Method and a System for Handling Components During Transferring of the Components from a Vessel to a Fixed Structure

Abstract

There is described a system for transferring components from a vessel to a fixed structure comprising a crane. The system comprises: A—providing a heave compensator between the bearing wire and the component, B-I providing at least one active clamp being arranged with connection means for connection between the vessel and the component, wherein said active clamp is arranged for being controlled by a controller being able to release the clamp and thereby free the component from its connection to the vessel, or B-II providing an accumulator is arranged for being controlled by a controller in order to release compressed air from the accumulator into the piston-cylinder unit and thereby free the component from its position on the vessel by initiating a lift of the component. The lifting of the component is effects when the vessel is near a wave crest based on a monitoring of the wave movement.

Claims

1. Method for handling components during transferring of the components from a vessel situated on a sea surface and influenced by wave movements, to a fixed structure, wherein a crane comprising a bearing wire is provided at the fixed structure and which crane is arranged for effecting the transferring of the components, the method comprising the steps of: A—providing a heave compensator being arranged with connection means for connection between the bearing wire and the component, wherein said heave compensator comprises at least one hydraulic piston-cylinder unit and at least one accumulator for compressed air, which accumulator is connected with the piston-cylinder unit, B-I providing at least one active clamp being arranged with connection means for connection between the vessel and the component, wherein said active clamp is arranged for being controlled by a controller being able to release the clamp and thereby free the component from its connection to the vessel, or B-II providing an accumulator which is arranged for being controlled by a controller in order to release compressed air from the accumulator into the piston-cylinder unit and thereby free the component from its position on the vessel by initiating a lift of the component, C—providing means for monitoring wave movements, D—arranging the vessel on site of the fixed structure, E—connecting the heave compensator to the bearing wire F—connecting the active clamps to the vessel and the component to be transferred, in the situation where step B-I is used, or connecting the accumulator to the piston-cylinder unit, in the situation where step B-II is used, G—pre-setting the heave compensator for the load of the component to be transferred, H—bringing the heave compensator in position for attachment to the component, I—connecting the heave compensator to the component to be transferred and tightening the bearing wire to a pull where the heave compensator is operated in a middle area where a constant over-pull is established in the component to be transferred, J—monitoring the wave movement and sending information of the wave movement to the controller, K—calculating in the controller the wave movement to determine at least when crests are expected at the vessel, L—releasing the active clamp, in the situation where step B-I is used, or releasing compressed air from the accumulator into the piston-cylinder unit, in the situation where step B-II is used, when the vessel is near a wave crest, which releasing is controlled by a control signal from the controller being submitted as a result of information from the monitoring of the wave movement, M—hoisting the component from the vessel and transferring it to the fixed structure, N—detaching the component from the heave compensator, O—repeating the steps E to N until all necessary components are unloaded from the vessel, P—removing the vessel from the site of the fixed structure, and Q—arranging a new vessel on site of the fixed structure if more components are needed and repeating steps E to P.

2. Method according to claim 1, wherein Step A includes providing a heave compensator which is a passive heave compensator.

3. Method according to claim 2, wherein Step A includes providing a heave compensator comprising at least two hydraulic piston-cylinder units and at least two accumulators for compressed air.

4. Method according to claim 3, wherein Step A includes providing the at least two hydraulic piston-cylinder units with same or different lifting capacities.

5. Method according to claim 3, wherein Step A includes combining a selected number of the hydraulic piston-cylinder units by connecting these by opening/closing hydraulic valves arranged in pipe connections between the hydraulic piston-cylinder units and activating the selected number of hydraulic piston-cylinder units in order to obtain a desired lifting capacity for the load of the component to be transferred.

6. Method according to claim 1, wherein Step B includes remote controlling the active clamp with a signal from the control unit.

7. Method according to claim 1, wherein Step L includes a releasing the active clamp from the component leaving the active clamp still connected to the vessel.

8. Method according to claim 1, wherein Step I includes providing a lifting yoke customized to the specific component, arranging the component in the lifting yoke and connecting the heave compensator to the lifting yoke.

9. System for handling components during transferring of the components from a vessel situated on a sea surface and influenced by wave movements, to a fixed structure wherein a crane comprising a bearing wire is provided at the fixed structure and which crane is arranged for effecting the transferring of the components, wherein the system comprises: A—a heave compensator being arranged with connection means for connection between the bearing wire and the component, wherein said heave compensator comprises at least one hydraulic piston-cylinder unit and at least one accumulator for compressed air, B-I at least one active clamp being arranged with connection means for connection between the vessel and the component, wherein said active clamp is arranged for being controlled by a controller being able to release the clamp and thereby free the component from its connection to the vessel, or B-II an accumulator which is arranged for being controlled by a controller in order to release compressed air from the accumulator into the piston-cylinder unit and thereby free the component from its position on the vessel by initiating a lift of the component, C—means for monitoring wave movements and D—a control unit which is connected with the means for monitoring the wave movement, with the heave compensator and with the clamp and/or the accumulator.

10. System according to claim 9, wherein the heave compensator comprises at least two hydraulic piston-cylinder units and at least two accumulators for compressed air, wherein the at least two hydraulic cylinders have different lifting capacities and wherein the hydraulic cylinders are connected through pipe connections comprising hydraulic valves, which valves are arranged for being opened/closed thereby activating a selected number of hydraulic cylinders in order to obtain a desired lifting capacity for the load of the component to be transferred.

Description

DESCRIPTION OF THE DRAWING

[0108] The invention will be described in further detail below by means of non-limiting embodiments with reference to the schematic drawing, in which:

[0109] FIG. 1 shows a schematic side view of heave compensator for use in a system according to the present invention,

[0110] FIG. 2 shows a top view of the heave compensator illustrated in FIG. 1 according to arrows A-A in FIG. 1,

[0111] FIGS. 3-14 illustrate steps of a method for transferring a component from a vessel to a fixed structure according to the present invention using an active clamp,

[0112] FIG. 15 corresponds to FIG. 12, however, illustrating the lifting of a different component,

[0113] FIG. 16 corresponds to FIG. 12, however, illustrating a lifting of a further different component,

[0114] FIGS. 17-18 illustrate steps of an alternative method for transferring a component from the vessel to the fixed structure according to the present invention using an accumulator,

[0115] FIG. 19 illustrates a sketch of a lifting scenario,

[0116] FIG. 20 illustrates a schematic view of an active clamp according to a first embodiment

[0117] FIG. 21 illustrates a schematic view of a further embodiment for an active clamp according to the present invention,

[0118] FIG. 22 illustrates a partial view of a part of an active clamp corresponding to the one illustrated in FIG. 21, and

[0119] FIG. 23 illustrates a further embodiment for an active clamp according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0120] In the drawing, the same reference numerals have been used for the designations of identical or like elements.

[0121] FIGS. 1 and 2 show a side view and a top view of a heave compensator 1. The heave compensator comprises a number of hydraulic piston-cylinder units 2, each comprising a cylinder 4 and a cooperating piston 3.

[0122] The cylinders are affixed to a structure 5 of the heave compensator 1.

[0123] The pistons are combined with a piston locking mechanism 6 being a part of the structure of the heave compensator.

[0124] The heave compensator is connected with a lifting shackle 7 for attaching to a hook in a bearing wire of a crane. Furthermore, the heave compensator 1 comprises accumulators 8 for compressed air.

[0125] The heave compensator 1 furthermore comprises trunnions 9 which may be used as lifting points for components to be transferred. The hydraulic piston-cylinder units 2 are illustrated with different sizes indicating that they are dimensioned for different loads.

[0126] FIG. 3 illustrates that a vessel 10 in form of a transport barge arrives on site of a fixed structure 11 in form of a jack-up ship.

[0127] The jack-up ship is provided with a crane 12 having a bearing wire 13 provided a connector 14 for connection with the lifting shackle 7 of the heave compensator. The fixed structure is provided with piles 15 which are affixed to the sea-bed (not illustrated).

[0128] The vessel 10 is floating on the sea-surface 16. As illustrated the waves are at the sea-surface, and 17 illustrates a wave crest.

[0129] FIG. 3 illustrates a foundation 18 for a wind turbine 19. The vessel 10 transports a nacelle 20, tower sections 21 and blades 22 which are provided on the deck 23 of the vessel 10. Alternatively a fully assembled tower (not illustrated) may be arranged on the vessel 10.

[0130] The nacelle 20, the tower sections 21 and the blades 22 will as indicated by arrows 24 in FIG. 4 be secured to the vessel 10 during transportation.

[0131] The fastening may be effected with active clamps which are arranged for being controlled by a controller indicated at 25 (only illustrated in FIG. 3). The control of the active clamps is primarily based on remote control. The controller 25 is furthermore connected with wave monitoring means 26 (only illustrated in FIG. 3). The wave monitoring means are intended for monitoring wave movements and sending a signal to the controller 25. The controller calculates the wave movement and can determine when a wave crest 17 arrives at the vessel 10.

[0132] FIG. 3 illustrates that the heave compensator 1 is arranged on the fixed structure 11.

[0133] It is noted that the different elements which are illustrated in FIGS. 3-18 are not explained in connection with each of these figures and that these elements are not indicated with reference numerals in all figures.

[0134] FIG. 4 illustrates that the vessel 10 is maintained in the position close to the fixed structure 11 by means of anchoring lines 27 connected to anchors at the seabed (not illustrated). The anchoring lines 27 allow the vessel 10 to follow wave movements.

[0135] Other anchoring methods and anchoring means which maintain the position close to the fixed structure 11 is also possible, e.g. clamps used for clamping the vessel 10 to the fixed structure 11.

[0136] FIG. 5 illustrates with arrow 28 that the heave compensator 1 is attached to the bearing wire 13. During this step the heave compensator will be configured for the appropriate load depending on whether it is the nacelle 20 to be transferred or a tower section 21 or one or more blades 22,

[0137] FIG. 6 illustrates that a nacelle lifting yoke 29 is attached to the heave compensator 1 and fitted with long slings 30. The length of the slings 30 will depend on the wave amplitude and alternatively quick connectors may be used.

[0138] FIG. 7 illustrates that e slings 30 are landed on top of the nacelle 20.

[0139] FIG. 8 illustrates that the slings 30 are attached to lifting equipment for the nacelle 20.

[0140] FIG. 9 illustrates an initial hoisting. In this step the heave compensator is pre-set for the load of the nacelle. Typically the pre-set of the load will be the weight of the nacelle+10%. For a nacelle weighing 500t the pre-set will be 550t.

[0141] FIG. 10 illustrates that the crane 12 tightens the slings 30. This is indicated by arrow 31. During this tightening of the slings 30, the nacelle is still clamped to the deck 23 of the vessel 10 by means of an active clamp.

[0142] FIG. 11 illustrates that the wave frequency is measured with the monitoring means 26 (see FIG. 3). When determine the wave frequency in the controller 25 (see FIG. 3) it is predicted how the movement of the wave will be and accordingly, also there is a prediction of the movement of the heave compensator 1. The movement of the heave compensator is indicated with arrow 32. Arrows 33 indicate the wave movements.

[0143] During the monitoring step, the heave compensator 1 maintains a constant load on the crane 12.

[0144] FIG. 12 illustrates the situation where the deck 23 of the vessel is at an upper position as the vessel is near the wave crest 17. At this time the deck clamps are released by remote control from the controller 25 (see FIG. 3.) and the nacelle 20 is gently lifted off the deck as indicated by arrow 34 using the force of the heave compensator 1 while the crane 12 hoists the nacelle 20 with the bearing wire 13.

[0145] The nacelle 20 is now freed from the vessel 10, and the crane can transfer the nacelle 20 to the fixed structure 11.

[0146] FIG. 13 illustrates that the crane 12 hoists the nacelle onto a deck 35 of the fixed structure 11. This lowering of the nacelle is indicated with arrow 36.

[0147] FIG. 14 illustrates that the bearing wire further lowering the heave compensator 1 whereby the slings 30 are loosened and can be detached from the nacelle 20.

[0148] The crane is now the ready to the next lift where a different lifting yoke may be used together with the heave compensator.

[0149] FIG. 15 illustrates a situation where further components are transferred from the vessel 10 to the fixed structure 11.

[0150] FIG. 15 illustrates with arrow 37 the lifting of a tower section 21. The tower section is connected with the slings 30 through a lifting bracket 38 connected to the tower section. The tower section is also connected with the deck 23 of the vessel 10 by means of active brackets.

[0151] The steps for transferring the tower section will be like the steps described above in relation to the transferring of the nacelle 20.

[0152] FIG. 16 illustrates the lifting of blades 22 from the vessel 10. The lifting is illustrated with arrow 39. The blades are attached to a rack 40 containing three blades with could be lifting simultaneously from the vessel 10 and transferred to the fixed structure 11. The rack 40 is connected to the vessel 10 with an active clamp.

[0153] The steps for transferring the blade rack 40 will be like the steps described above in relation to the transferring of the nacelle 20.

[0154] When the vessel 10 is emptied it can be removed from the site of the fixed structure and sail to a harbor for being loaded with new components.

[0155] A new vessel may be anchored close to the fixed structure and the procedure explained above may be repeated as many times as necessary.

[0156] FIG. 17 illustrates a picture corresponding to FIG. 12.

[0157] However, in the embodiment in FIG. 17 and FIG. 18 active clamps for affixing the nacelle 20 to the vessel 10 are not used. In the embodiment illustrated in FIG. 17 the heave compensator 1 is provided with an accumulator 41 for compressed air. The accumulator 41 is connected with the piston-cylinder unit of the heave compensator through a valve (not illustrated) which may be controlled in the same way and according to the same principle as the control of the release of the active clamp.

[0158] Accordingly, in this embodiment the valve is opened when the vessel 10 is near a wave crest 17 and the release of the compressed air will gently lift off the nacelle from the deck due to the force of the heave compensator while the crane lift the nacelle 20. This lifting is illustrated in FIG. 18 with the arrow 42, and the arrow 43 illustrates the release of the compressed air from the accumulator 41.

[0159] The crane will lift the major part of the load, typically around 90%. Before the compressed air is released and provide more power to the piston-cylinder unit. The piston-cylinder unit is thereby retracted causing the lift off of the component from the vessel.

[0160] Accordingly, the method illustrated in FIGS. 17 and 18 differs from the above mentioned method in that active clamps are not used for attaching and freeing the component from the vessel. In this embodiment the components situated on the vessel 10 shall be loosened from the deck, by releasing passive transport brackets which has been used during transport from harbor to the site of the fixed structure.

[0161] FIG. 19 illustrates a component 44 to be transferred when lifted by the bearing wire 13. 45 is an interface between the component 44 and an active clamp which is designated with 46. The active clamp 46 may be denoted as a release mechanism.

[0162] FIG. 20 illustrates the active clamp 46 in accordance with a first embodiment. The active clamp 46 comprises a first interface 47 to the component to be transferred and a second interface 48 to be connected to the deck 23 of the vessel. The first interface 47 comprises a rod having a pointed head 49. The pointed head 49 is wedged between claws 50 which are arranged to be rotated around shafts 51 in order to engage or disengage the active clamp.

[0163] FIG. 21 illustrates a further embodiment for an active clamp. The first interface 47 comprises a bore 47′ in a rod 47″. The second interface 48 comprises a ball lock mechanism 52. The ball lock mechanism 52 comprises balls 53 provided in a groove 54 in the rod 47′. A rod 55 is arranged in a tubular sleeve 57 having an inner surface 58. The rod 55 is provided with a pointed end 56 which may force the balls 53 into the groove 54 and engage the active clamp. When retracting the rod 55 as indicated by the double arrow the balls 53 are freed and the active clamp is disengaged.

[0164] FIG. 22 illustrates the principle for a ball lock mechanism which is slightly different from the ball lock mechanism illustrated in FIG. 21. The rod 55 illustrated in FIG. 22 comprises a narrowed part 60 ending in an enlarged head 59. The rod 55 is sliding within the tubular sleeve 57. The balls 53 are provided in openings 61 to enter into the groove 54 (not illustrated in FIG. 22), when activating the active clamp in order to provide an engagement. When disengaging the active clamp, the rod 55 is pushed to the left side, whereby the balls 53 will be situated in front of the narrowed part 60. Hereby the active clamp is disengaged.

[0165] FIG. 23 illustrates that the first interface 47 comprises a rod 61 provided with a toothing 62. The second interface 48 comprises sliding blocks 63 which may slide in a direction according to the double arrows. Hereby an oblique surface 64 of the sliding blocks 63 cooperate with an oblique surface 65 on a locking block 66 which are provided with toothing 67 corresponding to the toothing 62 on the rod 61. The locking blocks 66 may be displaced in order to bring the toothings in and out of engagement due to the action of the oblique surfaces as indicated by the double arrows 68. When a hydraulic pressure is released the active clamp may be disengaged.