Patent Application
20240166477
The invention relates to the field of offshore crane vessels with cranes, for example for use in the handling of one or more offshore wind turbine components, e.g. for installation and/or maintenance of an offshore wind turbine.
In the field of offshore wind turbines, the need exists for the handling very heavy components, like the foundation, e.g. the monopile, which can have a mass of 1000 tons or more. In addition the need exists for the handling of components “at the height of the nacelle”, which includes, for example, the handling of the nacelle itself and/or one or more components that are housed in a nacelle and/or mounted on the nacelle, e.g. a gearbox, an electric generator, the hub, and/or the rotor blades. Current designs propose or already have the nacelle at a height of more than 100 meters above sea level, e.g. at 120 meters or more, for example the Haliade-X 12 MW offshore wind turbine. Therefore, the handling of such components requires a both a very heavy load crane as well as a very tall crane. It is noted that also the mass of the nacelle may be several hundreds of tons, e.g. over 500 tons.
In a common approach, the offshore wind turbine is installed or serviced using a jack-up vessel that is positioned close to the wind turbine location and then the jack-up legs are extended and the vessel is lifted, at least in part but mostly entirely above the sea, to provide a stabilized situation for the crane operation.
It is noted that the invention is primarily envisaged for the field of offshore wind turbines, so for maintenance, and also for installation and/or decommission of wind turbines. However, the inventive crane may also be of use in other offshore applications, like oil & gas related operations, civil engineering operations, etc.
In the field, offshore crane vessels are known comprising a hull, a deck and a crane, the crane comprising:
The handling of one or more offshore wind turbine components, e.g. for installation and/or maintenance of an offshore wind turbine requires a tall crane. That is, the crane will have a long boom so as to have a long reach. A long boom has a length of at least 60 meters, e.g. between 80 and 200 meters. Such a boom protrudes outside a perimeter of the deck of the vessel when the boom is in a horizontally orientation, e.g. in a boom storage position, e.g. during transit.
The volume and weight of the protruding boom and main hoist block assembly has several disadvantages. A known solution is to provide a telescopic boom as disclosed in WO 2020/244973 of same applicant.
It is an object of a first aspect of the invention to provide an alternative offshore vessel crane.
According to the first aspect of the invention the offshore crane vessel is characterised in that the head structure is a travelling head structure which is slidable along a part of the boom from the tip end to a second position on the boom and wherein in the horizontal rest position of the boom and in the second position of the travelling head structure the main hoist block assembly is positioned above the deck of the vessel.
An advantage of the retracted travelling head structure in the second position is that the weight of the travelling head structure and main hoist block assembly is provided above deck, preferably in the vicinity of the boom rest. This prevents fatigue and/or boom bending, in particular during sailing. The retractability allows to select an advantageous distribution of weight on the vessel, by selecting a desired position of the of centre of gravity of main block.
Another advantage of the sliding of the weight is that oscillation of the boom during sailing can be prevented, as the natural frequency of the boom can be tuned.
Another advantage of the main block hoist assembly at the second position, above deck, is the accessibility of the travelling head structure and main block hoist assembly for inspection, maintenance and greasing.
Yet another advantage of the retraction of the travelling head structure and main block hoist assembly is that there is more clearance to the waves during sailing. The boom in the horizontal rest position is usually positioned 20-35 meters above sea level. By removing the volume of the travelling head structure and the main hoist block assembly and possibly a main load suspension device suspended therefrom, this 25-35 meters between sea level and the boom is free space, providing a clearance for waves.
Yet another advantage of the retraction of the travelling head structure and main block hoist assembly is that there is more clearance in harbours. As indicated above, the boom in the horizontal rest position is usually positioned 20-35 meters above sea level, which is commonly no problem above a cay. However, the volume of the main hoist block assembly closer to the waterline is often problematic. By removing the volume of the travelling head structure and the main hoist block assembly, and possibly a main load suspension device suspended therefrom, the space between waterline and boom is free space, providing a clearance for docking the vessel in a harbour.
In a method according to the invention, the offshore crane vessel of the first aspect of the invention is brought to a rest position having the above-indicated advantages. Such a method comprises the steps of:
In embodiments, in this rest position the main hoist block assembly is supported in a main hoist block assembly support. Possibly, the travelling head structure is also fixed to the boom at the second position.
The slidable travelling head structure, and a boom allowing the sliding of the travelling head structure therealong can be of a relatively simple construction. The boom needs to be strong enough to support the travelling head structure and allow the sliding thereof. Hence, a reinforced structure may be desired. However, the boom does not need to be hollow as e.g. required for telescopic boom sections. It is envisaged that cords of the boom function as rails for the travelling head structure. In particular when the sliding takes place in a horizontal position of the boom there additional forces on the boom during sliding are limited and do not require major modifications of the boom structure.
The offshore crane vessel of the invention can be a monohull or multihull vessel, a jack-up vessel or even a barge. It comprises a hull with a deck. A pedestal of the crane is mounted to, or formed integral with the hull of the vessel. For a jack-up vessel, it is conceivable that the pedestal is formed around a leg of the jack-up vessel to form a so-called ‘around the leg crane’.
A superstructure is rotationally supported by the pedestal for rotation of the superstructure relative to the pedestal about a vertical slew axis. The superstructure comprises a boom connection member.
A crane boom is provided having a longitudinal axis and a length of 60-200 meters between a pivot end and a tip end. The pivot end is connected to the boom connection member on the superstructure so that the boom is pivotable up and down about a horizontal boom pivot axis. The length of the boom is such that in a horizontal rest position the tip end protrudes outside a perimeter of the hull of the vessel. Possibly, the boom extends significantly outside the perimeter, e.g. more than 5 meters, e.g. more than 10 meters.
The vessel is provided with a boom rest to support the boom in a horizontal rest position, e.g. when the crane is not in use, such as during transit and in harbours. The horizontal rest position is essentially horizontal, and may in practical embodiments deviate 1-15 degrees.
The type of crane of the invention comprises a boom luffing assembly for pivoting the boom about the horizontal boom pivot axis. The boom luffing assembly comprises a boom luffing winch and an elongated luffing member extending to the tip end of the boom. The elongated luffing member comprises a luffing cable extending from the winch and preferably via a luffing cable guide provided at the superstructure.
A main hoisting device is provided for hoisting a load. The main hoisting device comprises a main hoisting winch, at least one associated main hoisting cable, a main hoist block assembly supported by a head structure. The main hoisting cable extends from the main hoisting winch to the main hoist block assembly. The main hoist block assembly comprises a number of sheaves for the hoisting cable. A main load suspension device is preferably suspended from the main block hoist assembly.
According to the present invention the head structure is a travelling head structure which is slidable along a part of the boom from the tip end to a second position on the boom. In the horizontal rest position of the boom and in the second position of the travelling head structure the main hoist block assembly is positioned above the deck of the vessel.
The travelling head structure is e.g. embodied such that it encompasses the boom entirely, as a box. It is also conceivable that the travelling head structure has an U-shape, extending over the bottom part and (part of) the sides of the boom.
In embodiments, a main hoist block assembly support is provided on the deck of the vessel, adapted to support the weight of the main hoist block assembly and possibly also the weight of the travelling head structure. Advantageously, the main hoist block assembly support is provided in line with the pedestal and the boom rest. It is also conceivable that the main hoist block assembly support is formed integral with the boom rest. In the horizontal rest position of the boom and in the second position of the main hoist block assembly the main hoist block assembly is aligned with the main hoist block assembly support. The alignment allows the main hoist block assembly support to, in the rest position of the boom, support the weight of the travelling head structure, and possibly that of the main hoist block assembly.
Advantageously, the main hoist block assembly support allows and simplifies installation and maintenance of the main hoist block assembly, and possibly also alterations of the block and/or cable configuration in the main hoist block assembly.
In embodiments, a head drive is provided to slide the travelling head structure along the boom. Such a head drive e.g. comprising a head winch and a head cable extending between the head winch and the travelling head structure. Such a drive system is e.g. known as a tugger winch and tugger cable. Alternative system, e.g. hydraulic systems or comprising a rack and pinion construction are also conceivable.
In embodiments, the travelling head structure is detachably fixable to the boom at the tip end of the boom and preferably also at the second position of the travelling head structure. This allows the travelling head structure to be fixed to the boom at the tip end thereof during hoisting operations, and detached to allow sliding thereof. Possibly a fastening mechanism is applied that can travel with the travelling head structure to the second position, to fix the travelling head structure to the boom at the second position.
In embodiments, a jib with an auxiliary hoist block is connected to the travelling head structure and slidable with the travelling head structure along the boom. Such an auxiliary hoist block is often present, and thus also protrudes outside the perimeter of the hull of the vessel. The retraction of this jib and auxiliary hoist block, together with the head structure, to a proximal position attributes to the above-indicated advantages of the invention, including an increased clearance and improved weight distribution. It is envisaged that the jib is configured as disclosed in WO2020225157.
In embodiments, the main hoist block assembly is pivotably supported by the travelling head structure about a horizontal pivot structure. This may be advantageous during hoisting operations. In addition, this may be advantageous when the main hoist block assembly in the second position of the travelling head structure. When pivoted to a horizontal position the distance to the deck may be increased in embodiments, thereby attributing to a clear deck space.
In embodiments, the second position on the boom is at a distance from the pivot end of 50-90% of the length of the boom. Most important is that in the second position of the travelling head structure the main hoist block assembly is positioned above the deck of the vessel. However, further weight-related advantages are achieved when the second position more remote from the pivot end. As elucidated later on, further advantages relating to the luffing of the boom are also conceivable, wherein the second position is more proximal than necessary to be above deck.
In embodiments, the boom is embodied as a hollow box structure, preferably a latticed hollow box structure. A possible advantageous configuration of the same applicant is disclosed in WO 2018/208158. It is known to provide a boom having a single leg embodied as a latticed hollow box structure. A known alternative is a A-frame booms which has generally the shape of an A with two boom legs connected, each embodied as a latticed hollow box structure.
Another known example, is a twin leg boom with two parallel legs, each embodied as a latticed hollow box structure, wherein the legs are interconnected by multiple cross members, distributed over the length thereof, interconnecting the boom legs.
In embodiments, a boom portion between the second position of the travelling head structure and the tip end is detachable and can preferably be parked on deck of the vessel. Preferably this is an end portion of the boom. When detaching this end portion from the boom, it is possible that in the horizontal rest position the boom no longer protrudes outside the perimeter of the hull of the vessel.
According to the invention, a boom luffing assembly is provided for pivoting the boom about the horizontal boom pivot axis. The boom luffing assembly comprises a boom winch and an elongated luffing member extending to the boom. The boom luffing assembly advantageously also comprises a luffing cable extending from the boom luffing winch.
Many of the above-indicated advantages are achieved with the elongated boom luffing member extending to the tip end of the boom.
In advantageous embodiments, the elongated luffing member can also engage the boom at a second luffing position opposite the main hoist block assembly at the second position of the travelling head structure. This allows a transfer of the load of the travelling head structure with the main hoist block assembly to the boom luffing assembly. Such a configuration with the luffing member opposite the travelling head structure is advantageous for luffing the boom out of its essentially horizontal rest position. In particular with very long booms with a heavy travelling head structure and main hoist block assembly at a tip end thereof, luffing causes high bucking loads on the boom. Hence, it is advantageous to be able to luff the boom out of the rest position while the travelling head structure and main hoist block assembly are at the second proximal position. Once sufficiently luffed, the travelling head structure and main hoist block assembly are slided along the boom to the tip end thereof.
When luffing at the second luffing position opposite the main hoist block assembly at the second position of the travelling head structure is desired, advantageously the boom is reinforced at this location to allow a transfer of the load of the travelling head structure with the main hoist block assembly to the boom luffing assembly.
In embodiments, the elongated luffing member is connected to the travelling head structure, and is slidable with the travelling head structure along the boom. In such embodiments, the travelling head structure may allow for the transfer of loads. In alternative embodiments, the elongated luffing member comprises an end part fixed to the tip end of the boom, and an auxiliary structure attachable to the boom at a second luffing position opposite the main hoist block assembly at the second position of the travelling head structure. Yet alternatively, an end part of the elongated luffing member is detachable from the boom, and can be attached to the boom at the tip end and at a second luffing position opposite the main hoist block assembly at the second position of the travelling head structure. Optionally, this end part is slidable along the boom.
The travelling head structure has the above-indicated advantages of displacing volume and weight of the head structure and main block hoist assembly.
In addition, the travelling head structure enables inventive methods of operation of such an offshore crane vessel.
In embodiments, the crane can subsequently be brought to an alternative operational position, wherein the method further comprises the steps of:
Such an operation a.o. involves the pivoting of the boom by the boom luffing assembly away from the horizontal rest position.
In a method according to the invention, the crane is brought to an alternative operational position, wherein the method comprises the steps of:
This alternative operational position is in particular advantageous for very long booms, wherein luffing with the elongated luffing member extending to the tip end of the boom is difficult.
In embodiments of the invention the elongated luffing member in the second position of the travelling head structure has slided with the travelling head structure to a position closer to the pivot end of the boom. In alternative embodiments, the elongated luffing member comprises an auxiliary structure attachable to the boom at a second luffing position opposite the second position of the travelling head structure. In both situations, the elongated luffing member engages at a position closer to the pivot end of the boom, which is highly advantageous for upending an elongated boom.
It is conceivable that after initial upending out of the horizontal rest position, the method comprises the following steps:
With the travelling head structure at the tip end further hoisting operations are possible.
In embodiments, the luffing member travels to the tip end with the travelling head structure. In alternative embodiments, the auxiliary structure of the elongated luffing member is detached from the boom at the second luffing position.
In embodiments, it is conceivable that the crane is brought to an alternative operational position with the boom at an upward pivoted, non-horizontal position of the boom, possibly wherein the boom is supported by a boom stop. Hence, the steps of detaching and sliding the travelling head structure are carried out with the boom out of the rest position.
A second aspect of the invention relates to a crane, preferably a crane on an offshore crane vessel, comprising:
A disadvantage of very long booms with a heavy travelling head structure and main hoist block assembly at a tip end thereof is that luffing causes high bucking loads on the boom. In particular when luffing a boom out of its essentially horizontal rest position this is disadvantageous.
It is an aim of the second aspect of the invention to provide an alternative crane.
According to the second aspect of the invention this is achieved in that the head structure is a travelling head structure which is slidable along a part of the boom from the tip end to a second position on the boom, and in that the elongated luffing member can engage the boom at a tip end and at a second luffing position opposite the main hoist block assembly at the second position of the travelling head structure.
This allows a transfer of the load of the travelling head structure with the main hoist block assembly to the boom luffing assembly. Such a configuration with the luffing member opposite the travelling head structure is advantageous for luffing the boom out of its essentially horizontal rest position. In particular with very long booms with a heavy travelling head structure and main hoist block assembly at a tip end thereof, luffing causes high bucking loads on the boom. Hence, it is advantageous to be able to luff the boom out of the rest position while the travelling head structure and main hoist block assembly are at the second proximal position. Once sufficiently luffed, the travelling head structure and main hoist block assembly are slided along the boom to the tip end thereof.
When luffing at the second luffing position opposite the main hoist block assembly at the second position of the travelling head structure is desired, advantageously the boom is reinforced at this location to allow a transfer of the load of the travelling head structure with the main hoist block assembly to the boom luffing assembly.
In embodiments, the elongated luffing member is connected to the travelling head structure, and is slidable with the travelling head structure along the boom. In such embodiments, the travelling head structure may allow for the transfer of loads. In alternative embodiments, the elongated luffing member comprises an end part fixed to the tip end of the boom, and an auxiliary structure attachable to the boom at a second luffing position opposite the main hoist block assembly at the second position of the travelling head structure. Yet alternatively, an end part of the elongated luffing member is detachable from the boom, and can be attached to the boom at the tip end and at a second luffing position opposite the main hoist block assembly at the second position of the travelling head structure. Optionally, this end part is slidable along the boom.
The second aspect of the invention also relates to a method wherein the crane is brought to an alternative operational position, wherein the method comprises the steps of:
This alternative operational position is in particular advantageous for very long booms, wherein luffing with the elongated luffing member extending to the tip end of the boom is difficult.
In embodiments of the invention the elongated luffing member in the second position of the travelling head structure has slided with the travelling head structure to a proximal position closer to the pivot end of the boom. In alternative embodiments, the elongated luffing member comprises an auxiliary structure attachable to the boom at a second luffing position opposite the second position of the travelling head structure. In both situations, the elongated luffing member engages at a position closer to the pivot end of the boom, which is highly advantageous for upending an elongated boom.
It is conceivable that after initial upending out of the horizontal rest position, the method comprises the following steps:
With the travelling head structure at the tip end further hoisting operations are possible.
In embodiments, the luffing member travels to the tip end with the travelling head structure. In alternative embodiments, the auxiliary structure of the elongated luffing member is detached from the boom at the second luffing position.
In embodiments, it is conceivable that the crane is brought to an alternative operational position with the boom at an upward pivoted, non-horizontal position of the boom, possibly wherein the boom is supported by a boom stop.
The invention will now be described with reference to the figures, in which like reference symbols designate like parts. In these figures:
In
The boom 50 of
The head structure 60 shown in
In
The position of the boom 50 in
The boom 50 is shown to be embodied as a latticed hollow box structure. It is noted that this is not essential to the invention.
In
In a method according to the invention, the crane 10 is brought to an alternative operational position. This can e.g. be done from the position as shown in
Possibly the steps mentioned above are carried out with the boom at an upward pivoted, non-horizontal position of the boom as shown in
It can be seen in
Furthermore, the crane can be brought to an alternative operational position. Then the method described above may further comprise the steps of
In
The head structure 160 of
In
The main hoist block assembly being pivotably supported as described for
In
The auxiliary hoist block can also be pivotable, this is shown in
In
In
| Number | Date | Country | Kind |
|---|---|---|---|
| 2027839 | Mar 2021 | NL | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/057219 | 3/18/2022 | WO |
