Patent Application
20250010950
The present invention concerns to a quick connector for coupling an offshore floating structure to a pre-laid mooring system and belongs to the field of floating offshore structures and more specifically to the field of offshore floating wind turbines, wave machines, and tidal stream turbines.
The present invention further concerns to a method for coupling an offshore floating structure to a pre-laid mooring system by using a quick connector.
Conventionally, floating offshore platforms, and in particular, floating wind turbine platforms are linked to the seabed by means of a plurality of mooring lines which limit the displacement and rotation of the structure. That is to provide station-keeping, required for the wind turbine to operate and maintain position. Also, conventionally, floating platforms with the wind turbines are transported to the installation site completely assembled, towed by tugboats. However, installation and tensioning of mooring lines requires the use of multiple vessels and can be complicated to execute, requiring the use of specialized teams, vessels, and good weather conditions. It is expected that floating wind turbine platforms may need to be towed to port multiple times during their 20-25-year lifetime to conduct maintenance on the turbine or the platform itself. Hence, it is highly desirable to have a means for safely and quickly disconnect and reconnect the platform.
The present invention therefore seeks to provide an apparatus for the connection and disconnection of the offshore floating platform to a pre-laid mooring system that makes this operation fast, easy, and not requiring complex planning such as multiple specialized vessels.
Document U.S. Pat. No. 6,294,844 describes an offshore structure consisting of a frame and multiple wind turbines, installed on a floating platform connected to a vertical axis in a way that allows weathervaning of the structure. The axis is kept stationary by means of an anchoring system.
Its connection with the frame of the rotatable structure is designed to support it in multiple planes, keeping the wind turbines upright and steady.
In some other designs the floating structure is rotatable around a single mooring point, as it is described in the case of document EP3642479B1 system. This invention further comprises means to disconnect the floating platform from a permanently moored structure by moving the lower and upper body with respect to each other using a semi-submersible barge. Furthermore, centring means consisting of a cone and a counter-cone pair guide the connection-disconnection manoeuvre.
In the last decades, many quick connectors were developed in the oil and gas offshore extraction industry to facilitate connection and disconnection of a vessel from a semi-submerged buoy. The buoy is conventionally anchored to the seabed, features a plurality of risers and drilling equipment, and is capable of withstanding sea waves and currents acting on the vessel so it can be kept in place even without a dynamic positioning system. The quick connector is usually located in the vessel below any kind of yaw system which allows the free rotation of the vessel around the buoy, allowing the alignment of the vessel to the direction of the wind.
Document U.S. Pat. No. 5,356,321 document discloses a disconnectable mooring system for production vessels. It includes a turret having a yaw system with a top bearing and a bottom bearing, and a quick connector progressing below the ship so it can weathervane and align to the wind, currents, or wave directions, and be driven to the harbour when fierce storms occur, or ice floes are present. The quick connector consists of a plurality of bear locks which are forced to interfere in an annular cavity machined on the buoy top interface by means of a collet driven by hydraulic cylinders.
Similarly, Document U.S. Pat. No. 5,363,789 patent describes a disconnectable mooring system that features a receiving member rotatably connected to the floating structure. The structural connection between the mooring buoy and the receiving member is made using a ring-shaped actuation member that engages circumferentially arranged latching members. Centring means used only allow the receiving member and mooring buoy to connect in a certain rotational position.
Document WO2007127531A2 describes a mooring method that allows a vessel to weathervane about a submerged buoy. The bearing assembly of the buoy has an inner hub coupled to an outer ring fixed to the buoy. The structural connector attached to the vessel is arranged to be releasably connectable to the inner hub. The connector comprises a plurality of collet segments which engage the inner hub to dog it securely to the connector. The radial load involved in the process of receiving the inner hub is transmitted between the vessel and the buoy through a radial bushing seat defined by the perimeter of a circular recess formed in the buoy.
Document EP1567727B1 relates to a method of mounting wind turbines, wave machines and tidal stream turbines offshore, using mechanical guiding which only requires self-propelled barges. The method comprises the use of a socket and an intermediate supporting part which provide an internal guiding surface for the conically shaped end part of a structure being installed. The structure is initially held in the reclined position by clamps attached to a barge. Then, the end part of the structure is led into the mounting socket using the guiding wire, lowered by adjusting removable alignment means until the geometrical alignment of the mounting surfaces is achieved, and released out of the clamps. Grout injection is used afterwards to secure the mounting.
Document U.S. Pat. No. 6,609,734 discloses a connector used to connect pressure vessels that features toroidal members sliding parallel to motion of locking segments. One of the toroidal members, an actuating torus, engages an inner piston, moving it down and thus rocking a plurality of circumferentially arranged locking segments onto the hubs on the surface of the pressure vessel.
The present invention comprises a quick connector configured to couple an upper body of an offshore floating structure to a lower body of a pre-laid mooring system. In some embodiments, the offshore floating structure may be a weathervaning floating offshore wind turbine (FOWT) platform, for example, and the pre-laid mooring system may be a Tension Leg Platform (TLP) type, for example, but the device could find use in other type of floating systems. The offshore floating structure and the pre-laid mooring system may be arranged aligned along a longitudinal axis. The quick connector may be configured to couple (preferably, coaxially couple) the offshore floating structure to the pre-laid mooring structure along the longitudinal axis. The longitudinal axis may be a geometrical longitudinal axis, not corresponding to a physical part of the quick connector.
The quick connector comprises a base structure configured to be coupled to an upper body of an offshore floating structure, a mooring interface configured to be attached to a lower body of a pre-laid mooring system, and a locking mechanism fluid-dynamically (hydraulically or pneumatically) actuated configured to couple and decouple the base structure from the mooring interface.
Preferably, the mooring interface is shaped as an outer female member designed to receive the base structure of the quick connector as an inner male member and matches it geometrically. However, the technical solution provided by the invention may also be applicable for configurations in which the mooring interface is configured as an inner male member and the base structure is configured as an outer male member. The base structure of the quick connector may be attached to a floating upper body of a FOWT platform or other type of offshore platform with the aim of securing it to the mooring system. The base structure and the mooring interface are configured to be connected (e.g., coaxially connected) to each other along a longitudinal axis. In preferred embodiments, the longitudinal axis, in an operative position, is configured as a vertical axis.
Once the base structure of the quick connector is guided until connection with the mooring interface is achieved, a plurality of peripherally or perimetrically (e.g., circumferentially) arranged locking claws (i.e., the locking claws may be arranged at a radial distance from the longitudinal axis) embedded into the base structure are aligned with a grooved surface of a ring-shaped portion of the mooring interface. In preferred embodiments, the grooved surface may be configured as an inner grooved surface of the ring-shaped portion of the mooring interface (e.g., the grooved surface may be configured as an inner surface of the ring-shaped portion).
Multiple hydraulic or pneumatic pistons may be mounted on the base structure and operatively connected to move the locking claws between a release position in which the locking claws are withdrawn (i.e., disconnected) from the grooved surface of the mooring interface and a lock position in which the locking claws are meshed (i.e., connected) with the grooved surface of the mooring interface.
In one embodiment, each locking claw may be included in a locking assembly guided to slide perpendicular, or at least partially perpendicular, to the longitudinal axis. In the context of the current invention, “partially perpendicular” must be interpreted as representing a movement in which a first component of the movement is perpendicular to the longitudinal axis, and a second component of the movement is parallel to the longitudinal axis, wherein “mainly (or mostly) perpendicular” is interpreted as a partially perpendicular movement in which the movement is predominantly perpendicular (i.e., the parallel component of the movement is smaller than the perpendicular component). A plurality of wedges may be mounted to the base structure to move parallel (or partially parallel or mainly parallel; wherein the descriptions of “partially parallel” and “mainly parallel” are based on the descriptions of “partially perpendicular” and “mainly perpendicular” provided above) to the longitudinal axis and the hydraulic or pneumatic pistons may be operatively connected to lower down and raise up the wedges. Each wedge may have wedge surfaces configured and arranged to interact with inclined surfaces of the locking assembly to move outwards and inwards the locking claws between the lock and release positions.
According to some embodiments, each wedge may comprise at least one expansion wedge surface and at least one retraction wedge surface, wherein each locking assembly may comprise at least one expansion inclined surface and at least one retraction inclined surface. The at least one expansion wedge surface may be configured and arranged to interact with the at least one expansion inclined surface of the locking assembly, and the at least one retraction wedge surface may be configured and arranged to interact with the at least one retraction inclined surface so as to move the locking claws outwards and inwards.
In some embodiments, each wedge may be configured as a part comprising a main wedge body and a base plate. The base plate may be configured to protrude laterally from the main wedge body, thereby forming one or two lateral wings. The main wedge body may be arranged in a central position with respect to two lateral wings, or may be arranged laterally (if there is only one lateral wing). The expansion and retraction wedge surfaces may be respectively configured as opposing faces of the base plate, wherein preferably the expansion wedge surfaces are parallel to the expansion wedge surfaces. The main wedge body may further comprise a guide surface arranged at an angle to the expansion and retraction wedge surfaces, wherein said guide surface may be configured such that, when the wedge slides into the inclined passage, the guide surface is pressed against a surface of the base structure, so that the pressing force is transmitted from the wedge to the locking claw to move the locking claw towards the grooved surface.
The expansion and retraction inclined surfaces of each locking assembly may be configured to form an inclined passage configured to receive the base plate of a respective wedge. The expansion and retraction inclined surfaces may be arranged mutually parallel. The inclined passage is also referred to as a slot (although lateral surfaces arranged to connect the respective expansion and retraction inclined surfaces are optional). The inclined passage may be open (i.e., it is not closed, but has an opening) on the retraction inclined surface, thereby allowing the movement of the main wedge body when the base plate slides within the inclined passage and limiting lateral displacement (i.e., in a direction transversal to the direction along which the base plate slides within the inclined passage) of the main wedge body when the base plate slides within the inclined passage.
According to some embodiments, the intermediate actuator may comprise one or more intermediate elastic elements. The one or more intermediate elastic elements may be at least partially housed in a respective cavity of the corresponding locking claw. The intermediate actuator may comprise at least one of the one or more expansion inclined surfaces of the locking assembly, wherein said at least one expansion inclined surface may be configured as a protruding expansion inclined surface. The at least one protruding expansion inclined surface may be configured to protrude from the cavity to come into contact with the at least one expansion wedge surface of the wedge. Thus, the at least one protruding expansion wedge surface may be configured to protrude into the inclined passage such that, when a wedge (or the base plate of a wedge) is inserted into the inclined passage, the expansion wedge surface of the wedge comes into contact with the protruding expansion inclined surface, therefore pushing the respective locking claw towards the respective grooved surface.
The intermediate actuators may be arranged with an angle of inclination with respect to a direction perpendicular to the longitudinal axis. The angle of inclination may be configured such that, when the intermediate actuator receives a compression force from the respective wedge, then intermediate actuator transmits a primary part (i.e., more than the 50% of the force) of the force in a direction perpendicular to the longitudinal axis and secondary part (i.e., less than the 50% of the force) of the force in a direction parallel to the longitudinal axis according to (i.e., aligned with) the movement of the wedge. The angle of inclination is an optional feature that ensures that the locking claws engage with the respective grooved surface in the locking position, while simultaneously a transversal force (i.e., parallel to the longitudinal axis) is provided, thereby generating a pretensioning force in the connection between the base structure and the mooring interface. Further, the transversal force helps to connect the locking ribs of the locking claws with the grooved surface. This last effect is especially important when the locking ribs are configured in a tooth-shaped pattern, and is even more especially important when said tooth-shaped pattern has an angle leaning towards a direction contrary to a direction of connection of the base structure with the mooring interface along the longitudinal axis. The angle of inclination may be in the range 5 to 25 degrees, preferably 10 to 20 degrees and, more preferably, 15 to 18 degrees. In other embodiments, the intermediate actuators may be arranged perpendicular to the longitudinal axis.
The protruding expansion inclined surface of the intermediate actuator may be arranged on the at least one intermediate elastic element. Optionally, the intermediate actuator may further comprise a push element connected to an end of the at least one intermediate elastic element, such that the protruding expansion inclined surface of the intermediate actuator is arranged on the push element. In preferred embodiments, the push element may be configured to have a wider cross-section area than the at least one intermediate elastic element. The cavity of the respective locking claw in which the intermediate actuator is housed comprises a lateral wall surrounding the cavity. Preferably, at least a part of said lateral wall may be configured to provide sliding contact with the push element and to remain separated from the intermediate elastic element. This may be achieved by providing a straight wall dimension to receive the wider cross-section of the push element. Thereby, a space is created between the intermediate elastic element and the part of the lateral wall configured to provide sliding contact with the push element, such that the friction between the cavity the lateral wall of the cavity and the intermediate elastic element is notably reduced.
To secure the alignment, the plurality of wedges may be, for example, peripherally or perimetrically (e.g., circumferentially) arranged on an optional actuator ring that is lowered down and raised up by means of the multiple hydraulic or pneumatic pistons which may have a first end connected to an optional collet arranged on top of the base structure and a second end connected to the actuator ring. In a coupling manoeuvre according to some embodiments, the actuator ring may be lowered down by the hydraulic or pneumatic pistons and each wedge may push out one of the corresponding locking claws to the lock position through the interaction with an intermediate actuator comprising one or more intermediate elastic elements, such as rubber mounts, of the locking assembly.
In the lock position, each claw is configured to press against the grooved surface of the mooring interface and is locked in place by its alignment with the grooves of the ring-shaped cavity. The intermediate elastic elements are located behind each locking claw and are used to ensure that the claws are pressed against the grooves with a known force, coming from the known stiffness of the intermediate elastic element, which remains preloaded once the coupling is engaged. This makes it so the locking force in the device is almost independent to manufacturing tolerance or in the presence of wear, which may otherwise lead to very large and difficult to estimate variations in the force exerted by each individual claw.
Decoupling manoeuvre is the exact same of the coupling manoeuvre described above but in reverse. In the decoupling manoeuvre, the hydraulic or pneumatic pistons are actuated to raise up the actuator ring thereby the wedges pull in the locking claws, preload on the intermediate elastic elements is released and thus the locking claws are moved to the release position and withdrawn from the grooved surface of the mooring interface. The base structure of the quick connector can be then taken out of the mooring interface attached to the mooring system and thereby the offshore floating structure is decoupled from the pre-laid mooring system.
In an alternative embodiment, the wedges may be configured and arranged so that the wedges push out the locking claws to the lock position when the actuator ring is raised up and the wedges pull in the locking claws to the release position when the actuator ring is lowered down.
In a further alternative embodiment, the locking claws may be guided with respect to the base structure to slide perpendicular (or at least partially perpendicular or mainly perpendicular) to the longitudinal axis, and an intermediate elastic element is interposed between each locking claw and the base structure. In this embodiment, the intermediate elastic elements are fluid-dynamically expansible and retractable and the fluid-dynamic device comprises a source of pressurized fluid, a valve arrangement and a fluid conduit. Each intermediate elastic element has an inner cavity which is in fluid communication with the source of pressurized fluid through the fluid conduit and through the valve arrangement.
With this construction, when pressurized fluid is injected into the inner cavity of the intermediate elastic element by the fluid-dynamic device, the intermediate elastic element expands and makes the corresponding locking claw to move outwards to the lock position. Inversely, when pressurized fluid is drawn out from the inner cavity of the intermediate elastic element by the fluid-dynamic device, the intermediate elastic element retracts thus making the corresponding locking claw to move inwards to the release position.
Another alternative embodiment is envisaged wherein the base structure of the quick connector may be shaped as the outer female member and the mooring interface is shaped as the inner male member, so that the base structure is configured to receive therein the mooring interface and to match it geometrically. Typically, these can be a conical geometry, spherical, or a combination of these.
Preferred embodiments of the quick connector are described below with reference to the attached drawings, in which:
Referring first to
In the shown embodiment, the offshore floating structure 31 is configured as a weathervaning structure that supports a floating offshore wind turbine 33 and that comprises an upper body 2 partially submerged with respect to the mean water level 35, and the pre-laid mooring system 32 is configured as a tension leg platform type comprising a submerged floating lower body 3 linked to the seabed 34 by means of a plurality of mooring lines 4. However, it is noted that the particular configurations for the floating structure 31 and for the pre-laid mooring 32 system are merely illustrative and not limiting, since other configurations for the floating structure 31 and for the pre-laid mooring system 32 are compatible with the quick connector 5 of
Referring to
The base structure 6 is designed as an inner male member having a longitudinal axis 50 aligned with an axis about which the offshore floating structure 31 may weathervane, and the mooring interface 13 is configured as an outer female member configured to receive in a fit manner the base structure 6 therein. However, in some embodiments of the invention, this solution may be adapted to be used with base structure 6 configured as an outer female member configured to receive in a fit manner the mooring interface 13 configured as an inner male.
As better shown in
As shown in
Alternatively, upper outer and inner spherical surfaces and lower outer and inner spherical surfaces may be provided instead of the upper outer and inner conical surfaces 24, 25 and lower outer and inner conical surfaces 26, 27.
The locking mechanism comprises a plurality of locking assemblies 36 movably mounted on the base structure 6, radially arranged and distributed around the longitudinal axis 50. Each locking assembly 36 is guided to slide perpendicular (although in some compatible embodiments the sliding may be at least partially perpendicular) to the longitudinal axis 50 and includes a locking claw 10 having a plurality of locking ribs 10a facing outwards, wherein the locking ribs 10a are preferably configured as horizontal locking ribs 10a. The mooring interface 13 has a ring-shaped portion sized to receive therein a region of the base structure 6 where the locking assemblies 36 are mounted, and a grooved surface 16 having circumferential grooves is formed on an inner surface of the ring-shaped portion of the mooring interface 13.
The base structure 6 and the mooring interface 13 are configured so that once coupled together the locking assemblies 36 are arranged at a set height in which the locking ribs 10a of the locking claws 10 are facing the circumferential grooves of the grooved surface 16 formed in the mooring interface 13.
The locking mechanism further comprises a plurality of wedges 18 attached to an actuator ring 9 arranged around the base structure 6 and guided to move parallel (or at least partially parallel) to the longitudinal axis 50 and a plurality of hydraulic pistons 8 mounted on the base structure 6 and operatively connected to lower down and raise up the actuator ring 9 together with the wedges 18 attached thereto. In the shown embodiment, each hydraulic piston 8 has a first end 8a connected to the collet 7 and a second end 8b connected to the actuator ring 9.
Alternatively, the first end 8a of each wedge 18 may be connected to any other element of the base structure 6 and/or the second end 8b of each wedge 18 may be directly connected to one of the wedges 18 and the actuator ring 9 may be omitted.
Anyway, the hydraulic pistons 8 are operatively connected to lower down and raise up the wedges 18, and each wedge 18 has wedge surfaces 38, 39 configured and arranged to interact with inclined surfaces 17, 21, 22, 28, 30, 48 of one of the locking assemblies 36 so as to move outwards and inwards the locking claws 10 included in the locking assemblies 36 between a release position (shown in
An intermediate actuator comprising an intermediate elastic element 11 is interposed between each wedge 18 and the locking claw 10 of the corresponding locking assembly 36. The intermediate elastic elements 11 may be selected with a given stiffness suitable to ensure that the locking claws 10 are pressed against the grooved surface 16 with a known force.
The expansion inclined surface 17 and the retraction inclined surface 28 are preferably mutually parallel and parallel to the expansion wedge surface 38 and the retraction wedge surface 39 of the wedge 18. Further, the locking assembly 36 is shown as comprising an optional expansion inclined surface 48 (also referred to as secondary expansion inclined surface), which is configured such that, when the expansion wedge surface 38 interacts with the protruding expansion inclined surface 17 so that the intermediate elastic element 11 receives a predetermined compression force, then the secondary expansion inclined surface 48 comes into contact with the expansion wedge surface 38, the secondary expansion inclined surface 48 being preferably located on the locking claw 10. The secondary expansion inclined surface 48 may be configured as a surface arranged to at least partially surround the protruding expansion inclined surface 17. In some embodiments, the predetermined compression force may be selected to be greater than a range of operating compression forces of the quick connector under standard operating conditions. Thus, in such cases, the locking assembly 36 may be configured such that, contact between the secondary inclined surface 48 and the expansion wedge surface 38 may take place only when an extraordinary compression force is generated (e.g., due to a non-standard operation, such as in a failure situation), or when the intermediate actuator (e.g., the intermediate elastic element 11) is deteriorated. In these cases, the contact of the expansion wedge surface 38 with the inclined secondary surface 48 provides a distribution of forces over a larger surface area, thus reducing the stress concentration.
It is noted that the retraction inclined surface 28 shown in
The inclined surfaces 17, 21, 28 and the wedge surfaces 38, 39 are configured so that when the wedge 18 is impelled by the hydraulic piston 8 to perform a vertical movement towards an expansion direction, which in this embodiment is a downwards movement, the wedge 18 makes the intermediate elastic element 11 together with the locking claw 10 to move outwards to the lock position, and when the wedge 18 is impelled by the hydraulic piston 8 to perform a vertical movement towards a retraction direction, which in this embodiment is an upwards movement, the wedge 18 makes the locking claw 10 together with the intermediate elastic element 11 to move outwards to the lock position.
The embodiment of
Further, the embodiments shown in
It is noted that the embodiment of
The locking assembly 36 of
More specifically, as shown in
In the situation shown in
In the situation shown in
In summary, in one embodiment of the present invention shown in
The locking assemblies 36 sit within the base structure 6 cone and each consists of several parts such as: in one embodiment, a locking claw 10 and an intermediate elastic element 11; in another embodiment, a locking claw 10, an intermediate elastic element 11 and a push element 20; in still another embodiment, a locking claw 10, an intermediate elastic element 11 and an inner support 12. Since the two or three parts fit together geometrically as described with reference to
The actuator ring 9 has a set of wedges 18, with each of them piercing the corresponding intermediate elastic element 11 or inner support 12 through the socket designed to match its shape. The released state of the quick connector, described with reference to
Once the base structure 6 of the quick connector 5 is guided into the receiving portion of the mooring interface 13, with the longitudinal axis 50 of the base structure 6 in alignment with the vertical axis of the mooring interface 13, and the base structure 6 is located at the set height in the mooring interface 13, pistons 8 are actuated until lowering down the actuator ring 9, thereby inserting the wedges 18 attached to the actuator ring 9 all the way down into the locking claws 10 or into the inner supports 12 linked to the locking claws 10, depending on the embodiment. In so doing, the wedges 18 are pressed down on the intermediate elastic elements 11 or on the push elements connected to the intermediate elastic elements 11, depending on the embodiment, thus driving the locking claws 10 away from the longitudinal axis 50 and out of the base structure 6 to the lock position. This makes the locking claws 10 to press against the inner grooved surface 16 of the mooring interface 13, as described above with reference to
It is worth noting that, in the embodiment shown in
Different stages in a coupling method or manoeuvre for coupling an offshore floating structure to a pre-laid mooring system by using the quick connector according to the embodiment of the present invention shown in
Stage 1—The base structure 6 of the quick connector is guided into the receiving portion of the mooring interface 13.
Stage 2—The base structure 6 is fully aligned with the mooring interface 13 and positioned at a set height but the base structure 6 and the mooring interface 13 are not locked together due to the release position of the locking claws 10.
Stage 3—The hydraulic pistons 8 of the quick connector 5 are actuated thereby the locking claws 10 in the base structure 6 are moved to the lock position and pressed against the grooved surface 16 of the mooring interface 13, thus fixing the base structure 6, which is coupled to the upper body 2 of the offshore floating structure, to the mooring interface 13, which is attached to the lower body 3 of the pre-laid mooring system.
A decoupling method or manoeuvre for decoupling the offshore floating structure from the pre-laid mooring system by using the quick connector of the present invention comprises performing the stages above in a reverse manner.
In another embodiment of the present invention shown in
The stages in a coupling and decoupling method by using the quick connector according to the embodiment shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| 21383017.7 | Nov 2021 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2022/060681 | 11/7/2022 | WO |
