the buffer member130, and against the separating partition151.

In practice, the fluid transfer system100is preferably configured so that a liquid flow is downward, i.e. according to gravity, as represented schematically by the arrow111, and so that a gas flow is upward, i.e. against the fluid flow, as represented schematically by the arrow121. It is then advantageous that the fluid inlet131of the buffer member be offset relative to the fluid outlet132along the longitudinal axis (X) of the liquid transfer pipe110.

As represented schematically here, at least one part of the fluid inlet131in the buffer member (here the leak passage142) is disposed at a lower height than a height of at least one part of the fluid outlet132(here the leak passage145) to ensure a lower level for liquid and a higher level for gas.

The buffer member130here includes an internal volume133forming a chamber between the liquid transfer pipe110and the gas transfer pipe120.

In the present example embodiment, the buffer member130includes at least one inner wall147forming a labyrinth for a fluidic flow in the buffer member.

Here, the inner wall147divides the internal volume133of the buffer member130into at least two chambers, and even here three chambers, the fluid inlet131being disposed in a first of the chambers, and the fluid outlet132being disposed in a second of the chambers; here a third chamber being formed between the first chamber and the second chamber.

For example, the inner wall147is configured to allow a passage of fluid from the first chamber to the second chamber.

In the present example embodiment, the inner wall147includes at least one balancing valve148disposed in an orifice, and a valve-free orifice149.

The balancing valve148is for example configured to balance a pressure between the two chambers of the buffer member130.

The safety valve141is for example configured to limit to 5 bar an overpressure in the liquid transfer pipe110relative to the buffer member130. For example, if dynamic sealing members143,146are tight and liquid has entered the buffer member, this liquid would evaporate and increase the pressure in the buffer member without however exceeding a calibration of a balancing valve which would release the excess pressure from the buffer member to the liquid transfer pipe110.

In the present example embodiment, the balancing valve may be calibrated at a few bar and mounted in the opposite direction of the safety valve141, or otherwise the at least one valve-free orifice149, of relatively small cross-section, may be disposed at the bottom (according to the direction of gravity) of the wall147. Such an orifice149is intended to draw fluid transfers in both directions without reducing a mechanical rigidity of the buffer member130, and to help the pressure inside a chamber not to be excessively greater than that present outside to prevent, at least in part, permanent deformations of the inner wall147.

Here, at least one balancing valve148is formed in a part of the inner wall147separating the first chamber from the third chamber and at least one balancing valve148is formed in another part of the inner wall147separating the third chamber from the second chamber.

As seen more clearly according toFIG.4in the present example embodiment, the buffer member130is here delimited, on one side, by the liquid transfer pipe110and, on the other, by the gas transfer pipe120, and shares a common wall with each.

However, the buffer member could include its own walls on either side, which would then be adjacent, on one side, to the internal wall of the gas transfer pipe and, on the other side, to the wall of the liquid transfer pipe.

At least the incident section112has here a rotatability relative to the buffer member130.

The fluid transfer system is here configured to compensate a length variation of the liquid transfer pipe110.

The length variation of the liquid transfer pipe is due to an axial deformation (expansion or contraction, optionally combined with the hydrostatic end force), i.e. according to a length of the pipe, along the axis X.

For illustration purposes, in operation with LNG, the fluid in the liquid transfer pipe is preferably maintained at a temperature between −160° C. and −140° C. Therefore the pipe is at a temperature between about −160° C. and −140° C. However, when the fluid flow is initiated in the pipe, the liquid transfer pipe is initially at ambient temperature. On account of the substantial cooling, the liquid transfer pipe contracts, and therefore reduces in length.

However, the gas transfer pipe is not subjected to the same contraction. Consequently, the liquid transfer pipe reduces in length relative to the gas transfer pipe surrounding it.

Immobilising the liquid transfer pipe relative to the gas transfer pipe would generate excessive stress to ensure pipe integrity, and/or would involve very high costs.

It is therefore advantageous that the fluid transfer system be configured to compensate such length variations.

For this, in the present example embodiment, the buffer member130is configured to glide relative to at least one from among the incident section112and the receiving section113, i.e. slide relative to the incident section and/or the receiving section.

The buffer member130then acts as a ring which can move in translation, vertically, while being tight in rotation, in particular here about the axis X.

As seen more clearly inFIG.4, the buffer member130is fastened to at most one from among the incident section and the receiving section, in this case to the receiving section113. Thus, in the present example embodiment, the buffer member130is configured to glide relative to the incident section112, and the receiving section113slides jointly with the buffer member130relative to the incident section112.

The buffer member is thus configured to compensate a deformation of the liquid transfer pipe, in particular by producing a junction between the incident section112and the receiving section113, by longitudinal sliding along the longitudinal axis (X).

In the present example embodiment, the buffer member includes a gas injection port161configured to inject a gas, in particular under pressure, into the buffer member, for example in at least one chamber of the buffer member.

The fluid transfer system may then include at least one overflow manifold160configured to inject gas into the buffer member via the gas injection port161.

The overflow manifold160thus connects the buffer member with, for example, a pressurisation system and/or the gas flow. In the latter case, the overflow manifold160is fluidically connected to the gas transfer pipe120, on one side, and to the gas injection port161of the buffer member, on the other side.

For example, the seal of the dynamic sealing member143may be actuated by pressure through at least one of the valve-free orifices149of the internal wall147.

The fluid transfer system100may include the pressurisation system (represented according to a particular embodiment inFIG.14) which then includes a gas.

The gas of the pressurisation system is for example an inert gas.

It consists for example of an inert and dry gas in which the boiling point at the pressure of use is lower than that of the liquid gas contained in the liquid transfer pipe110.

For example, the gas of the pressurisation system is configured to be in a gaseous state at a temperature greater than or equal to about −160° C.

For example, the gas of the pressurisation system is chosen to be in the gaseous state at a temperature slightly lower than −160° C. at atmospheric pressure when LG is Methane, at about −90° C. when LG is Ethane, −42° C. for Propane and −33° C. for Ammonia.

For example, the gas includes at least one gas from among: Nitrogen, Argon, Helium, or Methane, or any mixture thereof.

For example, the pressurisation system may include a pressurised dry gas cylinder.

For example, the fluid transfer system100may also include a pressure regulator (not shown) configured to regulate a predefined pressure in the buffer member130.

As also represented schematically inFIGS.3and4, the fluid transfer system described above is here part of a swivel joint device1000.

The swivel joint device1000includes a first, so-called fixed, annular part1100(seeFIG.4) and a second annular part1200rotatable about the axis of rotation (X) and relative to said first fixed annular part1100.

The swivel joint device generally has an internal space defined by an internal surface of the first fixed annular part.

The swivel joint device1000includes a transfer pipe1110which enters the first fixed annular part1100, and opens via an outlet coupling1210connected to the second mobile annular part1200.

A flow thus passes through the swivel joint device1000by entering the first fixed annular part1100via the transfer pipe1110and outflowing via the second mobile annular part1200via the outlet coupling1210.

Here, the transfer pipe1110includes at least the gas transfer pipe120of the fluid transfer system100, forming a gas inlet in the swivel joint device1000, and the second mobile part1200includes the outlet coupling1210which forms a gas outlet of the swivel joint device1000. As also seen inFIG.4, the second mobile annular part1200includes here the separating partition151.

Furthermore, the separating partition151includes at least one passage155allowing gas flowing from the gas transfer pipe120to move from the first fixed annular part1100to the second mobile annular part1200and thus pass through the swivel joint device1000and outflow via the outlet coupling1210.

The liquid transfer pipe110of the fluid transfer system100is disposed in the internal space of the swivel joint device1000.

Such a swivel joint device1000thus simultaneously enables liquid transfer and gas transfer by ensuring the rotation along the vertical axis (X) and the sealing of said circuits.

Furthermore, in the present example embodiment wherein the liquid transfer pipe110includes an incident section112and a receiving section113, the incident section112is fastened to the second mobile annular part1200whereas the receiving section113is fastened to the first fixed annular part1100.

For example here, the swivel joint device1000includes a hinge member152, for example with bearings, which is at least partially inserted between the first annular part1100and the second annular part1200, such that the second annular part1200is rotatable relative to the first annular part1100.

For example here, the hinge member152includes a first part153rigidly connected to the first fixed annular part1100and a second part154rigidly connected to the second mobile annular part1200, the second part154of the hinge member152being rotatable relative to the first part153of the hinge member152.

The swivel joint device1000furthermore includes here a fluid injection port156configured to inject a fluid into the hinge member152.

For example, the swivel joint device1000includes at least one manifold157configured to inject fluid into the hinge member152via the fluid injection port156.

The manifold157may be a manifold for oil or other lubricant (such as for example glycols or ethers of petroleum which make it possible to lubricate at −160° C.), the oil or other lubricant being chosen so as not to set at the operating temperature (about −160° C. at the lowest).

The swivel joint device1000may furthermore include a protective environmental seal170, referred to as “weather seal”, i.e. a seal which protects from the marine environment. Such a seal is here configured to protect the hinge member152.

In an example embodiment, the swivel joint device1000includes an insulating sheath158. The insulating sheath surrounds at least partially the first fixed annular part and/or the second mobile annular part.

The insulating sheath includes here a double-wall structure.

The insulation of the external structure is for example ensured at critical locations by the presence of a double wall which may include any type of insulating material and/or be put under vacuum inside the double wall.

An aim of such insulation is that of limiting heat exchanges which may cool the hinge member152or promote heating of the liquid transfer pipe110.

When there is a fluid flow, the liquid flows in the liquid transfer pipe110, for example from top to bottom according to the embodiment illustrated inFIGS.3and4.

A portion of the liquid that evaporates is introduced into the buffer member via the safety valve141and/or the leak passage142, until balancing of the pressures between the buffer member and the liquid transfer pipe110is substantially ensured. Once in the first chamber, fluid may be introduced into the third chamber via at least one balancing valve148and/or at least one valve-free orifice149, then into the second chamber via at least one other balancing valve148and/or at least one other valve-free orifice149communicating between the third chamber and the second chamber.

The fluid outflows from the buffer member130via at least the exhaust valve144and/or the leak passage145. The leak passage145serves in particular during a temperature and pressure conditioning phase during a commissioning of the fluid transfer system100.

The fluid inlet is for example secured by the at least one safety valve141to introduce fluid into the buffer member130, from the liquid transfer pipe110, whereas the fluid outlet is for example secured by the at least one exhaust valve144, and optionally by the at least one balancing valve148.

The fluid is then located in the gas transfer pipe120, carried in the flow along the arrow121.

In a swivel joint device1000, the fluid then enters the mobile annular part1200via the passage155and subsequently outflows from the device via the outlet coupling1210.

In the installation1ofFIG.1, the stack1010of swivel joint devices may for example include a first swivel joint device1000including such a fluid transfer system100.

The first swivel joint device1000is then connected via the outlet coupling1210to the liquefaction unit30and via the gas transfer pipe120to the storage and/or transport entity40.

The liquid transfer pipe110of the fluid transfer system100connecting the liquefaction unit30to the storage and/or transport entity40.

The stack1010of swivel joint devices may also include a second of the swivel joint devices10which includes an inlet pipe16which is connected to a pipe6of an underwater pipe system to extract natural gas, and an outlet coupling17which is connected to the liquefaction unit30.

For example, the second of the swivel joint devices10of the stack1010of swivel joint devices is a high-pressure high-temperature swivel joint device (annotated HPHTS).

FIG.5represents a fluid transfer system according to a second embodiment.

This embodiment differs from the preceding one in that the dynamic sealing member143includes here a seal in which a lug is disposed against the liquid transfer pipe110.

This embodiment also differs in that the dynamic sealing member146includes here two facing seals, each seal including a pair of lips facing the pair of lips of the other seal, and a spreader disposed between the lips of the two seals.

In other words, the dynamic sealing member146includes a radial double seal with a spacer between the two to prevent the lips from collapsing.

FIG.6represents a fluid transfer system according to a third embodiment.

This embodiment differs from the preceding ones by the arrangement of the buffer member130.

This is illustrated in comparison with a detail ofFIG.5for easier visualisation.

In this example, the buffer member130is devoid of a valve, insofar as unclosed chambers cannot self-pressurise and the control system may be entirely outside the swivel joint device1000via the port161.

The fluid inlet131only includes here the leak passage142, and the fluid outlet only includes the leak passage145.

The dynamic sealing member143includes here a journal bearing instead of a lip seal.

Another journal bearing143′ is furthermore present, the journal bearing143and the other journal bearing143′ delimiting between them a first chamber of the buffer member.

At the outlet, the dynamic sealing member146includes a lip seal in which the lips are oriented towards a chamber of the buffer member wherein pressurised gas may be injected via the port161. Thus, here, a lug of the lip seal of the dynamic sealing member146is disposed against the separating partition151.

On either side of the dynamic sealing member146, the system includes two journal bearings146′,146″.

FIG.7represents a fluid transfer system according to a fourth embodiment.

This embodiment is also illustrated in comparison with a detail ofFIG.5for easier visualisation.

However, this embodiment differs from the preceding one by the leak passage145of the fluid outlet.

At the outlet, the dynamic sealing member146includes two facing lip seals.

The two lip seals are separated here by two edges147′,147″ of parts of the internal wall147, the two edges147′,147″ delimiting between them a passage towards a chamber of the buffer member wherein pressurised gas may be injected via the port161.

FIG.8represents a fluid transfer system according to a fifth embodiment.

This embodiment is also illustrated in comparison with a detail ofFIG.5for easier visualisation.

However, this embodiment differs from the preceding one by the presence of a third chamber, and by a configuration of the leak passage145of the fluid outlet.

In this example, the buffer member includes two injection ports161, a first of the two ports configured to inject pressurised gas into the second chamber, and a second of the two ports configured to inject pressurised gas into the third chamber.

At the outlet, the dynamic sealing member146includes two lip seals, each lip seal being configured to be pressurised by one of the second chamber and the third chamber.

Furthermore, here, a lug of each the lip seals of the dynamic sealing member146is disposed against the separating partition151.

FIG.9represents a fluid transfer system according to a sixth embodiment forming a coaxial expansion joint.

A coaxial expansion joint is for example configured for transferring LNG in the central passage to a user's storage and transferring evaporated liquid to a supplier's liquefaction/storage unit.

This type of joint makes it possible to absorb longitudinal differential movements between the liquid transfer pipe110and the gas transfer pipe120.

It can operate in a horizontal position (orthogonal to gravity).

The gas transfer pipe120here has only a wall surrounding the liquid transfer pipe110, such that a gas flows between a wall of the liquid transfer pipe and the wall of the gas transfer pipe120.

Note also that the gas transfer pipe is formed here from two joined sections.

In such an embodiment, the buffer member130also forms a ring disposed around a junction of the incident section112and the receiving section113of the liquid transfer pipe110.

The fluid inlet131in the buffer member130includes here the leak passage142formed at the junction between the incident section112and the receiving section113, and bypassing the dynamic sealing member143.

The fluid outlet132includes, on one side, the exhaust valve144, and, on the other side, the leak passage145which is due to the presence of the dynamic sealing member146, which includes for example a seal and a journal bearing.

Here, the buffer member only includes a chamber forming the internal volume133, defined between the dynamic sealing member143, the dynamic sealing member146and the exhaust valve144. The buffer member is therefore here devoid of an inner wall147dividing the internal volume133.

FIG.10represents schematically a part of a fluid transfer system according to a seventh embodiment forming a coaxial expansion joint according to a first variant.

This embodiment differs from the preceding one in that it includes an additional buffer member2130, surrounding the gas transfer pipe120.

The additional buffer member is for example configured to guide and/or close the gas transfer pipe120.

The additional buffer member2130is for example rigidly connected to a first section2121of the gas transfer pipe120, and slidable relative to a second section2122of the gas transfer pipe120.

This additional buffer member2130also includes an internal volume2133, devoid of an inner wall147, such that it includes a single chamber.

A fluid inlet2131in the internal volume includes here a leak passage2142formed by a bypass of a dynamic sealing member2143including here a seal.

In a case of integration of the system part represented in a fluid transfer system, a fluid outlet2132includes a leak passage2145which is due to the presence of a dynamic sealing member2146, which includes for example here a seal and a journal bearing.

The internal volume2133is thus delimited on either side by the dynamic sealing member2143and the dynamic sealing member2146.

This representation does not account for the mechanical arrangement required for the recovery of the hydrostatic end forces generated by the fluid pressures.

This type of embodiment could accept small angles of rotation between the two sections insofar as the pressure and temperature constraints may cause them in sections along sinuous routes.

In a case of integration of the system part represented into another system, for example to form a connector to join two concentric pipes, it may be preferable to avoid the leak passage2145and render the dynamic sealing member2146tight.

FIG.11represents a fluid transfer system according to an eighth embodiment forming a coaxial expansion joint according to a second variant.

This embodiment differs from the preceding one in that the gas transfer pipe120includes here several sections, in particular three sections3121,3122,3123.

This embodiment forms a swivel device allowing a complete rotation. The rotation is allowed by a hinge member3152, for example with bearings, and/or journal bearings which can be pressurised, for example by the gas of the gas transfer pipe, or a lubricant accepting a temperature of −160° C. without setting.

It includes an additional buffer member3130surrounding here two sections3121,3122of the three sections of the gas transfer pipe120.

The additional buffer member3130is for example rigidly connected to a first section3121of the gas transfer pipe120, and slidable relative to a second section3122of the gas transfer pipe120.

This additional buffer member3130also includes an internal volume devoid of an inner wall, such that it only includes a chamber.

A fluid inlet3131in the internal volume includes here a leak passage3142formed by a clearance between the sections3121,3122.

A fluid outlet3132includes here a leak passage3145which is due to the presence of a dynamic sealing member3146, which includes for example here a schematised O-ring and a lip seal for the insulation of the hinge member3152.

FIG.12represents a fluid transfer system according to a ninth embodiment andFIG.13represents the system ofFIG.12, partially exploded.

This embodiment has a fluid transfer system in a swivel joint device corresponding for example to an offshore loading or offloading buoy.

In this example, the hinge member152also includes a first part153rigidly connected to the first fixed annular part and a second part154rigidly connected to the second mobile annular part. The second part154of the hinge member152is here rotatable relative to the first part153of the hinge member152.

However, the hinge member152includes here radial seals4153and friction bearings4154instead of the bearing ofFIGS.3to8for example.

A specificity of a purging and cleaning system is obtained using an inert and dry gas—in particular nitrogen—which may also serve to activate radial seals.

To operate this device, two manifolds, the overflow manifold160and the manifold157, are used: the overflow manifold160is configured to seal, purge or clean the buffer member130, the manifold157is configured for the same operations on the hinge member which is here configured to also seal the gas transfer pipe120with respect to an external environment. A seal referred to as “weather seal”, i.e. an external seal which protects the system from the marine environment, may be added if required.

It is possible to split the inlet/outlet ports for optimised flushing of the volumes in question. The use of journal bearings makes it possible for example to help reduce a thermal insulation to protect from the hinge member152.

The buffer member130includes here a fluid inlet4131having a leak passage4142bypassing the bearing115and dynamic sealing members4143,4143′, which here include radial seals. The dynamic sealing members4143,4143′ delimit a first chamber of the buffer member130between them.

At the outlet4132, a leak passage4145is formed by a dynamic sealing member4146including a bearing. The dynamic sealing member is here disposed between a wall of the buffer member130and the separating partition151and bearing against them.

As illustrated inFIG.13, the fixed elements between them are rigidly connected by studs.

The buffer member130may be made of several parts to allow an assembly of the radial seals in open grooves. For clearer illustration, static seals (i.e. annealed copper washers or fibre seals for cryogenic use) are not shown. The parts are assembled for example with hexacave screws.

FIG.14illustrates alternative embodiments of the liquid transfer pipe110including the two incident112and receiving113sections, according to a direction of liquid flow in the liquid transfer pipe110, and/or a desired pressure control for seals of the system.

The receiving section113may be oriented upwards (Figure A)) or downwards (Figure B)).

This can of course be transposed to all of the embodiments described above, and in the context of an embodiment according toFIG.14B), then the receiving section113is configured to slide relative to the corresponding buffer member130.

The fluid transfer system includes here a pressurisation system180.

The pressurisation system180is here configured to clean and/or drain the buffer member130.

In this example, the pressurisation system180includes at least one activation port181configured to activate a dynamic sealing member143,143′, and at least one purging port182, configured to drain at least a part of the internal volume of the buffer member.