Floating regasification system for liquefied natural gas (LNG)

Abstract

A floating regasification system for liquefied natural gas (LNG) comprises a floating structure having an upper installation surface, at least one regasification module attached to the upper installation surface, a first fluid transfer assembly in fluid communication with an input side of the at least one regasification module, and a second fluid transfer assembly in fluid communication with an output side of the at least one regasification module, wherein the at least one regasification module is configured to receive LNG through the first fluid transfer assembly, to vaporize the LNG to generate a gas, and to deliver the gas into the second fluid transfer assembly, and wherein each of the fluid transfer assemblies has at least one flexible hose for transferring LNG to the at least one regasification module or gas to an onshore consumer, respectively.

Description

[0001] Floating regasification system for liquefied natural gas (LNG)

[0002] Field of the invention

[0003] The present invention relates to a floating regasification system for liquefied natural gas.

[0004] Background

[0005] Floating storage units (FSU) for liquefied natural gas (LNG) are typically realized in the form of a vessel moored in the vicinity of a terminal and connected to a regasification unit for delivering natural gas (NG) to an onshore consumer. The regasification unit may be arranged on the vessel itself to form a floating storage and regasification unit (FSRU) or outside the vessel. The FSU may be supplied with LNG by LNG carriers and remain stationary itself. The FSU supplies LNG to a regasification unit, which vaporizes it to reach the gaseous state. This may, for example, be accomplished by submerged combustion vaporizers (SCV), which employ a combustion process for creating heated water as a heating medium for vaporizing the LNG. As an alternative, sea water flowing through a heat exchanger may be used as a heating medium in open rack vaporizers (ORV). Usually, the resulting gas (NG) is supplied to a consumer onshore through a fixedly installed pipe system.

[0006] Summary of the invention

[0007] Existing solutions for storage and regasification of LNG are not flexible in their setup. A higher demand for natural gas at least requires a higher regasification capacity. Manufacturing a floating storage and regasification unit, the conversion of an LNG carrier into a floating storage and regasification unit and manufacturing a new or modified onshore regasification terminal is cost-intensive, requires a long lead time and / or has a high environmental impact.

[0008] It is thus an object of the invention to provide a solution for providing a flexible regasification capacity for onshore consumers. This object is met by a floating regasification system for LNG as defined by the independent claim. Advantageous embodiments and further improvements can be gathered from the dependent claims and the following description.

[0009] A floating regasification system for liquefied natural gas (LNG) is proposed, the system comprising a floating structure having an upper installation surface, at least one regasification module attached to the upper installation surface, a first fluid transfer assembly in fluid communication with an input side of the at least one regasification module, and a second fluid transfer assembly in fluid communication with an output side of the at least one regasification module, wherein the at least one regasification module is configured to receive LNG through the first fluid transfer assembly, to vaporize the LNG to generate a gas, and to deliver the gas into the second fluid transfer assembly, and wherein each of the fluid transfer assemblies has at least one flexible hose for transferring LNG to the at least one regasification module or gas to an onshore consumer, respectively.

[0010] The floating regasification system as described herein mitigates or eliminates the need for expensive and intrusive permanent infrastructure. It limits the environmental footprint and seabed interaction and is scalable upon demand. It also enables a floating storage and regasification terminal (FSRU) with the inclusion of any storage vessel, being an LNGC or FSU. A modular approach enables the increase of regasification capacity in stages. It may further allow to increase the LNG storage volume that can be handled. The main features of the floating regasification system will be described in the following.

[0011] The floating structure may comprise a semi-submersible platform, a barge, a tension-leg platform or any other floating structure. For example, the semisubmersible platform may be understood as a type of floating structure that is primarily used in offshore drilling and oil or gas production. It is able to float on water and remains stable through buoyant and submerged components. It has a deck that is supported by generally vertical columns connected to a submerged structure. The submerged structure may, for example, comprise pontoons that ensure that the platform or other floating structure floats.

[0012] According to the invention, the floating structure is independent from floating storage units and onshore consumers. The platform is mechanically not connected to any other floating or onshore entity and may be held in its position by a plurality of mooring lines that are connected to anchors. However, for positioning the floating structure also mooring dolphins, a quay side or similar devices may be used, depending on the project.

[0013] The deck provides the usable area and contains the upper installation surface. The floating structure is thus independent from an FSU and from onshore systems. The design of the floating structure is simple, and the floating structure can be manufactured in a cost-efficient manner when compared to an FSRU. Especially when the FSRU is combined with traditional infrastructure required for berthing the vessel and transporting the natural gas to the consumers, such as a quay, jetties, loading arms, and onshore piping systems, etc. The FSRU may for instance be a modified liquefied natural gas carrier (LNGC) or FSU, or a newbuild FSRU The at least one regasification module serves for receiving and vaporizing LNG for delivering natural gas to an onshore device. Regasification skids or trains are common terms to represent a modular, pre-assembled system equipped with the necessary apparatus to independently transform LNG back into its gaseous state. One skid may deliver 125 MMscfd of natural gas and may consist of two trains. It is conceivable that each skid and / or each train and / or each regasification module is provided with at least one flexible hose.

[0014] The regasification modules may be compact and fully automated, designed for straightforward transportation and installation, often comprising vaporizers, pressure regulating units, automation control panels, odorizers, flowmeters, and optional electrical trim heaters. Their modular nature allows for easy scalability and adaptability, making them suitable for different regasification needs. Various heat exchange technologies, such as Ambient Air Vaporizers, Forced Air Vaporizers, shell and tube vaporizers, which may include submerged combustion vaporizers, and Open Rack Vaporizers, may be utilized depending on the specific requirements and installation environment of the skid-mounted systems. In general, the heat exchange technology may easily be adapted for different types of heaters, also as modification work later in the floating structure life if it is to be reallocated to a different location with different climate.

[0015] The terms “module” and “modular” indicate that the system according to the invention allows to equip the floating structure with a desired number of regasification modules, skids or trains depending on the demand of the respective onshore device.

[0016] The flexible hoses allow to position the floating structure between the onshore consumer and an FSU and to simply connect the hoses with either the onshore consumer or the FSU. A cumbersome planning, construction and installation of a jetty and / or piping system to the onshore consumer and the FSU can be eliminated. Furthermore, by using flexible hoses, a certain flexibility in the position of the floating structure can be achieved. Relative movements between the floating structure and the FSU and / or the onshore consumer can easily be tolerated and compensated. The flexible hoses may be provided in the form of an aerial- or submerged catenary. The submerged catenary may enable larger relative motion and also a larger separation distance between the floating structure and the floating storage unit.

[0017] The flexible hose may comprise a bonded or non-bonded pipe, a rubber hose, a corrugated steel hose, a composite hose, or any other type of hose suitable for the regasification system.

[0018] The connection between the floating regasification system and onshore consumers may include the provision of a riser tower, which is connected to a subsea gas pipe and provides a connector at a top section above the water. However, the connection may also be conducted without such a riser tower, i.e. by coupling the respective flexible hose with a subsea gas pipe directly or via a subsea pipeline end manifold (PLEM).

[0019] An advantage of the system according to the invention is the ability to flexibly react to changing demands for gas supply. If the demand increases, the floating structure may be equipped with further regasification modules. If the demand and the associated number of regasification modules exceeds the available size of the floating structure, a further floating structure may be provided and equipped with further regasification modules. By selecting the size of the flexible hoses, a connection to the onshore consumer and the FSU is simple. Increasing demand may even allow to simply add a further FSU and an associated floating structure in a time-efficient manner.

[0020] The upper installation surface may have a first edge and an opposite second edge, wherein the first fluid transfer assembly is arranged to protrude over the first edge, and wherein the second fluid transfer assembly is arranged to protrude over the second edge. Thus, the floating structure has two opposite edges, between which the at least one regasification module can be arranged. A general flow direction is defined from the first edge to the second edge, and the floating structure can be placed directly between an FSU and the onshore consumer. If multiple regasification modules are placed on the floating structure, they can be arranged parallel to each other and staggered in a direction perpendicular to the general flow direction. Multiple regasification modules may be connected to the first fluid transfer assembly and the second fluid transfer assembly by manifolds or connecting pipes that are perpendicularly arranged to the general flow direction.

[0021] At least one of the fluid transfer assemblies may comprise an upward opening chute or saddle configured to receive a section of the flexible hose for diverting the hose section from the upper installation surface into the sea. The chute or saddle may be understood as a channel or a passage through which materials can be conveyed by gravity, typically designed to manage the flow of bulk goods in industrial settings. However, in the context of the invention, the chute is to be understood as an elongated, channel- or trough-like component that has a cross-section which is open on one side and closed on an opposite side. It may be an upward opening reinforced conduit designed to restrict over-bending and support transverse and vertical forces. A path for guiding the flexible hose may be curved to provide a transition between a substantially horizontal extension direction on the floating structure, where the flexible hose is connected to the regasification module, and an inclined extension direction guiding the hose into the sea. The chute or saddle helps to compensate relative motion of the floating structure during operation. At least one of the fluid transfer assemblies may comprise an overhang structure protruding above the respective edge of the upper installation surface, and a connector device having an upper connecting side, and a lower connecting side, the connector device being mechanically attached to the overhang structure, wherein the associated at least one flexible hose is connected to the lower connecting side of the connector device. The overhang structure may also be referred to as a gas balcony or a flexible pipe vertical hang-off structure. It may be understood as a structure mounted outboard of the floating structure above the water. A connector device may be understood as a mechanical component that securely anchors and supports a flexible hose at the point where a transition from a rigid fluid line arranged on the floating structure and into the sea is conducted, mitigating mechanical stresses on the flexible hose and / or a rigid piping on the floating structure and preventing damage. The connector device may be a hang-off collar connector. The connector device may comprise hydraulically operated ram plates, a clamping device, quick connect / disconnect couplings (QCDC), an emergency release coupling (ERC), and / or a flange for being secured by a collar. For example, collar clamps may be arranged below a flange welded to an end termination of a flexible hose. The collar clamps may be secured by camlocks. The connector device may comprise load distribution elements to ensure the structural integrity of the flexible hose during both static and dynamic conditions. The flexible hose is safely held on the lower connecting side and may comprise a flange that can be attached to a corresponding flange on the lower connecting side. The upper connecting side may in turn be connected to a rigid pipe that leads to the at least one regasification module.

[0022] The floating regasification system may comprise at least one manually or automatically operable connector to establish or release the fluid communication with the input side or the output side. The connector may, for example, be a hang- off collar connector mentioned further above. It may also be a flange connector arranged at an inward end of a chute that holds a section of the flexible hose. The connector being capable of establishing or releasing a fluid communication allows to release the communication upon experience of undesirable weather conditions, during modification of the system or if an excessive relative motion between the floating structure and the onshore consumer or the FSU occurs or is expected.

[0023] The connector may comprise an emergency release system to be triggered by an external event. For example, the relative motion between the floating structure and the FSU or the onshore consumer is monitored and if it appears probable that the at least one flexible hose could be damaged, the emergency release system could be triggered. Another external event could be a mooring line failure. Interrupting the connection between the at least one flexible hose and the regasification module helps to maintain a safe operation of the system. The at least one flexible hose of the first fluid transfer assembly may be thermally insulated, prevent heat ingress during transfer. Thermal insulation of the flexible hose ensures that the LNG does not vaporize prematurely, which may cause operational inefficiencies, increased pressure in the hose, and potential safety hazards. Moreover, maintaining low temperatures within the hose reduces the risk of thermal expansion and mechanical stress, thus preserving the integrity and safety of the entire fluid transfer assembly.

[0024] The floating regasification system may comprise a plurality of anchors coupled with the floating structure through mooring lines. The mooring lines may be coupled with the floating structure through controllable winches, thus enabling the floating structure to be positioned accurately. Depending on the weather conditions it may be advantageous to control the winches during operation of the floating regasification system to maintain the position of the floating structure.

[0025] The upper installation surface may have a module installation section, wherein the module installation section may be configured to receive and hold a plurality of regasification modules, wherein each of the first fluid transfer assembly and the second fluid transfer assembly may comprise one flexible hose for each regasification module. For example, the module installation section comprises an installation infrastructure in the form of manifolds, fasteners, valves, pipes, and other elements that allow to simply add or remove individual regasification modules when the local demand for natural gas changes.

[0026] The at least one regasification module may comprise a vaporizer, which may be connected to a heat exchanger configured to be brought in thermal communication with the sea. Other variants, which include an active heating, are not ruled out. The skilled person may select the heat source according to the boundary conditions and requirements.

[0027] Short description of the drawings

[0028] In the following description this invention will be further explained by way of exemplary embodiments shown in the drawings:

[0029] Fig. 1 shows a floating regasification system in a perspective view.

[0030] Fig. 2 shows the floating regasification system in a further perspective view.

[0031] Fig. 3 shows a fluid connection between a floating storage unit and the floating regasification system.

[0032] Fig. 4 shows a hang-off collar connector on an overhang of a floating structure for connecting a flexible hose. Fig. 5 shows a connection between an FSU, the floating regasification system, and a subsea line supported by a riser tower.

[0033] Detailed description of the invention

[0034] Figs. 1 and 2 shows a floating regasification system 2 for liquefied natural gas (LNG) in a perspective view. The system 2 comprises a floating structure 4 in the form of a semi-submersible platform having an upper installation surface 5.

[0035] A first fluid transfer assembly 6 is in fluid communication with an input side 8 of exemplarily three regasification modules 10. A second fluid transfer assembly 12 is in fluid communication with an output side 14 of the regasification modules 10. The first fluid transfer assembly 6 comprises flexible hoses 16 for transferring LNG from a floating storage unit (not shown in Fig. 1) to the regasification modules 10. The flexible hoses 16 may be thermally insulated to minimize heat transfer into the hoses 16. The second fluid transfer assembly 12 comprise flexible hoses 18 for transferring natural gas to an onshore consumer (not shown in Fig. 1).

[0036] The regasification modules 10 are installed in an installation section 7 on the upper installation surface 5. The installation section 7 is configured to let regasification modules be attached upon demand. As apparent from Fig. 1, the size of the upper installation surface 5 allows to include further regasification modules 10 if an increased demand for natural gas on the consumer side is present.

[0037] The regasification modules 10 are configured to receive LNG through the first fluid transfer assembly 6, to vaporize the LNG to generate a gas and to deliver the gas into the second fluid transfer assembly 12. The flexible hoses 16 and 18 are connected to the regasification modules 10 through pipes 22 that are arranged on the upper installation surface 5. The upper installation surface 5 has a first edge 9 and an opposite second edge 11. The first fluid transfer assembly 6 protrudes over the first edge 9 and the second fluid transfer assembly 12 protrudes over the second edge 11.

[0038] The hoses 16 and 18 are arranged in chutes 24, which are upwards opening to receive a hose section for diverting the hose section from the upper installation surface 5 into the sea. The pipes 20 and 22 may be connected to the hoses 16 and 18 through flange connectors 26 arranged at inwardly facing ends of the chutes 24. The chutes 24 help to guide the hoses 16 and 18, to absorb mechanical loads resulting from a motion of the floating structure 4, and to reduce mechanical loads on the flange connectors 26.

[0039] The floating structure 4 is held in place by a plurality of mooring lines 28, which are connected to corners 30 of the floating structure 4. Here, two mooring lines 28 that are transverse to each other, are arranged at each of the corners 30. They are connected to the floating structure 4 through winches 32 that may be controllable to adjust the position of the floating structure 4, to compensate relative motions between the floating structure 4 and a floating storage unit, onshore piping or the like.

[0040] In this exemplary embodiment, the floating structure 4 comprises a rectangular, and exemplarily square upper installation surface 5 created on a deck 33, which is arranged on columns 34 that are supported on a pontoon 36 having a shape that exemplarily conforms the shape of the deck 33. The floating structure 4 is designed in a way that the deck 33 is located above the water, while the pontoon 36 is underwater.

[0041] The system 2 is to be arranged between an onshore consumer for natural gas and a floating storage unit for LNG. Thus, the flexible hoses 16 from the first fluid transfer assembly 6 are connected to the floating storage unit and receive LNG, while the hoses 18 of the second fluid transfer assembly 12 are connected to an onshore piping system to deliver natural gas.

[0042] Figs. 3 and 4 show a floating storage unit 38 connected to a floating regasification system 40 having a floating structure in the form of a barge through flexible hoses 16. The hoses 16 and 18 are connected through hang-off collar connectors 42 having an upper opening 44, a lower opening 46 (not visible herein), and a fluid duct 48 extending from the upper opening 44 to the lower opening 46. The hang-off collar connectors 42 is attached to an overhang structure 50, which laterally extends from the deck 33 like a balcony and reaches above the sea.

[0043] Fig. 5 shows a connection between the floating regasification system 2, the floating storage unit (FSU) 38 and an onshore consumer. Here, the FSU has an overhang structure 50 for connecting flexible hoses 16 to the floating regasification system 40. The flexible hoses 16 are connected to pipes 20, wherein a section of the flexible hoses 16 rest on chutes 24. The regasification modules 10 are supplied with LNG and provide natural gas into pipes 22. These are connected to flexible hoses 18 connected to the pipes 22 at an overhang structure 50 which is arranged on an outboard riser tower on the floating structure. The flexible hoses 18 extend to an overhang structure 50 of an intermediate bottom fixed tower structure 54, where an exemplarily rigid subsea flow line 56 to the gas consumer is arranged. Reference numerals

[0044] 2 floating regasification system

[0045] 4 floating structure

[0046] 5 upper installation surface

[0047] 6 first fluid transfer assembly

[0048] 7 module installation section

[0049] 8 input side

[0050] 9 first edge

[0051] 10 regasification module

[0052] 11 second edge

[0053] 12 second fluid transfer assembly

[0054] 14 output side

[0055] 16 flexible hose

[0056] 18 flexible hose

[0057] 20 pipe

[0058] 22 pipe

[0059] 24 chute

[0060] 26 flange connector

[0061] 28 mooring line

[0062] 30 corner

[0063] 32 winch

[0064] 33 deck

[0065] 34 column

[0066] 36 pontoon

[0067] 38 floating storage unit (FSU)

[0068] 40 floating regasification system

[0069] 42 hang-off collar connector

[0070] 44 upper opening

[0071] 46 lower opening

[0072] 48 flow duct

[0073] 50 overhang structure

[0074] 52 riser tower

[0075] 54 bottom fixed tower structure

[0076] 56 rigid subsea flow line

Claims

CLAIMS1. A floating regasification system (2, 40) for liquefied natural gas (LNG), comprising: a floating structure (4) having an upper installation surface (5), at least one regasification module (10) attached to the upper installation surface (5), a first fluid transfer assembly (6) in fluid communication with an input side(8) of the at least one regasification module (10), and a second fluid transfer assembly (12) in fluid communication with an output side (14) of the at least one regasification module (10), wherein the at least one regasification module (10) is configured to receive LNG through the first fluid transfer assembly (6), to vaporize the LNG to generate a gas, and to deliver the gas into the second fluid transfer assembly (12), and wherein each of the fluid transfer assemblies (6, 12) has at least one flexible hose (16, 18) for transferring LNG to the at least one regasification module (10) or gas to an onshore consumer, respectively.

2. The floating regasification system (2, 40) according to claim 1, wherein the upper installation surface (5) has a first edge (9) and an opposite second edge (11), wherein the first fluid transfer assembly (6) is arranged to protrude over the first edge (9), and wherein the second fluid transfer assembly (12) is arranged to protrude over the second edge (11).

3. The floating regasification system (2, 40) according to claim 1 or 2, wherein at least one of the fluid transfer assemblies (6, 12) comprises an upward opening chute (24) configured to receive a section of a flexible hose (16, 18) for diverting the section of the hose (16, 18) from the upper installation surface (5) into the sea.

4. The floating regasification system (2, 40) according to any of the preceding claims, wherein at least one of the fluid transfer assemblies (6, 12) comprises an overhang structure (50) protruding above the respective edge (9, 11) of the upper installation surface (5), anda connector device (42) having an upper connecting side (44), and a lower connecting side (46), the connector device (42) being mechanically attached to the overhang structure (50), and wherein the associated at least one flexible hose (16, 18) is connected to the lower connecting side (46) of the connector device (42).

5. The floating regasification system (2, 40) according to claim 4, wherein the connector device (42) comprises a hang-off collar connector(42).

6. The floating regasification system (2, 40) according to any of the preceding claims, comprising: at least one manually or automatically operable connector (26, 42) to establish or release the fluid communication with the input side (8) and / or the output side (14).

7. The floating regasification system (2, 40) according to claim 6, wherein the connector (26, 42) comprises an emergency release system to be triggered by an external event.

8. The floating regasification system (2, 40) according to any of the preceding claims, wherein the at least one flexible hose (16, 18) of the first fluid transfer assembly(6) is thermally insulated.

9. The floating regasification system (2, 40) according to any of the preceding claims, comprising a plurality of anchors coupled with the floating structure (4) through mooring lines.

10. The floating regasification system (2, 40) according to any of the preceding claims, wherein the upper installation surface (5) has a module installation section(7), wherein the module installation section (7) is configured to receive and hold a plurality of regasification modules (10), and wherein each of the first fluid transfer assembly (6) and the second fluid transfer assembly (12) comprises one flexible hose (16, 18) for each regasification module (10).

11. The floating regasification system (2, 40) according to any of the preceding claims,wherein the at least one regasification module (10) comprises a vaporizer, which is connected to a heat exchanger configured to be brought in thermal communication with the sea.

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