NO20100323A1 - Method and equipment arrangement for transporting wind turbine units. - Google Patents

Abstract

A method for moving several complete wind turbine units (37), each consisting of a tower with generator (22) attached to a foundation chassis (34), from a land-based production site to an offshore installation site by a vessel (9). The vessel (9) transports the wind turbine units (37) while being supported by support structures (14) with hydraulically driven support plates at the top against the wind turbine towers (22) and with anchoring legs (25) via sliding shoes (7) locked to sliding beams (6) during transport to the offshore site. There, the wind turbine units (37) are grinded, one by one, to a slotted bow with an opening (10), by means of an installation mechanism comprising installation towers (11) with wire jacks (1), wire bundles (2) and tension compensators (5). , to lower the wind turbine unit (37) through said opening (10) down onto the plug (27), either on pre-installed piles or on a suction-anchored foundation frame (32) on the seabed at said location offshore. This is done in such a way that the tension in the wire bundles (2) and the vertical movement of the wind turbine unit (37) are kept within predetermined limits by means of tension compensators (5) directly connected to the wire bundles (2) and as necessary by means of other compensating means under the wire checks (1), or by hydraulic damping effect built into the plugs.

Description

Procedure and equipment arrangement for transporting wind turbine units.

Summary

The EU's goal of having 20,000 wind turbines installed offshore by the year 2020 has revealed an enormous lack of available installation capacity. For wind turbines attached to the seabed, most existing concepts will require assembly work carried out at the installation site offshore using crane vessels. For this type of installation method, the most demanding part is to assemble the tower piece by piece, the very sensitive generator and the delicate blades due to the general weather sensitivity of this method. The ideal installation vessel should have good stability and be able to install complete wind turbine units and transport as many units as possible per trip. Each unit consists of a foundation construction, a tower and the turbine with the blades, as the foundation can be constructions of different types, such as a jacket, mono- or multi-pile, mono-tower or gravity construction of steel or concrete material. Different types of wide-hull vessels can be used or built, such as the barge type, or one can convert existing and suitable commercial vessels such as tankers, bulk carriers and others and provide these vessels with dynamic positioning or anchoring systems, high-placed guides to support the windmills during transport, and introduce an installation system. A commercial vessel of this type suitable for conversion is an Aframax hull, which has a deadweight of approximately 80,000 to 120,000 tonnes, but any wide-hulled barge or vessel can be used for the conversion. By incorporating pontoons, the hull of this vessel gains a new overall width of approximately 52m, providing sufficient stability to weather a summer storm. After the conversion, the vessel has the ability to slide on board over the bow, transport and install six typical wind turbine units per trip in approximately 20 to 60 m of water depth, each with a total height of approximately 150 m and a weight of approximately 1,500 tons. The wind turbine units, each of which can consist of a four-legged jacket structure, a tower and a generator with blades, are supported during transport by support structures on the vessel's deck. At the offshore installation site, the vessel's bow, which is a slotted bow, is positioned with the bow opening above a set of four precisely pre-installed piles with "sticks" above the seabed. The wind turbine units are slid to the bow and then lowered through the opening in the canyon bow using four cable jacks, each of which can have a capacity of 600 tonnes and are placed above the jack on jack decks that are supported in two installation towers arranged on either side of the canyon bow. Wire bundle coils have been placed above the jack decks in the installation towers, and compensators with a typical 600 tonne capacity can be arranged in the jack bundles between the jacks and the jack to reduce dynamic loads during the immersion and landing of the wind turbine unit. Other means of compensation or shock absorption can be introduced between the jacks and/or at the landing area of the jack legs on the pile risers, to maintain the tension in the jack bundles and keep the vertical movement of the wind turbine unit within defined limits and under the necessary control. A steering pin on two sides of the jacket provides lateral steering for the wind turbine units during submersion by following a steering channel on the side of the installation tower and the gap bow. At the same time, wind and moths will be supported by an articulated framework with a releasable clamp from the top of the installation tower. To complete the lowering operation when the guide pin is not in contact with the guide channels during the last part of the immersion, two guide line tensioners, with their guide lines connected to the guide line attachments on top of the pile risers, are used for lateral stabilization of the wind turbine assembly during the last part of the immersion and for fine tuning of the jacket's anchor legs on the risers of the piles or on a suction-anchored foundation frame. The gap bow or stern is held up against the wind/waves while the gap bow is positioned in the optimal position for landing the wind turbine jacket legs on the four pre-installed pile risers, or as an alternative of four risers on a pre-installed suction-anchored foundation frame. Halting winches are capable of rotating the wind turbine assembly 10 to 15 degrees as a final step in the arrangement before landing on the risers, depending on the orientation of the vessel with the jacket legs relative to the risers. Locking of the wind turbine unit jacket legs to the chute shoes, as well as locking of these to the risers in the sea, can be achieved by means of hydraulically actuated internal pile grippers which are an integral part of the foot of the jacket legs. The supports on the pre-installed piles or on the suction-anchored foundation frame provide full stability when the wind turbine unit is landed and locked to the frame by internal pile grippers in the jacket legs. The hinged frame with the clamp is then released from the connection with the wind turbine tower, the cable bundles and control cables are disconnected, and the vessel bow is pulled away from the installation position. The connection with the jacket legs and the risers is then shimmed into a permanent connection.

Brief technical description

The present invention shall be described in the following as a converted vessel 9 of the Aframax type, but where the vessel may be of any type of wide-hull vessel, such as of the barge type used or built for the purpose, or any commercial vessel such as tankers, bulk vessels and other suitable for conversion to a stable installation vessel. The vessel carries wind turbine units with a four-legged jacket as a foundation. However, the foundation can be of any type such as a jacket construction, mono- or multi-pile construction, mono-tower support structures or the gravity type built from steel or concrete material. Reference is made to attached drawings illustrating preferred designs, where: Figure 1 shows a side view of a converted vessel, in this case an Aframax vessel 9 provided with pontoons for reasons of stability, and further shows five wind turbine units 37, which are supported for the transport of hydraulically driven support plates at the top of support structures 14, while a sixth unit is slid to the bow slot 10, with its opening ready for installation. On the bow 10, two installation towers 11 are shown, which are provided with the necessary immersion mechanisms to be connected to the first wind turbine unit. On the seabed in front of the gap bow, stand-up 27 is shown on four precisely pre-installed piles, which provide full stability when the four jacket legs of the wind turbine units have been landed on these and the legs locked and shimmied to the stand-ups. Depending on the ground conditions, an alternative to piling may be four risers 27 mounted on a pre-installed suction-anchored frame foundation. Figure 2 shows a side view of the first wind turbine unit slid all the way forward in the bow. During this installation operation, either the vessel's bow or stern will be turned towards the weather.

The support structures 14 and the installation tower 11 are connected by two truss bridges 17. During sliding to the installation towers and the gap bow 10 of the vessel, the windmill tower is supported on two levels, i.e. by sliding shoes 7 on sliding beams 6 at deck level and by a supporting sliding carriage 15 arranged higher up on a rail passage 18 at bridge level 17 on the support structures 14.

At deck level, the jacket 34 is supported and slid by the windmill unit on four slide shoes 7, which run on two slide beams 6, so that the unit can be slid towards the vessel's bow bow 10. Two hydraulically driven slide units 35 are connected to two of the slide shoes, one unit on each slide beam .

The four jacket legs 25 are engaged at the foot in the slide shoes 7 and locked to the shoes by an internal hydraulic pile gripper, which is an integral part of the legs. This locking mechanism is also used during transport and finally after landing on pre-installed uprights 27 on piles or 32 on a suction-anchored foundation frame.

At the bridge level 17 on top of the support structures 14, a vertically aligned support carriage 15 is arranged on one of the two bridges on the rail passage 18, which will provide lateral support to the tops of the windmill unit when it is slid along the slide beams 6 on the deck towards the back. The bridges connect the two installation towers 11 on the bow with the six sets of support structures 14 which are used to support the wind turbine units during transport and sliding. Two hydraulically driven units 35 are connected to the support carriage 15 and the rail 18. An articulated frame 16, which includes a releasable clamp on the windmill tower, is arranged on one side of the carriage 15 to provide lateral support during sliding of the windmill and during immersion and rotation of the windmill.

Figure 3 shows a front view of the bow with the jacket legs 25 lifted clear of the slide shoes 7 so that the pile grippers 23 are shown. The opening 10 in the gap bow makes it possible to lower the wind turbine unit down through the opening in the bow 10 of the vessel by means of four (typically 600 ton) cable jacks 1. The jacks are placed on the jack decks 13 above the jack in the two installation towers 11, which are made as trusses, one on each side of the jacket to be lowered, and with two cable jacks on each. Each jack is installed on a support table 36 which enables the jack to align with the wire bundle direction, to minimize the force required to rotate the jack for final arrangement between the legs and risers 27, 32. Four wire bundle spools 3 are positioned above the jacks for storage of the four wire bundles 2.

The four lifting points 4 on the jacket are placed on the projecting horizontal truss beams on top of the jacket. Four (typically 600 tonnes) compensators are connected to the lifting points 4 and the wire bundles 2, one in each bundle above the lifting points, to reduce dynamic loads during immersion and landing of the wind turbine unit. Other compensating devices can be installed under the jacks 1 as part of the sub-sizing table 36 and/or on the risers 27 of the piles, or on the suction-anchored foundation frame 32, to maintain the tension in the immersion bundles 2 and keep the vertical movement of the wind turbine unit within predetermined limits and below necessary control.

During the immersion, the windmill will be supported on two levels. The wind turbine tower will be supported by the articulated frame with the releasable clamp 16 on top of the installation tower 11, as well as by a guide channel 19 on the side of the installation tower 11 and the gap bow 10 with a guide pin 20 on both sides of the jacket. The funnel at the lower end of the guide channel will enable the jacket with the guide pin to re-enter in the event of a reverse operation.

Figure 4 shows the jack anchor legs 25 lowered to a few meters above the stand-up foundation, with the guide pin out of contact with the installation guides. At this stage, the guide lines 38 are tightened by the guide line tensioners 21 to stabilize the wind turbine unit laterally, together with the clamp 16 on the articulated frame at the top of the installation tower 11.

Depending on the vessel's orientation when positioning the bow 10 over the jacks 27, the jack 34 may need to be rotated to be fully aligned with the jacks 27 or 32. Two (30 ton) hauling winches 12 are believed to be necessary to rotate the jack while suspended in the jacks 1 over the risers, to allow 10 - 15 degrees of rotation in each direction as required. Four (30 ton) hauling winches are arranged on a mezzanine deck in the installation tower 11 and are available for this operation. Support table 36 is provided below the jacks 1 to allow the jacks to align with the direction of the bundles 2 during such rotation.

As a first step in arranging the wind turbine unit on the bow with the seabed position, the vessel's bow or stern is turned towards the wind/waves with the bow positioned in an optimal position for landing the wind turbine unit's jacket anchor legs 25 on the pre-installed risers 27, which are either placed on pre-installed piles or on a suction foundation frame. The vessel must be able to maintain the bow's 10 position in weather up to a minimum of 30 degrees on the bow or stern.

Two of the above-mentioned trailing winches are used as a second step in aligning the jacket before landing the wind turbine unit's jacket legs on the risers by rotating the jacket which is suspended in the wire bundles up to 15 degrees, thereby giving at least 45 degrees in total as necessary in a most unfavorable weather direction. This enables the deployment system to be installed in an optimal position in relation to the weather direction in two of the four quadrants, while in two of the quadrants it will be somewhat less than optimal, depending on the actual sea conditions.

For a third and final step, it is planned as a minimum to use two steering lines 38 with steering line tensioners 21 for fine adjustment of the jacket anchoring legs 25 when inserting the legs on the risers 27.

After final alignment, the wind turbine units 37 shall be lowered with the jacks 1 while a WROV monitors when the first jacket anchor leg 25 enters the primary anchor pile riser 28, which is the highest of the risers, and then when the diagonal jacket anchor leg enters the secondary anchor pile riser, which is the second highest riser. followed by the last two legs entering the last two ups.

Figure 5 shows the wind turbine unit lowered onto the risers.

If necessary, the protrusions 27 can be designed to act as a hydraulic damper when the jacket legs 25 enter the protrusions, in that the jacket leg has a cone at the end to facilitate entry which acts like a piston in a cylinder, the latter being constituted by the protrusion, and by by providing a suitable throttling of the water flowing out of the riser, a damping effect of the landing shock can be achieved which can be important for the wind generators' shock resistance.

In order to avoid an undesired locking effect of the jacket leg 25 at the entry of the first riser 28, a gradual reduction of the inner diameter of the top of the risers can help to avoid such an effect.

The hydraulic actuated inner pile gripper 23 located in the jacket anchoring leg 25 will have to be activated by the WROV or from the vessel's control room to lock the jacket legs on the risers 27 after landing. At the same time, the articulated frame with the clamps 16 will be released from the tower 22 and moved to the next tower to be slid. The cable bundles, steering lines and trailing winches are then disconnected. Finally, the vessel will pull out of position and connect the ballast connections with the plugs and start pumping ballast into the connections. Alternatively, this last operation can be carried out by another, smaller vessel.

Figure 6 shows the articulated support frame with the clamp 16 released from the tower 22 when the jacket anchor legs 25 are locked to the pile supports.

Items shown in the figures:

1. 4 pcs. cable jacks (typically 600 tonnes)

2. 4 pcs. wire bundles

3. 4 pcs. wire bundle coils

4. 4 pcs. lifting points on jacket top construction

5. 4 pcs. compensators (typically 600 tonnes)

6. 2 pcs. chute beams

7. 4 pcs. chute shoes

8. 4 pcs. bulk tankers

9. Converted vessel hull including pontoons

10. Split bow with opening

11. 2 pcs. installation tower

12. 4 pcs. trailing winches

13. Jack tires

14. 12 pcs. support structures with hydraulically driven support plates at the top as part of sea protection during the transport phase.

15. 1 pc. supporting chute carriage

16. 1 pc. articulated support frame with releasable clamp connected to the tower for repulsion during sliding, lowering and rotation of the windmill unit 17. 2 pcs. load-bearing bridges connecting 12 support structures with the installation towers 18. 1 pc. rail passage for the carrying chute carriage. for re-entry at the lower end

20. 2 pcs. steering pins

21. 2 or 4 pcs. styrene line tighteners

22. 6 pcs. windmill tower with generator

23. 4 pcs. hydraulically actuated internal pile grippers for locking the jacket's four anchoring legs to chute shoes on deck and on risers on pre-installed

underwater piles or suction-anchored foundation frame

24. 4 pcs. adjustable guide line discs

25. 4 pcs. jacket anchoring legs that go down into chute shoes on deck and stick up under water

26. 2 or 4 pcs. Styre line funnels on jacket legs

27. 4 pcs. riser on pre-installed piles or on pre-installed suction-anchored foundation frame

28. 1 pc. high primary anchor piles

29. 1 pc. primary guide line fixture on high riser

30. 3rd subsection second highest secondary anchoring stake 31. 1 pc. secondary guide line fixture on the next highest riser

32. 1 pc. suction-anchored foundation frame with riser

33. 2 pcs. bow support beams

34. 6 pcs. jacket constructions

35. 4 pcs. hydraulic chute units

36. 4 pcs. support table for cable jack

37. 6 pcs. wind turbine units

38. 2 pcs. guide lines

Claims (12)

1. Procedure for moving several complete wind turbine units (37) from a production site, where each unit consists of a tower with a generator (22) attached to a foundation base (34) to an installation site offshore using a vessel (9), characterized in that the vessel (9) transports the wind turbine units (37) while they are supported by support structures (14) with hydraulically driven support plates at the top towards the wind turbine towers (22) and with anchor legs (25) via chute shoes (7) which are locked to chute beams (6) below the transport to the offshore site, followed by sliding the wind turbine units (37), one by one, to a split bow with an opening (10), for by means of an installation mechanism comprising an installation tower (11) with wire jacks (1), wire bundles ( 2) and strain compensators (5), to lower the wind turbine unit (37) through said opening (10) onto a riser (27), either on pre-installed piles or risers placed on a suction-anchored foundation frame (32) on the seabed on said ste d offshore, so that the tension in the cable bundles (2) and the vertical movement of the wind turbine unit (37) are kept within predetermined limits by means of tension compensators (5) which are directly connected into the cable bundles (2), and as necessary by means of other compensating means under the cable jacks (1), or by hydraulic damping effect built into the risers. 2. Method for moving a number of complete wind turbine units (37), each comprising a tower (22) with a generator attached to a foundation base (34), from a production site to an offshore site using a vessel (9), characterized by using a vessel which is equipped with dynamic positioning or anchor mooring or a combination of these methods, and which is able to hold the bow or stern against wind and waves, where the bow is a split bow with an opening (10) which at the installation site is positioned over pre-installed risers (27) to allow the lowering and landing of the wind turbine unit (37), with the possibility of keeping the bow in position above the risers in weather up to at least 30 degrees on the bow or stern, and with the possibility of subsequent rotation of the windmill unit (37) by approximately 15 degrees during the preparations for the final landing of the wind turbine's foundation undercarriage, where the foundation undercarriage can be different types of undercarriage, such as j acket structures, mono- or multi-pile structures, mono-tower or gravity structures of steel or concrete material, which chassis (34) has wire jacks (1) mounted on top of a series of support tables (36) which allow the jacks (1) to align with the wire bundle direction when the windmill unit (37) with the undercarriage (34) is rotated by means of two trailing winches (12), whereby the vessel is allowed to operate efficiently in two of the four quadrants and somewhat less efficiently in the other two quadrants, depending on the sea and wind direction. 3. Method according to claim 1 or 2, where the vessel is typically a converted vessel, such as a vessel (9) of the Aframax type, which has pontoons integrated into the sides of the vessel, or the vessel can be of any type of wide-hull vessel, such as of the type of barge used or built for the purpose, or any commercial vessel such as a tanker, bulk carrier or other suitable for conversion into a stable installation. 4. Method according to claim 1, 2 or 3, where the foundation substructures are jacket constructions (34), mono- or multi-pile constructions, mono-towers or gravity constructions of steel or concrete material. 5. Method according to any one of the preceding claims, where the underframes are provided with two guide pins (20) which follow two installation guide channels (19) on two of the sides of the installation towers (11), to provide lateral guidance of the jacket (34 ) down to the bottom of the vessel, whereupon by further lowering the undercarriage (34), lateral control of the wind turbine unit is achieved by means of a supporting chute carriage (15) which is connected to an articulated support frame with a clamp (16) around the tower (22), and with at least two steering lines (38) which are suspended and tensioned between two steering line tensioners (21) positioned at the level of the vessel's deck, and with steering line fasteners (29, 31) of external releasable pile grab type or a similar type of fastening device locked to the top of the risers ( 28, 30). 6. Method according to any of the preceding claims, where the installation tower (11) is provided with at least two guide line tensioners (21) which connect two guide lines (38) via funnels (26) on the anchoring legs (25) with guide line fasteners (29, 31) at the top of the risers (28) which are part of pre-installed piles or a suction-anchored frame, to provide fine adjustment of the undercarriage position before landing the anchor legs (25) on the risers. 7. Method according to any one of the preceding claims, where the anchoring legs (25) at the foot of the chassis (34) are provided with integrated hydraulic actuated internal pile grippers (23), a locking mechanism that locks the anchoring legs to the chute shoes (7) during transport so as well as during sliding, and which also locks the anchoring legs (25) to the risers (27) on pre-installed piles or a suction-anchored frame, with subsequent shuddering to provide permanent connections. 8. A method according to any one of the preceding claims, where the risers (27) are constructed as a hydraulic damper which acts when the anchoring legs (25) enter the risers, the anchoring legs being provided with a cone at the end to facilitate entry, also acts like a piston in a cylinder, where the latter is constituted by the riser, and where, by providing suitable throttling of the water flowing out of the risers, a damping effect of the landing shock can be achieved which can be important for the wind turbine generators' shock resistance. 9. Method according to any one of the preceding claims, where an undesired locking effect between the anchoring leg and the spike when entering the first and second spike is avoided by a gradual reduction of the inner diameter of the top of the spikes. 10. Method according to any one of the preceding claims, where the wind turbine unit (37) is removed from the field and returned to the construction site by using a reverse operation of the vessel (9), after the risers (27) have been cut, preferably using underwater diamond wire technique. 11. Method according to any one of the preceding claims, where the installation mechanism comprising cable jacks (1), cable bundles (2) and strain compensators (5) which are directly connected into the lifting string for lowering or lifting the wind turbine unit (37), is replaced by two or more winches and strain compensators (5) with cable sheaves and permanent accumulators, the whole placed on the vessel's deck, and with the cable brought to a lifting point on top of the undercarriage (34) via a sheave suspended from the top of the installation tower, as that the tension in the wire and the vertical movement of the windmill unit (37) are kept within predetermined limits by the tension compensator (5). 12. Method according to any one of the preceding claims, where the installation mechanism consisting of cable jacks (1), cable bundles (2) and strain compensators (5) directly connected into the lifting string for lowering or lifting the wind turbine unit (37) is replaced by two, four or more power cylinders which are vertically supported on the vessel's (9) deck with the rods connected to, and which are controlled by the installation towers and with four or more fixed and parallel hoist lines with one end anchored in the deck and the other end anchored in the top of the jacket and passed over discs suspended in the fields, thereby transferring the thrust from the power cylinders to the upward or downward movement of the jacket and the wind turbine unit (37), nitrogen gas accumulators being connected to the hydraulic system to allow it to work as a compensator, so that the tension in the wire and the vertical movement of the wind turbine unit (37) is kept within predetermined limits by means of the compensator.