NO20200460A1

NO20200460A1 - An emergency release system and an associated fluid transfer system and method for moored vessels or offshore structures

Info

Publication number: NO20200460A1
Application number: NO20200460A
Authority: NO
Inventors: Stian Tunestveit Magnusson; Patrick Fernand Constant Marie Englebert
Original assignee: Connect Lng As
Priority date: 2020-04-15
Filing date: 2020-04-15
Publication date: 2021-10-18
Also published as: NO346025B1

Description

TECHNICAL FIELD

The present invention is related to transfer of fluids such as liquids, liquefied gases, compressed gases and fluidized amorphous solids between a supply facility and a receiving facility. The supply facility is a floating structure such as a Floating Storage & Regasification Unit (FSRU) for LNG or LPG or a Floating Storage Unit (FSU) for LNG or LPG. Both an FSU and an FSRU are floating structures permanently moored near a market site. The receiving facility can be a floating or non-floating structure such as a power barge, an onshore regasification facility or an onshore or offshore pipe grid.

BACKGROUND

Transfer of temperate fluids from a vessel to an onshore facility is today achieved, among other methods, through a submerged flexible hose, which is lifted from the seabed and connected directly to the vessel’s manifold. To avoid excessive heat loss and accumulation of an external ice layer, the transfer of cryogenic fluids through any pipe in contact with water requires the pipe to be extensively insulated, resulting in considerably larger weight per meter than pipes used for transfer of temperate fluids. Comparably, to maintain the structural integrity of any flexible pipe transferring high-pressure fluids, a thicker structural layer is foreseen to increase radial and axial strength sufficient to withstand the high-pressure content, resulting in considerably larger weight per meter and a larger minimum allowable bending radius than a transfer pipe for transfer of low pressure, temperate fluids. The handling of transfer pipes for cryogenic and/or high-pressure applications will therefore often be unmanageable for the vessel’s lifting equipment and manifold. Furthermore, the transfer of cryogenic fluids requires precooling of the transfer pipes to avoid extensive vapor generation. The precooling must be conducted immediately prior to the transfer operation, and the transfer operation must commence shortly after arrival of the distribution carrier for cost efficient shipping. Moreover, the handling of many cryogenic fluids requires the implementation of special measures to minimize the risk of a spill in any event of default. Emergency shutdown systems, emergency release couplings, and special monitoring systems are often a deeply integrated part of a cryogenic transfer operation. Similarly, the handling of many high-pressure fluids also requires the implementation of special measures to minimize the risk of a large leak and/or component failure in any event of default. Emergency shutdown systems, emergency release couplings, and special monitoring systems are often a deeply integrated part of high-pressure fluid transfer operations. For high-pressure fluids however, there is a requirement for rapidly reducing the pressure prior to an emergency disconnection to avoid excessive forces and acceleration in the emergency release coupling and uncontrolled gas release. The emergency shut down systems are thus heavier, require more space and additional and/or different components when compared to standard designs for example for cryogenic purposes.

Transfer of fluids between an FSRU or FSU and shore is most often performed through articulated hard-pipe loading arms, whereas the FSRU is moored to a traditional quay or jetty. This transfer solution is dependent on relatively benign conditions to be able to continuously transfer fluids to shore due to both limited articulated motion in the loading arm joints and vessel mooring restrictions of the jetty or quay. For harsher environmental conditions, several alternative solutions exist. One such solution is a turret mooring system that is swivebly connected to the bottom of the vessel hull, where one or more flexible risers transfer fluid from the vessel to one or more subsea pipelines which again is connected to either a fixed-, an onshore- or a floating receiving facility. The vessel mooring is integrated in the turret allowing for weathervaning of the vessel. The turret solution requires a significant water depth to function. Another such alternative solution is a fixed tower structure combined with a swivably connected soft yoke mooring system that moors the vessel to the tower structure. Fluids are transferred from the bow of the vessel, through a flexible pipe or articulated hard pipe to the fixed tower structure.

From the tower structure, the fluid is transferred to a receiving facility through a subsea or trestled hard pipe or through a flexible pipe. The common factors among these solutions are the complexity and high cost which reduces the probability of a competitive gas price to the end user. A jetty or a fixed tower structure also has a significant environmental footprint, and with today’s environmentally friendly focus one will most likely have problems receiving the necessary permits for construction. Public pressure for more environmentally friendly energy sources demands an increased import of natural gas, but at the same time a requirement of a reduced environmental footprint demands new, cost efficient solutions with a small environmental footprint.

Further, most of the innovative floating transfer concepts that are used or suggested used for the transfer of fluids, e.g. for the petroleum industry, are often designed for temporary operations. A typical example is a shuttle tanker that approaches a receiving facility to offload its cargo. During this process, the shuttle tanker is moored to and/or near the receiving facility, the loading system connects, the transfer is performed and then the loading system disconnects. The shuttle tanker mooring system is then released, and the shuttle tanker leaves the site. The frequent connection and disconnection add complexity to the loading system, limits uptime and often requires large modifications to the shuttle tanker and/or receiving facility to accommodate transfer and/or station keeping.

Development work to date on a cost efficient, small footprint transfer solution is limited and the concepts available today clearly don’t take into account the complete set of challenges related to either the cryogenic or high-pressure transfer situation, nor the challenges with shallow water or permanent continuous fluid transfer. In a high-pressure system for instance, one cannot simply disconnect, but one needs to equalize the pressure in advance. Further, for a cryogenic system, the thermal contractions are significant and if not considered in the design, structural damage will occur. In addition, the freeboard of the vessels in question are often considerable, and an activation of the emergency release system has the potential to damage the vessel hull and/or the components at the free end of the flexible pipe. A pure catenary shape of a flexible hose will also require a significant water depth and if not corrected by buoyancy devices have large tension forces in the catenary line.

U.S. Pat. No.10,532,796 describes a non-weathervaning transfer structure for transfer of fluid between a floating structure and a floating or non-floating facility and/or transmission of electric power. The transfer structure is a semi-submersible structure, floating and connected to a floating or non-floating facility by releasable attachment means. Fluid is transferred through at least one transfer line and at least one aerial transfer line.

U.S. Pat. No. US 7,543,613 describes a method of transferring cryogenic fluid in a body of water and comprises a pipe spool piece swivably connected to a conduit first end. The pipe spool piece is connected to a first vessel by means of a quick release connection. The conduit is further maintained in a catenary shape between the first and second vessel. The transfer system is designed for quick connection and disconnection and to be stored on a conduit transfer vessel inbetween transfer operations.

WO 2019/048546 A1 describes a tie-in system for flexible transfer conduits, where lateral manifold forces are absorbed by a chute device while axial forces are supported by tie-in devices. Thermal contraction is accounted for using sliding supports and limit stops prevents excessive motion in the piping system.

U.S. Pat. No.6,915,753 describes an apparatus for mooring a tanker for transporting liquid natural gas. The apparatus is described as including a semi-submersible floating dock, a single point mooring system, and at least one rigid arm. Fluids from the ship are passed to the single point mooring system through flexible hoses. The ship is kept stationary by the single point mooring system. The flexible hoses are said to take a catenary form and are further said to be either held above the water or partially in contact with the water.

U.S. Pat. No.6,923,225 describes articulated hard-pipe loading arms for transferring liquid natural gas between a tanker vessel and a processing vessel.

U.S. Pat. No.4,718,459 describes an underwater cryogenic pipeline system for transporting liquefied natural gas in underwater locations between an onshore production or storage facility and an offshore vessel.

US2004/0011424 describes a transfer system between a floating vessel and a fixed installation. A tubular conveying arrangement is described, comprising a connection device and a flexible transfer pipe connected to the installation. The free end of the flexible transfer tube is provided with handling means to move the free end between a connection position to the connection device and a disengaged storage position.

However, the current methods for moderately harsh environmental conditions in shallow water have limited usefulness, especially for continuous transfer over several years. One needs a transfer system that enables transfer in shallow water with a design that reduces wave action in the flexible pipe, avoids seabed contact and risk of pipe damage while at the same time minimizing the risk of collision with floating objects. One also needs a system that enables a safe disconnection in case of emergency, with reliable trigger signals and without damaging any equipment or structures while at the same time offering a reliable, continuous transfer operation.

SUMMARY OF THE INVENTION

The present invention is set forth and characterized in the independent claims. Preferred embodiments are set forth in the dependent claims.

The present invention is particularly suited for high pressure fluid purposes due to the large weight of the reinforced transfer pipes for high-pressure application and the facilitation of convenient gas blow-down and flexible pipe emergency release, and also particularly suited for cryogenic purposes due to the challenges related to thermal contraction and the large weight of insulated transfer pipes for cryogenic application and the facilitation of convenient purging and precooling. The present invention is also particularly suited for continuous transfer of fluids for a substantial period of time where the supply facility and/or the receiving facility are stationary during the said substantial period of time. A substantial period of time in the light of this disclosure is defined as a time period longer than one week. The invention will presumably be a suitable alternative for protected and moderately protected waters where environmental conditions are not as harsh as in open waters and moderate distance between the supply facility and the receiving facility.

It is described an emergency release system for a fluid transfer system transferring pressurized fluids from a supply facility, such as a floating structure, to a receiving facility, such as a floating or a non-floating structure, wherein the emergency release system comprises:

- an emergency release coupling comprising: a first coupling half comprising a coupling inlet connectable to an upstream pipe, and a second coupling half comprising a coupling outlet connectable to a downstream flexible pipe, wherein the first and second coupling halves form a fluid connection between the coupling inlet and the coupling outlet when the first and second coupling halves are connected,

- a blow-down vent pipe, provided with a blow-down vent valve, connected to a blowdown connection in fluid communication with the emergency release coupling for controlled ventilation of pressure,

- a fall arrest device configured to retard a fall of at least one coupling half after a disconnection of the first and second coupling halves.

By connectable it is understood that the components can be directly connected or connected via one or more intermediate components. By connected it is understood that the components are directly connected or connected via one or more intermediate components.

It is thus achieved a system that prevents or at least significantly limits the damages to the downstream pipe in the event of an emergency disconnect. When the blow-down vent valve is opened, the blow-down vent pipe will ventilate the pressure in the emergency release coupling, such that the pressure in the emergency release coupling is sufficiently low prior to an emergency release. The reduction in pressure in the emergency release coupling greatly reduces the accelerations of the second coupling half when it is separated from the first coupling half. The fall arrest device will reduce the speed of the downstream pipe and the second coupling half when disconnected from the emergency release coupling. The downstream pipe and the second coupling half will be lowered down in a controlled manner preventing them from hitting the vessel. Generation of sparks is then also prevented, or at least significantly limited.

The first coupling half may comprise an upstream emergency shut down valve having an open and a closed position, wherein the upstream emergency shut down valve in the closed position is configured to isolate the first coupling half from the supply facility, wherein the upstream emergency shut down valve is arranged upstream the blow-down connection.

The second coupling half may comprise a downstream emergency shut down valve having an open and a closed position, wherein the downstream emergency shut down valve in the closed position is configured to isolate the second coupling half from the receiving facility wherein the downstream emergency shut down valve is arranged downstream the blow-down connection.

The emergency release system may further comprise an upstream emergency shut down valve having an open and a closed position, wherein the upstream emergency shut down valve is arranged upstream the first coupling half and in the closed position configured to isolate the first coupling half from the supply facility, wherein the upstream emergency shut down valve is arranged upstream the blow-down connection,

and/or

The emergency release system may further comprise a downstream emergency shut down valve having an open and a closed position, wherein the downstream emergency shut down valve is arranged downstream the second coupling half and in the closed position configured to isolate the second coupling half from the receiving facility, wherein the downstream emergency shut down valve is arranged downstream the blow-down connection.

The emergency release system may further comprise a chute device for arrangement around the flexible pipe.

The emergency release system may further comprise a bend restrictor for arrangement on the flexible pipe.

The chute and the bend restrictor will limit bending of the downstream pipe before and after an emergency release.

The chute and the bend restrictor will limit moments and shear forces in the upstream pipe before an emergency release.

The emergency release system may further comprise a retrieving mechanism and an alignment mechanism for reconnection of the first and second coupling halves after a disconnection of the first and second coupling halves.

The emergency release system may further comprise a buoyancy element for arrangement on the flexible pipe.

The buoyancy element will prevent seabed interaction with downstream pipe before and after an emergency disconnect.

The buoyancy element can be arranged such that it protects the emergency shut down valve actuator from impacts during and after an emergency release.

It is described a fluid transfer system for transfer of pressurized fluids from a supply facility to a receiving facility, wherein the fluid transfer system comprises:

- an emergency release system of the above-described type

- an upstream pipe comprising an upstream pipe inlet connectable to a supply facility outlet, and an upstream pipe outlet connected to the coupling inlet,

- a support structure installable on the supply facility and/or the receiving facility, the support structure being configured to support the upstream pipe,

- a downstream flexible pipe comprising a flexible pipe inlet connected to the coupling outlet, and a flexible pipe outlet connectable to an inlet of the receiving facility.

The fluid transfer system is configured for high pressures, such as 20 barg and above.

The support structure may be detachably connected to the supply facility and/or the receiving facility, preferably by means of a bolted connection.

Hot works can thus be avoided during installation and retrieval of the fluid transfer system. The support structure may have a horizontal connection interface and/or a vertical connection interface towards the supply facility and/or the receiving facility.

The support structure may encircle the upstream pipe.

The fluid transfer system may further comprise a swivel arranged between the second coupling half and the flexible pipe.

It is described a method for transferring pressurized fluids from a supply facility to a receiving facility by means of a fluid transfer system of the above-described type. The method comprises the steps of: connecting the flexible pipe outlet to the inlet of the receiving facility, installing the support structure on the supply facility or the receiving facility, connecting the upstream pipe inlet to the supply facility outlet, allowing pressurized fluids to be transported from the supply facility to the receiving facility.

Emergency shut down valves may be provided in the emergency release system or in the supply facility and the receiving facility. If an emergency disconnect is to be performed, the emergency disconnection may then comprise the steps of: closing the emergency shut down valves to isolate the emergency release coupling from the supply facility and the receiving facility, such that a volume is defined between the emergency shut down valves, opening the blow-down vent valve to reduce a pressure in the volume defined by the closed emergency shut down valves, disconnecting the first and second coupling halves, lowering the second coupling half by means of the fall arrest device to at least partly prevent a free fall of the second coupling half.

The system may further comprise a retrieving mechanism and an alignment mechanism. If a reconnection is to be performed the reconnection may comprise the steps of: retrieving the second coupling half to be adjacent the first coupling half by means of the retrieving mechanism, aligning the second coupling half with the first coupling half by means of the alignment mechanism, reconnecting the first and second coupling halves.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is a fluid transfer system 10 comprising a support frame 20, an upstream pipe 25 such as a flexible or non-flexible pipe section, a coupling assembly 30 and a flexible transfer pipe 50 for transfer of fluid such as e.g. cryogenic liquid or high-pressure gas from a supply facility 2 to a receiving facility 5. In this disclosure, the terms duct, pipe, hose and conduit are used interchangeably in reference to the transfer pipe means of this invention and these terms are to be deemed equivalent, unless otherwise stated. The upstream pipe 25 is arranged on the support frame 20 such that the flexible transfer pipe 50 is hanging vertically outboard the supply facility 2 and/or the receiving facility 5. For the purpose of this disclosure, the coupling assembly 30 comprises all components on the pipe string that is not the upstream pipe 25 and the flexible transfer pipe 50.

For the purpose of this disclosure, a high-pressure fluid is a gas and/or liquid phase fluid which is transferred at a pressure higher than 20 barg.

For the purpose of this disclosure, a cryogenic fluid is a gas and/or liquid phase fluid which is transferred at a temperature lower than -45°C.

For the purpose of this disclosure, a blow-down is the process of rapidly reducing pressure in a system, equalizing the pressure entrapped in a high-pressure finite boundary with a larger volume at atmospheric or close to atmospheric pressure.

For the purpose of this disclosure, an emergency release is defined as a controlled disconnection, isolating the supply facility from the receiving facility. There are various trigger signals for an emergency release and various emergency release systems (ERS) and these are well known in the industry. The emergency release coupling (ERC) is the mechanical component of the ERS and can include a valve system on each side of the release coupling (dry break away coupling) or be a standalone release coupling.

For the purpose of this disclosure, a drain process is the process of removing the liquid from the coupling assembly fixed portion 32 after an emergency release.

The illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. The words and phrases used herein should be understood and interpreted to have a meaning consistent with the understanding of those words and phrases by those skilled in the relevant art.

The supply facility 2 can be a floating vessel designed for storing and/or regasification of liquefied natural gas (LNG) or Liquid Petrochemical Gas (LPG), and the receiving facility 5 can be a facility for regasification of LNG or LPG and/or power generation. Both the supply facility 2 and the receiving facility 5 may be moored or installed at or near a market site for the fluid. The support frame 20 in this invention may be mounted on the supply facility 2 and/or the receiving facility 5 using a bolted connection. The bolted connection 23 should preferably be positioned such that the forces and moments are transferred directly onto the load bearing structure of the supply facility 2 and/or the receiving facility 5. Further, the bolted connection 23 can be positioned and designed such that no “hot-work” needs to be performed during installation of the support frame 20. Hot-work is a process that can be a source of ignition when flammable and/or explosive material is present or can be a fire hazard regardless of the presence of flammable material in the workplace and the term is known for a person skilled in the art. The bolted connection 23 is installed a sufficient distance away from manifolds on the supply facility 2 and/or the receiving facility 5 and/or flanges of the upstream pipe 25 and/or flanges in the coupling assembly 30, and the bolted connection 23 is not installed directly onto a cargo tank.

The purpose of the support frame 20 is to support the upstream pipe 25 and to support the equipment in the coupling assembly 30 necessary for conducting a safe and reliable transfer of fluid from the supply facility 2 to the receiving facility 5, and to withstand the forces and moments from the flexible transfer pipe 50. During transfer of any fluid, a situation may arise where there is a need to quickly disconnect the transfer system, isolating and/or separating the supply facility 2 from the receiving facility 5. A typical situation where an emergency disconnection is deemed necessary can be, among other things, a failure in the mooring system. To achieve an emergency disconnection, an emergency release coupling (ERC) 35 is required between the upstream pipe 25 and the flexible transfer pipe 50. The ERC 35 is a collar system holding two flanges together in a normal operation and separating the two flanges by releasing the collar. There are several types of ERCs. One type of ERC includes a valve on each immediate side of the collar such that it may isolate the coupling assembly releasable portion 31 and the coupling assembly fixed portion 32. If the fluid in the system is cryogenic, then after closure of these two valves, a small quantity of cryogenic liquid remains entrapped temporarily between the said valves; this liquid is released after opening of the collar 36 and could spill to the surrounding structures and the hull of the supply facility. Therefore, for cryogenic fluids, it is important that these valves are close together. For transfer of a high-pressure gas however, there is not the same need for an ERC 35 with integrated valves. For high-pressure gas it is more important to reduce the pressure in the system prior to a breakaway to avoid uncontrolled release of gas and high accelerations and forces in the releasable second coupling half 38 of the ERC 35 during an emergency release. For a high-pressure emergency release, it is therefore a need for a blow-down vent pipe 43 fluidly connected to the upstream pipe 25 and/or in-between a upstream and downstream emergency shut down valve 39,40 enclosing the ERC 35 in order to reduce the pressure inside the ERC 35 prior to a release. The upstream and downstream emergency shutdown valve 39,40 may be a component of the fluid transfer system 10 and/or be a part of the supply facility 2 and the receiving facility 5. The upstream and downstream emergency shutdown valve 39,40 will close and a “blow-down” will be initiated prior to an emergency disconnection of the ERC 35 In order to minimize the volume of high-pressure gas and thus the time required for the blow-down, a downstream emergency shutdown valve 40 may be fitted between the ERC 35 and the flexible transfer pipe 50. The upstream emergency shut down valve 39 may be the ESD valve of the supply facility 2. Alternatively, the ERC 35 may have a valve on each immediate side of the collar 36 with an integrated blow-down vent pipe 43 connected in-between the two valves. Further, these valves may be an integrated part of the ERC 35 such that the first coupling half 37 comprises an upstream emergency shut down valve 39 and the second coupling half 38 comprises a downstream emergency shut down valve 40. The blow-down connection 42 is then fluidly connected to the first coupling half in-between the upstream and downstream emergency shut down valve.

An emergency shut down valve is defined in this disclosure as a valve that has an open and a closed position and that can be placed in the closed position prior to an emergency release.

The support frame 20 is typically mounted at or near the main deck of the supply facility 2 and/or the receiving facility 5 and the ERC 35 is hence situated a certain level above the waterline. In order to avoid any damage to the hull of the supply facility 2 and/or the receiving facility 5 due to large velocities in a free-falling flexible transfer pipe 50, a fall arrest system 60 is required. A fall arrest system 60 limits the velocity of the falling free end of the ERC 35 by e.g. a constant velocity pump connected to a spool drum with a wire connected to the ERC and is a known component in the industry.

The support frame 20 can be mounted with bolts to the supply facility 2. Supported by the support frame 20 is at least one upstream pipe 25 bolted or welded to the supply facility outlet 3 on the supply facility 2. The supply facility outlet 3 may be a horizontal manifold and the upstream pipe 25 will then have a 90 degrees bend outboard such that the coupling assembly 30 hangs vertically. In fluid communication with the vertical section of the upstream pipe 25 is a coupling assembly 30 comprising an ERC 35 with two valves integrated on each side of the collar 36 and a blow-down vent pipe 43 fluidly connected in-between the two valves. On the support frame 20, there is a fall arrest system 60 connected to the ERC releasable portion 38. Fluidly connected to the coupling assembly releasable portion 31 is at least one flexible transfer pipe 50.

The coupling assembly 30 may comprise an ERC 35, and a downstream emergency shut down valve 40 and a blow-down vent pipe 43, whereas the downstream emergency shut down valve 40 is between the flexible transfer pipe 50 and the ERC 35, and the blow-down vent pipe 43 is connected between the ERC 35 and the supply facility outlet 3.

The fluid transferred may be cryogenic. The support frame 20 is preferably mounted with bolts to the supply facility 2. Supported by the support frame 20 is at least one upstream pipe 25 bolted to the supply facility outlet 3 of the supply facility 2 with a flexible bellow 115 inserted between the upstream pipe 25 and the supply facility outlet 3 in order to absorb the combined thermal contraction of the upstream pipe 25 and of the coupling assembly 30. If the supply facility outlet 3 is horizontal the upstream pipe 25 may have a 90 degrees bend outboard. Fluidly connected to the vertical section of the upstream pipe 25 is a coupling assembly 30 comprising an ERC 35 with two valves integrated on each side of the collar 36. On the support frame 20, there is a fall arrest system 60 connected to the releasable part of the ERC 35. Fluidly connected to the coupling assembly releasable portion 31 is at least one flexible transfer pipe 50.

The flexible transfer pipe 50 has two end portions, whereas the first end portion 51 may be fluidly connected to the coupling assembly 30 which is fluidly connected to the upstream pipe 25 on the support frame 20 mounted to the supply facility 2 and the other end portion 52 is fluidly connected to the receiving facility inlet 6 of the receiving facility 5. The upstream pipe 25 will be custom made for the actual manifold arrangement and can be connected with little or no modifications to the supply facility outlet 3. The flexible transfer pipe 50 in the present invention can connect to any connection means provided for the purpose of transfer to and/or from the receiving facility 5. For example, for a typical power barge the manifold is usually horizontal, located some distance inboard the barge’s sides and at a certain level above the main deck. The flexible duct second end portion 52 may be connected directly to the barge’s manifold supported by a chute and chains. It is sufficient with only allowing for an emergency disconnection of the first end portion 51 of the flexible transfer pipe 50 where the first end portion 51 of the flexible transfer pipe 50 is connected to the coupling assembly 30 on the supply facility 2.

The coupling assembly 30 consists of two parts, the first part being the coupling assembly releasable portion 31 which will remain connected to the coupling assembly fixed portion 32 until an emergency release is initiated and the second part being the coupling assembly fixed portion 32 which is permanently connected to the upstream pipe 25. The flexible transfer pipe 50 is connected to the coupling assembly releasable portion 31. The upstream pipe 25 is connected to the coupling assembly fixed portion 32. If an emergency release is initiated, the coupling assembly releasable portion 31 will separate from the coupling assembly fixed portion 32, and the coupling assembly releasable portion 31, together with the flexible transfer pipe 50, will fall into the water.

The coupling assembly 30 has a coupling assembly inlet 33 which is connectable with the upstream pipe 25, and a coupling assembly outlet 34 which is connectable with a downstream transfer pipe such as a flexible pipe.

The coupling assembly releasable portion 31 may comprise the second coupling half 38 and a downstream emergency shut down valve 40, and the coupling assembly fixed portion 32 comprises the first coupling half 37 and the blow-down connection pipe 43.

The coupling assembly releasable portion 31 may comprise the second ERC half 38 with an integrated valve, and the coupling assembly fixed portion 32 may comprise the first ERC half 37 with an integrated valve and the blow-down vent pipe 43 which is fluidly connected to the first ERC half and/or between the first- and second ERC half (37,38).

The coupling assembly releasable portion 31 may comprise a swivel device 45 in addition to the already mentioned components described in other embodiments.

The fluid transfer system 10 may be mounted on the receiving facility 5, allowing for disconnection on the second end portion 52 of the flexible transfer pipe 50.

The fluid transfer system 10 may be mounted on the supply facility 2 where the first end portion 51 of the flexible transfer pipe 50 is fluidly connected to the coupling assembly 30 fluidly connected to the upstream pipe 25 supported by the support frame 20 and where the second end portion 52 is fluidly connected to a second vessel acting as floating jettyless transfer system to facilitate connection to a third vessel. The third vessel being a transport vessel of fluid cargo. The upstream pipe may have a bend between 0 degrees and 180 degrees.

The supply facility 2 may have a vertical manifold and/or somewhere in between a horizontal and vertical manifold. The upstream pipe will 25, regardless of the orientation of the supply facility outlet 3, be designed such that the coupling assembly 30 is hanging vertically.

The flexible transfer pipe 50 may be a floating flexible hose and/or a submerged flexible hose. The flexible transfer pipe 50 may be a flexible riser with the first end portion 51 connected to the coupling assembly 30 while the second end portion 52 is connected to a rigid hard pipe on the seabed and/or on a trestle structure. The submerged flexible pipe 50 can, in locations with significant water depth take the shape of a catenary line. For areas with limited water depth, the catenary is not possible. In that case, and if the net buoyancy of the flexible pipe is negative, the submerged flexible hose 50 may be supported from buoys on the water surface, alternatively if the net buoyancy of the flexible hose is positive, the flexible hose may be retained by heavy weights and/or anchors on the seabed, or a combination of buoys and heavy weights and/or anchors if necessary. The reason one might want to submerge the flexible transfer pipe is to reduce the risk of collisions with boats or floating objects and/or reduce wave action on the transfer pipe.

A swivel device 45 may be included in the coupling assembly releasable portion 31. The swivel 45 is preferably the component in the coupling assembly releasable portion 31 that is closest to the flexible transfer pipe 50 in order to avoid entanglement and problems with tubing and cables when the flexible transfer pipe 50 rotates with the swivel 45. The purpose of the swivel device 45 is to reduce torsion in the flexible transfer pipe and coupling assembly 30. For high-pressure gas the coupling assembly 30 may include at least one blow-down connection pipe 43, at least one ERC 35 with valves integrated and a swivel device 45. For cryogenic fluids, the coupling assembly 30 may comprise a drain connection pipe 120, an ERC 35 and a swivel device 45, in that order with the swivel device 45 nearest the first end portion 51 of the flexible transfer pipe 50.

After an emergency release, the coupling assembly releasable portion 31 connected to the flexible transfer pipe 50 is floating on the water surface. In order to reset the transfer system one needs to reconnect the coupling assembly releasable portion 31 with the coupling assembly fixed portion 32 by connecting the two portions of the ERC 35, namely the second coupling half 38 and the first coupling half 37. In order to join the coupling assembly releasable and fixed portion 31,32, a retrieval device 110 is mounted on the support frame to retrieve the coupling assembly releasable portion 31 from the water. The retrieval device can for example be a winch system. The retrieval device can naturally be used when installing the coupling assembly 30 to the upstream pipe 25 and/or installing the flexible transfer pipe 50 to the coupling assembly 30 and/or installing the components in the coupling assembly 30.

The coupling assembly releasable portion 31 is often heavy, often comprising components manufactured in steel or other strong and heavy materials and is thus not positively buoyant. In order to keep the coupling assembly releasable portion 31 and the flexible transfer pipe first end portion 51 afloat in the water after an emergency release, a buoyancy and protection module 70 with sufficient buoyancy may be mounted to the coupling assembly 30. The buoyancy and protection module 70 also provides protection of the ESD valve actuator 41 and/or the ERC actuator of the ERC second coupling half 38, avoiding spurious opening of the downstream emergency shut down valve 40 and/or ERC valve 35 and assuring that critical components don’t become damaged during the fall. Furthermore, the buoyancy and protection device 70 also offers protection of the hull with its softer properties compared to steel and avoids the risk of sparks during the fall.

The buoyancy and protection module 70 may also comprise a screen to protect the surrounding structures and the hull of the supply facility 2 from cryogenic fluid spilled after release of the ERC collar 36.

Moreover, due to the high mass of the coupling assembly releasable portion 31 combined with the wave forces acting on the coupling assembly releasable portion 31 and the buoyancy and protection module 70, there is a risk of excessive bending of the flexible transfer pipe first end portion 51 connected to the coupling assembly releasable portion 31. In order to protect the flexible transfer pipe 50, a bend restrictor 53 may be included to limit the bending of the flexible transfer pipe first end portion 51. A bend restrictor is widely used in the industry.

Whether resetting after an emergency release or installing the coupling assembly 30 to the upstream pipe 25 and/or installing the flexible transfer pipe 50 to the coupling assembly 30 and/or installing the components in the coupling assembly 30 together, precision handling is important. In order to achieve this precision handling even with waves acting on the system, an alignment and locking device 100 is suggested. The alignment and locking device 100 has an alignment portion 101, a locking portion 102 and an alignment and locking device support beam 103. Furthermore, the alignment and locking device support beam 103 comprises a support beam first end portion 104, connected to or near the support frame 20, and a support beam second end portion 105 which is used to support the locking portion 102 and/or the alignment portion 101. The purpose of the locking portion 102 is to keep the component to be installed in place and the purpose of the alignment portion 101 is to adjust the position and/or the orientation of the component to be installed relative to the upstream pipe 25 in one, two or three degrees of freedom. The locking portion 102 may be a clamp that is pressed around the flexible transfer pipe’s first end portion 51. The clamp may be supported by an alignment and locking device support beam 103 pivotally connected to the support frame 20. The alignment device 101 may be a hydraulic or mechanical jack that is mounted on the alignment and locking device support beam 103 allowing for adjusting the vertical position of the coupling assembly 30 and flexible transfer pipe 50. Alternatively, the locking device 102 may be a lifting pad compatible with the hydraulic or mechanical jack. The lifting pad can be mounted on either of the flanges in the coupling assembly releasable portion 31, preferably the flange of the flexible transfer pipe first end portion 51. Furthermore, the alignment and locking device support beam 103 can be adjusted vertically along the support frame 20. The vertical adjustment of the support beam 103 may be achieved by mounting a sliding track 106, e.g. for a linear-motion bearing or similar, on the support frame 20. The support beam first end portion 104 may be designed to be compatible with and/or fit inside the sliding track 106 on the support frame 20, to allow vertical sliding of the alignment and locking device 100. A pin or similar may be used to fix the support beam 103 at the preferred vertical elevation. Moreover, the alignment and locking device 100 may be detachable from the support frame 20.

In harsh weather conditions and/or with longer lengths between the supply facility 2 and the receiving facility 5, the forces acting on the flexible transfer pipes may be large. The forces acting on the flexible transfer pipe 50 will be transferred as forces and moment acting on the connections between the components in the coupling assembly 30 and/or the connection between the flexible transfer pipe 50 and the coupling assembly 30. Therefore, there may be a chute device 80 mounted on the support frame 20 by means of a chute support 83. The chute device 80 absorbs forces and moments from the transfer pipe 50 and directs them to the support frame 20 and limits the bending of the hose 50. The chute 80 may have a 3D shape with a chute side wall 81 and a chute front wall 82. The chute 80 can also be curved such that the side walls 81 transition seamlessly into the front wall 82, providing support of the flexible transfer pipe 50 in all relevant horizontal directions. Furthermore, the chute 80 may comprise a chute edge 84 that is flush with the buoyancy and protection module 70 and functions partly as a guide of the coupling assembly releasable portion 31 during emergency release.

For cryogenic fluids it is important to be able to drain the coupling assembly fixed portion 32 some time after a breakaway. Therefore, in an embodiment of the invention, a drain pipe 120 is fluidly connected to the coupling assembly 30 or the upstream pipe 25.

FIGURE REFERENCE

Claims

1. An emergency release system (1) for a fluid transfer system transferring pressurized fluids from a supply facility (2), such as a floating structure, to a receiving facility (5), such as a floating or a non-floating structure, wherein the emergency release system (1) comprises:

• an emergency release coupling (35) comprising

i. a first coupling half (37) comprising a coupling inlet (47) connectable to an upstream pipe (25), and ii. a second coupling half (38) comprising a coupling outlet (48) connectable to a downstream flexible pipe (50),

wherein the first and second coupling halves (37,38) form a fluid connection between the coupling inlet and the coupling outlet when the first and second coupling halves are connected,

• a blow-down vent pipe (43), provided with a blow-down vent valve (44), connected to a blow-down connection (42) in fluid communication with the emergency release coupling (35) for controlled ventilation of pressure,

• a fall arrest device (60) configured to retard a fall of at least one coupling half (38) after a disconnection of the first and second coupling halves (37,38).

2. The emergency release system (1) according to claim 1,

wherein the first coupling half (37) comprises:

• an upstream emergency shut down valve (39) having an open and a closed position,

wherein the upstream emergency shut down valve (39) in the closed position is configured to isolate the first coupling half (37) from the supply facility (5),

wherein the upstream emergency shut down valve (39) is arranged upstream the blow-down connection (42), and

wherein the second coupling half (38) comprises:

• a downstream emergency shut down valve (40) having an open and a closed position,

wherein the downstream emergency shut down valve (40) in the closed position is configured to isolate the second coupling half (38) from the receiving facility (5)

wherein the downstream emergency shut down valve (40) is arranged downstream the blow-down connection (42).

3. The emergency release system (1) according to claim 1,

wherein the system further comprises:

wherein the upstream emergency shut down valve (39) is arranged upstream the first coupling half (37) and in the closed position configured to isolate the first coupling half (37) from the supply facility (2),

wherein the upstream emergency shut down valve (39) is arranged upstream the blow-down connection (42),

and/or

wherein the downstream emergency shut down valve (40) is arranged downstream the second coupling half (38) and in the closed position configured to isolate the second coupling half (38) from the receiving facility (5),

4. The emergency release system (1) according to any one of the preceding claims,

wherein the system further comprises:

• a chute device (80) for arrangement around the flexible pipe (50), and/or

• a bend restrictor (53) for arrangement on the flexible pipe (50).

5. The emergency release system (1) according to any one of the preceding claims,

wherein the system further comprises:

a retrieving mechanism (110) and an alignment mechanism (100) for reconnection of the first and second coupling halves (37,38) after a disconnection of the first and second coupling halves (37,38).

6. The emergency release system (1) according to any one of the preceding claims,

wherein the system further comprises:

• a buoyancy element (70) for arrangement on the flexible pipe (50).

7. A fluid transfer system (10) for transfer of pressurized fluids from a supply facility (2) to a receiving facility (5),

wherein the fluid transfer system (1) comprises:

• an emergency release system (1) according to any one of claims 1-6 • an upstream pipe (25) comprising

i. an upstream pipe inlet (26) connectable to a supply facility outlet (3), and

ii. an upstream pipe outlet (27) connected to the coupling inlet (47),

• a support structure (20) installable on the supply facility (2) and/or the receiving facility (5),

the support structure (20) being configured to support the upstream pipe (25),

• a downstream flexible pipe (50) comprising

i. a flexible pipe inlet (54) connected to the coupling outlet (48), and

ii. a flexible pipe outlet (55) connectable to an inlet of the receiving facility (5).

8. The fluid transfer system (10) according to claim 7,

wherein the system (10) is configured for pressures above 20 barg.

9. The fluid transfer system (10) according to claim 7 or 8,

wherein the support structure (20) is detachably connected to the supply facility (2) and/or the receiving facility (5), preferably by means of a bolted connection.

10. The fluid transfer system (10) according to claim 7-9,

wherein the support structure (20) has a horizontal connection interface (21) and/or a vertical connection interface (22) towards the supply facility (2) and/or the receiving facility (5).

11. The fluid transfer system (10) according to claim 7-10,

wherein the support structure (20) encircles the upstream pipe (25).

12. The fluid transfer system (10) according to claim 7-11,

wherein the system further comprises:

a swivel (45) arranged between the second coupling half (38) and the flexible pipe (50).

13. A method for transferring pressurized fluids from a supply facility (2) to a receiving facility (5) by means of a fluid transfer system (10) according to any one of claims 7-12,

wherein the method comprises the steps of:

• connecting the flexible pipe outlet to the inlet of the receiving facility (5),

• installing the support structure (20) on the supply facility (2) or the receiving facility (5),

• connecting the upstream pipe inlet to the supply facility outlet (3), • allowing pressurized fluids to be transported from the supply facility (2) to the receiving facility (5).

14. The method according to claim 13,

wherein emergency shut down valves (39,40) are provided in the emergency release system (1) or in the supply facility (2) and the receiving facility (5), wherein an emergency disconnect is to be performed, the emergency disconnection comprises the steps of:

• closing the emergency shut down valves (39,40) to isolate the emergency release coupling (35) from the supply facility (2) and the receiving facility (5), such that a volume is defined between the emergency shut down valves (39,40),

• opening the blow-down vent valve (44) to reduce a pressure in the volume defined by the closed emergency shut down valves (39,40), • disconnecting the first and second coupling halves (37,38),

• lowering the second coupling half (38) by means of the fall arrest device (60) to at least partly prevent a free fall of the second coupling half (38).

15. The method according to claim 14,

wherein the system further comprises:

• a retrieving mechanism (110) and

• an alignment mechanism (100),

wherein a reconnection is to be performed the reconnection comprises the steps of:

• retrieving the second coupling half (38) to be adjacent the first coupling half (37) by means of the retrieving mechanism (110), • aligning the second coupling half (38) with the first coupling half (37) by means of the alignment mechanism (100),

• reconnecting the first and second coupling halves (37,38).