Lifting System and Method for Taking up an Elongated Object

Abstract

Described is a lifting system for taking up an elongate object from a deck of a vessel. The lifting system has a crane arm which is connected to the deck and from which is suspended a take-up frame to which the elongate object can be attached. Also present is a winch setup and control lines connected thereto and configured to control the movement of the elongate object when this object is lifted off the deck. The control lines run from the take-up frame to the winch setup. The winch setup forms part of a support structure which extends from the deck to a height and is intended to be able to absorb the forces acting on the object while it is being lifted off the deck. Also described is a method for taking up an elongate object from a deck of a vessel.

Claims

1 - 22. (canceled)

23. A vessel comprising a lifting system for taking up an elongate object from a deck of the vessel, comprising a crane arm which is connected to the deck and from which is suspended a take-up frame to which the elongate object can be attached, and further a winch setup and control lines connected thereto and configured to control the movement of the elongate object when this object is lifted off the deck, wherein the control lines run from the take-up frame to a pulley setup and from there to the winch setup, which pulley setup and winch setup are provided on a support structure, which differs from the crane arm, extends from the deck of the vessel to a height and is strong enough to be able to absorb the forces acting on the object while it is being lifted off the deck, and wherein the pulley setup is movable relative to the support structure in a height direction.

24. The vessel according to claim 23, wherein the support structure comprises an existing structure of the vessel, such as the bridge.

25. The vessel according to claim 23, wherein the winch setup is situated on an upper side of the support structure.

26. The vessel according to claim 25, wherein the pulley setup is situated on an upper side of the support structure and the winch setup at a lower height.

27. The vessel according to claim 26, wherein the winch setup is situated on a lower side of the support structure.

28. The vessel according to claim 23, wherein the winch setup comprises at least two independently controllable winches for at least two control lines.

29. The vessel according to claim 23, wherein the pulley setup comprises at least two independent pulleys for at least two control lines.

30. The vessel according to claim 23, further comprising a tensioning device which acts on the winch device or on the control lines in order to hold the control lines under tension while the elongate object is being taken up.

31. A method for taking up an elongate object from a deck of a vessel, comprising the steps of: providing a vessel in accordance with claim 23; attaching the elongate object to the take-up frame which is suspended from the crane arm connected to the deck of the vessel; lifting the object off the deck using the crane arm and controlling the movement of the elongate object with the winch setup and control lines which are connected thereto and which run from the take-up frame to the pulley setup and from there to the winch setup; wherein the pulley setup and winch setup are provided on the support structure which differs from the crane arm, extends from the deck to a height and absorbs the forces acting on the object while it is being lifted off the deck, wherein the pulley setup is moved relative to the support structure in a height direction.

32. The method according to claim 31, wherein the support structure comprises an existing structure of the vessel, such as the bridge.

33. The method according to claim 31, wherein the winch setup is situated on an upper side of the support structure.

34. The method according to claim 31, wherein the pulley setup is situated on an upper side of the support structure and the winch setup at a lower height.

35. The method according to claim 34, wherein the winch setup is situated on a lower side of the support structure.

36. The method according to claim 31, wherein the winch setup comprises at least two winches for at least two control lines, and the two winches are controlled independently.

37. The method according to claim 31, wherein the pulley setup comprises at least two independent pulleys for at least two control lines.

38. The method according to claim 31, wherein a tensioning device acts on the winch device or on the control lines and holds the control lines under tension while the elongate object is being taken up.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0040] The invention will now be elucidated with reference to the following figures, without otherwise being limited thereto. In the figures:

[0041] FIG. 1 is a schematic side view of a vessel provided with a lifting system according to an embodiment of the invention;

[0042] FIG. 2 is a schematic top view of the vessel shown in FIG. 1, which is provided with a lifting system according to an embodiment of the invention;

[0043] FIG. 3 is a schematic side view of a support structure according to an embodiment of the invention;

[0044] FIG. 4 is a schematic perspective view of the embodiment shown in FIG. 3 of a support structure according to the invention; and, finally

[0045] FIG. 5 is a schematic diagram of the output of a tensioning device according to an embodiment of the invention, which acts on the winch device.

DESCRIPTION OF THE INVENTION

[0046] Referring to FIG. 1, a vessel 1 is shown which is provided with a lifting system (2, 3, 4) according to an embodiment of the invention. The vessel 1 can be provided with a storage rack 11 for a number of monopile 6, with a number of transition pieces 9 stored in upright position and, if desired, with a helipad 12. In order to bring the elongate objects, such as monopiles 6 and transition pieces 9, into a vertical position so as to lower them onto the underwater bottom (monopile) or onto an already placed monopile (transition piece) in this position the vessel 1 can be provided on a side edge thereof with a gripping device 13, this being movement-compensated if desired.

[0047] The lifting system (2, 3, 4) comprises a lifting means in the form of a lifting crane 2 placed on a deck 10 of the autonomously driven vessel 1. The lifting crane 2 comprises a base 20 connected to deck 10 and a crane arm 21, which can be rotated around a rotation axis 22 running perpendicularly of deck 10 of vessel 1. Running over crane arm 21 of lifting crane 2 is a number of hoisting cables 23 to which a hoisting block 24 is attached.

[0048] Suspended from crane arm 21 is a take-up frame 5 to which an elongate object such as a monopile 6 can be attached by means of slings 50 suspended from the take-up frame. The lifting system (2, 3, 4) further comprises a support structure 3 extending from deck 10 to a height 30. In the shown embodiment support structure 3 is formed by an existing structure of the vessel, namely the bridge. Support structure 3 can however also comprise a structure erected separately for the purpose, for instance a lattice structure erected on deck 10. Support structure 3 is configured to be able to absorb the forces acting on a monopile 6 or other object while it is being lifted off deck 10.

[0049] Arranged on a lower side of support structure 3 is a winch setup 7. Winch setup 7 can also be situated at a determined height above deck 10. In the shown embodiment winch setup 7 comprises two independently controllable winches (70, 71) which operate two control lines 4. Arranged on an upper side of support structure 3 is a pulley setup 8 comprising two independent pulleys (80, 81) for the two control lines 4. From the winch setup 7 shown clearly in FIGS. 3 and 4, control lines 4 run over the pulley setup 8 arranged at greater height and from there to take-up frame 5. As shown in FIG. 2, control lines 4 can be attached to outer ends of take-up frame 5, but also to a middle part thereof. Operating the winches (70, 71) independently of each other enables the orientation of take-up frame 5 and of a monopile 6 received therein to be manipulated. Control lines 4 are intended to control the orientation of a monopile 6 when this monopile 6 is lifted from a storage rack 11 off deck 10, wherein control lines 4 run from take-up frame 5 to winch setup 7.

[0050] Pulley setup 8 and, if desired, also winch setup 7 can be embodied movably in a height direction 31 relative to support structure 3, for instance by having the setup (7, 8) in question run on a rail guide. In the context of the present application movably is understood to mean that the setup (7, 8) in question can be moved in height direction 31 and fixed in variable height positions.

[0051] According to an embodiment, the lifting system (2, 3, 4) can further comprise a tensioning device 73 which acts on winch device 7 in order to hold control lines 4 under tension while taking up a monopile 6 or other elongate object.

[0052] An example of a tension/velocity diagram typically generated by tensioning device 73 is shown in FIG. 5. In a damping mode the tension 15 applied by the tugger winches (70, 71) can change with the velocity of hauling in and paying out 16 of control lines 4, for instance as according to the shown linear progression. A bias is typically set by the tugger winches (70, 71), for instance 15 tons. This tension can increase to an upper limit of for instance 25 tons when control lines 4 are payed out and decrease again to a lower limit of for instance 5 tons when control lines 4 are hauled in. With this setting of the tensioning device 73 the control lines 4 always remain under tension, this enhancing control of take-up frame 5.

[0053] Swinging movements of monopile 10 can be damped with the tensioning device 73. When the monopile 10 moves away from the tugger winches (70, 71), the tension in control lines 4 will increase as according to the linear progression of FIG. 5. When monopile 10 moves toward the tugger winches (70, 71), the tension in control lines 4 will decrease as according to the linear progression of FIG. 5. Energy is consumed in this way.

[0054] With the invented lifting system (2, 3, 4) a monopile 6 or other elongate object can be advantageously taken up from the deck 10 of vessel 1. A typical method comprises of attaching the monopile 6 or other elongate object to the take-up frame 5 which is suspended from a crane arm 21 connected to deck 10. Monopile 6 is then lifted off deck 10 with crane arm 21 and the orientation of the monopile 6 is controlled with the winch setup 7 and the control lines 4 which are connected thereto and which run from take-up frame 5 to winch setup 7. The control lines preferably run here from take-up frame 5, via pulley setup 8 to winch setup 7. During lifting, the tensioning device 73 acting on winch device 7 or on control lines 4 ensures that control lines 4 remain tensioned while taking up the monopile 6.

[0055] The lifting system allows optimal control line angles relative to deck 10. The crane winches which are sometimes applied in the prior art for damping the movement of a lifted monopile 6 do not do this. It can moreover be difficult to integrate the setting of the damping control in the known crane winches.

[0056] With the embodiment of the invented lifting system (2, 3, 4), described above in detail, an elongate object, particularly a monopile 6 of a wind turbine, can be taken up from a storage rack 11 in controlled manner and then, if desired via gripping device 13, be placed on a ground surface, particularly an underwater bottom, this in worse weather conditions than is possible with the known method. The risk of damage to the elongate object can be reduced here.

TABLE-US-00001 List of reference numerals 1 vessel 2 lifting crane 3 support structure 4 control lines 5 take-up frame 6 monopile 7 winch setup 8 pulley setup 9 transition piece 10 deck of the vessel 11 storage rack 12 helipad 13 gripping device 20 crane base 21 crane arm 22 vertical rotation axis 23 hoisting cables of the lifting crane 24 hoisting block of the lifting crane 30 height of the support structure 31 height direction 50 slings of the take-up frame 70 first independently controllable winch 71 second independently controllable winch 73 tensioning device 80 first independent pulley 81 second independent pulley